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MNX (Medium Duration Nutrition and Resistance-Vibration Exercise) Bed-Rest: Effect of Resistance Vibration Exercise Alone or Combined With Whey Protein Supplementation on Cardiovascular System in 21-Day Head-Down Bed Rest.

ABSTRACT: Current inflight countermeasures do not completely prevent bone and cardiovascular changes induced by microgravity. High load Resistance Exercise combined with whole body Vibration (RVE) demonstrated benefits on bone and cardiovascular system during previous Head-Down Bed Rest (HDBR) studies. We examined the effectiveness of RVE alone or combined with a nutritional supplementation of Whey protein (NeX) on cardiovascular deconditioning. Eight male subjects (age 34 ± 8 years) in a crossover design completed three 21-day HDBR campaigns (Control-CON, RVE, and NeX). Pre and post HDBR Orthostatic Tolerance (OT) was evaluated by a 15-min head-up tilt test followed by increasing levels of Lower Body Negative Pressure (LBNP). Heart rate (HR), blood pressure (BP), and Sympathetic Index (?I) through spectral analysis were measured during OT test. Plasma Volume (PV), and Maximal Oxygen Uptake (VO2max) were measured before and after each campaign. Left ventricular mass, left ventricular end diastolic (LVEDV), end systolic (LVESV), stroke (SV) volumes, and circumferential deformation at rest and during an orthostatic stress simulated by a 30 mmHg LBNP were measured by cardiac MRI. RVE failed to prevent any change in these variables and NeX did not have any additional effect over exercise alone. In the 3 groups, (1) OT time dropped similarly (bed rest p < 0.001), (2) HR and ?I were increased at rest at the end of HDBR and HR increased markedly during LBNP-tilt test, with inability to increase further the ?I, (3) PV dropped (bed rest p < 0.001), along with LVEDV, LVESV and SV (p = 0.08, p < 0.001, and p = 0.045, respectively), (4) Left ventricle mass did not change significantly, (5) Deformation of the heart assessed by global circumferential strain was preserved and early diastolic circumferential strain rate was increased during orthostatic stress at the end of HDBR, illustrating preserved systolic and diastolic function respectively, without any difference between groups. Despite the drop in PV and LV volumes, RVE and NeX tended to alleviate the decrease in VO2max. In conclusion, RVE and NeX failed to prevent the cardiovascular deconditioning induced by a 21 day-HDBR.

SUBMITTER: Guinet P

PROVIDER: S-EPMC7378749 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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MNX (Medium Duration Nutrition and Resistance-Vibration Exercise) Bed-Rest: Effect of Resistance Vibration Exercise Alone or Combined With Whey Protein Supplementation on Cardiovascular System in 21-Day Head-Down Bed Rest.

Guinet Patrick P MacNamara James Patrick JP Berry Matthieu M Larcher Françoise F Bareille Marie-Pierre MP Custaud Marc-Antoine MA Pavy-Le Traon Anne A Levine Benjamin D BD Navasiolava Nastassia N

Frontiers in physiology 20200716

Current inflight countermeasures do not completely prevent bone and cardiovascular changes induced by microgravity. High load Resistance Exercise combined with whole body Vibration (RVE) demonstrated benefits on bone and cardiovascular system during previous Head-Down Bed Rest (HDBR) studies. We examined the effectiveness of RVE alone or combined with a nutritional supplementation of Whey protein (NeX) on cardiovascular deconditioning. Eight male subjects (age 34 ± 8 years) in a crossover design ...[more]

PMID: 32765296

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Project description:Background/objectivesExercise is a front-line countermeasure used to maintain astronaut health during long-duration spaceflight; however, reductions in metabolic health still occur. Accordingly, we evaluated serial changes in metabolic parameters in a spaceflight analog and evaluated the efficacy of exercise with or without the addition of low-dose testosterone treatment on mitigating adverse metabolic changes.Subjects/methodsHealthy young (<55 years) men were randomly assigned to one of three groups during 70-days of strict, diet controlled, 6° head-down bed rest: Control (CON, n=9), exercise plus testosterone countermeasure (TEX, n=8), or exercise countermeasure plus placebo (PEX, n=9). Basal metabolic rate (BMR), glucose tolerance, and insulin sensitivity were measured before, during, and after bed rest. Exercise energy expenditure and excess post-exercise oxygen consumption were measured in TEX and PEX subjects during bed rest.ResultsLeptin decreased during bed rest (Pre to BR+0 changed from 6.9 ± 5.1, 5.8 ± 4.2, and 4.7 ± 4.1 to 7.9 ±3.6, 6.5 ± 4.6, and 4.1 ±3.0 ug• L-1 for CON, PEX, and TEX respectively). Bed rest induced a decrease in BMR (Pre to BR57 changed from 1655 ± 212, 1629 ± 108, and 1706 ± 146 to 1476 ± 166, 1668 ± 142, and 1603 ± 132 kcal • day-1 ± 95%CI for CON, PEX, and TEX respectively). Similarly, bed rest negatively affected glucose metabolism assessed by 2hr OGTT glucose (Pre to BR66 changed from 6.29 ± 0.72, 5.13 ± 0.72, and 5.87 ± 0.73 to 6.62 ± 0.72, 5.83 ± 0.72, and 7.08 ± 0.72 mmol • L-1 ± 95%CI). Reambulation following bed rest positively affected glucose tolerance in CON (2hr OGTT glucose at BR+12: 5.3 ± 0.72, 6.42 ± 0.73, and 6.04 ± 0.73 mmol • L-1 ± 95%CI). Testosterone protected against bed rest induced insulin resistance (HOMA-IR from Pre to BR+66 changed from 1.74 ± 0.54, 1.18 ± 0.55, and 1.45 ± 0.56 to 2.24 ± 0.56, 1.47 ± 0.54, and 1.07 ± 0.54).ConclusionThis study confirmed that inactivity during 70 days of head-down bed rest adversely affects metabolic health. The daily exercise countermeasures were beneficial but not completely protective of bed rest induced decrements in metabolic health. Supplementary countermeasures such as testosterone may provide additional benefits not provided by exercise alone.

Dataset Information

MNX (Medium Duration Nutrition and Resistance-Vibration Exercise) Bed-Rest: Effect of Resistance Vibration Exercise Alone or Combined With Whey Protein Supplementation on Cardiovascular System in 21-Day Head-Down Bed Rest.

Publications

MNX (Medium Duration Nutrition and Resistance-Vibration Exercise) Bed-Rest: Effect of Resistance Vibration Exercise Alone or Combined With Whey Protein Supplementation on Cardiovascular System in 21-Day Head-Down Bed Rest.

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