Hip- and thigh-muscle activation during the star excursion balance test.

CONTEXT: The Star Excursion Balance Test (SEBT) is often used to train and assess dynamic balance and neuromuscular control. Few studies have examined hip- and thigh-muscle activation during the SEBT. OBJECTIVE: To quantify hip- and thigh-muscle activity during the SEBT. DESIGN: Repeated measures. SETTING: Laboratory. PARTICIPANTS: 22 healthy individuals, 11 men and 11 women. METHODS: EMG measurements were taken as participants completed 3 trials of the anterior (A), medial (M), and posteromedial (PM) reach directions of the SEBT. MAIN OUTCOME MEASURES: Mean EMG data (% maximal voluntary isometric contraction) from the gluteus medius (Gmed), gluteus maximus (Gmax), and vastus medialis (VM) were measured during the eccentric phase of each SEBT reach direction. Test-retest reliability of EMG data across the 3 trials in each direction was calculated. EMG data from each muscle were compared across the 3 reach directions. RESULTS: Test-retest reliability ranged from ICC3,1 values of .91 to .99. A 2-way repeated-measure ANOVA revealed a significant interaction between muscle activation and reach direction. One-way ANOVAs showed no difference in GMed activity between the A and M directions. GMed activity in the A and M directions was greater than in the PM direction. There was no difference in GMax and VM activity across the 3 directions. CONCLUSION: GMed was recruited most effectively when reaching was performed in the A and M directions. The A, M, and PM directions elicited similar patterns of muscle recruitment for the GMax and VM. During all 3 SEBT directions, VM activation exceeded the 40-60% threshold suggested for strengthening effects. GMed activity also exceeded the threshold in the M direction. GMax activation, however, was below the 40% threshold for all 3 reach directions, suggesting that performing dynamic lower extremity reaching in the A, M, and PM directions may not elicit strengthening effects for the GMax.

The effect of context and age on functional reach performance in healthy adults aged 21 to 94 years.

BACKGROUND: Activities of daily living require an individual to exhibit dynamic standing balance, while reaching beyond arm's length under varying contexts that involve an object to reach toward or grasp. Research shows that object context impacts the kinematics of reaching; however, there has been less research regarding the effect of context on functional reach (FR) ability. The purpose of the present study was to assess FR ability under 3 conditions between 3 age groups: (1) traditional FR, (2) reaching to an object (object present FR), and reaching to grasp an object (FR to grasp). METHODS: Reach distance was measured as 142 apparently healthy participants performed the 3 contexts in random order. A 2-way repeated-measures analysis of variance (age group × reach context) determined the effect of age and context on reach ability. RESULTS: For all age groups, both object-present contexts resulted in greater reach ability than the traditional FR condition. The task goal, touching or grasping, however, impacted reach ability differently in each age group. For the young and older age groups, there was no difference between reaching to touch an object or to grasp an object. Reach distance was less, however, for the middle-age group when grasping an object compared with touching an object. CONCLUSION: These results suggest that the presence of an object enhances dynamic standing balance as indicated by greater reach distances compared with traditional FR when an object is absent. Applications of these findings might extend to balance testing and balance training.

The effect of balance confidence and context on functional reach ability in healthy older adults.

OBJECTIVE: To assess functional reach (FR) ability in 4 contexts in older adults (≥ 60 years) with high balance confidence (HBC) and low balance confidence (LBC). DESIGN: A repeated-measures design was used to compare 2 groups in 4 reaching contexts. SETTING: Community setting. SUBJECTS: Twenty-four healthy older adults with HBC and 27 healthy older adults with LBC. METHODS: FR distance was assessed in 4 contexts presented in random order: (1) traditional FR (TFR); (2) functional reach on foam (FRF); (3) object present functional reach (OPFR); and (4) object present functional reach on foam (OPFRF). For TFR and FRF, 3 trials were performed for each task, and the average reach distance across 3 trials was calculated. During the OPFR and OPFRF contexts, the object was moved toward or away from the participant in 1.3-cm increments until maximal reach distance to the object was obtained. MAIN OUTCOME MEASURE: Maximal reach distance in each of the 4 FR contexts. RESULTS: Participants in the HBC group scored significantly higher than did participants in the LBC group regardless of reaching contexts (P =.004). For both balance confidence groups, reaching distance increased significantly from FRF to TFR to OPFRF to OPFR (P < .001). CONCLUSION: The results of this study highlight the beneficial effect of an external target on balance performance, even with the added challenge of an unstable surface. These findings suggest that although balance performance is greater for persons with HBC, the same pattern of reaching ability in differing FR contexts is found regardless of whether balance confidence is high or low. The clinical utility of these findings pertain to the importance of the use of task objects during FR balance assessment to determine an individual's balance capacity. Future research is needed to assess the effectiveness of context-oriented reaching tasks in balance training programs.

Concurrent validity and reliability of two-dimensional video analysis of hip and knee joint motion during mechanical lifting.

Movement patterns used during mechanical lifting are usually assessed subjectively by clinicians as a stoop or squat based on visual estimation of joint motion and position. Two-dimensional (2D) video analysis has the potential to objectively measure joint motion during a mechanical lifting task. This study investigated concurrent validity, intrarater, interrater, and test-retest reliability of 2D video analysis using Dartfish software for the measurement of sagittal plane angles at the hip and knee during mechanical lifting. Fifteen healthy female participants (mean age 27.1 ± 7.1 years) were recruited to perform mechanical lifting on 2 separate test days. Concurrent validity was determined by comparing 2D derived hip and knee flexion angles to goniometric measures. Intrarater and interrater reliability of the 2D kinematic procedures was determined by using examiners with varying experience in the use of Dartfish software. Between-day test-retest reliability of hip and knee 2D kinematics during mechanical lifting was assessed. Concurrent validity of 2D angle analysis using Dartfish software was supported by high correlations (Pearson r ≥ 0.95) and nonsignificant differences between 2D and goniometric measures of sagittal plane hip and knee motion. Both intrarater and interrater reliability values of hip and knee flexion angles were excellent (ICC ≥ 0.91). ICCs for test-retest reliability were 0.79 and 0.91 for hip and knee flexion, respectively. These findings and the ease of data capture using this system provide support for the clinical utility of 2D video analysis to provide objective measures of movement patterns at the hip and knee during a dynamic functional task.