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H:Q Ratios and Bilateral Leg Strength in College Field and Court Sports Players

100%
Cheung R., Smith A., Wong D.
Journal of Human Kinetics
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2012
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vol. 33
63-71
EN
One of the key components in sports injury prevention is the identification of imbalances in leg muscle strength. However, different leg muscle characteristics may occur in large playing area (field) sports and small playing area (court) sports, which should be considered in regular injury prevention assessment. This study examined the isokinetic hamstrings-to-quadriceps (H:Q) ratio and bilateral leg strength balance in 40 male college (age: 23.4 ± 2.5 yrs) team sport players (field sport = 23, soccer players; court sport = 17, volleyball and basketball players). Five repetitions of maximal knee concentric flexion and concentric extension were performed on an isokinetic dynamometer at two speeds (slow: 60 °·s-1 and fast: 300°·s-1) with 3 minutes rest between tests. Both legs were measured in counterbalanced order with the dominant leg being determined as the leg used to kick a ball. The highest concentric peak torque values (Nm) of the hamstrings and quadriceps of each leg were analyzed after body mass normalization (Nm·kg-1). Court sport players showed significantly weaker dominant leg hamstrings muscles at both contraction speeds (P < 0.05). The H:Q ratio was significantly larger in field players in their dominant leg at 60°·s-1 (P < 0.001), and their non-dominant leg at 300°·s-1 (P < 0.001) respectively. Sport-specific leg muscle strength was evident in college players from field and court sports. These results suggest the need for different muscle strength training and rehabilitation protocols for college players according to the musculature requirements in their respective sports.
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Gender Differences in Postural Stability Among Children

100%
Smith A., Ulmer F., Wong D.
Journal of Human Kinetics
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2012
|
vol. 33
25-32
EN
This study aimed to examine the gender differences in postural stability among 8-12 year-old children. Twenty-six children participated in this repeated measures study to measure the centre of pressure (COP) under one normal condition (CONTROL: hard surface, eyes open, and looking straight ahead) and two challenging sensory conditions (ECHB: eyes closed and head back; and EOCS: eyes open and compliant surface) in randomized order. Girls had significantly lower COP path velocity (COP-PV, p < 0.05, medium effect), smaller radial displacement (COP-RD, p < 0.05, medium effect), and lower area velocity (COP-AV, p < 0.05, medium effect) as compared to boys when the three conditions were pooled. Gender differences were found in the percentage changes in COP-RD during ECHB (p < 0.05, large effect) and EOCS (p < 0.05, medium effect), and in COP-AV during both ECHB and EOCS conditions (p < 0.05, medium effect). Postural stability performance of girls had higher correlations with age (-0.62 vs. -0.40), body mass (-0.60 vs. -0.42), foot length (-0.68 vs. -0.45), and physical activity level (-0.45 vs. 0.02), as compared to boys. Girls had better postural stability than boys but were more affected by altered sensory input information. Girls are more capable of integrating their sensory inputs, whereas boys treat each sensory input somewhat separately and rely more on somatosensory feedback. Exercises such as standing on unstable surfaces with eyes open instead of eye closed and head back are more beneficial to children's postural stability control system.
3
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Heart Rate Responses and Training Load During Nonspecific and Specific Aerobic Training in Adolescent Taekwondo Athletes

88%
Haddad M., Chaouachi A., Wong D., Castagna C., Chamari K.
Journal of Human Kinetics
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2011
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vol. 29
59-66
EN
The efficacy of replacing generic running with Taekwondo (TKD) specific technical skills during interval training at an intensity corresponding to 90-95% of maximum heart rate (HRmax) has not yet been demonstrated. Therefore, the purpose of this study was to compare the HR responses and perceived exertion between controlled running and high-intensity TKD technical interval training in adolescent TKD athletes. Eighteen adolescent, male TKD athletes performed short-duration interval running and TKD specific technical skills (i.e. 10-20 [10-s of exercise interspersed with 20 s of passive recovery]) in a counterbalanced design. In both training methods, HR was measured and expressed as the percentage of HR reserve (%HRres). Rating of perceived exertion (RPE, Borg's category rating-10 scale), Banister's training impulse (TRIMP) and Edwards' training load (TL) were used to quantify the internal training load. Recorded cardiovascular responses expressed in %HRres in the two training methods were not significantly different (p > 0.05). Furthermore, the two training methods induced similar training loads as calculated by Banister and Edwards' methods. Perceived exertion ranged between "hard" and "very hard" during all interval training sessions. These findings showed that performing repeated TKD specific skills increased HR to the same level, and were perceived as producing the same training intensity as did short-duration interval running in adolescent TKD athletes. Therefore, using specific TKD kicking exercises in high-intensity interval training can be applied to bring more variety during training, mixing physical and technical aspects of the sport, while reaching the same intensity as interval running.
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