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Gender Differences in Postural Stability Among Children

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Smith A., Ulmer F., Wong D.

Journal of Human Kinetics

2012

vol. 33

25-32

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.

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

100%

Cheung R., Smith A., Wong D.

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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2 Journal of Human Kinetics

2 2012

2 Smith A.

2 Wong D.

1 Cheung R.

1 Ulmer F.

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Gender Differences in Postural Stability Among Children

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