| 1. |
|
|
| 2. |
- Caparrós, T., et al.
(författare)
-
The relationship of practice exposure and injury rate on game performance and season success in professional male basketball
- 2016
-
Ingår i: Journal of Sports Science and Medicine. - 1303-2968. ; 15:3, s. 397-402
-
Tidskriftsartikel (refereegranskat)abstract
- The objectives of this study were to determine the relationship among game performance, injury rate, and practice exposure in a professional male basketball team. A retroospective analysis of prospective collected data was conducted over seven consecutive seasons (2007/2008 to 2013/2014). Data collection included sports performance during competition (statistical evaluation), injury rate, and total exposure (games and practices). Over the surveillance period, 162 injuries (91 practice; 71 matches) occurred over 32,668 hours of exposure (556 games and 2005 practices). There was a strong positive correlation between: 1) exposure (total number of practices and hours of exposure) and the total number of injuries (r = 0.77; p = 0.04); 2) exposure (total hours of exposure and total hours of practice exposure) and performance (total team ranking) (r = 0.77 and p = 0.04, and r = 0.8 and p = 0.03, respectively); and 3) total number of injuries and performance (total team ranking) (r = 0.84; p = 0.02). While increasing practice and competition time is related to greater team performance, it also increases the number of injuries. However, higher injury rates were not associated with worse overall team performance. Efforts to reduce high-risk activity during practice, optimally replaced with injury prevention training, might help to reduce injury risk. © Journal of Sports Science and Medicine.
|
|
| 3. |
|
|
| 4. |
- Edvardsson, Arne, et al.
(författare)
-
Is a cognitive-behavioural biofeedback intervention useful to reduce injury risk in junior football players?
- 2012
-
Ingår i: Journal of Sports Science and Medicine (JSSM). - Bursa, Turkey : Journal of Sports Science and Medicine. - 1303-2968. ; 11:2, s. 331-338
-
Tidskriftsartikel (refereegranskat)abstract
- Athletes participating in sport are exposed to a relatively high injury risk. Previous research has suggested that it could be possible to reduce sports injuries through psychological skills training. The purpose of this study was to examine the extent to which a cognitive behavioural biofeedback intervention could reduce the number of sports injuries in a sample of players in Swedish elite football high schools. Participants from four elite football high schools (16-19 years old) were divided into one experiment (n = 13) and one control group (n = 14). Participants were asked to complete three questionnaires to assess anxiety level (Sport Anxiety Scale), history of stressors (Life Event Scale for Collegiate Athletes) and coping skills (Athletic Coping Skills Inventory - 28) in a baseline measure. Mann-Whitney Utests showed no significant differences in pre-intervention scores based on the questionnaires. The experimental group participated in a nine-week intervention period consisting of seven sessions, including: somatic relaxation, thought stopping, emotions/problem focused coping, goal setting, biofeedback training as well as keeping a critical incident diary. A Mann-Whitney U test showed no significant difference between the control and experimental group U (n1 = 13, n2 = 14) = 51.00, p = 0.054. However, considering the small sample, the statistical power (0.05 for present study), to detect effects was low. The results of the study are discussed from a psychological perspective and proposals for future research are given. © Journal of Sports Science and Medicine.
|
|
| 5. |
- Gerber, M, et al.
(författare)
-
Concerns regarding hair cortisol as a biomarker of chronic stress in exercise and sport science
- 2012
-
Ingår i: Journal of Sports Science and Medicine. - 1303-2968. ; 11, s. 571-581
-
Forskningsöversikt (refereegranskat)abstract
- Hair cortisol has the potential to fill the methodological void of long-term cortisol assessment while becoming a widely accepted measure in biopsychology. This review critically examines the applicability and relevance of hair cortisol measurement specifically within the field of exercise and sport science. Current measures of the HPA axis only cover a brief time period, whereas hair cortisol is a unique, non-invasive means to capture long-term cortisol secretion. Studies have shown that individuals who have elevated cortisol secretion (e.g. due to diseases associated with a disturbed activation of the HPA axis or exposure to stressful life events) reveal increased hair cortisol. By contrast, only weak correlations exist between hair cortisol and perceived stress, and the direction of the relationship between hair cortisol levels and mental disorders is unclear. Acute exercise, however, results in increased levels of cortisol that eventually is reflected in higher levels of cortisol in hair samples and studies have shown that exercise intensity is related to hair cortisol level. Thus, elevated hair cortisol levels found among regular exercisers are not necessarily pathological. Thus, one should practice caution when associating athletes’ elevated hair cortisol with poor mental health or disease. Hair cortisol analysis can contribute to a more complete understanding of how long-term cortisol elevation mediates stress-related effects on the health and performance of recreational exercisers and elite athletes. Nevertheless, it is crucial for exercise and sport scientists to consider whether their research questions can be adequately addressed, given that regular intense exercise results in substantially augmented hair cortisol levels.
|
|
| 6. |
|
|
| 7. |
- Ivarsson, Andreas, et al.
(författare)
-
Psychological factors as predictors of injuries among senior soccer players : a prospective study
- 2010
-
Ingår i: Journal of Sports Science and Medicine (JSSM). - Bursa, Turkey : Dept. of Sports Medicine, Medical Faculty of Uludag University. - 1303-2968. ; 9:2, s. 347-352
-
Tidskriftsartikel (refereegranskat)abstract
- It is reported that between 65–91% of elite soccer players in Sweden have at least one injury per year (Hägglund, 2007). Several studies define different physiological and psychological factors affecting athletic injury-risk. A number of models contain proposals that specify relationships between psychological factors and an increased athletic injury-risk. Examples include Williams and Andersen’s (1998) stress-injury model and Johnson and Ivarsson’s (in press) empirical model of injury risk factors which proposes that factors such as trait anxiety and ineffective coping skills are influential. The purpose of this study was to examine the relationship between (a) personality factors, b) coping variables, and (c) stress and injury risk. Participants were 48 male soccer players from 3 Swedish teams ranging in age from 16 to 36 years (M = 22 years). Participants completed 5 questionnaires: Football Worry Scale, Swedish universities Scales of Personality, Life Events Survey for Collegiate Athletes, Daily Hassle Scale and Brief COPE. Information on injuries was collected by athletic trainers of the teams over 3-months. Results suggest injury was significantly predicted by 4 personality trait predictors: somatic trait anxiety, psychic trait anxiety, stress susceptibility, and trait irritability. Collectively, the predictors self-blame and acceptance could explain 14.6% of injury occurrence. More injuries were reported among players who score high in daily hassles. These results support previous findings (e.g. Fawkner et al., 1999). Recommendations are given for both the athletes and the trainers on working to prevent sport injuries.
|
|
| 8. |
|
|
| 9. |
- Metaxas, Thomas I, et al.
(författare)
-
Muscle fiber characteristics, satellite cells and soccer performance in young athletes.
- 2014
-
Ingår i: Journal of Sports Science and Medicine (JSSM). - 1303-2968. ; 13:3, s. 493-501
-
Tidskriftsartikel (refereegranskat)abstract
- This study is aimed to examine the muscle fiber type, composition and satellite cells in young male soccer players and to correlate them to cardiorespiratory indices and muscle strength. The participants formed three Groups: Group A (n = 13), 11.2 ± 0.4yrs, Group B (n=10), 13.1 ± 0.5yrs and Group C (n = 9), 15.2 ± 0.6yrs. Muscle biopsies were obtained from the vastus lateralis. Peak torque values of the quadriceps and hamstrings were recorded and VO2max was measured on the treadmill. Group C had lower type I percentage distribution compared to A by 21.3% (p < 0.01), while the type IIA relative percentage was higher by 18.1% and 18.4% than in Groups A and B (p < 0.05). Groups B and C had higher cross-sectional area (CSA) values in all fiber types than in Group A (0.05 < p < 0.001). The number of satellite cells did not differ between the groups. Groups B and C had higher peak torque at all angular velocities and absolute VO2max in terms of ml·min(-1) than Group A (0.05 < p < 0.001). It is concluded that the increased percentage of type IIA muscle fibers noticed in Group C in comparison to the Groups A and B should be mainly attributed to the different workload exercise and training programs. The alteration of myosin heavy chain (MHC) isoforms composition even in children is an important mechanism for skeletal muscle characteristics. Finally, CSA, isokinetic muscle strength and VO2max values seems to be expressed according to age. Key PointsFifteen years old soccer players have higher IIA percentage distribution than the younger players by approximately 18%.The age and the training status play a crucial role in muscle fibers co-expression.Specific training in young athletes seems to alter significantly the muscular metabolic profile.
|
|
| 10. |
- Mishica, Christina, et al.
(författare)
-
Relationships between Heart Rate Variability, Sleep Duration, Cortisol and Physical Training in Young Athletes
- 2021
-
Ingår i: Journal of Sports Science and Medicine (JSSM). - : Department of Sports Medicine, Medical Faculty of Uludag University. - 1303-2968. ; 20:4, s. 778-788
-
Tidskriftsartikel (refereegranskat)abstract
- The aims of the current study were to examine the relationships between heart rate variability (HRV), salivary cortisol, sleep duration and training in young athletes. Eight athletes (16 ± 1 years) were monitored for 7 weeks during training and competition seasons. Subjects were training for endurance-based winter sports (cross-country skiing and biathlon). Training was divided into two zones (K1, easy training and K2, hard training). Heart rate and blood lactate during submaximal running tests (SRT), as well as cortisol, sleep duration and nocturnal HRV (RMSSD), were determined every other week. HRV and cortisol levels were correlated throughout the 7-week period (r = -0.552, P = 0.01), with the strongest correlation during week 7 (r = -0.879, P = 0.01). The relative changes in K1 and HRV showed a positive correlation from weeks 1-3 (r = 0.863, P = 0.006) and a negative correlation during weeks 3-5 (r = -0.760, P = 0.029). The relative change in sleep during weeks 1-3 were negatively correlated with cortisol (r = -0.762, P = 0.028) and K2 (r = -0.762, P = 0.028). In conclusion, HRV appears to reflect the recovery of young athletes during high loads of physical and/or physiological stress. Cortisol levels also reflected this recovery, but significant change required a longer period than HRV, suggesting that cortisol may be less sensitive to stress than HRV. Moreover, our results indicated that during the competition season, recovery for young endurance athletes increased in duration and additional sleep may be beneficial.
|
|
| 11. |
- Mårtensson, Sandra, et al.
(författare)
-
High Training Volumes are Associated with a Low Number of Self-Reported Sick Days in Elite Endurance Athletes
- 2014
-
Ingår i: Journal of Sports Science and Medicine (JSSM). - 1303-2968. ; 13:4, s. 929-933
-
Tidskriftsartikel (refereegranskat)abstract
- It has been proposed that high exercise loads increase the risk of infection, most frequently reported as upper respiratory tract infections, by suppressing the immune system. Most athletes will not train when experiencing sickness due to the fear of health complications. However, high training volumes are incompatible with high rates of non-training days, regardless of the cause. The purpose of this observational study was to examine the relationship between self-reported, exercise-constraining days of sickness (days when the athlete decided not to train due to symptoms of disease, either self-reported or by a physician) and the volumes of exercise training in elite endurance athletes by analyzing data from training logs kept for several years. The subjects included 11 elite endurance athletes (8 male, 3 female) competing at national and international levels in cross-country skiing, biathlon and long-distance running. Training logs available from these 11 subjects added to a total of 61 training years. The number of training hours per year (462, 79-856; median, range) was significantly and negatively correlated to the reported number of days not training due to sickness (15, 0-164) by a 3rd degree polynomial regression (R-2 = 0.48, F ratio = 18, p < 0.0001). We conclude that elite endurance athletes can achieve high training volumes only if they also experience few sickdays.
|
|
| 12. |
- Perchthaler, Dennis, et al.
(författare)
-
Acute Effects of Whole-Body Vibration on Trunk and Neck Muscle Activity in Consideration of Different Vibration Loads
- 2015
-
Ingår i: Journal of Sports Science and Medicine. - 1303-2968. ; 14:1, s. 155-162
-
Tidskriftsartikel (refereegranskat)abstract
- The intention of this study was to systematically analyze the impact of biomechanical parameters in terms of different peakto- peak displacements and knee angles on trunk and neck muscle activity during whole-body vibration (WBV). 28 healthy men and women (age 23 ± 3 years) performed four static squat positions (2 peak-to-peak displacements x 2 knee angles) on a side alternating vibration platform with and without vibration stimulus. Surface electromyography (EMG) was used to record the neuromuscular activity of the erector spinae muscle, the rectus abdominis muscle, and of the splenius muscle. EMG levels normalized to maximal voluntary contractions ranged between 3.2 – 27.2 % MVC during WBV. The increase in muscle activity caused by WBV was significant, particularly for the back muscles, which was up to 19.0 % MVC. The impact of the factor ‘condition’ (F-values ranged from 13.4 to 132.0, p ≤ 0.001) and of the factor ‘peak-to-peak displacement’ (F-values ranged from 6.4 to 69.0 and p-values from < 0.001 to 0.01) were statistically significant for each muscle tested. However, the factor ‘knee angle’ only affected the back muscles (F-value 10.3 and 7.3, p ≤ 0.01). The results of this study should give more information for developing effective and safe training protocols for WBV treatment of the upper body.
|
|
| 13. |
- Petré, Henrik, et al.
(författare)
-
The Effect of Two Different Concurrent Training Programs on Strength and Power Gains in Highly-Trained Individuals.
- 2018
-
Ingår i: Journal of Sports Science and Medicine (JSSM). - 1303-2968. ; 17:2, s. 167-173
-
Tidskriftsartikel (refereegranskat)abstract
- The effects of concurrent strength and endurance training have been well studied in untrained and moderately-trained individuals. However, studies examining these effects in individuals with a long history of resistance training (RT) are lacking. Additionally, few studies have examined how strength and power are affected when different types of endurance training are added to an RT protocol. The purpose of the present study was to compare the effects of concurrent training incorporating either low-volume, high-intensity interval training (HIIT, 8-24 Tabata intervals at ~150% of VO2max) or high-volume, medium-intensity continuous endurance training (CT, 40-80 min at 70% of VO2max), on the strength and power of highly-trained individuals. Sixteen highly-trained ice-hockey and rugby players were divided into two groups that underwent either CT (n = 8) or HIIT (n = 8) in parallel with RT (2-6 sets of heavy parallel squats, > 80% of 1RM) during a 6-week period (3 sessions/wk). Parallel squat performance improved after both RT + CT and RT + HIIT (12 ± 8% and 14 ± 10% respectively, p < 0.01), with no difference between the groups. However, aerobic power (VO2max) only improved after RT + HIIT (4 ± 3%, p < 0.01). We conclude that strength gains can be obtained after both RT + CT and RT + HIIT in athletes with a prior history of RT. This indicates that the volume and/or intensity of the endurance training does not influence the magnitude of strength improvements during short periods of concurrent training, at least for highly-trained individuals when the endurance training is performed after RT. However, since VO2max improved only after RT + HIIT and this is a time efficient protocol, we recommend this type of concurrent endurance training.
|
|
| 14. |
- Pojskić, Haris, 1978-, et al.
(författare)
-
Reliability, Validity and Usefulness of a New Response Time Test for Agility-Based Sports : A Simple vs. Complex Motor Task
- 2019
-
Ingår i: Journal of Sports Science and Medicine (JSSM). - : Uludag University, Turkey. - 1303-2968. ; 18:4, s. 623-635
-
Tidskriftsartikel (refereegranskat)abstract
- The importance of response time (RT) in sports is well known, but there is an evident lack of reliable and valid sport-specific measurement tools applicable in the evaluation of RT in trained athletes. This study aimed to identify the validity, reliability, and usefulness of four newly developed RT testing protocols among athletes from agility-saturated (AG) and non-agility-saturated (NAG) sports. Thirty-seven AG and ten NAG athletes (age: 20.9± 2.9; eleven females) volunteered to undergo: three randomized simple response time (SRT-1, SRT-2, and SRT-3) protocols that included a single limb movement, and one complex response time (CRT) protocol that included multi joint movements and whole body transition over a short distance (1.5 and 1.8m). Each RT test involved 3 trials with 5 randomized attempts per trial. Two sensors were placed at the left- and right-hand side for SRT-1 and SRT-2. Three sensors were positioned (left, middle, right) in SRT-3 and CRT. The intra-class-correlation coefficient (ICC) was calculated as a measure of reliability. Independent sample t test, effect size (d), and area-under-the-curve (AUC) were calculated to define discriminative validity of the tests. The results showed the newly developed tests were more reliable and useful in the AG than NAG athletes (i.e., ICC between 0.68 and 0.97versus 0.31 - 0.90, respectively). The RT of AG athletes was faster than that of NAG athletes in the CRT test from the left (p<0.01, d = 2.40, AUC: 0.98), centre (p < 0.01, d = 1.57, AUC:0.89), and right sensor (p < 0.01, d = 1.93, AUC: 0.89) locations. In contrast, there were no differences between the groups in the SRT tests. The weak correlation (i.e., r= 0.00 - 0.33) between the SRT and CRT tests suggests that response time of the single limb and multijoint limb movements should not be considered as a single motor capacity. In conclusion, this study showed that AG athletes had faster response time than their NAG peers during complex motor tasks. Such enhanced ability to rapidly and accurately reprogram complex motor tasks can be considered one of the essential qualities required for advanced performance in agility based sports.
|
|
| 15. |
- Pojskić, Haris, 1978-, et al.
(författare)
-
The Reliability and Validity of a Novel Sport-Specific Balance Test to Differentiate Performance Levels in Elite Curling Players
- 2020
-
Ingår i: Journal of Sports Science and Medicine (JSSM). - : JSSM. - 1303-2968. ; 19:2, s. 337-346
-
Tidskriftsartikel (refereegranskat)abstract
- Balance as a skill and task-specific capacity is considered an essential physical quality in curling, required for executing effective stone delivery. However, no testing protocols have been developed to test curling-specific balance in the delivery position. Thus, the primary aim of this study was to investigate the reliability, validity and usefulness of a newly-developed, curling-specific balance test (CSBT) which involved the delivery position. The secondary aim was to examine the differences between elite and sub-elite curlers for core strength and flexibility, which have previously been identified as important qualities in curling and determinants of balance. Twenty curling players (13 females aged 19 ± 3.1 years; 7 males aged 19.6 ± 2.3 years) from five Swedish super-league curling clubs were divided into two groups according to playing level: elite and sub-elite. Variables included body mass, body height, body mass index, age, playing experience, training frequency, plank test, sit and reach test, standing single-leg balance test (SLBT) and CSBT. The CSBT was executed on a multiaxial tilting balance plate while mimicking the curling delivery position (i.e., a deep lunge position with the front foot on the plate). The participants completed the CSBT on three separate occasions, with each test consisting of three, 20-s attempts. Both the relative and absolute reliability were good for the CSBT (ICC = 0.90; CV = 14.5%). The CSBT demonstrated good measurement usefulness, being sensitive to detect moderate changes that exceeded 0.5 times the test standard deviation. Construct validity of the CSBT was evidenced by the large discriminatory capacity to differentiate expertise level in curling players (t-test: 2.85, p < 0.01; large ES), irrespective of other physical capacities (e.g., flexibility and core strength). However, the elite and sub-elite players also differed in age, playing experience and training frequency. Content validity was confirmed by a weak correlation (r = 0.21; 95%CI: -0.26 to 0.60) between the CSBT and SLBT, which suggests that curling-specific and standing balance should be considered as independent and task-specific motor skills. In conclusion, the CSBT can be used as a reliable, valid and useful tool for the assessment of curling-specific balance performance. In addition, longer and more extensive involvement in curling training contributed to superior specific balance in elite curlers.
|
|
| 16. |
- Poulios, A., et al.
(författare)
-
Protein-Based Supplementation to Enhance Recovery in Team Sports: What is the Evidence?
- 2019
-
Ingår i: Journal of Sports Science and Medicine. - 1303-2968. ; 18:3, s. 523-536
-
Tidskriftsartikel (refereegranskat)abstract
- Protein supplementation is a major nutritional practice among professional and amateur team-sport athletes representing a market of $5 billion in the USA alone. This practice, however, may not be supported by evidence-based science. Our objective as to present a thorough review of literature investigating the effects of protein supplementation on performance recovery and exercise-induced muscle damage following team-sport activity. PubMed-derived, full English language articles investigating the effects of protein-based supplementation/feeding on skeletal muscle performance, muscle damage and inflammatory status during recovery following team-sport activity were included. Studies investigated professional or amateur team-sport athletes participating in regular training and competition as well as examining the impact of protein supplementation on performance, muscle damage/soreness and inflammatory markers after team-sport activity. Finally, ten articles (150 participants) met the inclusion criteria. Experimental designs were evaluated for confounders. All protocols employing team-sport activity increased systemic muscle damage indicators and inflammatory markers and deteriorated performance during recovery. Protein-based supplementation attenuated the rise in muscle damage markers and enhanced performance recovery in six (60% of the studies included) and three (30% of the studies included) out of 10 studies, respectively. In contrast, immunity and muscle soreness remained unaffected by protein ingestion, independent of dosage and distribution pattern. In conclusion, there are limited and inconsistent data showing that protein supplementation may enhance performance recovery following team-sport activity despite an attenuation of indirect markers of muscle damage. Interpretation of results is limited by small sample sizes, high variability in tested supplements, participants' training level, length of recovery periods, absence of direct measurement of myofibrillar disruption, protein turnover and protein metabolism, and lack of dietary monitoring during experimentation.
|
|
| 17. |
- Sommer, Marius, 1974-, et al.
(författare)
-
Improved motor-timing : effects of synchronized metronome training on golfshot accuracy
- 2009
-
Ingår i: Journal of Sports Sciences & Medicine. Free electronic journal. - Ankara / Turkey : Asist Group. - 1303-2968. ; 8:4, s. 648-656
-
Tidskriftsartikel (refereegranskat)abstract
- This study investigates the effect of synchronized metronome training (SMT) on motor timing and how this training might affect golf shot accuracy. Twenty-six experienced male golfers participated (mean age 27 years; mean golf handicap 12.6) in this study. Pre- and post-test investigations of golf shots made by three different clubs were conducted by use of a golf simulator. The golfers were randomized into two groups: a SMT group and a Control group. After the pre-test, the golfers in the SMT group completed a 4-week SMT program designed to improve their motor timing, the golfers in the Control group were merely training their golf-swings during the same time period. No differences between the two groups were found from the pre-test outcomes, either for motor timing scores or for golf shot accuracy.However, the post-test results after the 4-weeks SMT showed evident motor timing improvements. Additionally, significant improvements for golf shot accuracy were found for the SMT group and with less variability in their performance. No such improvements were found for the golfers in the Control group. As with previous studies that used a SMT program, this study’s results provide further evidence that motor timing can be improved by SMT and that such timing improvement also improves golf accuracy.
|
|
| 18. |
- Sperlich, Paula F., et al.
(författare)
-
Individual versus Standardized Running Protocols in the Determination of VO2max
- 2015
-
Ingår i: Journal of Sports Science and Medicine (JSSM). - 1303-2968. ; 14:2, s. 386-393
-
Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was to determine whether an individually designed incremental exercise protocol results in greater rates of oxygen uptake (VO2max) than standardized testing. Fourteen well-trained, male runners performed five incremental protocols in randomized order to measure their VO2max: i) an incremental test (INCS+I) with pre-defined increases in speed (2 min at 8.64 km.h(-1), then a rise of 1.44 km.h(-1) every 30 s up to 14.4 km.h(-1)) and thereafter inclination (0.5.every 30 s); ii) an incremental test (INCI) at constant speed (14.4 km.h(-1)) and increasing inclination (2 degrees every 2 min from the initial 0 degrees); iii) an incremental test (INCS) at constant inclination (0 degrees) and increasing speed (0.5 km.h(-1) every 30 s from the initial 12.0 km.h(-1)); iv) a graded exercise protocol (GXP) at a 1 degrees incline with increasing speed (initially 8.64 km.h(-1) + 1.44 km.h(-1) every 5 min); v) an individual exercise protocol (INDXP) in which the runner chose the inclination and speed. VO2max was lowest (-4.2%) during the GXP (p = 0.01; d = 0.06 - 0.61) compared to all other tests. The highest rating of perceived exertion, heart rate, ventilation and end-exercise blood lactate concentration were similar between the different protocols (p < 0.05). The time to exhaustion ranged from 7 min 18 sec (INCS) to 25 min 30 sec (GXP) (p = 0.01). The VO2max attained by employing an individual treadmill protocol does not differ from the values derived from various standardized incremental protocols.
|
|
| 19. |
- Stöggl, Thomas, et al.
(författare)
-
A Systematic Review of the Effects of Strength and Power Training on Performance in Cross-Country Skiers
- 2022
-
Ingår i: Journal of Sports Science and Medicine (JSSM). - : Department of Sports Medicine, Uludag University. - 1303-2968. ; 21:4, s. 555-579
-
Forskningsöversikt (refereegranskat)abstract
- To identify and evaluate current scientific literature concerning the effect of strength, power and speed training on relevant phys-iological and biomechanical characteristics and performance of competitive cross-country skiers (XCS), the databases Scopus and PubMed were searched systematically for original articles in peer-reviewed journals. Of the 599 studies retrieved, 12 met the inclusion criteria (i.e., assessment of outcome measures with rel-evance for XCS performance; involvement of traditional re-sistance training; application of external resistance to the body; intervention longer than 4 weeks; randomized controlled trial). The methodological rigor of each study was assessed using the PEDro scale, which were mostly poor-to-fair, with good method-ological quality in only two articles. All of the strength/power/speed interventions improved 1RM (0.8 -6.8 ES), but findings with respect to jump performance, ability to generate force rapidly and body composition were mixed. Interventions demonstrated moderate-to-high ES on XCS specific performance compared with control (mean ES = 0.56), but the pattern observed was not consistent. None of the interventions changed anaerobic capacity, while in most studies VO2max was either unchanged or increased. Work economy or efficiency was enhanced by most of the interventions. In conclusion, present research indicates that strength training improves general strength, with moderate effects on XCS performance, and inconclusive effects on work economy and VO2max/VO2peak. Strength training with high loads, explosive strength training, or sprint interval training seem to be promising tools for modern XCS training. Future investigations should in-clude long-term (e.g., >6 months) strength training to allow suf-ficient time for increased strength and speed to influence actual XCS performance. Moreover, they should include both sexes, as well as upper-and lower-body muscles (trained separately and together) and employ free weights and core training. Methodo-logical differences and limitations highlighted here may explain discrepancies in findings and should be taken into consideration in future research in this area.
|
|
| 20. |
- Stöggl, Thomas, et al.
(författare)
-
Impact of incline, sex and level of performance on kinematics during a distance race in classical cross-country skiing
- 2018
-
Ingår i: Journal of Sports Science and Medicine (JSSM). - 1303-2968. ; 17:1, s. 124-133
-
Tidskriftsartikel (refereegranskat)abstract
- Here, female and male elite cross-country (XC) skiers were compared on varying terrain during an official 10-km (women) and 15-km (men) Norwegian championship race. On the basis of race performance, 82 skiers were classified as fast (FS) (20 women, 20 men) or slower (SS) (21, 21) skiers. All were video recorded on flat (0°), intermediate (3.5°), uphill (7.1°) and steep uphill (11°) terrain during the race at a distance of 0.8, 1.2, 2.1 and 7.1 km from the start, respectively. All skiers employed exclusively double-poling (DP) on the flat section and, except for the male winner, exclusively diagonal stride (DIA) on the uphill sections. On the intermediate section, more men than women utilized DP and fewer DIA (p = 0.001), with no difference in kick double-poling (DPK). More FS than SS utilized DPK and fewer DIA (p = 0.001), with similar usage of DP. Males skied with faster and longer cycles but lower cycle rate compared with females (p < 0.001), with largest absolute sex differences on flat terrain (p < 0.001) and largest relative differences for cycle velocity and length on intermediate and uphill terrain. External power output rose with increasing incline, being higher for men and FS (p < 0.001). Cycle velocity on flat terrain was the best predictor of mean race velocity for the men, while cycle velocity on steep uphill was the best predictor for the women (both p < 0.001). In conclusion, incline, sex and level of performance influenced cycle characteristics and power output. Greatest absolute sex gap was on flat terrain, whereas the relative difference was greatest on intermediate and steep uphill terrain. We recommend usage of more DP and/or DPK, and less DIA and fewer transitions between techniques on intermediate terrain. Predictors of race performance are sex specific with greatest potential for enhancing performance on flat terrain for men and on steep uphill terrain for women.
|
|
| 21. |
- Timpka, Toomas, et al.
(författare)
-
Protocol Design for Large-Scale Cross-Sectional Studies of Sexual Abuse and Associated Factors in Individual Sports : Feasibility Study in Swedish Athletics
- 2015
-
Ingår i: Journal of Sports Science and Medicine (JSSM). - : JOURNAL SPORTS SCIENCE & MEDICINE, MEDICAL FACULTY ULUDAG UNIV, DEPT SPORTS MEDICINE, BURSA, TURKEY. - 1303-2968. ; 14:1, s. 179-187
-
Tidskriftsartikel (refereegranskat)abstract
- To ensure health and well-being for their athletes, sports organizations must offer preventive measures against sexual abuse. The aim of this study was to design and evaluate feasibility of a research protocol for cross-sectional epidemiological studies of sexual abuse in athletics. Examination of the requirements on the study of sexual abuse in athletics was followed by iterated drafting of protocol specifications and formative evaluations. The feasibility of the resulting protocol was evaluated in a national-level study among elite athletics athletes (n = 507) in Sweden. The definition of sexual abuse, the ethical soundness of the protocol, reference populations and study of co-morbidity, and the means for athlete-level data collection were identified as particularly complex issues in the requirements analyses. The web-based survey defined by the protocol facilitates anonymous athlete self-reporting of data on exposure to sexual abuse. 198 athletes (39%) fully completed the feasibility survey. 89% (n = 177) reported that they agreed with that the questions in the survey were important, and 95% (n = 189) reported that they answered truthfully to all questions. Similarly, 91% (n = 180) reported that they did not agree with that the questions were unpleasant for them. However, 16% (n = 32) reported that they did not find the survey to be of personal value, and 12% (n = 23) reported that the survey had caused them to think about issues that they did not want to think about. Responding that participation was not personally gratifying was associated with training more hours (p = 0.01). There is a scarcity of research on the prevention of sexual abuse in individual sports. The present protocol should be regarded as a means to overcome this shortcoming in athletics. When implementing the protocol, it is necessary to encourage athlete compliance and to adapt the web-based survey to the particular infrastructural conditions in the sports setting at hand.
|
|
