Supine lower body negative pressure exercise during bed rest maintains upright exercise capacity

Abstract

Bed rest and spaceflight reduce exercise fitness. Supine lower body negative pressure (LBNP) treadmill exercise provides integrated cardiovascular and musculoskeletal stimulation similar to that imposed by upright exercise in Earth gravity. We hypothesized that 40 min of supine exercise per day in a LBNP chamber at 1.0-1.2 body wt (58 +/- 2 mmHg LBNP) maintains aerobic fitness and sprint speed during 15 days of 6 degrees head-down bed rest (simulated microgravity). Seven male subjects underwent two such bed-rest studies in random order: one as a control study (no exercise) and one with daily supine LBNP treadmill exercise. After controlled bed-rest, time to exhaustion during an upright treadmill exercise test decreased 10%, peak oxygen consumption during the test decreased 14%, and sprint speed decreased 16% (all P < 0.05). Supine LBNP exercise during bed rest maintained all the above variables at pre-bed-rest levels. Our findings support further evaluation of LBNP exercise as a countermeasure against long-term microgravity-induced deconditioning.

Lower body negative pressure treadmill exercise as a countermeasure for bed rest-induced bone loss in female identical twins

“…The EX subjects exercised in an LBNP chamber with a sealed flexible waist seal [9,28,36,43]. On 6 d per week, during LBNP, the EX subjects exercised for 40 min (40-80% pre-bed rest peak oxygen consumption) and then rested for 5 min during LBNP.…”

“…On 6 d per week, during LBNP, the EX subjects exercised for 40 min (40-80% pre-bed rest peak oxygen consumption) and then rested for 5 min during LBNP. Previous works describe LBNP exercise equipment and procedures in more detail [43].…”

Hemodynamic responses to simulated weightlessness of 24-h head-down bed rest and KAATSU blood flow restriction

“…Both LBNP and KAATSU induce the retention of blood flow in lower extremities, and induce subsequent hemodynamic changes such as decreased SV and CO and increased TPR (Stevens and Lamb 1965;Güell et al 1990Güell et al , 1992Melchior et al 1994;Murthy et al 1994;Lee et al 1997;Watenpaugh et al 2000;Iida et al 2007). The mechanism triggered by these methods (negative pressure vs. KAATSU) is quite different.…”

“…The most effective countermeasure for preventing cardiovascular deconditioning appears to be imposition of a gravity-like stress, such as lower-body negative pressure (LBNP) (Güell et al 1990(Güell et al , 1992Lathers and Charles 1993). When combined with intensive exercise, LBNP is a potent orthostatic stimulus, which presumably provides an effective prevention of orthostatic intolerance following space flight (Lee et al 1997;Watenpaugh et al 2000). However, a large-scale apparatus combined with exercise machine is required.…”

“…The KAATSU training is a unique technique of performing low-load exercises such as resistance exercises and treadmill with restricted muscle blood flow that results in an increase in muscle mass and muscular strength comparable to high-intensity training (Takarada et al 2000;Abe et al 2006;Fujita et al 2007). Since KAATSU femoral blood flow restriction induces the retention of blood flow in lower extremities, it reduces venous return, and induces subsequent hemodynamic changes such as decreased SV and CO and increased TPR like LBNP (Stevens and Lamb 1965;Güell et al 1990Güell et al , 1992Melchior et al 1994;Murthy et al 1994;Lee et al 1997;Watenpaugh et al 2000;Iida et al 2007). Thus, KAATSU may partly provide an orthostatic stimulus, and an effective countermeasure for cardiovascular deconditioning in weightlessness like LBNP.…”