Treadmill exercise within lower body negative pressure protects leg lean tissue mass and extensor strength and endurance during bed rest

Schneider, Suzanne M.; Lee, Stuart M. C.; Feiveson, Alan H.; Watenpaugh, Donald E.; Macias, Brandon R.; Hargens, Alan R.

doi:10.14814/phy2.12892

Cited by 10 publications

(8 citation statements)

References 58 publications

(152 reference statements)

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“…Fourty five studies specified a time period ahead of the bed rest period in which baseline measures were recorded ranging from 1 to 21 days. Of these, 11 (Greenleaf et al, 1983, 1989, 1994b; Dudley et al, 1989; Ellis et al, 1993; Ferrando et al, 1995; Portero et al, 1996; Muir et al, 2011; Lee et al, 2014; English et al, 2016; Schneider et al, 2016) stated utilizing a pre-bed rest ambulatory control period in their methods section. However, it was not clear in any of the studies what the control period involved or if there was any pre-bed rest deconditioning that was measured or adjusted for.…”

Section: Resultsmentioning

confidence: 99%

Effect of Time on Human Muscle Outcomes During Simulated Microgravity Exposure Without Countermeasures—Systematic Review

et al. 2019

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Background: Space Agencies are planning human missions beyond Low Earth Orbit. Consideration of how physiological system adaptation with microgravity (μG) will be managed during these mission scenarios is required. Exercise countermeasures (CM) could be used more sparingly to decrease limited resource costs, including periods of no exercise. This study provides a complete overview of the current evidence, making recommendations on the length of time humans exposed to simulated μG might safely perform no exercise considering muscles only. Methods: Electronic databases were searched for astronaut or space simulation bed rest studies, as the most valid terrestrial simulation, from start of records to July 2017. Studies were assessed with the Quality in Prognostic Studies and bed rest analog studies assessed for transferability to astronauts using the Aerospace Medicine Systematic Review Group Tool for Assessing Bed Rest Methods. Effect sizes, based on no CM groups, were used to assess muscle outcomes over time. Outcomes included were contractile work capacity, muscle cross sectional area, muscle activity, muscle thickness, muscle volume, maximal voluntary contraction force during one repetition maximum, peak power, performance based outcomes, power, and torque/strength. Results: Seventy-five bed rest μG simulation studies were included, many with high risk of confounding factors and participation bias. Most muscle outcomes deteriorated over time with no countermeasures. Moderate effects were apparent by 7–15 days and large by 28–56 days. Moderate effects (>0.6) became apparent in the following order, power and MVC during one repetition maximum (7 days), followed by volume, cross sectional area, torques and strengths, contractile work capacity, thickness and endurance (14 days), then muscle activity (15 days). Large effects (>1.2) became apparent in the following order, volume, cross sectional area (28 days) torques and strengths, thickness (35 days) and peak power (56 days). Conclusions: Moderate effects on a range of muscle parameters may occur within 7–14 days of unloading, with large effects within 35 days. Combined with muscle performance requirements for mission tasks, these data, may support the design of CM programmes to maximize efficiency without compromising crew safety and mission success when incorporated with data from additional physiological systems that also need consideration.

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Section: Resultsmentioning

confidence: 99%

Effect of Time on Human Muscle Outcomes During Simulated Microgravity Exposure Without Countermeasures—Systematic Review

et al. 2019

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“…Future studies should assess the effect of nutrition, together with exercise, on muscle and hemodynamic parameters during bedrest immobilization. This is important as physical activity has been singly identified as an important intervention in preventing deleterious effects of bedrest confinement 60,61 . Additional interventions that could be tested include cognitive training 21 , LBNP 62 , and artificial gravity 63 ; all of these have been shown to alleviate the symptoms of bedrest induced physiological deconditioning.…”

Section: Limitations and Future Workmentioning

confidence: 99%

Cardio-postural interactions and muscle-pump baroreflex are severely impacted by 60-day bedrest immobilization

Tremblay

Verma

et al. 2020

Sci Rep

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To understand fundamental mechanisms associated with post-flight orthostatic intolerance we investigated the interaction between the cardiovascular and postural functions before and after 60 days of head down bedrest (HDBR). Twenty healthy young males (35.0 ± 1.7 years) were subjected to 60-day HDBR at 6˚ to simulate spaceflight-induced fluid shifts. A supine-to-stand (STS) test was conducted to evaluate cardio-postural control before and after (R) HDBR while an assessment of cardiovascular function was performed during HDBR. Beat-to-beat heart period, systolic blood pressure, and electromyography impulses were derived for wavelet transform coherence and causality analyses of the cardio-postural control and used to assess changes in the muscle-pump baroreflex. During quiet stand of the STS test, compared to baseline, heart rate was 50% higher on the day of exit from bedrest (R0) and 20% higher eight days later (R8). There was a 50% increase in deoxygenated hemoglobin on R0 and R8. Leg muscle activity reduced, and postural sway increased after HDBR. Causality of the muscle-pump baroreflex was reduced on R0 (0.73 ± 0.2) compared to baseline (0.87 ± 0.2) with complete recovery by R8. The muscle-pump baroreflex also had decreased gain and fraction time active following HDBR. Overall, our data show a significantly impaired muscle-pump baroreflex following bedrest. Spaceflight-induced weightlessness produces time-dependent physiological adaptation responses 1-3. Once adapted to weightlessness, many responses become inappropriate upon return to a gravitational environment. The resulting physiological deconditioning could pose a serious challenge in the event of a critical post-landing situation requiring rapid escape from a spacecraft. Orthostatic intolerance after spaceflight remains a health and safety concern for astronauts, not just on landing day but also in the days of recovery 4. Similar physiological deconditioning is seen following long lasting bedrest confinements (e.g. in young persons participating in head down bedrest studies, or in older persons due to chronic diseases or after falls and falls-related injuries) 5. Gravitational effects on the cardiovascular system during upright posture (orthostatic loading) induce a decrease in blood pressure which, if not compensated for, will cause loss of consciousness 6. Baroreflex plays an essential role in maintaining blood pressure equilibrium under orthostatic loading. In regards to the arterial baroreflex, two processes exist in tandem: one in which blood pressure alters baroreceptor output and hence heart rate and vasomotor tone 7-9 ; and, a second in which changes in heart rate and vasomotor tone alters blood pressure-the former a baroreflex (feed-back) and the latter a non-baroreflex (feed-forward) control of blood pressure 10. Similarly, conscious movement could place a person in a position of instability, which would require post-movement adjustment to maintain an upright stance. Therefore, any change in body position (feed-forward) must be accompanied with ...

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“…The current constraint bungee cord in space flight is an elastic material, implying that the constraint loading changes linearly with the body height during running. However, previous studies proposed that a constant constraint loading may better prevent the musculoskeletal decline in spaceflight [ 14 , 25 ], which could be achieved by manipulating the loading devices. Second, the kinematical data of treadmill exercise at gravity was also used to drive the musculoskeletal model at weightlessness, because weightless experiment has reported that the gait at weightlessness approached to the gait at gravity when the resultant constraint force increased to body weight on earth.…”

Section: Discussionmentioning

confidence: 99%

“…In the weightless condition, bungee cords were applied instead of gravity to constrain the body on the treadmill during exercise. Previous studies have suggested that providing a constraint force equal to gravity could better prevent musculoskeletal decline in spaceflight [ 14 , 25 ]. Therefore, in the present study, the resultant force of the bungee cords was assumed to be constantly equal to gravity.…”

Section: Methodsmentioning

confidence: 99%

“…Currently, the used exercise devices in the International Space Station (ISS) include treadmill, bicycle ergometer, and resistance exercise device. Among these countermeasures, a significant correlation between treadmill training intensity and the muscle mass maintenance was observed, and muscle losses of astronauts with high-volume treadmill exercise were about 59% less than those with low-volume treadmill exercise [ 3 , 14 ]. During the training, astronauts have to be restrained with bungee cords, which provide the vertical loading instead of the gravity effect.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Constraint Loading on the Lower Limb Muscle Forces in Weightless Treadmill Exercise

Guo

Fan

Yan-ru

et al. 2018

Journal of Healthcare Engineering

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Long exposure to the microgravity will lead to muscle atrophy and bone loss. Treadmill exercise could mitigate the musculoskeletal decline. But muscle atrophy remains inevitable. The constraint loading applied on astronauts could affect the muscle force and its atrophy severity. However, the quantitative correlation between constraint loading mode and muscle forces remains unclear. This study aimed to characterize the influence of constraint loading mode on the lower limb muscle forces in weightless treadmill exercise. The muscle forces in the full gait cycle were calculated with the inverse dynamic model of human musculoskeletal system. The calculated muscle forces at gravity were validated with the EMG data. Muscle forces increased at weightlessness compared with those at the earth's gravity. The increasing percentage from high to low is as follows: biceps femoris, gastrocnemius, soleus, vastus, and rectus femoris, which was in agreement with the muscle atrophy observed in astronauts. The constraint loading mode had an impact on the muscle forces in treadmill exercise and thus could be manipulated to enhance the effect of the muscle training in spaceflight. The findings could provide biomechanical basis for the optimization of treadmill constraint system and training program and improve the countermeasure efficiency in spaceflight.

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Treadmill exercise within lower body negative pressure protects leg lean tissue mass and extensor strength and endurance during bed rest

Cited by 10 publications

References 58 publications

Effect of Time on Human Muscle Outcomes During Simulated Microgravity Exposure Without Countermeasures—Systematic Review

Effect of Time on Human Muscle Outcomes During Simulated Microgravity Exposure Without Countermeasures—Systematic Review

Cardio-postural interactions and muscle-pump baroreflex are severely impacted by 60-day bedrest immobilization

Effect of Constraint Loading on the Lower Limb Muscle Forces in Weightless Treadmill Exercise

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