SPRINT AND BALANCE ABILITY AFTER 30 DAYS OF BEDREST WITH VERSUS WITHOUT SUPINE LBNP EXERCISE

Abstract

Introduction: We hypothesized supine treadmill exercise in lower body negative pressure (LBNP) would decrease losses of sprint and balance ability in subjects exposed to prolonged microgravity, simulated by 30 days of bedrest in 6 degree head down tilt. Methods: Six pairs of male identical twins (n = 12) were tested PRE and POST bedrest for one foot rail balance eyes closed (EC) (up to 30 sec), sprint time (30.5m) and rail walk balance eyes open (EO) (4.9m beam). Each twin was randomly assigned to: 1) an experimental group that ran on a vertically oriented treadmill 40 minutes, 6 days per week in LBNP (EXP) or 2) a control group that did not (CON). Rail balance performance was determined by averaging percent distance traveled divided by total time. Results: EXP performed better (but not significantly) than CON in POST left and right EC rail balance (EXP left: 17.5 (4.82)s; right: 13.8 (4.80)s, CON left: 8.6 (4.24)s; right: 10.0 (4.73)s (mean (SE))) and in POST sprint (EXP 5.2 (0.15)s, CON 5.8 (0.16)s). Significant differences (P < 0.05) existed between PRE and POST performances for the subsequent reported comparisons. Left and right foot balance times EC were longer PRE than POST for both CON (left: 26.0 (4.02)s; right: 21.56 (5.34)s vs. left: 8.6 (4.24)s; right: 10.0 (4.73)s) and EXP (left: 24.4 (3.34)s; right: 16.8 (3.14)s vs. left: 17.5 (4.82)s; right: 13.8 (4.80)s). PRE sprint times were faster than POST times for both CON (4.8 (0.20)s vs. 5.8 (0.16)s) and EXP (4.7 (0.35)s vs. 5.2 (0.15)s). Rail walk EO was better PRE than POST for both CON (10.7 (1.80) % s-1 vs. 8.3 (1.48) % s-1) and EXP (10.2 (1.47) % s-1 vs. 7.6 (1.97) % s-1). Trends in results suggest exercise in LBNP may reduce loss of sprint and balance ability. This research was supported by National Aeronautics and Space Administration grant #199–26–12–34.