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The Physiology of Bed Rest

Suzanne M. Fortney, Victor S. Schneider, John E. Greenleaf

10.1002/cphy.cp040239

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 History of Bed‐Rest Research
1.1 Early Period (1855–1929)
1.2 Intermediate Period (1930–1959)
2 Cardiopulmonary System
2.1 Initial Hemodynamic Responses
2.2 Fluid–Electrolyte Responses
2.3 Cardiac Function
2.4 Cardiovascular Autonomic Regulation
2.5 Venous Compliance
2.6 Pulmonary Function
2.7 Recovery
2.8 Summary of Cardiopulmonary Adaptation to Bed Rest
3 Musculoskeletal System
3.1 Bone and Calcium Metabolism
3.2 Normal Metabolism
3.3 Bone Loss and Muscle Atrophy
3.4 Body Composition
3.5 null
4 Energy Metabolism and Thermoregulation
4.1 Energy Metabolism
4.2 Thermal Regulation
5 Immune Cellular and Humoral Parameters
5.1 Bed Rest < 30 Days
5.2 Bed Rest > 30 Days
6 Psychophysiological Factors
6.1 Group Interaction
6.2 Response Stages
6.3 Performance
6.4 Visual and Auditory Responses
6.5 Sleep
6.6 Posture: Equilibrium, Balance, and Gait
Figure 1. Figure 1.

Mean (± SE) heart rate, arterial pressure, and hormonal responses in eight men during 24 h of 6° recumbency. *P < 0.05 from time 0.

From Dallman et al. 71 with permission
Figure 2. Figure 2.

Mean change in body weight in 10 men during 7 days of bed rest (BR) and 10 days of the recovery period (RP) in the horizontal (dashed line, N = 5) and 6° head‐down (solid line, N = 5) positions.

From Noskov et al. 282 with permission
Figure 3. Figure 3.

Percent change in plasma volume with data from studies that utilized horizontal bed rest with no remedial procedures.

From Greenleaf et al. 130 with permission
Figure 4. Figure 4.

Regression of plasma vasopressin on plasma osmolality (upper panel), and free water clearance (TH2OC) on plasma vasopressin (lower panel) in cosmonauts before and after short‐ and long‐term spaceflights. Shaded area indicates normal limits.

From Natochin et al. 274 with permission
Figure 5. Figure 5.

Mean (± SE) plasma, extracellular, red cell, and total body water volumes in 10 men before (C1, C9), during (B2, B14, B28), and after (R7, R14) 28 days of horizontal bed rest. *P < 0.05 from C9 value.

From Fortney et al. 93 with permission
Figure 6. Figure 6.

Heart rate time series and spectra from one healthy woman before (A) and during (B, day 4; C, day 9) bed rest.

From Goldberger and Rigney 117 with permission
Figure 7. Figure 7.

Forearm vascular resistance (upper panels) and venous tone (lower panels) during infusions of tyramine and norepinephrine in four men during control (C, day 8), horizontal bed rest (BR, day 12), and ambulatory recovery (R, day 6) periods. The dose‐response curves were constructed from data from all three (C, BR, R) periods. Relative potency values compare dose of drug needed to produce given levels of resistance or venous tone. For example, a dose of tyramine 7.052 times larger than that in the recovery period was required to result in a certain level of resistance. The upper and lower limits of the dose are 7,680.7 and 2.096, respectively. * Indicates upper vs. lower limit differences are significant (P < 0.05).

From Schmid et al. 327 with permission
Figure 8. Figure 8.

Left column: mean carotid baroreceptor‐cardiac reflex responses in nonsyncopal (N = 6) and syncopal (N = 4) men before and after 30 days of 6° head‐down bed rest. Right column: mean (± SE) decreases in baroreflex slopes (pre‐ vs. post‐bed rest) in the nonsyncopal and syncopal men; *P < 0.05 (a); and regression of change in standing systolic blood pressure on change in maximum baroreflex slope (N = 10) in b.

From Convertino et al. 58 with permission
Figure 9. Figure 9.

Percent changes in blood volume shifts (133Indium) with lower‐body negative pressure (LBNP) during control and after 120 days of head‐down bed rest.

From Savilov et al. 325 with permission
Figure 10. Figure 10.

Adaptive responses of prolonged bed rest that influence maximal oxygen uptake.
Figure 11. Figure 11.

Interaction of physiological responses to deconditioning: spaceflight, bed rest, or water immersion.

Revised from Sandler 318 with permission
Figure 12. Figure 12.

Mean changes in urinary calcium excretion during 6 wk of bed rest in control (quiet activity) and body‐casted subjects.
Figure 13. Figure 13.

Mean changes in urinary calcium and hydroxyproline in the ambulatory control period and during 17 wk of bed rest.
Figure 14. Figure 14.

Mean serum total calcium, ionized calcium, and phosphorus concentrations in the ambulatory control period and during 17 wk of bed rest. N = 30.
Figure 15. Figure 15.

Mean (± SE) cardiorespiratory responses in five men during submaximal and peak loads in sitting and supine positions. Data at 350 W from only two subjects.

From Greenleaf et al. 143 with permission
Figure 16. Figure 16.

Mean oxygen uptakes and heart rates in seven men under basal, resting, submaximal, and peak exercise loads for three regimens during 14 days of horizontal bed rest. *P < 0.05 from corresponding pre‐bed rest value.

From Stremel et al. 348 with permission
Figure 17. Figure 17.

Average rectal, mean body and mean skin temperatures, and tissue conductances (Hsk) in seven men during supine submaximal (43%–48% peak) leg exercise during ambulatory control, and after 14 days of horizontal bed rest with no exercise, and isotonic (dynamic) and isometric exercise training.

From Greenleaf and Reese 136 with permission
Figure 18. Figure 18.

Natural killer (NK) cell activity during 120 days of 4.5° head‐down bed rest in six male nonresponders (upper panel), and in nine male responders (lower panel). The index of cytotoxicity was determined in vitro from response of NK cells on 3H‐uridine‐labeled human K‐562 leukocytes.

Redrawn from Konstantinova 208 with permission
Figure 19. Figure 19.

Mean daily composite values in 18 men for eight performance tests during orientation (10 trials), ambulatory‐control, bed rest, and ambulatory‐recovery periods for the three exercise groups.

From Greenleaf 127 with permission
Figure 20. Figure 20.

Mean change in affective and activation mood parameters and sleep quality scales during bed rest in the three exercise groups. Zero (y‐axis) indicates no change: positive is improvement and negative is deterioration. *P < 0.05 from zero slope (linear regression), †P < 0.05 from no‐exercise group, and ‡P < 0.05 from isotonic exercise group.

From DeRoshia and Greenleaf 74 with permission
Figure 21. Figure 21.

Mean (± SE) tympanic membrane displacement in six subjects in various postures: 90° is sitting, 0° is horizontal, and ‐6° and ‐15° are head‐down tilt. *P < 0.05 from 90°, ‡P < 0.05 from 0°, and †P < 0.05 from ‐6°. Contraction of the stapedius muscle moves the tympanic membrane (via the oval window and ossicles) inward or outward, reflecting increased or decreased, respectively, perilymphatic pressure which reflects intracranial pressure.

Redrawn from Murthy et al. 271 with permission
Figure 22. Figure 22.

Mean body sway in six men during pre‐bed rest control and for 5 days after 3 wk of horizontal bed rest. Lack of practice for 3 wk had no effect on post‐bed rest responses.

Redrawn from Taylor et al. 353 with permission
Figure 23. Figure 23.

Mean frequency and amplitude of frontal plane oscillations of six men (35–40 yr) before (ambulatory control, AC) and during 182 days of 4° head‐down bed rest. Variability unspecified.

Redrawn from Kotovskaya et al. 212 with permission
Figure 24. Figure 24.

Mean (± range) arm tremor during bed rest. Exercise group utilized leg cycle ergometer and arm resistance exercise at 1,200 kcal/day.

Redrawn from Purakhin and Petukhov 300 with permission


Figure 1.

Mean (± SE) heart rate, arterial pressure, and hormonal responses in eight men during 24 h of 6° recumbency. *P < 0.05 from time 0.

From Dallman et al. 71 with permission


Figure 2.

Mean change in body weight in 10 men during 7 days of bed rest (BR) and 10 days of the recovery period (RP) in the horizontal (dashed line, N = 5) and 6° head‐down (solid line, N = 5) positions.

From Noskov et al. 282 with permission


Figure 3.

Percent change in plasma volume with data from studies that utilized horizontal bed rest with no remedial procedures.

From Greenleaf et al. 130 with permission


Figure 4.

Regression of plasma vasopressin on plasma osmolality (upper panel), and free water clearance (TH2OC) on plasma vasopressin (lower panel) in cosmonauts before and after short‐ and long‐term spaceflights. Shaded area indicates normal limits.

From Natochin et al. 274 with permission


Figure 5.

Mean (± SE) plasma, extracellular, red cell, and total body water volumes in 10 men before (C1, C9), during (B2, B14, B28), and after (R7, R14) 28 days of horizontal bed rest. *P < 0.05 from C9 value.

From Fortney et al. 93 with permission


Figure 6.

Heart rate time series and spectra from one healthy woman before (A) and during (B, day 4; C, day 9) bed rest.

From Goldberger and Rigney 117 with permission


Figure 7.

Forearm vascular resistance (upper panels) and venous tone (lower panels) during infusions of tyramine and norepinephrine in four men during control (C, day 8), horizontal bed rest (BR, day 12), and ambulatory recovery (R, day 6) periods. The dose‐response curves were constructed from data from all three (C, BR, R) periods. Relative potency values compare dose of drug needed to produce given levels of resistance or venous tone. For example, a dose of tyramine 7.052 times larger than that in the recovery period was required to result in a certain level of resistance. The upper and lower limits of the dose are 7,680.7 and 2.096, respectively. * Indicates upper vs. lower limit differences are significant (P < 0.05).

From Schmid et al. 327 with permission


Figure 8.

Left column: mean carotid baroreceptor‐cardiac reflex responses in nonsyncopal (N = 6) and syncopal (N = 4) men before and after 30 days of 6° head‐down bed rest. Right column: mean (± SE) decreases in baroreflex slopes (pre‐ vs. post‐bed rest) in the nonsyncopal and syncopal men; *P < 0.05 (a); and regression of change in standing systolic blood pressure on change in maximum baroreflex slope (N = 10) in b.

From Convertino et al. 58 with permission


Figure 9.

Percent changes in blood volume shifts (133Indium) with lower‐body negative pressure (LBNP) during control and after 120 days of head‐down bed rest.

From Savilov et al. 325 with permission


Figure 10.

Adaptive responses of prolonged bed rest that influence maximal oxygen uptake.



Figure 11.

Interaction of physiological responses to deconditioning: spaceflight, bed rest, or water immersion.

Revised from Sandler 318 with permission


Figure 12.

Mean changes in urinary calcium excretion during 6 wk of bed rest in control (quiet activity) and body‐casted subjects.



Figure 13.

Mean changes in urinary calcium and hydroxyproline in the ambulatory control period and during 17 wk of bed rest.



Figure 14.

Mean serum total calcium, ionized calcium, and phosphorus concentrations in the ambulatory control period and during 17 wk of bed rest. N = 30.



Figure 15.

Mean (± SE) cardiorespiratory responses in five men during submaximal and peak loads in sitting and supine positions. Data at 350 W from only two subjects.

From Greenleaf et al. 143 with permission


Figure 16.

Mean oxygen uptakes and heart rates in seven men under basal, resting, submaximal, and peak exercise loads for three regimens during 14 days of horizontal bed rest. *P < 0.05 from corresponding pre‐bed rest value.

From Stremel et al. 348 with permission


Figure 17.

Average rectal, mean body and mean skin temperatures, and tissue conductances (Hsk) in seven men during supine submaximal (43%–48% peak) leg exercise during ambulatory control, and after 14 days of horizontal bed rest with no exercise, and isotonic (dynamic) and isometric exercise training.

From Greenleaf and Reese 136 with permission


Figure 18.

Natural killer (NK) cell activity during 120 days of 4.5° head‐down bed rest in six male nonresponders (upper panel), and in nine male responders (lower panel). The index of cytotoxicity was determined in vitro from response of NK cells on 3H‐uridine‐labeled human K‐562 leukocytes.

Redrawn from Konstantinova 208 with permission


Figure 19.

Mean daily composite values in 18 men for eight performance tests during orientation (10 trials), ambulatory‐control, bed rest, and ambulatory‐recovery periods for the three exercise groups.

From Greenleaf 127 with permission


Figure 20.

Mean change in affective and activation mood parameters and sleep quality scales during bed rest in the three exercise groups. Zero (y‐axis) indicates no change: positive is improvement and negative is deterioration. *P < 0.05 from zero slope (linear regression), †P < 0.05 from no‐exercise group, and ‡P < 0.05 from isotonic exercise group.

From DeRoshia and Greenleaf 74 with permission


Figure 21.

Mean (± SE) tympanic membrane displacement in six subjects in various postures: 90° is sitting, 0° is horizontal, and ‐6° and ‐15° are head‐down tilt. *P < 0.05 from 90°, ‡P < 0.05 from 0°, and †P < 0.05 from ‐6°. Contraction of the stapedius muscle moves the tympanic membrane (via the oval window and ossicles) inward or outward, reflecting increased or decreased, respectively, perilymphatic pressure which reflects intracranial pressure.

Redrawn from Murthy et al. 271 with permission


Figure 22.

Mean body sway in six men during pre‐bed rest control and for 5 days after 3 wk of horizontal bed rest. Lack of practice for 3 wk had no effect on post‐bed rest responses.

Redrawn from Taylor et al. 353 with permission


Figure 23.

Mean frequency and amplitude of frontal plane oscillations of six men (35–40 yr) before (ambulatory control, AC) and during 182 days of 4° head‐down bed rest. Variability unspecified.

Redrawn from Kotovskaya et al. 212 with permission


Figure 24.

Mean (± range) arm tremor during bed rest. Exercise group utilized leg cycle ergometer and arm resistance exercise at 1,200 kcal/day.

Redrawn from Purakhin and Petukhov 300 with permission
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Article Title: The Physiology of Bed Rest
 

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Suzanne M. Fortney, Victor S. Schneider, John E. Greenleaf. The Physiology of Bed Rest. Compr Physiol 2011, Supplement 14: Handbook of Physiology, Environmental Physiology: 889-939. First published in print 1996. doi: 10.1002/cphy.cp040239