Sports Med Open, 2017; 3(1): 40, PMID: 29134470

The effect of long-term confinement and the efficacy of exercise countermeasures on muscle strength during a simulated mission to Mars: data from the Mars500 study.

Year: 2017

Gaffney CJ, Fomina E, Babich D, Kitov V, Uskov K, Green DA
Institute of Biomedical Problems (IBMP), Moscow, Russia. chrisjamesgaffney@gmail.com.

Abstract

BACKGROUND: Isolation and long duration spaceflight are associated with musculoskeletal deconditioning. Mars500 was a unique, high-fidelity analogue of the psychological challenges of a 520-day manned mission to Mars. We aimed to explore the effect of musculoskeletal deconditioning on three outcome measures: (1) if lower limb muscle strength was reduced during the 520-day isolation; (2) if type I or II muscle fibres were differentially affected; and (3) whether any 70-day exercise interventions prevented any isolation-induced loss of strength. METHODS: Six healthy male subjects (mean +/- SEM) (34 +/- 3 years; 1.76 +/- 0.02 metres; 83.7 +/- 4.8 kg) provided written, informed consent to participate. The subjects" maximal voluntary contraction (MVC) was assessed isometrically in the calf (predominantly type I fibres), and maximal voluntary isokinetic force (MVIF) was assessed in the quadriceps/hamstrings (predominantly type II fibres) at 0.2 and 0.4 ms-1 using the Multifunctional Dynamometer for Space (MDS) at 35-day intervals throughout Mars500. Exercise interventions were completed 3-7 days/week throughout the 520-day isolation in a counterbalanced design excluding 142-177 days (rest period) and 251-284 days (simulated Mars landing). Exercise interventions included motorized treadmill running, non-motorized treadmill running, cycle ergometry, elastomer-based resistance exercise, whole-body vibration (WBV), and resistance exercise using MDS. RESULTS: Calf MVC did not reduce across the 520-day isolation and MDS increased strength by 18% compared to before that of 70-day exercise intervention. In contrast, there was a significant bilateral loss of MVIF across the 520 days at both 0.2 ms-1 (R 2 = 0.53; P = 0.001) and 0.4 ms-1 (0.4 ms-1; R 2 = 0.42; P = 0.007). WBV (+ 3.7 and 8.8%) and MDS (+ 4.9 and 5.2%) afforded the best protection against isolation-induced loss of MVIF, although MDS was the only intervention to prevent bilateral loss of calf MVC and leg MVIF at 0.2 and 0.4 ms-1. CONCLUSIONS: Mars500 induced significant loss of quadriceps/hamstrings MVIF but not calf MVC. Collectively, these data suggest that muscles with predominantly type I fibres were affected less by isolation compared to type II dominant muscles. MDS and WBV afforded the best protection against isolation-induced loss of strength and thus may have virtue in exploration class missions.

Keywords: Mars500, Confinement, Muscle strength, Spaceflight, Ground-based analogue, Spaceflight analogue, Intervention
GID: 4564; Last update: 20.11.2017
More information: Original Article