Differential atrophy of the postero-lateral hip musculature during prolonged bedrest and the influence of exercise countermeasures

Abstract

As part of the 2nd Berlin BedRest Study (BBR2-2), we investigated the pattern of muscle atrophy of the postero-lateral hip and hamstring musculature during prolonged inactivity and the effectiveness of two exercise countermeasures. Twenty-four male subjects underwent 60 days of head-down tilt bedrest and were assigned to an inactive control (CTR), resistive vibration exercise (RVE), or resistive exercise alone (RE) group. Magnetic resonance imaging (MRI) of the hip and thigh was taken before, during, and at end of bedrest. Volume of posterolateral hip and hamstring musculature was calculated, and the rate of muscle atrophy and the effect of countermeasure exercises were examined. After 60 days of bedrest, the CTR group showed differential rates of muscle volume loss (F = 21.44; P ≤ 0.0001) with fastest losses seen in the semi-membranosus, quadratus femoris and biceps femoris long head followed by the gluteal and remaining hamstring musculature. Whole body vibration did not appear to have an additional effect above resistive exercise in preserving muscle volume. RE and RVE prevented and/or reduced muscle atrophy of the gluteal, semi-membranosus, and biceps femoris long head muscles. Some muscle volumes in the countermeasure groups displayed faster recovery times than the CTR group. Differential atrophy occurred in the postero-lateral hip musculature following a prolonged period of unloading. Short-duration high-load resistive exercise during bedrest reduced muscle atrophy in the mono-articular hip extensors and selected hamstring muscles. Future countermeasure design should consider including isolated resistive hamstring curls to target this muscle group and reduce the potential for development of muscle imbalances.

Gluteal muscle function and size in swimmers

“…In the context of deloading, the results are consistent with the relatively low degree and rate of GMed atrophy demonstrated in bed rest studies 8,25 and could imply that GMed is not necessarily adversely affected by a lack of gravitational stimulus.…”

“…7 These local stabilising properties suggest that GMin may be more vulnerable than gluteus medius (GMed) to adverse changes in size or function in response to a lack of gravitational load, 8 as in swimming. Dysfunction of GMin may affect the ability to bear weight during functional tasks such as walking.…”

Terrestrial neuro-musculoskeletal rehabilitation and astronaut reconditioning: Reciprocal knowledge transfer

“…Countermeasure studies have been conducted during bed rest (e.g. Belavy et al, 2010;Blottner et al 2006;Miokovic et al, 2011), which provides an analogue of microgravity; a useful tool given the methodological constraints of conducting studies inflight (see below regarding methodological challenges). Members of the Reconditioning Topical…”

Quadratus femoris: An EMG investigation during walking and running

“…With reference to biomechanical modelling (Torry et al, 2006) and radiological literature (Miokovic et al, 2011), the authors identified that these muscles have favorable morphological features to contribute to stability of the hip joint, much like the rotator cuff of the shoulder. It is for this reason that targeted interventions for improving deep hip external rotator strength are becoming a fundamental component of contemporary hip rehabilitation protocols (Bennell et al, 2014).…”

“…It is for this reason that targeted interventions for improving deep hip external rotator strength are becoming a fundamental component of contemporary hip rehabilitation protocols (Bennell et al, 2014). Quadratus femoris (QF) is considered a particularly important constituent of the deep external rotators (Miokovic et al, 2011), yet due to the technical difficulty and perceived discomfort associated with accessing this deep muscle with fine wire electrodes, and the proximity to the sciatic nerve, it is only recently that a published account of QF EMG has been documented (Hodges et al, 2014). The investigation by Hodges et al on ten healthy participants confirmed that QF was highly active in maximum isometric hip external rotation and extension.…”