INTRODUCTION:Exercise capacity is reduced after both short- and long-duration exposures to microgravity. Previously, we have documented that supine treadmill exercise within lower-body negative pressure (LBNP(ex)) maintains upright exercise responses in men after 5 and 15 d of bed rest, as a simulation of microgravity. PURPOSE: The purpose of this study was to determine whether LBNP(ex) would protect against loss of upright exercise capacity (VO2peak) and sprint performance during a longer-duration bed rest. METHODS:Eight sets of male twins participated in 30 d of bed rest. Within each twin pair, one was randomly assigned to a control group (CON) who performed no exercise, and the other was assigned to an exercise group (EX) that performed a 40-min interval (40-80% pre-bed rest VO2peak) LBNP(ex) (55 +/- 4 mm Hg) protocol, plus 5 min of resting LBNP, 6 d.wk(-1). LBNP produced footward force equivalent to 1.0-1.2 body weight. Before and after bed rest, subjects completed an upright graded exercise test to volitional fatigue and a sprint test of 30.5 m. RESULTS: After bed rest, VO2peak was decreased significantly in the CON subjects (-23 +/- 4%, P < 0.01) but was maintained in the EX subjects (-3 +/- 3%). Sprint time was increased in the CON subjects (24 +/- 8%, P < 0.05) but was maintained in the EX group (8 +/- 2%). CONCLUSIONS: This exercise countermeasure protocol may help prevent microgravity-induced deconditioning during long-duration space flight.
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INTRODUCTION: Exercise capacity is reduced after both short- and long-duration exposures to microgravity. Previously, we have documented that supine treadmill exercise within lower-body negative pressure (LBNP(ex)) maintains upright exercise responses in men after 5 and 15 d of bed rest, as a simulation of microgravity. PURPOSE: The purpose of this study was to determine whether LBNP(ex) would protect against loss of upright exercise capacity (VO2peak) and sprint performance during a longer-duration bed rest. METHODS: Eight sets of male twins participated in 30 d of bed rest. Within each twin pair, one was randomly assigned to a control group (CON) who performed no exercise, and the other was assigned to an exercise group (EX) that performed a 40-min interval (40-80% pre-bed rest VO2peak) LBNP(ex) (55 +/- 4 mm Hg) protocol, plus 5 min of resting LBNP, 6 d.wk(-1). LBNP produced footward force equivalent to 1.0-1.2 body weight. Before and after bed rest, subjects completed an upright graded exercise test to volitional fatigue and a sprint test of 30.5 m. RESULTS: After bed rest, VO2peak was decreased significantly in the CON subjects (-23 +/- 4%, P < 0.01) but was maintained in the EX subjects (-3 +/- 3%). Sprint time was increased in the CON subjects (24 +/- 8%, P < 0.05) but was maintained in the EX group (8 +/- 2%). CONCLUSIONS: This exercise countermeasure protocol may help prevent microgravity-induced deconditioning during long-duration space flight.
Authors: Stuart M C Lee; Suzanne M Schneider; Wanda L Boda; Donald E Watenpaugh; Brandon R Macias; R Scott Meyer; Alan R Hargens Journal: J Appl Physiol (1985) Date: 2008-12-26
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Authors: Timothy R Macaulay; Brandon R Macias; Stuart Mc Lee; Wanda L Boda; Donald E Watenpaugh; Alan R Hargens Journal: NPJ Microgravity Date: 2016-06-30 Impact factor: 4.415