| 1. |
- Alghadir, Ahmad H., et al.
(författare)
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Effect of voluntary teeth clenching and sitting posture on maximal static force of limb muscles
- 2019
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Ingår i: Journal of Sports Medicine and Physical Fitness. - Turin : Edizioni Minerva Medica. - 0022-4707 .- 1827-1928. ; 59:5, s. 774-778
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: People clench their teeth to activate facial, neck and abdominal muscles when they need to generate heavy muscle force against large resistance like lifting heavy objects, in order to gain possible ergogenic advantage. These are termed as remote voluntary contractions. Aim of this study was to evaluate the effect of voluntary teeth clenching on maximal voluntary contraction of extensors and flexors of the knee, shoulder and elbow joints of the dominant side during slouch and unsupported upright sitting.METHODS: One hundred healthy young male adults (mean age 23.3 years) participated in this study. Maximal voluntary contraction was measured using a hand-held dynamometer.RESULTS: Jaw clenching caused different ergogenic effect during slouch versus unsupported sitting postures. The data revealed that during unsupported upright sitting, the effect of jaw clenching consistently results in larger maximal voluntary contraction of both extensor and flexor muscles of all the three studied joints. However, during slouch sitting, only the maximal voluntary contraction of extensors of elbow and flexors of knee were larger with clenched teeth position.CONCLUSIONS: Jaw clenching can affect the maximal voluntary contraction of limb muscles which is sitting posture dependent. Jaw clenching can consistently facilitate certain muscles of the upper and lower limbs to generate greater force production during upright sitting.
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| 2. |
- Bengtsson, Victor, et al.
(författare)
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Could the negative effects of static stretching in warm-up be restored by sport specific exercise?
- 2018
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Ingår i: Journal of Sports Medicine and Physical Fitness. - : Edizioni Minerva Medica. - 0022-4707 .- 1827-1928. ; 58:9, s. 1185-1189
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Static stretching (SS) is widely used in warm-up as it is generally believed to increase mobility and reduce the risk of injury; however, SS has been shown to induce transient negative effects on subsequent muscle performance. Interestingly, recent studies have shown that sport specific exercise could restore SS-induced negative effects on certain sports, especially of explosive muscular performance. Whether sport specific exercise could restore SS-induced negative effects on isokinetic muscle performance remains unclear.METHODS: The present study conducted two different warm-ups: 2-component warm-up and 3-component warm-up on 15 university students. Both protocols contained low intensity aerobic exercise and sport specific exercise, whereas the 3-component warm-up also contained SS which has been previously proven to induce negative effects on subsequent muscle performance. After the warm-ups, the subjects performed an isokinetic test on a Biodex. To make the sport specific exercise mimic the subsequent test, both included concentric isokinetic knee extension. During the tests, muscle performance of peak torque, mean power, and total work was recorded. Comparison of the measurements on each parameter between the two warm-ups was performed using paired t test.RESULTS: The comparisons did not reveal any significant difference in the measurement of any parameter between the two different warm-up protocols, and calculation of Cohen's revealed small effect sizes on all of the three variables.CONCLUSIONS: On basis of the present results and that the SS could induce transient negative effects on subsequent muscle performance, we concluded that the negative effects of the SS on the variables were restored by the isokinetic contractions.
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| 3. |
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| 4. |
- Carlsson, Magnus, et al.
(författare)
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The acute effects of a short technique-intense training period on side-foot kick performance among elite female soccer players
- 2019
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Ingår i: Journal of Sports Medicine and Physical Fitness. - 0022-4707 .- 1827-1928. ; 59:9, s. 1442-1449
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Previously, it was shown that elite soccer teams were 24% more likely to win matches if their passing effectiveness were increased by 1%. However, research interventions aiming to improve passing performance are scarce. The current study aimed to investigate the effect of a short technique-intense training period on side-foot kick performance among elite female soccer players.METHODS: Four side-foot kick tests were completed before and after a training period: kicking a stationary ball using match-relevant (SBRS) and maximal ball speed (SBMS), passing the ball on the move using match-relevant ball speed (RBRS), and repeated side-foot kicks onto a rebound-box with continuously increasing passing distance (RRB). The players were assigned to either the intervention group or the control group. The training intervention consisted of six 55-min training sessions with five side-foot kick exercises. Within-group and between-group differences were investigated using paired-samples t-test and Mann-Whitney U test, respectively.RESULTS: The intervention group improved the performance in the RBRS and RRB tests (both P < 0.05), but no differences were found for the SBRS and SBMS tests (both P > 0.05). No improvements were found for the control group independent of test condition (all P > 0.05). Significant between-group differences were found for the RBRS and RRB tests (both P < 0.05), whereas no differences were found for the SBRS and SBMS tests (both P > 0.05).CONCLUSIONS: The fundamental soccer skill of passing a moving ball was improved in elite female soccer players by a short technique-intense training period.
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| 5. |
- Iglesias, Xavier, et al.
(författare)
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Physiological demands of standing and wheelchair fencing in able-bodied fencers
- 2019
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Ingår i: Journal of Sports Medicine and Physical Fitness. - : Edizioni Minerva Medica. - 0022-4707 .- 1827-1928. ; 59:4, s. 569-574
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The purpose of this study was to determine the cardiorespiratory demands of standing and wheelchair (seated) fencing in a group of able-bodied fencers during simulated competitive bouts.METHODS: Participants were ten male able-bodied fencers of regional level with previous training experience in wheelchair fencing. After a standardised warm-up participants performed two series of simulated competitive épée bouts (5 and 15 touches) in a random order, either while standing or while sitting in a wheelchair. Expired gas was analyzed for oxygen consumption (V̇ O2) and respiratory exchange ratio (RER) and heart rate were continually monitored. Energy expenditure (EE) was subsequently calculated.RESULTS: V̇ O2, HR and EE peak responses were greater during standing than seated fencing (p< .05). Mean V̇ O2 during all ST bouts (5 and 15 touch) was 43% greater than in WC fencing (44.2 ± 7.8 vs. 25.1 ± 5.4 ml·kg-1·min-1). Mean HR during the standing 5 and 15 touch bouts was 91% ± 20% and 84% ± 7% of that recorded during the seated bouts. HR,V̇O2 and EE data also indicated that the 15-touch bouts were more physiologically demanding than the 5-touch bouts (P < .01). The HR-V̇ O2 relationship was similar between both fencing modes. The duration of the 5 and 15 touch bouts were shorter for the seated than the standing bouts (P < .01).CONCLUSIONS: The physiological demands of wheelchair fencing are lower than those for standing fencing. Furthermore, the physiology of 5 vs. 15 touch bouts, similar to those undertaken in fencing competition, also differs.
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| 6. |
- Malmgren, Andreas, et al.
(författare)
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Cardiac dimensions and function in female handball players.
- 2015
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Ingår i: Journal of Sports Medicine and Physical Fitness. - : Minerva Medica. - 0022-4707 .- 1827-1928. ; 55:4, s. 320-328
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Tidskriftsartikel (refereegranskat)abstract
- AIM: Long-term intensive endurance training leads to increased left ventricular mass and increased left ventricular end-diastolic and left atrial end-systolic diameters. Different types of sports tend to give rise to distinct morphological forms of the athlete's heart. However, the sport-specific aspects have not been fully investigated in female athletes. The purpose of the present study was to investigate differences in left and right cardiac dimensions, cardiac volumes, and systolic and diastolic function in elite female handball players compared to sedentary controls. METHODS: A cross-sectional study of 33 elite female handball players was compared to 33 matched sedentary controls. Mean age was 21.5±2 years. The subjects underwent echocardiography examinations, both 2-dimensional (2DE) and 3-dimensional (3DE). Cardiac dimensions and volumes were quantified using M-mode, 2DE and 3DE. Systolic and diastolic left ventricular functions were also evaluated. All cardiac dimensions and volumes were adjusted for body surface area (BSA). RESULTS: Left atrium and left ventricle volumes were significantly (P<0.001) larger in elite female handball players compared with sedentary controls. Even right atrium area as well as right ventricular end-diastolic and end-systolic area were significantly (P<0.001) larger in elite female handball players. Significant differences were observed in three out of five systolic parameters. Most diastolic function parameters did not differ between the two groups. CONCLUSION: The findings from the present study suggest that similar cardiac remodeling takes place in elite female handball players as it does in athletes pursuing endurance or team game sports.
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| 7. |
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| 8. |
- Rago, Vincenzu, et al.
(författare)
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Variability of activity profile during medium-sided games in professional soccer
- 2019
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Ingår i: The Journal of Sports Medicine and Physical Fitness. - 1827-1928. ; 59:4, s. 547-554
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: In Southern European countries it is very frequent to perform medium-sized games (MSG) as last training drill. We analyzed the individual variability and changes in activity patterns during MSG throughout the preseason. METHODS: Activity profile during MSGs (10v10+goalkeepers, duration: 10-min, field length: 50 m, width: 90 m, area per player: 204.5 m2) was quantified using a GPS in 14 professional male players (6 defenders, 5 midfielders 5 and attackers). RESULTS: Inter-individual variability was higher for high-intensity (HIR), very-high speed (VHS), maximum acceleration (Accmax) and maximum deceleration (Decmax) distance (CV=25.2 to 43.3%), compared to total distance (TD), total acceleration (Acctot) and total deceleration (Dectot) distance (CV= 8.3 to 18.3 %). Defenders showed higher variability in TD, HIR, VHS, Acctot and Dectot (ES= 1.30 to 11.28) compared to the other field positions, whereas attackers showed higher variability in HIR, VHS Accmax and Decmax (ES=-4.92 to 2.07) than other the field positions. Variability in TD regularly increased (ES= -2.13 to -0.91) towards the end of the preseason, while HIR and VHS variability tended to increase over the 3rd and the 4th preseason week (ES=-0.94 to -3.05). However, the behavior of variability across the preseason period was more unpredictable for Acctot and Dectot, both decreasing in the 3rd week (ES= 0.70 to 1.20), while Decmax increased in the 4th week (ES=-0.91±0.59). CONCLUSIONS: During MSGs, individual variability of activity differs among field positions, and tends to increase with either speed or acceleration intensity, underlining the need of an individualized approach for training load monitoring.
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| 9. |
- Rano, Jacqueline, et al.
(författare)
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Effects of acute psychological stress on athletic performance in elite male swimmers
- 2019
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Ingår i: Journal of Sports Medicine and Physical Fitness. - 0022-4707 .- 1827-1928. ; 59:6, s. 76-1068
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: While physical activity has been shown to affect psychological as well as physiological stress responses, less research has explored the effects of acute stress on athletic performance. The current study hence aimed to investigate the effect of an Acute Psychological Stress (APS) provocation on performance and plasma lactate concentration during a following 200m swim race among male elite swimmers. Furthermore, associations between physiological stress responses (salivary cortisol and testosterone), and outcome measures (speed and lactate) were explored.METHODS: Twenty-three elite male swimmers participated in an experimental counterbalanced within-group repeated measures design consisting of an APS provocation followed by a 200m race and, on a separate day, a control race without prior stress exposure. Salivary cortisol and testosterone were collected prior to each race. Race time was recorded, and serum lactate were collected immediately following, and five min after completed race.RESULTS: Race speed was significantly slower (1.53 (95% CI: 0.08-2.79) seconds) following the APS provocation than under control conditions. Pre-race cortisol levels were positively associated with lactate response when preceding stress exposure was present (rho =.483 immediately, and rho=.429 five minutes post race, p's<0.05). Under control conditions however, both increased testosterone (rho= -657, p=0.001) and cortisol (rho= -.491, p=0.020) levels were associated with faster race times.CONCLUSIONS: The results indicated a negative impact of APS exposure on athletic performance. Further, potential beneficial effects on performance from physiological stress responses (as reflected by salivary cortisol and testosterone) may be diminished during performance following an APS provocation, compared with a regular non-provoked performance situation.
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| 10. |
- Ryman Augustsson, Sofia, et al.
(författare)
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Jump height as performance indicator for the selection of youth football players to national teams
- 2019
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Ingår i: Journal of Sports Medicine and Physical Fitness. - Turin : Edizioni Minerva Medica. - 0022-4707 .- 1827-1928. ; 59:10, s. 1669-1675
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Tidskriftsartikel (refereegranskat)abstract
- Background: Different jump tests such as the Countermovement Jump (CMJ), Abalakov Jump (AJ) and Standing Long Jump (SLJ) are often used in practice to evaluate muscular power and functional performance in football. These tests are also used in different selection processes and talent identification, but the significance of the tests for the selection of youth players to national teams are relatively unknown. The aim of this study was to compare jump ability between youth football players selected or not selected for the national team.Methods: In this cross-sectional study, 22 players (aged 17±2 years), 11 national players (NP) and 11 non-national players (NNP) were evaluated in three different jump tests; CMJ, AJ and SLJ. Mean scores for the tests were analyzed and compared.Results: Significant differences were found between the groups regarding jump height in favor of the NP group in both the CMJ (NP 39.9±5.0 cm vs. NNP 34.2±4.9 cm, P=0.013) and the AJ (NP 47.1±5.4 vs. NNP 40.9±4.7, P=0.010). No group difference was found regarding jump length in SLJ (NP 246.2±17.9 vs. NNP 232.9±16.5, P=0.084).Conclusions: The results suggest that tests, measuring jump height, could be used as a performance indicator and part of the selection process of youth football players to national teams, whereas the use of jump length could be questioned. Copyright © 2019 Edizioni Minerva Medica
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