Regional muscle loss after short duration spaceflight.

TLDR

Muscle mass loss during spaceflight is a well‑documented medical concern that threatens the feasibility of long‑duration missions and the economic viability of space operations. The study aimed to quantify the magnitude and timing of muscle atrophy in Shuttle crew members after an eight‑day weightless flight to inform countermeasure development. MRI scans of calf, thigh, and lower‑back muscles were taken before and 24 h after the STS‑47 mission, and statistical analysis compared pre‑flight volumes to post‑flight values. Muscle volumes decreased by 3.9–10.3 % immediately after landing, and hamstrings and lower‑back muscles remained below baseline two weeks later, confirming that even short flights cause significant atrophy.

Abstract

Muscle strength and limb girth measurements during Skylab and Apollo missions suggested that loss of muscle mass may occur as a result of spaceflight. Extended duration spaceflight is important for the economical and practical use of space. The loss of muscle mass during spaceflight is a medical concern for long duration flights to the planets or extended stays aboard space stations. Understanding the extent and temporal relationships of muscle loss is important for the development of effective spaceflight countermeasures.We hypothesized that significant and measurable changes in muscle volume would occur in Shuttle crewmembers following 8 d of weightlessness.MRI was used to obtain the muscle volumes of the calf, thigh and lower back before and after the STS-47 Shuttle mission.Statistical analyses demonstrated that the soleus-gastrocnemius (-6.3%), anterior calf (-3.9%), hamstrings (-8.3%), quadriceps (-6.0%) and intrinsic back (-10.3%) muscles were decreased, p < 0.05, compared to baseline, 24 h after landing. At 2 weeks post recovery, the hamstrings and intrinsic lower back muscles were still below baseline, p < 0.05.These results demonstrate that even short duration spaceflight can result in significant muscle atrophy.