The effects of leg preference and leg dominance on static and dynamic balance performance in highly-trained tennis players

Symmetric unipedal balance in quiet stance and dynamic tasks in older individuals

Previous evidence of increased difference of muscular strength between the dominant and non-dominant legs in older adults suggests the possibility of dissimilar balance control between the legs (between-leg asymmetry) associated with aging. In the current investigation, we evaluated between-leg asymmetries in older adults when performing quiet and dynamic balance tasks. Fifty-two physically active and healthy older adults within the age range of 60 to 80 years were recruited. Participants performed balance tasks in unipedal stance, including quiet standing and cyclic sway (rhythmic oscillation) of the non-supporting leg in the anteroposterior or mediolateral directions, producing foot displacements with amplitudes of 20 cm paced in 1 Hz through a metronome. Body balance was evaluated through trunk accelerometry, by using the sensors embedded into a smartphone fixed at the height of the 10th-12th thoracic spines. Analysis revealed lack of significant differences in balance control between the legs either when comparing the right versus left or the preferred versus non-preferred legs, regardless of whether they were performing quiet stance or dynamic tasks. Further examination of the data showed high between-leg correlation coefficients (rs range: 0.71-0.84) across all tasks. Then, our results indicated symmetric and associated between-leg balance control in the examined older adults.

Sport-specific training induced adaptations in postural control and their relationship with athletic performance

Effects of various exercise programs on postural balance control in athletes and their underlying physiological mechanisms have been extensively investigated. However, little is known regarding how challenging sport-specific conditions contribute to the improvement of body balance and to what extent these changes may be explained by sensorimotor and/or neuromuscular function adaptations. Analysis of the literature could provide useful information on the interpretation of changes in postural sway variables in response to long-term sport-specific training and their association with performance measures. Therefore, the aim of this scoping review was (1) to analyze the literature investigating postural control adaptations induced by sport-specific training and their relationship with measures of athletic performance, and (2) to identify gaps in the existing research and to propose suggestions for future studies. A literature search conducted with Scopus, Web of Science, MEDLINE and Cochrane Library was completed by Elsevier, SpringerLink and Google Scholar with no date restrictions. Overall, 126 articles were eligible for inclusion. However, the association between variables of postural balance control and measures of sport-specific performance was investigated in only 14 of the articles. A relationship between static and/or dynamic balance and criterion measures of athletic performance was revealed in shooting, archery, golf, baseball, ice-hockey, tennis, and snowboarding. This may be ascribed to improved ability of athletes to perform postural adjustments in highly balanced task demands. However, the extent to which sport-specific exercises contribute to their superior postural stability is unknown. Although there is a good deal of evidence supporting neurophysiological adaptations in postural balance control induced by body conditioning exercises, little effort has been made to explain balance adaptations induced by sport-specific exercises and their effects on athletic performance. While an enhancement in athletic performance is often attributed to an improvement of neuromuscular functions induced by sport-specific balance exercises, it can be equally well ascribed to their improvement by general body conditioning exercises. Therefore, the relevant experiments have yet to be conducted to investigate the relative contributions of each of these exercises to improving athletic performance.

Reliability of the Wii Balance Board for measurement of steady state balance in children aged 6-9 years

PURPOSE

The Wii Balance Board (WBB) can be used for assessment of steady state balance (SSB), but its reliability has not been studied in children aged 6-9 years. This study aimed to determine the test-retest reliability of the WBB for measuring SSB in this population. A secondary aim was to determine the minimum detectable change (MDC) and standard error of measurement (SEM) of the WBB in children aged 6-9 years.

METHODS

52 children between 6-9 years of age participated. "One leg stand balance" was used to assess center of pressure velocity (COPV) and center of pressure area (COPA) on three occasions by the same tester. Two tests were conducted on the same day (Day 1) and the third test was performed on another day (Day 2), with a period of 5-13 days between the two test days. Intraclass correlation coefficient (ICC 3,1), SEMs, and MDC were calculated.

RESULTS

Intra-day test-retest reliability of COPA was found to be good (ICC3,1 =0.86; 95% confidence interval [CI]: 0.75, 0.92) and that of COPV was also found to be good (ICC3,1 =0.87; 95% CI: 0.77, 0.92). Inter-day test-retest reliability was found to be good for COPA (ICC3,1 = 0.87; 95% CI: 0.75, 0.93) and COPV (ICC3,1 = 0.89; 95% CI: 0.81, 0.94). SEM for COPA in intra-day testing was 18.90 mm2 (15.78%), and in inter-day testing it was 16.44 mm2 (13.61%). SEM for COPV in intra-day testing was 1.12 mm/s (7.6%), and in inter-day testing it was 1.01 mm/s (6.9%). MDC for COPA in intra-day testing was 52.41mm2 (42.75%), and in inter-day testing was 45.58 mm2 (35.75%). MDC for COPV in intra-day testing was 3.11 mm/s (21.2%), and in inter-day testing it was 2.80 mm/s (18.9%).

CONCLUSION

The WBB has good test-retest reliability for assessing SSB of children between 6-9 years. COPA measurements appear to be less sensitive to clinical changes in SSB when compared to COPV. Assessment of validity of the WBB in this age group is recommended before it can be considered as a potential balance assessment tool in children.