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 (VO 2 max) 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

Physiology of physical inactivity, sedentary behaviours and non‐exercise activity: insights from the space bedrest model

“…Effect of resistance exercise alone: Resistance exercise has been shown to mitigate the decrease in cardiorespiratory fitness (Guinet et al, 2020;Kenny et al, 2020) and prevent the loss of muscle function and mass including the reduction in fiber diameter during bedrest (Trappe et al, 2004;Moriggi et al, 2010). However, the mechanisms underlying the protective effects of resistance exercise against unloading-muscle atrophy are not fully clear.…”

“…It protects against the rise in visfatin (Rudwill et al, 2013), an adipocytokine that mimics the effects of insulin, but does not prevent the increase in IL-6 and C-reactive protein, two pro-inflammatory markers, or the decrease in adiponectin (Brooks et al, 2014), a change associated with inflammation, lipid abnormalities, and insulin resistance. Even when performed at high intensity, resistance exercise does not mitigate the decrease in HDL (Brooks et al, 2014;Guinet et al, 2020), the development of insulin resistance, hyperlipidemia, or the shift towards the use of carbohydrate as fuel (Bergouignan et al, 2006). This later observation is surprising knowing that resistance exercise prevents against the shift of muscle fibers from oxidative to glycolytic types (Trappe et al, 2004), offsets the transcriptomic alterations in muscle related to aerobic energy metabolism (e.g.…”

“…Resistance exercise has been shown to mitigate the decrease in cardiorespiratory fitness (Guinet et al . 2020; Kenny et al . 2020) and prevent the loss of muscle function and mass including the reduction in fibre diameter during bedrest (Trappe et al .…”

“…2014; Guinet et al . 2020), the development of insulin resistance, hyperlipidaemia, or the shift towards the use of carbohydrate as fuel (Bergouignan et al . 2006).…”

Implementation of exercise countermeasures during spaceflight and microgravity analogue studies: Developing countermeasure protocols for bedrest in older adults (BROA)

“…Six-degree head-down bedrest (HDBR) is widely used as an experimental model to simulate the effects of microgravity and evaluate the effectiveness of different exercise countermeasures before implementing them during spaceflight; however, there are some notable differences between spaceflight and HDBR related to fluid shifts (see Table 1 ), spinal dysfunction and radiation exposure ( Hargens and Vico, 2016 ). Different exercise countermeasures have been tested during HDBR, such as aerobic ( Stremel et al, 1976 ; Greenleaf et al, 1989 ) or resistance training protocols ( van Duijnhoven et al, 2010b ), novel exercise modalities ( Kramer et al, 2017a ), and combinations of exercise with fluid loading ( Shibata et al, 2010 ), artificial gravity ( Watenpaugh et al, 2000 ; Iwasaki et al, 2005 ; Schneider et al, 2009 ) or whole-body vibration ( van Duijnhoven et al, 2010b ; Coupé et al, 2011 ; Guinet et al, 2020 ). In addition to aerospace medicine research, bedrest experimental models are also useful for examination of the rapid physiological deconditioning that occurs during prolonged hospitalization and inactivity on Earth.…”