MUSCLE LOSS IS ASSOCIATED WITH RISK OF ORTHOSTATIC HYPOTENSION IN OLDER MEN AND WOMEN

Background Muscle provides a reservoir for water to maintain fluid volume and blood pressure, so older adults may be at risk for orthostatic hypotension due to muscle loss with age. Objectives To evaluate the association between muscle loss with age and postural blood pressure. Design Longitudinal comparison of overnight changes in hydration, postural blood pressure, and strength. Setting Community field study. Participants Sixty-nine men and women (76.0 +/- 0.8 years) with low (Low) or normal (Normal) muscle based on the Lean Mass Index. Measurements Body composition was measured with bioelectrical impedance analysis. Postural blood pressure was measured sequentially (lying, sitting, standing). Strength was measured with a handgrip dynamometer, Arm Curl test, and Chair Stand test. Results On Day 1, Low had less hydration and a significant drop in postural systolic blood pressure compared to Normal (lying to standing: -11.06 +/- 2.36 vs. + 1.14 +/- 2.20 mmHg, p < 0.001). Overnight, both groups lost significant total body water, while fluid volume was unchanged. On Day 2, both groups experienced significant drops in postural systolic blood pressure, although the drop in Low was more profound and significantly greater than Normal (lying to standing: -16.85 +/- 2.50 vs. -3.89 +/- 2.52 mmHg, p = 0.001). On both days, Normal compensated for postural changes with increases in postural diastolic blood pressure not observed in Low. Only Low experienced significant overnight decreases in all strength measures. Conclusions In older men and women, muscle loss with age is accompanied by loss of hydration and less stable early morning postural systolic blood pressure that increase risk for orthostatic hypotension and can also increase risk for falls.