Low-Back Pain and Knee Position-Related Differences on Postural Control Measures During a One-Legged Stance in Athletes.

CONTEXT: Chronic low-back pain (CLBP) may be associated with changes in postural balance in athletes as poor postural control during sports practice. OBJECTIVE: To compare the postural control of athletes with and without CLBP during 2 one-legged stance tasks and identify the center of pressure (COP) cutoff values to determine the main differences. Designed: A cross-sectional study. SETTING: Laboratory of functional evaluation and human motor performance. PARTICIPANTS: A total of 56 male athletes, 28 with and 28 without CLBP (mean age = 26 y). INTERVENTION: The one-legged stance with knee extension and with the knee at 30° flexion tasks were measured and analyzed on a force platform. The participants completed three 30-second trials (30 s of rest between each trial). MAIN OUTCOME MEASURES: The COP parameters: the area of COP, mean COP sway velocity in both the anteroposterior and mediolateral directions, and total COP displacement were computed, and a receiver operating characteristics curve analysis was applied to determine the group differences. RESULTS: Athletes with CLBP had poorer postural control (P < .01) in both tasks. The 30° knee flexion reported more postural instability than the knee extension for all COP parameters (a large effect size d = 0.80).The knee extension cutoffs identified were >7.1 cm2 for the COP area, >2.6 cm/s for the COP sway velocity in the anterior-posterior direction, and >3.2 cm/s for the mediolateral direction. Whereas, the 30° knee flexion cutoffs were >10.9 cm2 for the COP area, >2.9 cm/s for the COP sway velocity in the anterior-posterior direction, and >4.1 cm/s for the mediolateral direction. Both measures showed enough sensitivity and specificity (ie, area under the curve = 0.88 in and 0.80, respectively) to discriminate both groups. CONCLUSIONS: The athletes with CLBP had poorer postural control than the healthy athletes and obtained specific cutoff scores from the COP values.

Effect of body mass index and fat mass on balance force platform measurements during a one-legged stance in older adults.

The purpose of this study was to evaluate the impact of body mass index (BMI) and fat mass on balance force platform measurements in older adults. The sample consisted of 257 participants who were stratified into four groups by BMI: low weight, normal weight, pre-obesity and obesity. For fat mass variables, older individuals were classified into low and high-fat mass. All groups investigated performed three trials of one-legged stance balance on a force platform. Center of pressure (COP) domain parameters were computed from the mean across trials. Analysis of variance results revealed no significant interactions for groups and sexes for all COP parameters. Comparable balance results were found for BMI and fat groups for all COP parameters. A statistical effect (P < 0.05) was only reported for sex differences for COP parameters, regardless of BMI and fat mass variables. Overall, women presented better balance than men. In conclusion, BMI and fat mass do not seem to influence the balance of older adults during a one-leg stance task.

Changes on Walking During Street Crossing Situations and on Dorsiflexion Strength of Older Caribbean Americans After an Exercise Program: A Pilot Study.

The objective of this pilot study was to evaluate a 6-month exercise program completed by 10 older Caribbean Americans. Assessments were done at baseline and 3 and 6 months, and included walks on an instrumented mat at preferred speed, and during street crossing simulations with regular (10 s) and reduced time (5 s). There were no significant differences on preferred walking speed over time. Differences between the street crossing conditions were found only at 6 months. Significant changes over time among the assessments were found only during street crossing with reduced time. Street crossing with reduced time was the only walking condition sensitive to capture changes associated with participating in the exercise program. There was a significant increase in dorsiflexion strength overtime. At 6 months it was significantly higher than at baseline and 3 months. The program was feasible, acceptable, and had some positive effects on walking, knee flexion, and dorsiflexion strength.

Effect of different types of exercise on postural balance in elderly women: a randomized controlled trial.

Different types of exercise are indicated for the elderly to prevent functional capacity limitations due to aging and reduce the risk of falls. This study aimed to evaluate the effect of three different exercises (mini-trampoline, MT; aquatic gymnastics, AG and general floor gymnastics, GG) on postural balance in elderly women. Seventy-four physically independent elderly women, mean age 69±4 years, were randomly assigned to three intervention groups: (1) MT (n=23), (2) AG (n=28), and (3) GG (n=23). Each group performed physical training, including cardiorespiratory, muscular strength and endurance, flexibility and sensory-motor exercises for 12 weeks. To determine the effects on each intervention group, five postural balance tasks were performed on a force platform (BIOMEC 400): the two-legged stand with eyes open (TLEO) and two-legged stand with eyes closed (TLEC); the semi-tandem stand with eyes open (STEO) and semi-tandem stand with eyes closed (STEC) and the one-legged stand. Three trials were performed for each task (with 30s of rest between them) and the mean was used to compute balance parameters such as center of pressure (COP) sway movements. All modalities investigated such as the MT, AG and GG were significantly (P<0.05) efficient in improving the postural balance of elderly women after 12 weeks of training. These results provide further evidence concerning exercise and balance for promoting health in elderly women.

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.