Supine Lower Body Negative Pressure Treadmill Exercise Maintains Upright Exercise Capacity In Women And Men After 30-d Bed Rest

Abstract

INTRODUCTION We previously reported that supine lower body negative pressure exercise (LBNPex) maintains upright treadmill exercise capacity in men after 5-, 15-, and 30-d of bed rest (BR). PURPOSE This study sought to determine whether the same LBNPex protocol protects exercise capacity during a 30-d BR in women. METHODS Eight sets of male and seven sets of female identical twins completed a 30-d BR. Pre- and post-BR, subjects completed a graded exercise test to volitional fatigue to measure peak exercise capacity (VO2pk). Within each set of twins, one was randomly assigned to a control group (CON) who performed no LBNPex and one was assigned to an exercise group (EX) and performed 40 min of LBNPex, followed by 5 min of LBNP without exercise, six times per week. During LBNPex, −55±4 mmHg was applied to produce footward force equivalent to 1.0–1.2 times static body weight, and subjects performed an interval exercise protocol (40–80% pre-BR VO2pk). Caloric consumption was prescribed to maintain pre-BR body weight. Pre- and post-BR VO2pk were compared between groups and within genders using repeated measures ANOVA. RESULTS VO2pk was significantly decreased in CON after BR in both men and women but was not different from pre-BR in EX. Body weight was similar pre- to post-BR in both CON (64±3.2 vs. 63.8±3.1 kg) and EX (61.3±2.7 vs. 61.7±2.7 kg).TableCONCLUSIONS Our supine interval LBNPex protocol maintains upright exercise capacity during 30-d BR in both women and men. This exercise countermeasure protocol may help prevent microgravity-induced deconditioning during long duration space flight. Supported by NASA NAG9-1425 & UCSD GCRC NIH M01 RR00827