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Exercise and Adaptation to Microgravity Environments

Victor A. Convertino

10.1002/cphy.cp040236

Source: Supplement 14: Handbook of Physiology, Environmental Physiology

Originally published: 1996

Published online: January 2011

Full Article on Wiley Online Library



Abstract

The sections in this article are:

1 Exercise Performance After Adaptation to Microgravity
1.1 Maximal Oxygen Uptake
1.2 Exercise Endurance
1.3 Oxygen Uptake and Mechanical Efficiency during Submaximal Exercise
1.4 Time Course of V.O2max Change in Microgravity
1.5 Age and Gender
1.6 Level of Aerobic Fitness
1.7 Muscle Function: Strength and Fatigability
1.8 Effects of Return to Terrestrial Gravity
2 Physiological Changes Associated with Reduced Exercise Capacity
2.1 Pulmonary Function
2.2 Blood Volume
2.3 Cardiovascular Function
2.4 Morphological Changes in Skeletal Muscle
2.5 Cellular Metabolism of Skeletal Muscle
2.6 Venous and Muscle Compliance
2.7 Changes in Thermoregulation
3 Recovery after Return to the One‐Gravity Environment
3.1 Effects of Ambulation and Exercise during Recovery
3.2 Repeated Exposures to Microgravity
4 Exercise as a Countermeasure to Microgravity Adaptation
4.1 V.O2 and Hemodynamic Responses to Exercise
4.2 Effects on Muscle Structure and Function
4.3 Orthostatic Hypotension after Microgravity Exposure
4.4 Considerations of Future Exercise Prescriptions for Microgravity
5 Summary
Figure 1. Figure 1.

Oxygen uptake () kinetics during constant‐load exercise (115 W) before (solid line) and after (broken line) bed rest.

Modified from Convertino et al. 41 with permission
Figure 2. Figure 2.

Cross‐sectional relationship between duration of bed rest and percent change (%Δ) in . Compilation of data from 19 independent investigations (see Table 2. The linear regression of best fit is %Δ = ‐0.85 [Days] + 1.4, r = 0.730.
Figure 3. Figure 3.

Time course of percent change (%Δ) in during adaptation to simulated microgravity (bed rest) from two independent studies 69,73.
Figure 4. Figure 4.

Mean (± SE) percent reductions in (open bars), blood volume (hashed bars), and plasma volume (shaded bars) after 10 days of bed rest in fit and unfit subjects.

Data from Convertino et al. 44
Figure 5. Figure 5.

Average torque‐velocity relationships before (closed circles and solid lines) and after (open circles and broken lines) exposure of the calf muscles of 12 subjects to 7 days of spaceflight (Panel A) and the knee extensors of 7 subjects to 30 days of 6° head‐down bed rest (Panel B).

Modified from Grigoryeva and Kozlovskaya 81 (Panel A) and Dudley et al. 61 (Panel B) with permission
Figure 6. Figure 6.

Cross‐sectional relationship between duration of bed rest and percent change (%Δ) in strength of handgrip (HG), elbow flexors (EF), ankle flexors (AF), ankle extensors (AE), knee flexors (KF), and knee extensors (KE). Compilation of data from 17 independent investigations (see Table 5.
Figure 7. Figure 7.

Comparison of time courses of percent change (%Δ) in plasma volume during adaptation to actual spaceflight (closed symbols and solid line) and bed rest (open circles and broken line). Spaceflight data from Gemini IV 63, Spacelab 116 and Skylab IV 93. Bed rest data from Convertino et al. 35.
Figure 8. Figure 8.

Relationships between percent changes (%Δ) in plasma volume and after adaptation to microgravity (bed rest). Panel A represents a cross‐sectional compilation of data from 12 independent investigations (%Δ = 0.82 [%Δ PV] + 0.3, r = 0.841). Panel B is generated from Convertino et al. 44 and represents longitudinal data from 10 fit (closed circles) and 10 unfit (open circles) subjects (%Δ = 0.76 [%Δ PV] ‐ 1.7, r = 0.787).
Figure 9. Figure 9.

Comparison of time courses of percent changes (%Δ) in peak and plasma volume during bed rest in subjects who underwent no exercise (open circles and broken line), resistive exercise (closed circles and solid line), and dynamic cycling exercise (closed triangles and hashed line).

Data modified from Greenleaf et al. 73,80
Figure 10. Figure 10.

Mean (± SE) left ventricular ejection fraction and stroke volume during rest and graded exercise before (closed circles and solid lines) and after (open circles and broken lines) 10 days of bed rest.

Modified from Hung et al. 89 with permission
Figure 11. Figure 11.

Mean (± SE) cardiac responses of two cosmonauts during rest and at 125 W and 175 W of exercise on a cycle ergometer before (closed circles and solid lines) and during (open circles and broken lines) a 237 day space mission.

Modified from Atkov et al. 1 with permission
Figure 12. Figure 12.

Time course of post‐spaceflight recovery of stroke volume (open circles and broken lines) and cardiac output (closed circles and solid line) for all Skylab missions. Values are mean ± SE expressed as percent of preflight values.

Modified from Buderer et al. 14 with permission
Figure 13. Figure 13.

Maximal oxygen uptakes () of three astronauts before and during an 84 day space mission. Circles and linesrepresent means ± SE and asterisks indicate that all subjects changed in the same direction.

Data plotted from Michel et al. 126


Figure 1.

Oxygen uptake () kinetics during constant‐load exercise (115 W) before (solid line) and after (broken line) bed rest.

Modified from Convertino et al. 41 with permission


Figure 2.

Cross‐sectional relationship between duration of bed rest and percent change (%Δ) in . Compilation of data from 19 independent investigations (see Table 2. The linear regression of best fit is %Δ = ‐0.85 [Days] + 1.4, r = 0.730.



Figure 3.

Time course of percent change (%Δ) in during adaptation to simulated microgravity (bed rest) from two independent studies 69,73.



Figure 4.

Mean (± SE) percent reductions in (open bars), blood volume (hashed bars), and plasma volume (shaded bars) after 10 days of bed rest in fit and unfit subjects.

Data from Convertino et al. 44


Figure 5.

Average torque‐velocity relationships before (closed circles and solid lines) and after (open circles and broken lines) exposure of the calf muscles of 12 subjects to 7 days of spaceflight (Panel A) and the knee extensors of 7 subjects to 30 days of 6° head‐down bed rest (Panel B).

Modified from Grigoryeva and Kozlovskaya 81 (Panel A) and Dudley et al. 61 (Panel B) with permission


Figure 6.

Cross‐sectional relationship between duration of bed rest and percent change (%Δ) in strength of handgrip (HG), elbow flexors (EF), ankle flexors (AF), ankle extensors (AE), knee flexors (KF), and knee extensors (KE). Compilation of data from 17 independent investigations (see Table 5.



Figure 7.

Comparison of time courses of percent change (%Δ) in plasma volume during adaptation to actual spaceflight (closed symbols and solid line) and bed rest (open circles and broken line). Spaceflight data from Gemini IV 63, Spacelab 116 and Skylab IV 93. Bed rest data from Convertino et al. 35.



Figure 8.

Relationships between percent changes (%Δ) in plasma volume and after adaptation to microgravity (bed rest). Panel A represents a cross‐sectional compilation of data from 12 independent investigations (%Δ = 0.82 [%Δ PV] + 0.3, r = 0.841). Panel B is generated from Convertino et al. 44 and represents longitudinal data from 10 fit (closed circles) and 10 unfit (open circles) subjects (%Δ = 0.76 [%Δ PV] ‐ 1.7, r = 0.787).



Figure 9.

Comparison of time courses of percent changes (%Δ) in peak and plasma volume during bed rest in subjects who underwent no exercise (open circles and broken line), resistive exercise (closed circles and solid line), and dynamic cycling exercise (closed triangles and hashed line).

Data modified from Greenleaf et al. 73,80


Figure 10.

Mean (± SE) left ventricular ejection fraction and stroke volume during rest and graded exercise before (closed circles and solid lines) and after (open circles and broken lines) 10 days of bed rest.

Modified from Hung et al. 89 with permission


Figure 11.

Mean (± SE) cardiac responses of two cosmonauts during rest and at 125 W and 175 W of exercise on a cycle ergometer before (closed circles and solid lines) and during (open circles and broken lines) a 237 day space mission.

Modified from Atkov et al. 1 with permission


Figure 12.

Time course of post‐spaceflight recovery of stroke volume (open circles and broken lines) and cardiac output (closed circles and solid line) for all Skylab missions. Values are mean ± SE expressed as percent of preflight values.

Modified from Buderer et al. 14 with permission


Figure 13.

Maximal oxygen uptakes () of three astronauts before and during an 84 day space mission. Circles and linesrepresent means ± SE and asterisks indicate that all subjects changed in the same direction.

Data plotted from Michel et al. 126
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Article Title: Exercise and Adaptation to Microgravity Environments
 

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Victor A. Convertino. Exercise and Adaptation to Microgravity Environments. Compr Physiol 2011, Supplement 14: Handbook of Physiology, Environmental Physiology: 815-843. First published in print 1996. doi: 10.1002/cphy.cp040236