The effects of space flight on the structure and function of human muscle

This painting, An Experiment on a Bird in the Air Pump depicts an experiment performed by Robert Boyle in to test the effect of a vacuum on a living system. Human physiology is adapted to living within the atmosphere of Earth, and a certain amount of oxygen is required in the air we breathe.

Introduction The goals of the international space community are to conduct long-termed manned missions beyond the low earth orbit of the International Space Station ISS. First, a number of issues regarding the deleterious effects of microgravity on human biology need to be addressed and resolved Fitts et al.

It is clear from the last 40 years of space research, particularly studies conducted on the Skylab and MIR space stations and on mission STS of the Space Shuttle Columbia with the Life and Microgravity Spacelab, LMSthat limb skeletal muscle is particularly susceptible to microgravity-induced deterioration in both structure and function Convertino, ; Fitts et al.

A consistent observation is significant atrophy of both upper and lower leg muscles with the response occurring more rapidly in the triceps surae muscle group ankle plantar flexors than the anterior tibial group ankle dorsal flexors Fitts et al.

The primary cause of the decline in muscle mass appears to be the unloading of the skeletal and muscular systems rather than reduced activation.

Support for this comes from the work of Edgerton et al. The authors concluded that space flight on Shuttle missions is a model not just of space flight but rather microgravity plus the programmed work schedule.

The composite data from Skylab, MIR and Shuttle flights suggest that the loss of limb muscle mass is exponential with the duration of flight, and that a microgravity steady state may be reached by approximately days Fitts et al. The loss in muscle force primarily reflects the decline in mass.

Consequently, when single fibre force is expressed relative to cross-sectional area, there is little difference between pre- and post-flight values Widrick et al.

In addition to the decline in muscle mass and peak force, crew members showed a depressed ability to generate power that was generally greater than the loss of force Widrick et al. The latter was greater than the loss in single-fibre power after the day LMS flight suggesting that factors other than atrophy contributed to the decline Widrick et al.

Following the LMS flight, we found that the decline in peak power was partially protected by an increased maximal velocity V0 of both slow and fast fibres such that the velocity obtained at peak power was higher post-flight Widrick et al.

The elevated fibre V0 was associated with and likely caused by an increase in myofilament lattice spacing that resulted from a reduction in thin filament density. It is unknown whether or not this adaptation persists with prolonged space flight or reflects a transient response to short duration flight.

A hallmark of space flight is that considerable variability in the extent of muscle atrophy and functional loss exists among crew members. Similarly, Zange et al.

Following the day LMS flight, two crew members showed 2—3 times the reduction in peak force mN noted for the other two Widrick et al. An additional goal was to determine the extent to which the observed functional changes were fibre and muscle specific, and whether or not they could be explained by structural alterations.

Changes in structure and function were to the extent possible related to differences in the type and amount of countermeasure exercise. To allow for scientific comparisons between the single fibre results described here and our recently published whole muscle data on the same subjects Trappe et al.

The exercise countermeasure performed by each crew member was presented in detail in Trappe et al. The results were also compared to the known cell changes following short duration space flight.

Methods Flight and subjects The 10 crew members, five American astronauts and five Russian cosmonauts, who participated in this study flew aboard the International Space Station ISS from Increments 5 to 11 — All flights except for the first Increment 5 originated and landed in Russia aboard the Russian Soyuz spacecraft.

The post-flight muscle samples for one crew member were damaged during shipment from Russia to the USA, and thus the data for this subject were not included.

Prior to volunteering to participate in this study, all crew members were briefed on the project objectives and testing procedures by a member of the research team.

Astronaut muscles waste in space

This study was conducted in accordance with the Declaration of Helsinki. Pre- and in-flight exercise and nutritional profile The pre- and in-flight exercise programmes of each crew member have been published elsewhere by our research team Trappe et al. The treadmill could be used in a passive subject driven or active motorized mode of operation.

The exercise countermeasure programme was individually structured to allow for personal preference with guidance from staff within NASA and the Russian Space Agencies.

A summary of the in-flight exercise is shown in Table 1. For more detailed information about the exercise prescription performed while on the ISS and individual aerobic and resistance exercise data profiles for each crew member see Trappe et al. The exercise profiles were determined from crew member logbooks and from downloaded analog data from the treadmill and cycle ergometer Trappe et al.

The nutrient content of the pre- and post-flight foods was calculated using the Nutrient Data System for Research Schakel et al.The primary goal of this study was to determine the effects of prolonged space flight (∼ days) on the structure and function of slow and fast fibres in human skeletal muscle.

Our primary goal was to determine the effects of 6-mo flight on the International Space Station (ISS) on selected anaerobic and aerobic enzymes, and the content of glycogen and lipids in slow and fast fibers of the soleus and gastrocnemius.

The primary goal of this study was to determine the effects of prolonged space flight (∼ days) on the structure and function of slow and fast fibres in human skeletal muscle.

Biopsies were obtained from the gastrocnemius and soleus muscles of nine International Space Station crew members ∼45 days pre- and on landing day (R+0) .

Space travel (detraining) has detrimental effects on skeletal muscle structure, metabolism and function, including reductions in muscle size, strength and endurance.

Effect of spaceflight on the human body - Wikipedia

Exercise (training) in space can counteract some of these deleterious effects. Applications. Space Applications It is well established that muscle mass and strength decrease during space flight. The atrophy of muscles in space can affect not only the performance of astronauts during missions, but it can lead to severe muscle injuries upon return to Earth.

Calf muscle function tests will be conducted 90, 60, 30 and 15 days before launch to the Space Station, and again seven, 14, 21 and 30 days after return to Earth.