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Abstract. The purpose of this study was to determine whether knee and ankle muscle fatigue affect oneleg static standing balance. We compared the affects of muscle fatigue between the knee and ankle joints on one-leg static standing balance. Sixty-four healthy subjects were used for this study: 44 men and 20 women, with an average age of 19.5. One leg static standing balance was measured at pre-fatigue and post-fatigue status by an instrumented balance assessment system (Kinesthetic Ability Training Balance Platform) which is commercially available for testing and balance training. Isokinetic exercises performed at 180 degree/sec on the Cybex 1200 were used to induce muscle fatigue. One-leg static standing balance ability was significantly decreased after knee and ankle muscle fatigue. There was a significantly greater decrease in one-leg static standing balance ability in ankle joint muscle fatigue as opposed to the knee joint muscles. Although these phenomena were not clearly understood, these results have important implications for rehabilitation of fatigable patients. These results suggest that excessive fatigue during rehabilitation may increase risk of reinjury and falling due to balance disturbance in patients with diseases involving fatigue. Further studies are required to determine the physiological mechanisms of muscle fatigue that play a role in decreasing one-leg static standing balance.

1)Excessive lumbar flexion during sit-to-stand (STS) is a risk factor for lower back pain. Postural taping can prevent unwanted flexion of the lumbar spine. This study aimed to demonstrate the effect of taping the lower back on the lumbopelvic region and hip joint kinematics during STS. Sixteen healthy subjects participated. All subjects performed the STS with and without taping of the lower back. A three-dimensional motion analysis system was used to measure the kinematics of the lumbar spine, pelvis, and hip joint during STS. The angle of the peak lumbar flexion, pelvic anterior tilting, and hip flexion and angular displacement of the lumbar spine between starting position and maximal lumbar flexion were collected. Paired t-tests, or Wilcoxon's rank-sum test for non-parametric distribution, were used to assess differences in the measurements with and without taping. A p-value <.05 was taken to indicate a significant difference. Significant differences were observed in the angle of the peak lumbar flexion, pelvic anterior tilting, hip flexion and angular displacement of the lumbar spine (p<.05). Taping was associated with a significant decrease in the angle of peak lumbar flexion and angular displacement of the lumbar spine between the starting position and maximal lumbar spine flexion. In addition, the peak angle of pelvic anterior tilting and hip flexion were significantly increased with taping. The findings of this study suggest that taping the lower back can decrease excessive lumbar flexion, and increase the pelvic anterior tilting and hip flexion motion during STS.

Asymmetric sitting posture may cause asymmetric buttock pressure and unilateral low back pain (LBP). The purpose of this study was to compare the differences of buttock pressure between both sides, and pelvic angle (sagittal and coronal planes) during typing in a sitting position on a pressure mat (Baltube) in individuals with and without unilateral LBP. Ten subjects with unilateral LBP and ten subjects without unilateral LBP were recruited for this study. Buttock pressure was measured using a pressure mat and pelvic angles were measured using a palpation meter. The subjects performed typing in a sitting posture for 30 minutes. Pressure data were collected and averaged at initial term (from start to first minutes) and final term (last minutes of 30 minutes). Angles of pelvic tilting were measured after 30 minutes typing. Pressure asymmetry values (difference in pressure between both sides) were calculated at the initial and final terms. A two-way analysis of variance was used to compare the differences between the initial and final pressure asymmetry values in subjects with and without unilateral LBP. An independent t-test was applied to compare the pelvic tilt angles between the two groups. To compare the change of pressure from the initial term to the final term between the symptomatic and asymptomatic sides in the unilateral LBP group, a paired t-test was applied. In the unilateral LBP group, the pressure asymmetric value at the final term was significantly greater than that of the initial term (p<.05). The angle of pelvic tilting in coronal plane was significantly greater in the unilateral back pain group compared to the without unilateral LBP group (p<.05), however, there was no significant difference in the angle of pelvic tilting in the sagittal plane between the two groups (p>.05). In the unilateral LBP group, the change of pressure from the initial term to the final term was significantly less in the symptomatic side (-6.90 ㎜Hg) than the asymptomatic side (5.10 ㎜Hg). This asymmetric sitting posture may contribute to unilateral LBP in the sitting position. Further studies are needed to determine if asymmetric weight bearing in sitting causes unilateral LBP or if unilateral back pain causes asymmetric weight bearing, and if the correction of asymmetric weight bearing in sitting can reduce unilateral LBP.