Submitted on November 18, 2008
Accepted on December 18, 2008
LBNP exercise protects aerobic capacity and sprint speed of female twins during 30 days of bed rest
Stuart M.C. Lee1*, Suzanne M. Schneider2, Wanda L Boda3, Donald E. Watenpaugh4, Brandon R. Macias5, R. Scott Meyer, and Alan R. Hargens6
1 Wyle Integrated Science and Engineering
2 University of New Mexico
3 Sonoma State University
4 Sleep Consultants, Inc.
5 UCSD
6 University of California
* To whom correspondence should be addressed. E-mail: stuart.lee-1{at}nasa.gov.
INTRODUCTION: We have shown previously that treadmill exercise within lower body negative pressure (LBNPex) maintains upright exercise capacity (VO2pk) in men after 5-, 15-, and 30-d of bed rest (BR). PURPOSE: We hypothesized that LBNPex protects treadmill VO2pk and sprint speed in women during a 30-d BR. METHODS: Seven sets of female monozygous twins volunteered to participate. Within each twin set, one was randomly assigned to a control group (CON) who performed no countermeasures and the other to an exercise group (EX) who performed a 40-min interval (40-80% pre-BR VO2pk) LBNPex (51±5 mmHg) protocol, plus 5 minutes of static LBNP, 6 days per week. Before and immediately after BR subjects completed a 30.5 m sprint test and an upright graded treadmill test to volitional fatigue. These results in women were compared to previously-reported reductions in VO2pk and sprint speed in male subjects after BR. RESULTS: In women, sprint speed (-8±2%) and VO2pk (-6±2%) were not different after BR in EX. In contrast, both sprint speed (-24±5%) and VO2pk (-16±3%) were significantly less after BR in CON. The effect of BR on sprint speed and VO2pk after BR was not different between women and men. CONCLUSIONS: Treadmill exercise within lower body negative pressure protects against simulated microgravity-induced reductions in VO2pk and sprint speed in women and should prove effective during long duration space flight.
