| 1. |
- Holmberg, Hans-Christer, et al.
(författare)
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Reliability and validity of a new double poling ergometer for cross-country skiers
- 2008
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Ingår i: Journal of Sports Sciences. - : Informa UK Limited. - 0264-0414 .- 1466-447X. ; 26:2, s. 171-179
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Tidskriftsartikel (refereegranskat)abstract
- Thirty-eight competitive cross-country skiers were divided into three groups to assess the reliability and validity of a new double poling ergometer. Group A (n = 22) performed two maximal 60-s tests, Group B (n = 8) repeated peak oxygen uptake tests on the double poling ergometer, and Group C (n = 8) performed a maximal 6-min test on the double poling ergometer and a double poling time-trial on snow. The correlation between the power calculated at the flywheel and the power applied at the base of the poles was r = 0.99 (P < 0.05). The power at the poles was 50 - 70% higher than that at the flywheel. There was a high test - retest reliability in the two 60-s power output tests (coefficient of variation = 3.0%) and no significant difference in peak oxygen uptake in the two 6-min all-out tests (coefficient of variation = 2.4%). There was a strong correlation between the absolute (W) and relative power (W . kg(-1)) output in the 6-min double poling ergometer test and the double poling performance on snow (r = 0.86 and 0.89 respectively; both P < 0.05). In conclusion, our results show that the double poling ergometer has both high reliability and validity. However, the power calculated at the flywheel underestimated the total power produced and needs to be corrected for in ergonomic estimations.
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| 2. |
- Karlsen, Jon, et al.
(författare)
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The stroke has only a minor influence on direction consistency in golf putting among elite players.
- 2008
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Ingår i: Journal of Sports Sciences. - : Informa UK Limited. - 0264-0414 .- 1466-447X. ; 26:3, s. 243-50
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Tidskriftsartikel (refereegranskat)abstract
- In the golf instructional literature, the putting stroke is typically given higher priority than green reading and aiming. The main purpose of this study was to assess the importance of the putting stroke for direction consistency in golf putting. Kinematic stroke parameters were recorded from 71 elite golf players (mean handicap = 1.8, s = 4.2) on 1301 putts from about 4 m. Of the different factors deciding stroke direction consistency, face angle was found to be the most important (80%), followed by putter path (17%) and impact point (3%). This suggests that improvements in consistency of putter path and impact point will have very little effect on overall putting direction consistency and should not be prioritized in the training of elite players. In addition, mean stroke direction variability for an elite player (European Tour) was found to be 0.39 degrees, which is good enough to hole about 95% of all 4-m putts. In practice, however, top professionals in tournaments only hole about 17% of 4-m putts. We conclude that the putting stroke of elite golfers has a relatively minor influence on direction consistency.
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| 3. |
- Lundqvist, Carolina, et al.
(författare)
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Competitive State Anxiety Inventory-2 : Evaluating the Swedish version by confirmatory factor analyses
- 2005
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Ingår i: Journal of Sports Sciences. - : Informa UK Limited. - 0264-0414 .- 1466-447X. ; 23:7, s. 727-736
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Tidskriftsartikel (refereegranskat)abstract
- The Competitive State Anxiety Inventory-2 (CSAI-2) is one of the most frequently used instruments when assessing competitive state anxiety in sport psychology research. However, doubts have been expressed about the factorial validity of both the English and the Greek versions of the scale. Hence, a revised version of the inventory (CSAI-2R) has recently been suggested to be more psychometrically sound (Cox et al., 2003). In the present study, the aim was to evaluate the psychometric properties of the Swedish version of the CSAI-2 using confirmatory factor analyses. A total of 969 athletes (571 men and 398 women) competing in 26 different sports completed the Swedish version of the CSAI-2. Three different factor structures were evaluated: the original three-factor model (with cognitive anxiety, somatic anxiety and self-confidence), a two-factor model in which self-confidence was excluded, and a three-factor model containing 17 items (CSAI-2R). The results revealed that only the 17-item model displayed an acceptable fit to the data. Although some doubts remain about the amount of variance that can be attributed to error variance in the subscales, the results suggest that it is better to use the CSAI-2R rather than the original CSAI-2.
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| 4. |
- Nilsson, Johnny, et al.
(författare)
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A new device for evaluating distance and directional performance of golf putters.
- 2006
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Ingår i: Journal of Sports Sciences. - : Informa UK Limited. - 0264-0414 .- 1466-447X. ; 24:2, s. 143-7
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was to construct and evaluate the reliability of an apparatus for testing golf putters with respect to distance and direction deviation at different impact points on the clubface. An apparatus was constructed based on the pendulum principle that allowed putter golf clubs to swing at different speeds. The mean speed of the club head before ball impact, and of the ball after impact, was calculated from time measurements with photocells. A pin profile rig was used to determine the directional deviation of the golf ball. Three different putters were used in the study, two that are commercially available (toe-heel weighted and mallet types) and one specially made (wing-type) putter. The points of impact were the sweet spot (as indicated by the manufacturer's aim line), and 1, 2 and 3 cm to the left and right of the sweet spot. Calculation of club head speed before impact, and of ball speed after impact (proportional to distance), showed errors < or = 0.5% of interval duration. The variability in ball impacts was tested by measuring time and direction deviations during 50 impacts on the same ball. The mean duration (+/- s) after ball impact in the test interval (1.16 m long) was 206 (0.8) ms and the standard deviation in the perpendicular spreading of the balls in relation to the direction of the test interval was 0.005 m. A test-retest of one putter on two consecutive days after remounting of the putter on the test apparatus showed less than 1% difference in distance deviation. We conclude that the test apparatus enables a precise recording of distance and direction deviation in golf putters as well as comparisons between different putters. The apparatus and set-up can be used in the laboratory as well as outdoors on the putting green.
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| 5. |
- Nilsson, Johnny, et al.
(författare)
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Knee angular displacement and extensor muscle activity in telemark skiing and in ski-specific strength exercises.
- 2004
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Ingår i: Journal of Sports Sciences. - 0264-0414 .- 1466-447X. ; 22:4, s. 357-64
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Tidskriftsartikel (refereegranskat)abstract
- Much of the training of competitive telemark skiers is performed as dry-land exercises. The specificity of these exercises is important for optimizing the training effect. Our aim here was to study the activation of the knee extensor musculature and knee angular displacement during competitive telemark skiing and during dry-land strength training exercises to determine the specificity of the latter. Specificity was analysed with respect to angular amplitude, angular velocity, muscle action and electromyographic (EMG) activity. Five male telemark skiers of national and international standard volunteered to participate in the study, which consisted of two parts: (1) skiing a telemark ski course and (2) specific dry-land strength training exercises for telemark skiing (telemark jumps and barbell squats). The angular displacement of the right knee joint was recorded with an electrogoniometer. A tape pressure sensor was used to measure pressure between the sole of the foot and the bottom of the right ski boot. Electromyographic activity in the right vastus lateralis was recorded with surface electrodes. The EMG activity recorded during maximum countermovement jumps was used to normalize the EMG activity during telemark skiing, telemark jumps and barbell squats. The results showed that knee angular displacement during telemark skiing and dry-land telemark jumps had four distinct phases: a flexion (F1) and extension (E1) phase during the thrust phase of the outside ski/leg in the turn/jump and a flexion (F2) and extension (E2) phase when the leg was on the inside of the turn/jump. The vastus lateralis muscle was activated during F1 and E1 in the thrust phase during telemark skiing and telemark jumps. The overall net knee angular amplitude was significantly greater (P < 0.05) for telemark jumps than for telemark skiing. Barbell squats showed a knee angular amplitude significantly greater than that in telemark skiing (P < 0.05). The mean knee angular velocity of the F1 and E1 phases during telemark skiing was about 0.47 rad x s(-1); during barbell squats, it was about 1.22 rad x s(-1). The angular velocity during telemark jumps was 2.34 and 1.59 rad x s(-1) in the F1 and E1 phase, respectively. The normalized activation level of the EMG bursts during telemark skiing, telemark jumps and barbell squats was 70-80%. In conclusion, the muscle action and level of activation in the vastus lateralis during the F1 and E1 phases were similar during telemark skiing and dry-land exercises. However, the dry-land exercises showed a larger knee extension and flexion amplitude and angular velocity compared with telemark skiing. It appears that an adjustment of knee angular velocity during barbell squats and an adjustment of knee angle amplitude during both telemark jumps and barbell squats will improve specificity during training.
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| 6. |
- Nilsson, Johnny, et al.
(författare)
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Work-time profile, blood lactate concentration and rating of perceived exertion in the 1998 Greco-Roman Wrestling World Championship.
- 2002
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Ingår i: Journal of Sports Sciences. - : Informa UK Limited. - 0264-0414 .- 1466-447X. ; 20:11, s. 939-45
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to examine work-time profiles, blood lactate concentrations and perceived exertion among Greco-Roman wrestlers in the 1998 World Championship. Forty-two senior wrestlers from nine nations were studied in 94 matches. Each match was recorded with a video camera (Panasonic AG 455, film rate: 25 Hz) and analysed for duration of work (wrestling) and rest (interrupt) periods. Blood lactate concentration was determined with an electrochemical device (Analox P-LM5) and a rating of perceived exertion scale (Borg) was used to estimate general exertion and exertion in the extremity and trunk muscles. The mean duration of the matches was 427 s (range 324-535 s), with mean durations of work and rest of 317 and 110 s, respectively. The mean periods of work and rest were 37.2 and 13.8 s, respectively. Mean blood lactate concentration was 14.8 mmol x 1(-1) (range 6.9-20.6). The difference in mean blood lactate concentration between the first- and final-round matches was not significant (P > 0.05). Blood lactate concentration was significantly higher (P < 0.04) in matches of long duration than in those of short duration. The mean general rating of perceived exertion for all matches was 13.8 according to the scale used. Most of the wrestlers (53.3%) perceived exertion to be highest in the flexors of the forearm, followed by the deltoids (17.4%) and the biceps brachii muscles (12.0%). In addition to a relatively high rating of perceived exertion in the arm muscles, this indicates a high specific load on the flexor muscles of the forearm.
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| 7. |
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| 8. |
- Andersson, Helena M, et al.
(författare)
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Elite football on artificial turf versus natural grass : movement patterns, technical standards, and player impressions
- 2008
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Ingår i: Journal of Sports Sciences. - : Informa UK Limited. - 0264-0414 .- 1466-447X. ; 26:2, s. 113-22
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the present study was to examine the movement patterns, ball skills, and the impressions of Swedish elite football players during competitive games on artificial turf and natural grass. Time - motion analyses (36 observations) and technical analyses (16 team observations) were performed and 72 male and 21 female players completed a questionnaire. No differences were observed between artificial turf and natural grass in terms of total distance covered (mean 10.19 km, s = 0.19 vs. 10.33 km, s = 0.23), high-intensity running (1.86 km, s = 0.10 vs. 1.87 km, s = 0.14), number of sprints (21, s = 1 vs. 22, s = 2), standing tackles (10, s = 1 vs. 11, s = 1) or headers per game (8, s = 1 vs. 8, s = 1), whereas there were fewer sliding tackles (P < 0.05) on artificial turf than natural grass (2.1, s = 0.5 vs. 4.3, s = 0.6). There were more short passes (218, s = 14 vs. 167, s = 12) and midfield-to-midfield passes (148, s = 11 vs. 107, s = 8) (both P < 0.05) on artificial turf than natural grass. On a scale of 0-10, where 0 = "better than", 5 = "equal to", and 10 = "worse than", the male players reported a negative overall impression (8.3, s = 0.2), poorer ball control (7.3, s = 0.3), and greater physical effort (7.2, s = 0.2) on artificial turf than natural grass. In conclusion, the running activities and technical standard were similar during games on artificial turf and natural grass. However, fewer sliding tackles and more short passes were performed during games on artificial turf. The observed change in playing style could partly explain the male players' negative impression of artificial turf.
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| 9. |
- Andersson, Mitchell, et al.
(författare)
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Symptoms of depression and anxiety among elite high school student-athletes in Sweden during the COVID-19 pandemic : A repeated cross-sectional study
- 2023
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Ingår i: Journal of Sports Sciences. - : Taylor & Francis. - 0264-0414 .- 1466-447X. ; 41:9, s. 874-883
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Tidskriftsartikel (refereegranskat)abstract
- The COVID-19 pandemic precipitated numerous changes in daily life, including the cancellation and restriction of sports globally. Because sports participation contributes positively to the development of student-athletes, restricting these activities may have led to long-term mental health changes in this population. Using a repeated cross-sectional study design, we measured rates of depression using the Patient Health Questionnaire-2 and anxiety using the Generalized Anxiety Disorder-2 scale in student-athletes attending elite sport high schools in Sweden during the second wave of the pandemic (February 2021; n = 7021) and after all restrictions were lifted (February 2022; n = 6228). Depression among student-athletes decreased from 19.8% in 2021 to 17.8% in 2022 (p = .008, V = .026), while anxiety screening did not change significantly (17.4% to 18.4%, p > .05). Comparisons between classes across years revealed older students exhibited decreases in depressive symptoms, while younger cohorts experienced increases in symptoms of anxiety from 2021 to 2022. Logistic regressions revealed that being female, reporting poorer mental health due to COVID-19, and excessive worry over one’s career in sports were significant predictors of both depression and anxiety screenings in 2022. Compared to times when sports participation was limited, the lifting of restrictions was associated with overall reduced levels of depression, but not anxiety.
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| 10. |
- Aujla, Imogen J, et al.
(författare)
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Multidisciplinary predictors of adherence to contemporary dance training : findings from the UK Centres for Advanced Training.
- 2015
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Ingår i: Journal of Sports Sciences. - : Informa UK Limited. - 0264-0414 .- 1466-447X. ; 33:15, s. 1564-73
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Tidskriftsartikel (refereegranskat)abstract
- Little is known about the predictors of adherence in a dance context. The aim of this study was to investigate adherence to a dance talent programme using a multidisciplinary set of variables representing psychological correlates of adherence, maturation and physical factors relating to dance talent. Psychological (passion, motivational climate perceptions, eating attitudes), physical competence (vertical jump height, handgrip strength, hamstring flexibility, external hip rotation, aerobic fitness), and maturation-related (age of menarche) variables were gathered from female students enrolled on a dance talent programme. Participation behaviour (adherence/dropout) was collected from the talent programme's records approximately two years later. Logistic regression analysis of 287 participants revealed that greater levels of harmonious passion predicted greater likelihood of adherence to the programme, and greater ego-involving motivational climate perceptions predicted less likelihood of adherence. Neither measures of physical competence nor maturation distinguished adhering from dropout participants. Overall, the results of this study indicate that psychological factors are more important than physical competence and maturation in the participation behaviour of young talented dancers.
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| 11. |
- Battochio, Randy C., et al.
(författare)
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Stages and demands in the careers of Canadian National Hockey League players
- 2015
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Ingår i: Journal of Sports Sciences. - Abingdon, Oxon : Routledge. - 0264-0414 .- 1466-447X. ; 34:3, s. 278-288
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Tidskriftsartikel (refereegranskat)abstract
- Researchers have identified some demands of Canadian National Hockey League (NHL) players, yet there is little direction for players hoping to reach the lucrative league. The objectives of this study were to identify the stages, statuses and demands in Canadian NHL players’ careers and propose an empirical career model of Canadian NHL players. In total, 5 rookies, 5 veterans and 13 retirees had their interviews undergo an interpretive thematic analysis. Prospects face the NHL combine, training camp and minor league assignment. While developing into NHL players, rookies deal with NHL call-ups, team competition and formative production while sophomores seemed preoccupied by the opposition. Prime veterans become All-Stars by garnering point production and challenging for the Stanley Cup while seasoned veterans remain relevant through training camps. A discussion about the model’s viability is followed by applications for sport psychology researchers and practitioners. © 2015 Taylor & Francis
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| 12. |
- Beaven, Christopher, 1977-
(författare)
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Effects of a short-term pre-season training programme on the body composition and anaerobic performance of professional rugby union players
- 2010
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Ingår i: Journal of Sports Sciences. - 0264-0414 .- 1466-447X. ; 28:6, s. 679-686
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Tidskriftsartikel (refereegranskat)abstract
- Pre-season rugby training develops the physical requisites for competition and consists of a high volume of resistance training and anaerobic and aerobic conditioning.However, the effects of a rugby union pre-season in professional athletes are currently unknown.Therefore, the purpose of this investigation was to determine the effects of a 4-week pre-season on 33 professional rugby union players.Bench press and box squat increased moderately (13.6 kg, 90% confidence limits+2.9 kg and 17.6+8.0 kg, respectively) over the training phase.Small decreases in bench throw (70.6+53.5 W), jump squat (280.1+232.4 W), and fat mass (1.4+0.4 kg) were observed.In addition, small increases were seen in fat-free mass (2.0+0.6 kg) and flexed upper-arm girth (0.6+0.2 cm), while moderate increases were observed in mid-thigh girth (1.9+0.5 cm) and perception of fatigue (0.6+0.4 units).Increases in strength and body composition were observed in elite rugby union players after 4 weeks of intensive pre-season training, but this may have been the result of a return to fitness levels prior to the off-season.Decreases in power may reflect high training volumes and increases in perceived of fatigue.
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| 13. |
- Björklund, Glenn, 1972-, et al.
(författare)
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The balancing act between skiing and shooting – the determinants of success in biathlon pursuit and mass start events
- 2022
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Ingår i: Journal of Sports Sciences. - : Informa UK Limited. - 0264-0414 .- 1466-447X. ; 40:1, s. 96-103
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Tidskriftsartikel (refereegranskat)abstract
- This study aimed to investigate how skiing speed (SS), number of missed targets (MT) and range time (RT) were associated with final rank in biathlon pursuit and mass start competitions. Data were collected from the International Biathlon Union’s database over 17 seasons. Biathletes were categorised into three groups (rank 1–3, G3; rank 4–10, G10; rank 11–20, G20). Multinomial regression was used to identify odds ratios associated with group rank in both sexes. The only variable found to be consistently related to G3 in both pursuit and mass start was MT (men OR 1.206–1.729 and women OR 1.340–3.124, all p < 0.01). SS during lap four of pursuit and mass start was most strongly related to G3 for both sexes (men OR 0.231–0.094 and women OR 0.339–0.126, all p < 0.001). RT during shooting four in pursuit was most strongly related to G3 compared to G10 and G20 (men OR 1.067; 95% CI, 1.030–1.105 and women OR 1.076; 95% CI, 1.020–1.134, all p < 0.001, respectively). Accordingly, MT was most strongly related to final rank in both sexes, while SS during lap four and last RT was also significant.
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| 14. |
- Byrkjedal, Per Thomas, et al.
(författare)
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In-season autoregulation of one weekly strength training session maintains physical and external load match performance in professional male football players
- 2023
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Ingår i: Journal of Sports Sciences. - : Routledge. - 0264-0414 .- 1466-447X. ; 41:6, s. 536-546
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to compare the effects of autoregulating strength training volume based on an objective (external load match performance) versus a subjective (self-selected) method in professional male football players. Sixteen players completed a 10-week strength training programme where the number of sets was regulated based on football match high-intensity running distance (HIR >19.8 km/h, AUTO, n = 7), or self-selected (SELF, n = 9). In addition to traditional physical performance assessments (30-m sprint, countermovement jump, leg-strength, and body composition), external load match performance was assessed with five matches in the beginning and in the end of the study period. Both groups performed ~ 1 weekly bout of ~ 6 sets in leg extensor exercises during the 10-week period, and maintained physical performance during the competitive season, with no group differences detected after the training period. Non-overlap of all pairs (NAP) analysis showed weak-to-moderate effects in external load match performance from before to after the study period, suggesting that players maintained or improved their performance. In conclusion, no group differences were observed, suggesting that both external load autoregulated and self-selected, low-volume in-season strength training maintained physical, and external load match performance in professional male football players. © 2023 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.
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| 15. |
- Cadenas-Sanchez, Cristina, et al.
(författare)
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Fitness, physical activity and academic achievement in overweight/obese children
- 2020
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Ingår i: Journal of Sports Sciences. - : TAYLOR & FRANCIS LTD. - 0264-0414 .- 1466-447X. ; 38:7, s. 731-740
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to examine the associations of fitness and physical activity with academic achievement in children with overweight/obesity. A total of 106 (10.0 +/- 1.1y, 61 boys) children participated. The fitness components were assessed by field and laboratory-based tests. Physical activity was measured via accelerometry. The academic achievement was assessed by a standardised test and school-grades. Field-based cardiorespiratory fitness was associated with language skills (ss-standardised- ranging from 0.281 to 0.365, p amp;lt; 0.01). The field-based muscular strength was associated with grade point average, natural and social sciences, and foreign language (ss = 0.280-0.326, all p amp;lt;= 0.01). Speed-agility was associated with some language-related skills (ss = 0.325-0.393, all p amp;lt;= 0.01). The laboratory-based muscular strength also showed an association with mathematics skills (ss = 0.251-0.306, all p amp;lt;= 0.01). Physical activity did not show significant association with academic achievement (p amp;gt; 0.01). Overall, the significant associations observed for muscular strength and speed/agility were attenuated and disappeared in many cases after additional adjustments for body mass index and cardiorespiratory fitness, indicating that these associations are inter-dependent. Our study contributes by indicating that other fitness components apart from cardiorespiratory fitness, such as muscular strength and speed-agility, are positively associated with academic achievement. However, these associations appear to be dependent on body mass index and cardiorespiratory fitness.
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| 16. |
- Cardinale, Daniele A., 1982-, et al.
(författare)
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Hyperoxia for performance and training.
- 2018
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Ingår i: Journal of Sports Sciences. - : Informa UK Limited. - 0264-0414 .- 1466-447X. ; :13, s. 1515-1522
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Tidskriftsartikel (refereegranskat)abstract
- Recent technological developments have made it possible to use hyperoxia as an enhancement aid during training. Athletes wearing a mask can breathe a higher fraction of oxygen from a stationary or portable apparatus while exercising. A large body of evidence indicates that the oxygen transport capacity, lactate metabolism, power output and work tolerance (endurance) are improved when breathing hyperoxia. The physiological mechanisms underlying these performance improvements, although still not fully elucidated, are based on higher oxygen delivery and reduced central fatigue. Although much is known about the acute effects of hyperoxia, the effect of hyperoxic-supplemented endurance training on performance and the mechanisms beneath training adaptations are not very well understood, especially in well-trained endurance athletes. The few studies on the physiological effects of hyperoxia training have been conducted with conflicting results, discussed in this paper. Potential detrimental effects have not yet been shown experimentally and warrant further investigation.
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| 17. |
- Carlsson, Tomas, et al.
(författare)
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Scaling maximal oxygen uptake to predict performance in elite-standard men cross-country skiers
- 2013
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Ingår i: Journal of Sports Sciences. - : Routledge. - 0264-0414 .- 1466-447X. ; 31:16, s. 1753-1760
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was to: 1) establish the optimal body-mass exponent for maximal oxygen uptake (O2max) to indicate performance in elite-standard men cross-country skiers; and 2) evaluate the influence of course inclination on the body-mass exponent. Twelve elite-standard men skiers completed an incremental treadmill roller-skiing test to determine O2max and performance data came from the 2008 Swedish National Championship 15-km classic-technique race. Log-transformation of power-function models was used to predict skiing speeds. The optimal models were found to be: Race speed = 7.86 · O2max · m −0.48 and Section speed = 5.96 · O2max · m −(0.38 + 0.03 · α) · e−0.003 · Δ (where m is body mass, α is the section's inclination and Δ is the altitude difference of the previous section), that explained 68% and 84% of the variance in skiing speed, respectively. A body-mass exponent of 0.48 (95% confidence interval: 0.19 to 0.77) best described O2max as an indicator of performance in elite-standard men skiers. The confidence interval did not support the use of either “1” (simple ratio-standard scaled) or “0” (absolute expression) as body-mass exponents for expressing O2max as an indicator of performance. Moreover, results suggest that course inclination increases the body-mass exponent for O2max.
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| 18. |
- Carlsson, Tomas, et al.
(författare)
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Scaling of upper-body power output to predict time-trial roller skiing performance
- 2013
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Ingår i: Journal of Sports Sciences. - : Taylor & Francis. - 0264-0414 .- 1466-447X. ; 31:6, s. 582-588
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of the present study was to establish the most appropriate allometric model to predict mean skiing speed during a double-poling roller skiing time-trial using scaling of upper-body power output. Forty-five Swedish junior cross-country skiers (27 men and 18 women) of national and international standard were examined. The skiers, who had a body mass (m) of 69.3 ± 8.0 kg (mean ± s), completed a 120-s double-poling test on a ski ergometer to determine their mean upper-body power output (W). Performance data were subsequently obtained from a 2-km time-trial, using the double-poling technique, to establish mean roller skiing speed. A proportional allometric model was used to predict skiing speed. The optimal model was found to be: Skiing speed = 1.057 · W 0.556 · m −0.315, which explained 58.8% of the variance in mean skiing speed (P < 0.001). The 95% confidence intervals for the scaling factors ranged from 0.391 to 0.721 for W and from −0.626 to −0.004 for m. The results in this study suggest that allometric scaling of upper-body power output is preferable for the prediction of performance of junior cross-country skiers rather than absolute expression or simple ratio-standard scaling of upper-body power output.
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| 19. |
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| 20. |
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| 21. |
- Crenshaw, Albert G., et al.
(författare)
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Oxygenation and EMG in the proximal and distal vastus lateralis muscle during submaximal isometric knee extension
- 2010
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Ingår i: Journal of Sports Sciences. - : Informa UK Limited. - 0264-0414 .- 1466-447X. ; 28:10, s. 1057-1064
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Tidskriftsartikel (refereegranskat)abstract
- Muscle oxygenation responses are reportedly greater in the distal muscle region than in the proximal muscle region. We combined near infrared spectroscopy and electromyography (EMG) to determine whether regional differences in oxygenation are associated with differences in (1) muscle activation and/or (2) fatigue development. Nine males performed 2-min sustained isometric knee extensions at 15% and 30% maximum voluntary contraction during which oxygenation and EMG were recorded simultaneously from proximal and distal locations of the vastus lateralis muscle. Near infrared spectroscopy variables for oxygen saturation (StO2%) were initial slope at contraction onset, peak drop, and recovery slope at contraction end. Electromyography produced the root mean square to indicate muscle activation and mean power frequency changes over time (decreasing slope) to indicate fatigue development. For StO2%, significantly greater peak drop and steeper recovery slope were found for the distal muscle region than for the proximal muscle region. Root mean square, however, was not different between locations. Mean power frequency decreased throughout the contractions but changes were not different between locations. Our results indicate that for modest submaximal contractions, regional differences in oxygenation are not associated with differences in muscle activation or with fatigue development (as interpreted by changes in mean power frequency over time).
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| 22. |
- Davis, Louise, 1982-, et al.
(författare)
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Coach-athlete attachment and the quality of the coach-athlete relationship : implications for athlete's well-being
- 2014
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Ingår i: Journal of Sports Sciences. - : Routledge. - 0264-0414 .- 1466-447X. ; 32:15, s. 1454-1464
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Tidskriftsartikel (refereegranskat)abstract
- This study examined whether athletes’attachment styles with the coach were linked to aspects of the coach–athlete relationship quality and, in turn, whether relationship quality was linked to athletes’well-being. One hundred and ninety- two athletes completed a questionnaire measuring their attachment styles and relationship quality with the coach as well as their feelings of positive affect (PA) and negative affect (NA). Structural equation modelling (SEM) analysis found athletes’ avoidant and secure attachment styles to be associated with aspects of coach–athlete relationship quality such as social support, relationship depth, and interpersonal conflict. Interpersonal conflict appeared to play a key role in athletes’PA and NA. From a practical perspective, an understanding of conflict management could provide a resource that allows athletes (and coaches) to enhance the quality of their sporting relationships. Specifically, an awareness of proactive strategies (e.g., steps to clarify expectations) and reactive strategies (e.g., cooperation during the discussion of disagreements) could potentially lead both coaches and athletes to "broaden" their viewpoints and in turn "build" connections that are capable of generating positive emotions including interest, excitement, happiness, and zeal.
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| 23. |
- Davis, Louise, 1982-, et al.
(författare)
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The role of coach-athlete relationship quality in team sport athletes’ psychophysiological exhaustion : implications for physical and cognitive performance
- 2018
-
Ingår i: Journal of Sports Sciences. - : Taylor & Francis. - 0264-0414 .- 1466-447X. ; 17, s. 1985-1992
-
Tidskriftsartikel (refereegranskat)abstract
- The present study aimed to examine associations between the quality of the coach-athlete relationship and athlete exhaustion by assessing physiological and cognitive consequences. Male and female athletes (N = 82) representing seven teams across four different sports, participated in a quasi-experimental study measuring physical performance on a 5-meter multiple shuttle test, followed by a Stroop test to assess cognitive performance. Participants provided saliva samples measuring cortisol as a biomarker of acute stress response and completed questionnaires measuring exhaustion, and coach-athlete relationship quality. Structural equation modelling revealed a positive relationship between the quality of the coach-athlete relationship and Stroop performance, and negative relationships between the quality of the coach-athlete relationship and cortisol responses to high-intensity exercise, cognitive testing, and exhaustion. The study supports previous research on socio-cognitive correlates of athlete exhaustion by highlighting associations with the quality of the coach-athlete relationship. © 2018 Informa UK Limited, trading as Taylor & Francis Group
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| 24. |
- Davis, Louise, Dr, 1982-, et al.
(författare)
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The role of quality relationships and communication strategies for the fulfilment of secure and insecure athletes' basic psychological needs
- 2023
-
Ingår i: Journal of Sports Sciences. - : Taylor & Francis. - 0264-0414 .- 1466-447X. ; 40:21, s. 2424-2436
-
Tidskriftsartikel (refereegranskat)abstract
- The correlates of coach-athlete relationship quality have been the focus of research for over a decade; however, little is known about the mediating and moderating mechanisms underlying these associations. The present study conducted a moderated mediation analysis to examine (a) the mediating role of communication strategies (via COMPASS) on the association between the quality of the coach-athlete relationship and athlete psychological needs satisfaction and (b) whether individual differences in athletes' attachment style (secure, anxious, avoidant) moderates the mediational relationship. 350 Swedish athletes representing a range of sports and competition levels completed a multi-section questionnaire. Mediation and moderation analysis partially found that coach-athlete relationship quality and athletes basic psychological needs were associated via the COMPASS strategies of support, motivation, assurance and openness. It was also found that athletes secure attachment with their coach significantly moderated the mediated effects of motivation and support. These findings highlight the practical utility of motivation, support, openness and assurance strategies in enhancing the quality of the coach-athlete relationship. Moreover, these findings demonstrate that the attachment orientation of athletes towards their coaches play a significant role in determining what communication strategies to use to enhance both the relationship quality and an athlete's competence, autonomy and relatedness.
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| 25. |
- Dekerle, Jeanne, et al.
(författare)
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Critical power is not attained at the end of an isokinetic 90-second all-out test in children
- 2009
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Ingår i: Journal of Sports Sciences. - : Informa UK Limited. - 0264-0414 .- 1466-447X. ; 27:4, s. 379-385
-
Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was to establish whether critical power, as traditionally determined from the performance of three constant-load tests to exhaustion, is attained at the end of a 90-s all-out test in children. Sixteen healthy children (eight males and eight females; mean age 12.3 years, sx = 0.1; body mass 39.6 kg, sx = 1.8; peak VO2 2.0 litres · min−1, sx = 0.1) completed an incremental test to exhaustion to determine peak oxygen uptake (peak VO2), three separate constant-load tests to exhaustion to calculate critical power, and an isokinetic 90-s all-out test. The end power of the 90-s test averaged over the last 10 s (140 W, sx = 8) was significantly higher than critical power (105 W, sx = 6; t = 6.8; P < 0.01), yet the two parameters were strongly correlated (r = 0.74; P < 0.01). After 60 s, there were no further reductions in power output during the 90-s test (P < 0.0001). In conclusion, at the end of a 90-s all-out test, children are able to produce power outputs well above critical power. This suggests that 90 s is not long enough to completely exhaust the anaerobic work capacity in children.
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| 26. |
- Dencker, Magnus, et al.
(författare)
-
Accelerometer-measured daily physical activity related to aerobic fitness in children and adolescents.
- 2011
-
Ingår i: Journal of Sports Sciences. - : Informa UK Limited. - 0264-0414 .- 1466-447X. ; 29:9, s. 887-895
-
Tidskriftsartikel (refereegranskat)abstract
- Maximum oxygen uptake ([Vdot]O(2PEAK)) is generally considered to be the best single marker for aerobic fitness. While a positive relationship between daily physical activity and aerobic fitness has been established in adults, the relationship appears less clear in children and adolescents. The purpose of this paper is to summarise recently published data on the relationship between daily physical activity, as measured by accelerometers, and [Vdot]O(2PEAK) in children and adolescents. A PubMed search was performed on 29 October 2010 to identify relevant articles. Studies were considered relevant if they included measurement of daily physical activity by accelerometry and related to a [Vdot]O(2PEAK) either measured directly at a maximal exercise test or estimated from maximal power output. A total of nine studies were identified, with a total number of 6116 children and adolescents investigated. Most studies reported a low-to-moderate relationship (r = 0.10-0.45) between objectively measured daily physical activity and [Vdot]O(2PEAK). No conclusive evidence exists that physical activity of higher intensities are more closely related to [Vdot]O(2PEAK), than lower intensities.
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| 27. |
- Dencker, Magnus, et al.
(författare)
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Maximal oxygen uptake versus maximal power output in children
- 2008
-
Ingår i: Journal of Sports Sciences. - : Informa UK Limited. - 0264-0414 .- 1466-447X. ; 26:13, s. 1397-1402
-
Tidskriftsartikel (refereegranskat)abstract
- Maximal oxygen uptake ([Vdot]O2max) is considered the optimal method to assess aerobic fitness. The measurement of [Vdot]O2max, however, requires special equipment and training. Maximal exercise testing with determination of maximal power output offers a more simple approach. This study explores the relationship between [Vdot]O2max and maximal power output in 247 children (139 boys and 108 girls) aged 7.9-11.1 years. Maximal oxygen uptake was measured by indirect calorimetry during a maximal ergometer exercise test with an initial workload of 30W and 15Wmin-1 increments. Maximal power output was also measured. A sample (n=124) was used to calculate reference equations, which were then validated using another sample (n=123). The linear reference equation for both sexes combined was: [Vdot]O2max (mlmin-1)=96 + 10.6maximal power + 3.5body mass. Using this reference equation, estimated [Vdot]O2max per unit of body mass (mlmin-1kg-1) calculated from maximal power correlated closely with the direct measurement of [Vdot]O2max (r=0.91, P0.001). Bland-Altman analysis gave a mean limits of agreement of 0.22.9 (mlmin-1kg-1) (1s). Our results suggest that maximal power output serves as a good surrogate measurement for [Vdot]O2max in population studies of children aged 8-11 years.
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| 28. |
- Dencker, Magnus, et al.
(författare)
-
Objectively measured daily physical activity related to aerobic fitness in young children.
- 2010
-
Ingår i: Journal of Sports Sciences. - : Informa UK Limited. - 0264-0414 .- 1466-447X. ; 28, s. 139-145
-
Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was to investigate by direct measurement the cross-sectional relationship between accelerometer-measured physical activity and peak oxygen uptake ([Vdot]O(2peak): ml . min(-1) . kg(-1)), in a population-based cohort of young children, since such data are scarce. The study included 468 children (246 boys, 222 girls) aged 6.7 +/- 0.4 years, recruited from a population-based cohort. Peak oxygen uptake was measured by indirect calorimetry during a maximal treadmill exercise test. Physical activity was assessed by accelerometers over a 4-day period. Minutes of sedentary, light, moderate, moderate-to-vigorous, and vigorous activity per day were calculated. Mean counts per minute were considered to reflect total physical activity. Pearson correlation coefficients indicated a weak relationship between daily physical activity variables and [Vdot]O(2peak) in boys (r = 0.15-0.28, P < 0.05), with the exception of time in sedentary and light activity, which was not related to [Vdot]O(2peak). None of the daily physical activity variables were related to [Vdot]O(2peak) in girls, with the exception of a very weak relationship for moderate activity (r = 0.14, P < 0.05). Multiple regression analyses indicated that the various physical activity variables explained between 2 and 8% of the variance in [Vdot]O(2peak) in boys. In this population-based cohort, most daily activity variables were positively related to aerobic fitness in boys, whereas less clear relationships were observed in girls. Our finding that physical activity was only uniformly related to aerobic fitness in boys partly contradicts previous studies in older children and adolescents.
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| 29. |
- Dunlop, Gordon, et al.
(författare)
-
Examination of the validity of the Injury-Psychological Readiness to Return to Sport (I-PRRS) scale in male professional football players : A worldwide study of 29 professional teams
- 2023
-
Ingår i: Journal of Sports Sciences. - Abingdon, Oxon : Routledge. - 0264-0414 .- 1466-447X. ; 41:21, s. 1906-1914
-
Tidskriftsartikel (refereegranskat)abstract
- Perceived confidence is an important dimension of an athlete’s psychological readiness to return-to-play. However, there is no established and validated tool to evaluate confidence in professional football. This study aimed to provide preliminary evaluation of the internal structure of the Injury-Psychological Readiness to Return-to-Sport scale (I-PRRS) in a cohort of injured male professional footballers. Over an 18-month period, 29 teams from 17 leagues participated. Players sustaining injuries eliciting (Formula presented.) 3 weeks’ time-loss were recruited. Cross culturally adapted to 4 further languages, the I-PRRS was administered on two occasions: 1) day before returning-to-training and 2) day before returning-to-match-play. In total, 113 injuries were recorded with 96 completed I-PRRS data sets collected. Confirmatory factor analysis indicated the I-PRRS was a unidimensional scale, with all items measuring the same construct. The scale demonstrated good internal consistency (ω =.88). When examining longitudinal invariance of the I-PRRS across administration time-points, indices of model fit supported scalar invariance. There was preliminary evidence of good internal structure for the I-PRRS in professional male footballers. However, before further research involving the I-PRRS can be endorsed, efforts to confirm or refute empirical developments pertaining to psychological readiness are necessary. © 2024 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.
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| 30. |
- Elsborg, Peter, et al.
(författare)
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Factorial validity, predictive validity and measurement invariance of the Danish version of the coach-created Empowering Disempowering Motivational Climate Questionnaire (EDMCQ-C)
- 2023
-
Ingår i: Journal of Sports Sciences. - Abingdon : Routledge. - 0264-0414 .- 1466-447X. ; 41:8, s. 715-726
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose: The purpose of this study was to translate and validate a Danish version of the coach-created Empowering and Disempowering Motivational Climate Questionnaire (EDMCQ-C), retest the factor structure and provide further investigation into the psychometric properties in terms of measurement invariance across gender, age and competitive level, reliability and predictive validity. Methods: The participants were 1719 male and 551 female Danish football players 12–20 years of age (M = 14.81) playing at recreational, medium and elite levels. Participants filled in EDMCQ-C as well as questionnaires measuring psychological needs (BPNESS) and behaviour regulation (BRSQ). Factor structure of the EDMCQ-C was tested using Exploratory Structural Equation Modelling. To test whether the factor structure differed across gender, age group and competitive level, an invariance analysis comparing configurational, metric and scalar models was conducted. Results: EDMCQ-C showed good psychometric properties and measurement invariance across age, gender and competitive level. Both dimensions of EDMCQ-C were associated to needs satisfaction and behaviour regulation in expected directions and had high internal consistency. Conclusion: This study provides evidence for the reliability of the two dimensions of EDMCQ-C, their predictive validity and for measurement invariance across age, gender and competitive level and provides a Danish version of the EDMCQ with sound psychometric properties. © 2023 Informa UK Limited, trading as Taylor & Francis Group.
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| 31. |
- Enqvist, Jonas K, et al.
(författare)
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Energy turnover during 24 hours and 6 days of adventure racing.
- 2010
-
Ingår i: Journal of Sports Sciences. - : Routledge. - 0264-0414 .- 1466-447X. ; 28:9, s. 947-955
-
Tidskriftsartikel (refereegranskat)abstract
- Energy turnover was assessed in two conditions of mixed ultra-endurance exercise. In Study 1, energy expenditure and intake were measured in nine males in a laboratory over 24 h. In Study 2, energy expenditure was assessed in six males during an 800-km Adventure race (mean race time 152.5 h). Individual correlations between heart rate and oxygen uptake ([Vdot]O(2)) were established during pre-tests when kayaking, cycling, and running. During exercise, energy expenditure was estimated from continuous heart rate recordings. Heart rate and [Vdot]O(2) were measured regularly during fixed cycling work rates to correct energy expenditure for drift in oxygen pulse. Mean energy expenditure was 18,050 +/- 2,390 kcal (750 +/- 100 kcal . h(-1)) and 80,000 +/- 18,000 kcal (500 +/- 100 kcal . h(-1)) in Study 1 and Study 2 respectively, which is higher than previously reported. Energy intake in Study 1 was 8,450 +/- 1,160 kcal, resulting in an energy deficit of 9,590 +/- 770 kcal. Body mass decreased in Study 1 (-2.3 +/- 0.8 kg) but was unchanged in Study 2. Fat mass decreased in Study 2 (-2.3 +/- 1.5 kg). In Study 1, muscle glycogen content decreased by only 60%. Adventure racing requires a high energy expenditure, with large inter-individual variation. A large energy deficit is caused by inadequate energy intake, possibly due to suppressed appetite and gastrointestinal problems. The oxygen pulse, comparing start to 12 h of exercise and beyond, increased by 10% and 5% in Study 1 and Study 2 respectively. Hence, estimations of energy expenditure from heart rate recordings should be corrected according to this drift.
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| 32. |
- Eriksson, Martin, et al.
(författare)
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Immediate effect of visual and auditory feedback to control the running mechanics of well-trained athletes
- 2011
-
Ingår i: Journal of Sports Sciences. - : Informa UK Limited. - 0264-0414 .- 1466-447X. ; 29:3, s. 253-262
-
Tidskriftsartikel (refereegranskat)abstract
- The correlation between mechanical factors of running and running economy as measured by metabolic cost is a subject of much interest in the study of locomotion. However, no change in running technique has been shown to result in an immediate improvement in running economy on an intra-individual basis. To evaluate the effect of a modified running technique, it is probably necessary that the individual trains with the new technique for a longer period using a feedback system to control the new kinematics. In this study, we examine the feasibility of using visual and auditory feedback to adapt running technique according to a simplistic model of the mechanical cost of running. The model considers only the mechanical work against gravity, which is the product of the magnitude of the vertical displacement of the runner's centre of mass and the step-frequency. In the experiments reported here, 18 trained runners, running at 16km center dot h-1 on a treadmill, were given feedback on these parameters together with indicated target levels. In almost all cases, the runners were able to adjust their technique accordingly.
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| 33. |
- Fliess Douer, Osnat, et al.
(författare)
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Challenges and opportunities in wheelchair basketball classification - A Delphi study.
- 2021
-
Ingår i: Journal of Sports Sciences. - : Routledge. - 0264-0414 .- 1466-447X. ; 39:Sup1, s. 7-18
-
Tidskriftsartikel (refereegranskat)abstract
- The International Paralympic Committee (IPC) mandates Paralympic Sports to develop evidence-based classification systems that allocate athletes into 'classes' according to the impact of their impairment on sport-specific performance. In wheelchair-basketball, a panel of classifiers assesses athlete's performance through observation. One key barrier to evidence-based classification is the absence of defined eligible impairments, including clear guidelines on how to assess them and their impact on wheelchair basketball performance. This study aims to reach expert consensus on issues specific to wheelchair basketball that can benefit from evidence-based classification. It offers recommendations for refining the classification manual, thus improving adherence to the IPC classification code. A three-round Delphi study was conducted with 29 experts in wheelchair basketball. The experts agreed with the new definition for the aim of wheelchair basketball classification, which is in line with the IPC code. Cases identified as having the highest risk for disagreement between classifiers included classifying players with upper limb deficiency or with impaired coordination. The panel failed to agree on changing the classification procedures and on defining the eligible impairment list. This study identifies issues specific to wheelchair basketball classification to be addressed in future research. Additional discussions need to take place to promote further resolution.
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| 34. |
- Ford, Paul R., et al.
(författare)
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The developmental activities of elite soccer players aged under-16 years from Brazil, England, France, Ghana, Mexico, Portugal and Sweden
- 2012
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Ingår i: Journal of Sports Sciences. - : Routledge. - 0264-0414 .- 1466-447X. ; 30:15, s. 1653-1663
-
Tidskriftsartikel (refereegranskat)abstract
- The developmental activities of 328 elite soccer players aged under-16 years from Brazil, England, France, Ghana, Mexico, Portugal and Sweden were examined using retrospective recall in a cross-sectional research design. The activities were compared to the early diversification, early specialisation, and early engagement pathways. Players started their involvement in soccer at approximately 5 years of age. During childhood, they engaged in soccer practice for a mean value of 185.7, s ¼ 124.0 h _ year71, in soccer play for 186.0, s ¼ 125.3 h _ year71, and in soccer competition for 37.1, s ¼ 28.9 h _ year71. A mean value of 2.3, s ¼ 1.6 sports additional to soccer were engaged in by 229 players during childhood. Players started their participation in an elite training academy at 11 to 12 years of age. During adolescence, they engaged in soccer practice for a mean value of 411.9, s ¼ 184.3 h _ year71, in soccer play for 159.7, s ¼ 195.0 h _ year71, and in soccer competition for 66.9, s ¼ 48.8 h _ year71. A mean value of 2.5, s ¼ 1.8 sports other than soccer were engaged in by 132 players during this period. There were some relatively minor differences between countries, but generally the developmental activities of the players followed a mixture of the early engagement and specialisation pathways, rather than early diversification.
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| 35. |
- Ford, Paul R., et al.
(författare)
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The developmental and professional activities of female international soccer players from five high-performing nations
- 2020
-
Ingår i: Journal of Sports Sciences. - : Informa UK Limited. - 0264-0414 .- 1466-447X. ; 38:11-12, s. 1432-1440
-
Tidskriftsartikel (refereegranskat)abstract
- We study the developmental and professional activities engaged in by 86 female adult soccer players from the senior national teams of Australia, Canada, England, Sweden, and the United States of America. Players completed the Participation History Questionnaire (PHQ) to elicit the amount and type of activities engaged in across their developmental and professional years, including milestones, soccer-specific activity and engagement in other sport activity. Greater specialisation than diversification characterised their childhood developmental activities, including all players starting in soccer in childhood and accumulating more hours in soccer activity than other sports during this period. However, interindividual variation further characterised these childhood activities, with a proportion of players diversifying into other sports and/or soccer play to a greater or lesser degree during childhood when compared to the other players. The amount of coach-led soccer practice increased for all players across their development culminating in an average of 15-16 h/wk across a 40-week season in early adulthood. In contrast, the amount of engagement in other sports and soccer peer-led play varied between players but generally decreased across adolescence to negligible amounts in late adolescence. Findings are commensurate with the deliberate practice framework and early engagement.
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| 36. |
- Fröberg, Andreas, 1985, et al.
(författare)
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Leisure-time organised physical activity and dietary intake among Swedish adolescents.
- 2022
-
Ingår i: Journal of Sports Sciences. - : Routledge. - 0264-0414 .- 1466-447X. ; 40:11, s. 1198-1205
-
Tidskriftsartikel (refereegranskat)abstract
- This study aimed to investigate associations between participation in leisure-time organised physical activity (LTOPA) and dietary intake in a large representative sample of Swedish adolescents participating in the national dietary survey Riksmaten Adolescents 2016-2017. A sample of 2807 participants aged 11-12, 14-15 and 17-18 years were included. Information about LTOPA and dietary intake were collected through questionnaires and two 24-hour recalls on the web (RiksmatenFlex). For dietary intake, overall healthy eating index, intake of fruit, vegetables, candy, sugar-sweetened beverages, and the proportion of added sugar to total energy intake were analysed. Significance-testing for associations was performed with analysis of covariance. LTOPA was associated with lower sugar-sweetened beverages intake among adolescent boys (p < 0.001, ηp2 = 0.012) and girls (p = 0.007, ηp2 = 0.005), higher fruit intake among boys (p = 0.043, ηp2 = 0.003), and lower vegetable intake among girls (p < 0.001, ηp2 = 0.009). However, LTOPA was unrelated to the overall healthy eating index, candy intake, and the proportion of added sugar to total energy intake (p > 0.05). LTOPA was only associated with some healthy eating behaviours, and there is much room for improvement in the diets of Swedish adolescents.
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| 37. |
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| 38. |
- Gerber, M., et al.
(författare)
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Implicit and explicit attitudes towards sport among young elite athletes with high versus low burnout symptoms
- 2019
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Ingår i: Journal of Sports Sciences. - : Routledge. - 0264-0414 .- 1466-447X. ; 37:14, s. 1673-1680
-
Tidskriftsartikel (refereegranskat)abstract
- The development of cynical attitudes towards elite sport is a core symptom of athlete burnout and has been associated with dropout from elite sport. To date, this phenomenon has mainly been studied by investigating explicit attitudes towards sport, whereas athletes’ automatic evaluations (i.e. implicit attitudes) that have been shown to influence behavior as well were not considered. This study aimed to compare explicit and implicit attitudes towards sport of young elite athletes with high (N = 24) versus low (N = 26) burnout symptoms. Using self-reported measures, general and athlete burnout symptoms were assessed. Additionally, a single-target implicit association test was administered to examine participants’ automatic evaluation of sport. Statistical analysis revealed greater emotional/physical exhaustion and sport devaluation in athletes reporting high compared to low burnout symptoms. Implicit attitudes towards sport did not significantly differ between the groups. Furthermore, no significant correlations were observed between different athlete burnout symptoms and implicit attitudes. Athletes with high burnout symptoms show a tendency to explicitly detach themselves from sport, thus fostering sport devaluation as a core symptom of athlete burnout. However, this process does not seem to be reflected in their implicit attitudes towards sport.
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| 39. |
- Gerber, M, et al.
(författare)
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Longitudinal relationships between perceived stress, exercise self-regulation, and exercise involvement among physically active adolescents
- 2015
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Ingår i: Journal of Sports Sciences. - : Informa UK Limited. - 0264-0414 .- 1466-447X. ; 33:4, s. 369-380
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Tidskriftsartikel (refereegranskat)abstract
- Stress exposure may undermine exercisers’ capability to self-regulate their exercise behaviour. This longitudinal study examined the interplay between perceived stress, exercise self-regulation (assessment of action and coping planning) and participation in vigorous exercise in vocational students. Moreover, this study examined whether high exercise self-regulation moderates the assumed negative relationship between stress and exercise. A sample of 580 physically active vocational students (x ± s 17.8 ± 1.3 years, 33.8% girls) was assessed. All participants completed two identical validated questionnaires assessing stress, exercise self-regulation and exercise with a span of 10 months in between survey completion periods. The cross-sectional analyses show that high exercise self-regulation attenuated the assumed negative relationship between stress and exercise. In the longitudinal analyses, however, only a non-significant trend was found. Significant longitudinal relationships existed between exercise self-regulation and exercise involvement. Latent difference score models revealed that a drop in the exercise self-regulation was associated with a concurrent decrease in exercise participation. Cross-lagged panel analyses showed that high exercise self-regulation levels positively predicted exercise behaviour, but an inverse relationship was not supported. The findings suggested that higher exercise self-regulation levels were positively associated with future exercise involvement in currently active adolescents. While partial support was found that exercise selfregulation moderated the influence of stress on exercise, the findings demonstrated that higher exercise self-regulation levels had a positive impact on future exercise involvement in already active individuals.
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| 40. |
- Gracia-Marco, Luis A., et al.
(författare)
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Seasonal variation in physical activity and sedentary time in different European regions. The HELENA study
- 2013
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Ingår i: Journal of Sports Sciences. - : Routledge. - 0264-0414 .- 1466-447X. ; 31:16, s. 1831-1840
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Tidskriftsartikel (refereegranskat)abstract
- This report aims (1) to examine the association between seasonality and physical activity (PA) and sedentary time in European adolescents and (2) to investigate whether this association was influenced by geographical location (Central-North versus South of Europe), which implies more or less extreme weather and daylight hours. Valid data on PA, sedentary time and seasonality were obtained in 2173 adolescents (1175 females; 12.5-17.5 years) included in this study. Physical activity and sedentary time were measured by accelerometers. ANCOVA was conducted to analyse the differences in PA and sedentary time across seasons. Results showed that girls had lower levels of moderate to vigorous PA (MVPA) and average PA, and spent more time in sedentary activities in winter compared with spring (all P < 0.05). Stratified analyses showed differences in PA and sedentary time between winter and spring in European girls from Central-North of Europe (P < 0.05 for sedentary time). There were no differences between PA and sedentary time across seasonality in boys. In conclusion, winter is related with less time spent in MVPA, lower average PA and higher time spent in sedentary activities in European adolescent girls, compared with spring. These differences seem to mainly occur in Central-North Europe.
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| 41. |
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| 42. |
- Gray, Stuart R, et al.
(författare)
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ATP and phosphocreatine utilization in single human muscle fibres during the development of maximal power output at elevated muscle temperatures.
- 2008
-
Ingår i: Journal of Sports Sciences. - : Informa UK Limited. - 0264-0414 .- 1466-447X. ; 26:7, s. 701-7
-
Tidskriftsartikel (refereegranskat)abstract
- In this study, we examined the effect of muscle temperature (Tm) on adenosine triphosphate (ATP) and phosphocreatine utilization in single muscle fibres during the development of maximal power output in humans. Six male participants performed a 6-s maximal sprint on a friction-braked cycle ergometer under both normal (Tm = 34.3 degrees C, s = 0.6) and elevated (T(m) = 37.3 degrees C, s = 0.2) muscle temperature conditions. During the elevated condition, muscle temperature of the legs was raised, passively, by hot water immersion followed by wrapping in electrically heated blankets. Muscle biopsies were taken from the vastus lateralis before and immediately after exercise. Freeze-dried single fibres were dissected, characterized according to myosin heavy chain composition, and analysed for ATP and phosphocreatine content. Single fibres were classified as: type I, IIA, IIAX25 (1 - 25% IIX isoform), IIAX50 (26 - 50% IIX), IIAX75 (51 - 75% IIX), or IIAX100 (76 - 100% IIX). Maximal power output and pedal rate were both greater (P < 0.05) during the elevated condition by 258 W (s = 110) and 22 rev . min(-1) (s = 6), respectively. In both conditions, phosphocreatine content decreased significantly in all fibre types, with a greater decrease during the elevated condition in type IIA fibres (P < 0.01). Adenosine triphosphate content was also reduced to a greater (P < 0.01) extent in type IIA fibres during the elevated condition. The results of the present study indicate that after passive elevation of muscle temperature, there was a greater decrease in ATP and phosphocreatine content in type IIA fibres than in the normal trial, which contributed to the higher maximal power output.
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| 43. |
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| 44. |
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| 45. |
- Gustafsson, Henrik, et al.
(författare)
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Exploring the relationship between hope and burnout in competitive sport
- 2010
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Ingår i: Journal of Sports Sciences. - : Informa UK Limited. - 0264-0414 .- 1466-447X. ; 28:14, s. 1495-1504
-
Tidskriftsartikel (refereegranskat)abstract
- Researchers have postulated that hope may be an important factor associated with burnout. Consistent with hope theory contentions, low-hope individuals may be susceptible to burnout because they are prone to experience goal blockage, frustration, and negative affect, all of which likely increase the risk of burnout. We examined the relationship between hope and athlete burnout among 178 competitive athletes (63 females and 115 males) aged 15-20 years. Hope was significantly and negatively correlated with all three burnout subscales: emotional/physical exhaustion, a reduced sense of accomplishment, and sport devaluation. Moreover, results of a multivariate analysis of variance showed that low-hope athletes scored significantly higher than medium- and high-hope athletes on all three burnout dimensions. Finally, results revealed that agency thinking was a significant predictor of all burnout dimensions. Frustration over unmet goals and a perceived lack of agency, a characteristic of low-hope athletes, might pose a risk factor in athlete burnout, whereas being able to maintain hope appears to be associated with health and well-being.
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| 46. |
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| 47. |
- Hallen, Anna, et al.
(författare)
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Return to play following muscle injuries in professional footballers
- 2014
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Ingår i: Journal of Sports Sciences. - : Taylor and Francis: SSH Journals. - 0264-0414 .- 1466-447X. ; 32:13, s. 1229-1236
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Tidskriftsartikel (refereegranskat)abstract
- This prospective cohort study described return-to-play (RTP) data for different types of muscle injuries in male elite-level football players in Europe. Eighty-nine European professional teams were followed between 2001 and 2013. Team medical staff recorded individual player exposure and time-loss injuries. A total of 17,371 injuries occurred, including 5603 (32%) muscle injuries. From 2007, we received results from 386 magnetic resonance imaging (MRI) examinations, and radiological grading was performed. A negative MRI was associated with shorter recovery time (6 +/- 7 days). Lay-off days were correlated with MRI grading of thigh muscle injuries (P less than 0.001). Among hamstring injuries, 83% occurred to the biceps femoris, 12% affected the semimembranosus and 5% the semitendinosus. Recurrence rate was higher among biceps femoris injuries (18%) compared with semitendinosus and semimembranosus injuries (2% together). Groin muscle injuries caused shorter median absence (9 days) than hamstring (13 days; P less than 0.001), quadriceps (12 days; P less than 0.001) and calf muscle (13 days; P less than 0.001) injuries. Overall, we found that MRI was valuable for prognosticating RTP, with radiological grading associated with lay-off times after injury. Re-injuries were common in biceps femoris injuries but rare in semitendinosus and semimembranosus injuries.
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| 48. |
- Han, Xiaolei, et al.
(författare)
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Accelerometer-assessed sedentary behaviour among Chinese rural older adults : Patterns and associations with physical function
- 2022
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Ingår i: Journal of Sports Sciences. - : Informa UK Limited. - 0264-0414 .- 1466-447X. ; 40:17, s. 1940-1949
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Tidskriftsartikel (refereegranskat)abstract
- Sedentary behaviour is associated with a range of adverse health conditions. Population-based studies have rarely examined the distribution and associated factors of accelerometer-measured sedentary behaviour patterns in rural-dwelling older adults. This population-based study included 2096 rural-dwelling older adults (age ≥60 years; 59.0% women) derived from baseline participants of the MIND-China Study. Total sedentary time and patterns (e.g., uninterrupted bouts and breaks) were derived from the hip-worn accelerometers for 7 days. Physical function was assessed using the Short Physical Performance Battery test. Data were analysed using general linear models. Overall, participants spent 58.8% of daily waking time in sedentary behaviour, with nearly half of sedentary time being accumulated through sedentary bouts of 30+ minutes. Men spent more total and accumulated sedentary time than women in each sedentary bout duration, while women had more daily 1+ minute sedentary bouts than men (all P < 0.001). Controlling for moderate-to-vigorous physical activity and other confounders, more prolonged sedentary time and fewer breaks were significantly associated with poor physical function, balance, lower limb strength, and walking speed (all P < 0.001). In older adults living in rural communities, prolonged sedentary behaviour and less frequent breaks are associated with poor physical function.
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| 49. |
- Hanstock, Helen, 1989-, et al.
(författare)
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Evaluation of physiological and nutritional risk factors for upper respiratory illness using a zero-inflated negative binomial model
- 2018
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Ingår i: Journal of Sports Sciences. - : Routledge. - 0264-0414 .- 1466-447X. ; , s. 44-45
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Konferensbidrag (refereegranskat)abstract
- Intensified training periods may increase incidence of upper respiratory illness (URI) in athletes (Meeusen et al., 2013,Medicine and Science in Sports and Exercise, 45(1), 186–205). Many physiological and nutritional risk factors have beenassociated with increased risk of URI (Bermon et al., 2017, Exercise Immunology Review, 23, 8–50), including reductionsin salivary IgA (sIgA), elevated cortisol, vitamin D insufficiency, iron deficiency and low energy availability (EA). However, few studies have explored the relative importance of each of thesehealth-related biomarkers in a multivariate model. Our aimwas therefore to investigate the relationship between multiplebiological risk factors for illness and incidence, duration andseverity of URIs that present during intensified training. 3815Twenty-five well-trained male cyclists and triathletes (age 30 ± 9 y, VO2peak 64 ± mL· kg−1· min−1) performed one ofthree different high-intensity interval training (HIT) programmes for three sessions per week over four weeks in November-December. The study received local ethical approval and participants provided written, informed consentto participate. Participants performed each HIT session at “isoeffort” intensity and sessions were matched for total accumulated work duration. Participants logged upper respiratorysymptoms (URS) daily using the Jackson Common Cold Scale; episodes of URI were identified retrospectively using the followinga priori criteria: weekly symptom score > 14 or selfreportedcommon cold for > 2 consecutive days (Jacksonet al., 1958, American Medical Association Archives of Internal Medicine, 101, 267–278). Before commencing the training period, VO2peak was determined using an incremental maximal cycling protocol and participants provided rested, fasted blood and saliva samples prior to the training period foranalysis of plasma 25(OH)D, ferritin, cortisol, testosterone and sIgA secretion rate. EA was calculated based on a 3-day registration of energy intake and expenditure relative to fat-free mass measured in a rested, fasted state using indirect calorimetry (Torstveit et al., 2018 February, International Journal of Sport Nutrition and Exercise Metabolism, 1–28). We used a zero-inflated negative binomial model to investigate the relationship between baseline VO2peak, health-related biomarkers and URI incidence/duration/global URS severity. Fourteen athletes(56%) reported an episode of URI during the four-week monitoring period. Higher sIgA was associated with reduced risk of URI (odds ratio = 0.90, 90% confidence interval (CI): [0.83,0.97]). Lower plasma cortisol (P = 0.02) and higher EA (P = 0.02) were associated with longer URI duration; holding cortisol constant, the incidence risk ratio (IRR) for a one-unit increase in EA was 1.04 (90% CI: [1.01, 1.07]). Participants with higher VO2peak reported higher total symptom scores during the intervention period (P = 0.03, IRR = 1.07, 90% CI: [1.01,1.13]). Several health-related biomarkers and physiological parameters may therefore be associated with risk and severityof URI, including sIgA, cortisol, EA and VO2peak.
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| 50. |
- Hanstock, Helen, 1989-, et al.
(författare)
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Influence of interval duration on immunological responses to 4-weeks’ high-intensity interval training
- 2018
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Ingår i: Journal of Sports Sciences. - : Routledge. - 0264-0414 .- 1466-447X. ; , s. 1-94
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Konferensbidrag (refereegranskat)abstract
- High-intensity interval training (HIT) encompasses a wide range of training prescriptions where up to nine variables can be manipulated (Buchheit and Laursen, 2013, Sports Medicine, 43(5), 313–338). Four weeks of HIT with longer intervals and accumulated work durations (AWD) has been shown to elicit greater improvements in peak oxygen consumption (V O 2peak ) despite more modest physiological, hormonal and perceptual responses (Sylta et al., 2017, Medicine & Science in Sports & Exercise, 49(6), 1137–1146). However, immunological responses to different HIT pre- scriptions have rarely been investigated. The purpose of this study was to compare the cumulative effects of a four-week HIT intervention, performed either as short or long intervals with the same AWD, on V O 2peak , the immunological biomarker salivary secretory IgA (s-IgA) and upper respiratory illness (URI) incidence. In addition, we explored the influence of HIT on serum cortisol, testosterone, 25(OH)D and ferritin as biomarkers related to immune competence. Following local ethics committee approval, twenty-five well-trained male cyclists and triath- letes provided written consent to take part and were randomised to one of three HIT groups (Long Intervals [LI]: 4 × 8min; Short Intervals 1 [SI1]: 4×[12 × 40/20s]; Short Intervals 2 [SI2]: 4×[8 ×40/20s]). Participants per- formed three cycling HIT sessions per week for four weeks at maximal session effort (“isoeffort”) intensity, supplemented with ad libitumlow-intensity training. Participants recorded upper respiratory symptoms (URS) daily using the Jackson Common Cold Scale; episodes of URI were identified retrospectively. V O 2peak as well as rested saliva and blood biomarkers were analysed before and after the training period. Fourteen of twenty-five participants reported an episode of URI (LI: 4/8, SI1: 4/8, SI2: 6/9) but there were no differences in URI incidence, severity or duration between groups. Following the train- ing intervention, we observed a moderate increase in V O 2peak across the cohort (mean± SD: 4.75 ± 0.42 to 4.86 ± 0.43 L· min−1 ,Cohen’s d= 0.65, 90% confidence intervals: [0.16, 1.13]) but the change in V O 2peak was not different between groups. Serum cortisol displayed a moderate increase (367 ± 98 to 415 ± 108 nmol· L −1 ,d=0.60 [0.12, 1.08]) and 25(OH)D a large decrease (79.2 ± 17.1 to 70.4 ± 17.6 nmol· L −1 ,d= -0.87 [−1.36,−0.37]) from pre- to post-training, but there were no differences in the magnitude of the responses between groups. Four weeks’HIT did not influence s-IgA secretion rate, serum testosterone or ferritin. We conclude that four weeks’ AWD-matched HIT performed as short- or long-intervals at isoeffort intensity does not differentially influence ill- ness incidence, immunological responses to training nor other immune-related biomarkers. This observation can be viewed as a positive finding for training planning, since it could allow coaches some flexibility in constructing AWD-matched isoeffort HIT sessions to achieve performance goals, without concern about detrimental effects on athletes’ immune status.
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