Search

BACKGROUND: Aging-related deterioration of the lower limb muscle strength could highly influence the functional performance of elderly individuals. OBJECTIVE: To investigate how advancing age impacts the lower limb muscle strength and consequently affects the balance and walking performance. METHODS: Twenty-seven community-dwelling elderly females underwent isokinetic ankle dorsi/plantar flexion (ADF/APF), inversion/eversion (AIN/AEV), knee flexion/extension (KFL/KEX), hip flexion/extension (HFL/HEX), and abduction/adduction (HAB/HAD) tests, the six-minute walk test, open-eyed biped balance test on foam rubber and the performance-oriented mobility assessment (POMA). RESULTS: The Pearson's product-moment correlation coefficients demonstrated that advancing age negatively influenced the relative work and moment produced in all the muscle groups, the POMA score (r = - 0.51), walking speed (r = - 0.62), and the vertical (r = 0.55) and anteroposterior (r = 0.54) postural sway velocities. The peak moment and work values of AINs and APFs; KFLs and KEXs; and HABs, HFLs, and HEXs showed a significantly positive correlation with the walking speed (α ⩽ 0.05). CONCLUSION: The strength of HFLs, HEXs and HABs, as the important contributors to the walking performance, underwent attenuation as the age increased, consequently resulting in impairments of stepping profiles of elderly females. Elderly females are needed to be trained to reach the optimum levels of lower limb muscular strength to overcome premature incapacitation and have control over their independence in daily activities. [ABSTRACT FROM AUTHOR]

Previous studies reported a significant association between postural control and lower-limb strength of several muscle groups, however, they were focused especially on knee muscles and ankle plantar and dorsal flexors. The aim of the present study is to examine the correlation between the muscle strength of ankle invertors, evertors, plantar flexors, and dorsal flexors and the control of bipedal stance in young and older adults. Thirty one young (aged 22.8 ± 2.6 years) and thirty one older adults (aged 70.5 ± 7.2 years) voluntarily participated in this study. Ankle muscle strength was evaluated by an isokinetic dynamometer. Normalized peak torque and work were averaged for four repetitions and for both lower limbs. The control of bipedal stance was evaluated by the sample entropy derived from an accelerometer placed on the lumbar spine while the subject stood on a foam pad with eyes open. Results showed significant age-related differences in ankle muscle strength and sample entropy in medial-lateral direction. More interestingly, the correlation between ankle muscle strength and the sample entropy was significantly different between young and older adults. Indeed, no significant correlation was observed in the younger adults. Conversely, in the older adults, the work of the ankle evertors positively correlated with sample entropy in the medial-lateral direction during bipedal stance (r = 0.36), whereas the peak torque and work of the dorsal flexors were significantly correlated with sample entropy in the anterior-posterior direction during bipedal stance (r = 0.44 for both variables). In the young adults, results suggest that, standing on foam with eyes open is a relatively easy postural task that does not require the full ankle muscle strength capacity. Taken together, the present findings suggest that older adults have a different association between ankle muscle strength and the sample entropy during bipedal stance. [ABSTRACT FROM AUTHOR]

Balance and lower limb strength deficits are associated with a high incidence of falls in older adults. This study investigated the association between balance control during and after stair descent onto a compliant surface and lower limb strength. Thirty-five women and 14 men participated in this study. Stair descent time, mean center of pressure velocity in anteroposterior and mediolateral direction during stair descent (CoP V AP and CoP V ML), and CoP velocity in the first 5 s of restabilization phase (CoP V 5) were evaluated. Bilateral strength of the knee flexors and extensors, and ankle plantar and dorsal flexors was evaluated. Spearman correlation analysis with Bonferroni correction yielded a significant association between the strength of the knee flexors on the trailing limb and stair descent time in women (r = 0.502, p = 0.002, R2 = 0.246). The same analysis in men revealed a significant association between the strength of the knee flexors on the trailing limb and CoP V AP (r = −0.820, p < 0.001, R2 = 0.280) and CoP V ML (r = −0.697, p = 0.006, R2 = 0.359). The strength of the ankle plantar flexors on the trailing limb was significantly associated with stair descent time (r = 0.684, p = 0.007, R2 = 0.429) and CoP V AP (r = −0.723, p = 0.003, R2 = 0.408) in men. Stair descent balance control is associated with knee flexion strength on trailing limb in women, and with ankle plantar flexion and knee flexion strength on the same limb in men. [ABSTRACT FROM AUTHOR]