MEASUREMENT OF BALANCE IN BLACK AND WHITE ELDERLY WOMEN

Abstract

Research comparing older black (BW) and white women (WW) has found BW to have greater bone mineral density (BMD), lean body mass (LBM), and muscle strength even though physical activity is lower in BW. It has also been suggested that BW are at a greater risk for falls than WW. Muscle mass and strength have been shown to influence balance control in older persons. This relationship has not been examined in BW. PURPOSE: To evaluate muscle mass, strength, physical activity, and balance in older BW and WW. METHODS: Nineteen BW and 56 WW participated (BW: 72 ± 5 yrs; WW: 70 ± 7 yrs). Muscle strength was assessed using the chest press and leg extension. Body composition and BMD were determined with Dual Energy X-ray Absorptiometry (DEXA). Volitional and non-volitional control of dynamic balance was measured using limits of stability, rhythmic weight shift, motor control, and sit-to-stand tests. Physical activity ratings were assessed using the Physical Activity Scale for the Elderly. Means and standard deviation, non-paired t-tests, and correlations were used to analyze the data. RESULTS: A trend (p = 0.07) was observed for BW to have a higher total BMD (BW: 1.133 ± 0.154; WW: 1.071 ± 0.119 g/cm2). There were no differences in LBM (BW: 45 ± 8; WW: 43 ± 6 kg), upper (BW: 29 ± 12; WW: 29 ± 10 kg), or lower (BW: 43 ± 13; WW: 47 ± 14 kg) body strength between groups. Physical activity ratings were higher for WW than BW (p < 0.05). WW exhibited better control of rapid volitional movements, as evidenced in limits of stability (Reaction Time, BW: 1.80 ± 0.49 s; WW: 1.29 ± 0.34 s) and rhythmic weight shift (Lateral On-Axis-Velocity, BW: 2.8 ± 0.6 deg/s; WW: 3.1 ± 0.6 deg/s) tests. However, no differences between BW and WW were observed in non-volitional control of balance (motor control test) or in functional volitional balance (sit-to-stand test). The relationships of strength and muscle mass to balance were weak. CONCLUSION: The lack of differences in non-volitional balance and physiological factors between BW and WW may indicate that differences for risk of falling are due to other factors.