Impact Case Study

Microgravity - how muscles and bones react

Musculoskeletal research has made a major impact on UK Government policy towards full participation in EU space programmes.

The problem

Microgravity has an adverse effect on the muscles, bones and tendons of the human body. The stresses associated with spaceflight can have a potentially serious effect on astronauts, their ability to carry out missions safely and their function on return to earth. Solutions are needed to combat these harmful musculoskeletal responses as the average ‘space time’ of missions increases.

Findings from research into the effect that microgravity has on the human body have relevance in the real world too, where people are confined to bed rest due to disease and particularly old age.

What we did

Over the last decade, the university has carried out pioneering research using simulated gravity scenarios. This varied from putting volunteers on 21-90 days of bedrest, to asking them to hop around on crutches for six weeks. Animal models of disuse were also used. The research team pioneered non-invasive techniques that combine ultrasound imaging with dynamometry to look at how muscles and tendons behave in real life situations and explored in muscle biopsies and animal studies the consequences of disuse on muscle metabolism, microvascular supply and size of individual muscle cells.

The findings triggered development of a number of gravity-independent devices and exercise systems and application of whey protein supplementation in the diet. The devices and exercise systems have been tested by ESA and NASA within various ‘live’ missions on board the International Space Station.

What we discovered

Under simulated microgravity conditions, this research showed for the first time that human tendons decrease their mechanical stiffness as a result of deterioration. Bone mineral content goes down in response to a prolonged period of simulated microgravity - equivalent to 90 days of bed-rest. The way the muscle is structured is compromised and the muscle shrinks in size, due to fibre atrophy. The metabolic capacity of the muscle is also reduced, but there was no evidence of loss of microvessels.

Key researcher Professor Rittweger pioneered applying resistive vibration exercise, as an effective countermeasure for preventing muscle and bone loss due to microgravity exposure. The responses to this led to a training regimen being developed. This was the first to be fully effective at preventing structural bone breakdown in the tibia – where simulated microgravity has shown greatest bone loss occurs.

The researchers also took part in a series of microgravity simulation studies around long-term bed rest organised by the European Space Agency (ESA) and in one of them it was observed that whey protein supplementation modified the disuse-induced reduction in muscle metabolic capacity. ESA is an inter-governmental organisation dedicated to the exploration of space.

Why it matters

The research has impacted on International Spaceflight Policy. Staff acted as lead advisors to committees concerned with spaceflight and physiology, including the ESA’s Artificial Gravity Expert Group and Exercise in Space team. Researchers contributed to a document in support of the UK Government joining the ‘European Life and Physical Sciences Programme (ELIPS). This resulted in a £12.4M investment from the UK to use insights into the human ageing process from space missions.

"Over the last decade there have been a small number of British people who have been active in space life science R&D to an extent that has impacted the European research scene. The work carried out by Manchester Met is recognised at an international level".

The Coordinator of UK Space Biomedicine Consortium