scholarly journals Developing Proprioceptive Countermeasures to Mitigate Postural and Locomotor Control Deficits After Long-Duration Spaceflight

2021 ◽  
Vol 15 ◽  
Author(s):  
Timothy R. Macaulay ◽  
Brian T. Peters ◽  
Scott J. Wood ◽  
Gilles R. Clément ◽  
Lars Oddsson ◽  
...  

Astronauts experience post-flight disturbances in postural and locomotor control due to sensorimotor adaptations during spaceflight. These alterations may have adverse consequences if a rapid egress is required after landing. Although current exercise protocols can effectively mitigate cardiovascular and muscular deconditioning, the benefits to post-flight sensorimotor dysfunction are limited. Furthermore, some exercise capabilities like treadmill running are currently not feasible on exploration spaceflight vehicles. Thus, new in-flight operational countermeasures are needed to mitigate postural and locomotor control deficits after exploration missions. Data from spaceflight and from analog studies collectively suggest that body unloading decreases the utilization of proprioceptive input, and this adaptation strongly contributes to balance dysfunction after spaceflight. For example, on return to Earth, an astronaut’s vestibular input may be compromised by adaptation to microgravity, but their proprioceptive input is compromised by body unloading. Since proprioceptive and tactile input are important for maintaining postural control, keeping these systems tuned to respond to upright balance challenges during flight may improve functional task performance after flight through dynamic reweighting of sensory input. Novel approaches are needed to compensate for the challenges of balance training in microgravity and must be tested in a body unloading environment such as head down bed rest. Here, we review insights from the literature and provide observations from our laboratory that could inform the development of an in-flight proprioceptive countermeasure.

1978 ◽  
Vol 87 (6) ◽  
pp. 797-803 ◽  
Author(s):  
George T. Singleton ◽  
Kathryn Nolan Post ◽  
Marc Simeon Karlan ◽  
Douglas G. Bock

Fifty-one patients suspected of having a perilymph fistula were evaluated. We postulated that many patients with predominantly vestibular complaints had unrecognized perilymph fistulas. An analysis was made of symptoms, physical findings, vestibular and audiometric test results in order to determine appropriate diagnostic criteria for the presence of perilymph fistulas. The patient population was divided into two groups, those with and without fistulas. Data from both groups were compared by mean values of variables, step-wise discriminant analysis, and factor analysis. A history of trauma with sudden onset of dizziness and/or hearing loss should alert the physician to a fistula. Findings of significance were positional nystagmus of short latency and long duration without import of nystagmus direction, canal paresis and reduced speech reception threshold with poor speech discrimination scores. Discriminant analysis correctly classified 19 fistula and 10 nonfistula cases explored operatively and identified two error judgments in 22 nonoperated cases. Bed rest for the first five days proved to be the most effective means of therapy. Surgical intervention with repair of the fistula by perichondrial graft provided effective control of vertigo more frequently than restoration of hearing.


2016 ◽  
Author(s):  
Edwin Mulder ◽  
Alexandra Noppe ◽  
Ulrich Limper

In the context of space physiology, research is being conducted to understand the physiological effects from radiation, hypogravity, spaceflight and planetary environments. The goal is to identify new methods to address the unique challenges in medical treatment, human factors, and behavioral health support on future exploration missions. As crew size is small and time is limited during actual missions, space agencies resort to addressing the effects of space travel in analog environments that have features similar to those of spaceflight. Head-down tilt bed rest (HDBR), for instance, is one of the established terrestrial models used to simulate some of the physiological changes experienced during spaceflight under weightless conditions and is therefore considered a valuable testbed to prepare for future long-duration exploration missions. HDBR studies are performed in extremely-well controlled laboratory settings, offering the possibility to test the effects of – what is in essence - physical inactivity and fluid shift. However, HDBR studies have a dual purpose, as they are also invaluable for the development, testing and validation of countermeasures aimed at mitigating microgravity-induced changes to the human body. With respect to the latter, the consensus is that short-term bed rest studies (< 14 days) serve foremost as a first screening of potential promising countermeasures, particularly for the cardiovascular system. Screening of preventative procedures and protocols for the muscular system requires at least mid-term (14 -28 days), whereas studies aiming to validate countermeasures for bone require long-term HDBR studies, in the order of 60-90 days. Hitherto the preferred countermeasure during spaceflight has been physical exercise. The presentation will therefore provide a short overview of the current onboard exercise regimen and will, in light of this, outline the scientific background and aims of the ongoing 60-day HDBR study at the :envihab (from the words ‘Environment’ and ‘Habitat’), the DLR Institute of Aerospace Medicine’s state-of-the-art research facility.


2020 ◽  
Vol 120 (11) ◽  
pp. 2407-2415 ◽  
Author(s):  
Julia Attias ◽  
Andrea Grassi ◽  
Alessandra Bosutti ◽  
Bergita Ganse ◽  
Hans Degens ◽  
...  

Abstract Purpose The objective of this study was to assess whether artificial gravity attenuates any long-duration head-down 60 bed rest (HDBR)-induced alterations in motor unit (MU) properties. Methods Twenty-four healthy participants (16 men; 8 women; 26–54 years) underwent 60-day HDBR with (n = 16) or without (n = 8) 30 min artificial gravity daily induced by whole-body centrifugation. Compound muscle action potential (CMAP), MU number (MUNIX) and MU size (MUSIX) were estimated using the method of Motor Unit Number Index in the Abductor digiti minimi and tibialis anterior muscles 5 days before (BDC-5), and during day 4 (HDT4) and 59 (HDT59) of HDBR. Results The CMAP, MUNIX, and MUSIX at baseline did not change significantly in either muscle, irrespective of the intervention (p > 0.05). Across groups, there were no significant differences in any variable during HDBR, compared to BDC-5. Conclusion Sixty days of HDBR with or without artificial gravity does not induce alterations in motor unit number and size in the ADM or TA muscles in healthy individuals.


2018 ◽  
Vol 119 (6) ◽  
pp. 2145-2152 ◽  
Author(s):  
Peng Yuan ◽  
Vincent Koppelmans ◽  
Patricia Reuter-Lorenz ◽  
Yiri De Dios ◽  
Nichole Gadd ◽  
...  

Head-down tilt bed rest (HDBR) has been used as a spaceflight analog to study some of the effects of microgravity on human physiology, cognition, and sensorimotor functions. Previous studies have reported declines in balance control and functional mobility after spaceflight and HDBR. In this study we investigated how the brain activation for foot movement changed with HDBR. Eighteen healthy men participated in the current HDBR study. They were in a 6° head-down tilt position continuously for 70 days. Functional MRI scans were acquired to estimate brain activation for foot movement before, during, and after HDBR. Another 11 healthy men who did not undergo HDBR participated as control subjects and were scanned at four time points. In the HDBR subjects, the cerebellum, fusiform gyrus, hippocampus, and middle occipital gyrus exhibited HDBR-related increases in activation for foot tapping, whereas no HDBR-associated activation decreases were found. For the control subjects, activation for foot tapping decreased across sessions in a couple of cerebellar regions, whereas no activation increase with session was found. Furthermore, we observed that less HDBR-related decline in functional mobility and balance control was associated with greater pre-to-post HDBR increases in brain activation for foot movement in several cerebral and cerebellar regions. Our results suggest that more neural control is needed for foot movement as a result of HDBR. NEW & NOTEWORTHY Long-duration head-down bed rest serves as a spaceflight analog research environment. We show that brain activity in the cerebellum and visual areas during foot movement increases from pre- to post-bed rest and then shows subsequent recovery. Greater increases were seen for individuals who exhibited less decline in functional mobility and balance control, suggestive of adaptive changes in neural control with long-duration bed rest.


2009 ◽  
Vol 106 (3) ◽  
pp. 919-928 ◽  
Author(s):  
Stuart M. C. Lee ◽  
Suzanne M. Schneider ◽  
Wanda L. Boda ◽  
Donald E. Watenpaugh ◽  
Brandon R. Macias ◽  
...  

We have shown previously that treadmill exercise within lower body negative pressure (LBNPex) maintains upright exercise capacity (peak oxygen consumption, V̇o2peak) in men after 5, 15, and 30 days of bed rest (BR). We hypothesized that LBNPex protects treadmill V̇o2peak and sprint speed in women during a 30-day BR. Seven sets of female monozygous twins volunteered to participate. Within each twin set, one was randomly assigned to a control group (Con) and performed no countermeasures, and the other was assigned to an exercise group (Ex) and performed a 40-min interval (40–80% pre-BR V̇o2peak) LBNPex (51 ± 5 mmHg) protocol, plus 5 min of static LBNP, 6 days per week. Before and immediately after BR, subjects completed a 30.5-m sprint test and an upright graded treadmill test to volitional fatigue. These results in women were compared with previously reported reductions in V̇o2peak and sprint speed in male twins after BR. In women, sprint speed (−8 ± 2%) and V̇o2peak (−6 ± 2%) were not different after BR in the Ex group. In contrast, both sprint speed (−24 ± 5%) and V̇o2peak (−16 ± 3%) were significantly less after BR in the Con group. The effect of BR on sprint speed and V̇o2peak after BR was not different between women and men. We conclude that treadmill exercise within LBNP protects against BR-induced reductions in V̇o2peak and sprint speed in women and should prove effective during long-duration spaceflight.


2006 ◽  
Vol 290 (4) ◽  
pp. H1680-H1685 ◽  
Author(s):  
Monica Kukielka ◽  
Douglas R. Seals ◽  
George E. Billman

The present study investigated the effects of long-duration exercise on heart rate variability [as a marker of cardiac vagal tone (VT)]. Heart rate variability (time series analysis) was measured in mongrel dogs ( n = 24) with healed myocardial infarctions during 1 h of submaximal exercise (treadmill running at 6.4 km/h at 10% grade). Long-duration exercise provoked a significant (ANOVA, all P < 0.01, means ± SD) increase in heart rate (1st min, 165.3 ± 15.6 vs. last min, 197.5 ± 21.5 beats/min) and significant reductions in high frequency (0.24 to 1.04 Hz) power (VT: 1st min, 3.7 ± 1.5 vs. last min, 1.0 ± 0.9 ln ms2), R-R interval range (1st min, 107.9 ± 38.3 vs. last min, 28.8 ± 13.2 ms), and R-R interval SD (1st min, 24.3 ± 7.7 vs. last min 6.3 ± 1.7 ms). Because endurance exercise training can increase cardiac vagal regulation, the studies were repeated after either a 10-wk exercise training ( n = 9) or a 10-wk sedentary period ( n = 7). After training was completed, long-duration exercise elicited smaller increases in heart rate (pretraining: 1st min, 156.0 ± 13.8 vs. last min, 189.6 ± 21.9 beats/min; and posttraining: 1st min, 149.8 ± 14.6 vs. last min, 172.7 ± 8.8 beats/min) and smaller reductions in heart rate variability (e.g., VT, pretraining: 1st min, 4.2 ± 1.7 vs. last min, 0.9 ± 1.1 ln ms2; and posttraining: 1st min, 4.8 ± 1.1 vs. last min, 2.0 ± 0.6 ln ms2). The response to long-duration exercise did not change in the sedentary animals. Thus the heart rate increase that accompanies long-duration exercise results, at least in part, from reductions in cardiac vagal regulation. Furthermore, exercise training attenuated these exercise-induced reductions in heart rate variability, suggesting maintenance of a higher cardiac vagal activity during exercise in the trained state.


2006 ◽  
Vol 20 (4) ◽  
Author(s):  
Scott M. Smith ◽  
Susan A. Mathews Oliver ◽  
E. Lichar Dillon ◽  
J. Vernell Fesperman ◽  
Sara R. Zwart

2021 ◽  
Vol 12 ◽  
Author(s):  
Abdeldjallil Naceri ◽  
Yasemin B. Gultekin ◽  
Alessandro Moscatelli ◽  
Marc O. Ernst

Whenever we grasp and lift an object, our tactile system provides important information on the contact location and the force exerted on our skin. The human brain integrates signals from multiple sites for a coherent representation of object shape, inertia, weight, and other material properties. It is still an open question whether the control of grasp force occurs at the level of individual fingers or whether it is also influenced by the control and the signals from the other fingers of the same hand. In this work, we approached this question by asking participants to lift, transport, and replace a sensorized object, using three- and four-digit grasp. Tactile input was altered by covering participant's fingertips with a rubber thimble, which reduced the reliability of the tactile sensory input. In different experimental conditions, we covered between one and three fingers opposing the thumb. Normal forces at each finger and the thumb were recorded while grasping and holding the object, with and without the thimble. Consistently with previous studies, reducing tactile sensitivity increased the overall grasping force. The gasping force increased in the covered finger, whereas it did not change from baseline in the remaining bare fingers (except the thumb for equilibrium constraints). Digit placement and object tilt were not systematically affected by rubber thimble conditions. Our results suggest that, in each finger opposing thumb, digit normal force is controlled locally in response to the applied tactile perturbation.


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