Older adults present better back endurance than young adults during a dynamic trunk extension exercise.

BACKGROUND AND OBJECTIVE: Poor back endurance is a predictor of low back pain. Few studies have investigated back muscle fatigue in older people. The purpose of this study was to compare the back muscle fatigue by endurance time and perceived effort between young and older adults during dynamic exercise. METHOD: Sixteen older and 16 young adults, all healthy, participated in this study. The subjects performed a fatiguing trunk extension-flexion exercise on a Roman chair until exhaustion. Endurance time and perceived muscle fatigue (Borg CR-10 scale) were used as fatigue criteria. RESULTS: The older adults were significantly (T_{(30)} = -2,073; p = 0.039) more resistant to back muscle fatigue (time in mean 133 ± 52 s) than the young adults (mean 97 ± 27 s). In general, both groups had the same perception of high-level fatigue during the exercise bout (T_{(29)} = 1.73; p=0.092). CONCLUSION: The older adults presented better back endurance than young adults during a dynamic trunk extension exercise. These results have implications for back endurance in the primary prevention of low back pain in both young and older adults.

Effect of trunk extensor fatigue on the postural balance of elderly and young adults during unipodal task.

Muscle fatigue can influence the various mechanisms that regulate balance. Few studies have investigated the effects of trunk extensor muscle fatigue on postural control. The purpose of this study was to evaluate the impact of trunk extensor fatigue during a one-leg balance test in young and elderly adults, as well as to determine the time necessary to recover posture control after fatigue. A total of 36 subjects (18 elderly and 18 young adults) participated in the study. Subjects were tested on a force platform to assess the postural control parameters associated with center of pressure (COP) movements, before and after a fatiguing trunk extension-flexion exercise on a roman chair carried out to exhaustion. Post-fatigue effects and postural control recovery were investigated at different times in minutes (MIN): immediately post-fatigue (postIME), after 5 (rec5MIN), 10 (rec10MIN), and 20 min (rec20MIN). Elderly subjects had greater sway (P < 0.05) than young adults in all COP parameters. In both groups, there was an increase in postIME sway compared with pre-fatigue values for all COP parameters. However, the differences were significant only for the COP velocity parameter, with more pronounced effects in young adults that did not return to pre-fatigue values at the end of rec20MIN. The present study demonstrated a significant effect of trunk extensor muscle fatigue on postural control, which was more evident in young adults than in the elderly.

Age-related differences in time-limit performance and force platform-based balance measures during one-leg stance.

Poor posture control has been associated with an increased risk of falls and mobility disability among older adults. This study was conducted to assess the test-retest reliability and sensitivity to group differences regarding the time-limit (TLimit) of one-leg standing and selected balance parameters obtained with a force platform in older and young adults. A secondary purpose was to assess the relationship between TLimit and these balance parameters. Twenty-eight healthy older adults (age: 69±5years) and thirty young adults (age: 21±4years) participated in this study. Two one-leg stance tasks were performed: (1) three trials of 30s maximum and (2) one TLimit trial. The following balance parameters were computed: center of pressure area, RMS sway amplitude, and mean velocity and mean frequency in both the anterio-posterior and medio-lateral directions. All balance parameters obtained with the force platform as well as the TLimit variable were sensitive to differences in balance performance between older and young adults. The test-retest reliability of these measures was found to be acceptable (ICC: 0.40-0.85), with better ICC scores observed for mean velocity and mean frequency in the older group. Pearson correlations coefficients (r) between balance parameters and TLimit ranged from -0.16 to -0.54. These results add to the current literature that can be used in the development of measurement tools for evaluating balance in older and young adults.

Age-related differences in center of pressure measures during one-leg stance are time dependent.

The aim of this study was to evaluate the changes in center of pressure (COP) movement in four time intervals (5, 10, 15 and 30 s) during a one-leg stance test performed by young and elderly adults. Twelve young adults (mean 20 years) and 12 elderly subjects (mean 68 years) participated in this study. The subjects performed three 30 s trials of an eyes open one-leg stance test on a force platform, in which the COP parameter was computed at four points in time from same original COP signal. Significant differences were found between the young and elderly adults (P < .007) only at the 10, 15 and 30 s intervals. For both groups, COP changes were significantly different between the 5 s time interval and other intervals (10, 15 and 30 s). In conclusion, these results pointed out that age-related difference in COP changes were time dependent. This suggests that the use of longer durations increases the possibility of distinguishing more subtle differences in postural strategy among different groups of subjects.

Postural balance and physical activity in daily life (PADL) in physically independent older adults with different levels of aerobic exercise capacity.

Balance impairs with aging and may cause mobility limitations and functional decline. We aimed to evaluate postural balance and PADL in physically independent older adults with different levels of exercise capacity. One hundred fifty seven physically independent individuals, aged 60 years or older were evaluated. Postural balance assessment was performed during one-legged stance test using a force-platform and maximum exercise capacity with the incremental shuttle walking test (ISWT). PADL was assessed subjectively by the modified Baecke questionnaire and objectively using a pedometer. Based on the performance achieved in the ISWT, according to the percentage of the predicted value, the older adults were separated into 3 groups: low performance group (LP group, ISWT < 80% predicted, n = 32, 19 women), normal performance group (NP group, 80 ≤ ISWT ≤ 100% predicted, n = 30, 22 women) and high performance group (HP group, ISWT > 100% predicted, n = 95, 67 women). The HP group showed better postural balance when compared to LP groups (p < 0.001) and also higher levels of PADL measured with pedometer (p < 0.001). There was a modest correlation (r = 0.45) between exercise capacity and PADL in the LP group and a weak correlation between exercise capacity and balance (r = -28) in the HP group. Physically independent older adults with more preserved exercise capacity have better postural balance and higher levels of PADL in comparison to those older adults who show a poorer condition in terms of exercise capacity.