APPROACH:
Functional task test (FTT) data samples were collected from 26 male subjects, including 10 bed rest controls and 16 bed rest exercisers. During each session, subjects were asked to complete the following physiological and functional task tests: Plasma Volume, Seat Egress and Walk, Recovery from Fall/Stand, Fine Motor Control, Dynamic Posturography, Rock Translation, Torque Generation, Construction Activity Board, Jump Down, Treadmill Locomotion, Ladder Climb, and Muscle Performance Measures. During testing, subjects were equipped with hardware that recorded heart rate, blood pressure, body position data, and electrical activity from the muscles. Body position measurement units were secured to the head and trunk. Surface electrodes were placed on the lower limbs to collect muscle electrical activity signals and on the upper body to collect electrical signals from the heart during each test session. Surface electrodes were placed on the thigh for stimulating the thigh muscles during each test session. During each test session, subjects were asked to complete seven functional tests in addition to a series of physiological tests. Muscle performance measures were performed as the last test in the FTT series. Subjects wore the same instrumentation for all sessions.

RESULTS:
The muscle function data showed reductions in lower body muscle performance metrics in bed rest subjects who did not exercise. Bed rest subjects who performed an integrated high intensity interval-type resistance and aerobic training program while in bed showed significantly improved lower body muscle performance compared to bed rest control subjects.

Bed rest subjects experienced deficits both in functional tests with balance challenges and in sensorimotor tests designed to evaluate postural and gait control indicating that body support unloading experienced during space flight plays a central role in post-flight alteration of functional task performance. Taken together the bed rest and in-flight exercise training data point to the importance of providing increased body loading during in-flight treadmill and lower body resistive exercise.

Lastly, bed rest data indicate that an elevated heart rate was required to maintain arterial blood pressure during performance of multiple functional tasks.

Madansingh S. and Bloomberg JJ. Understanding the effects of spaceflight on head–trunk coordination during walking and obstacle avoidance. Acta Astronautica. 2015. October-November; 115:165-72. [DOI]

Mulavara AP, Peters BT, Miller CA, Kofman IS, Reschke MF, Taylor LC, Lawrence EL, Wood SJ, Laurie SS, Lee SMC, Buxton RE, May-Phillips TR, Stenger MB, Ploutz-Snyder LL, Ryder JW, Feiveson AH, and Bloomberg JJ. Physiological and functional alterations after spaceflight and bed rest. Medicine and Science in Sports and Exercise. 2018. September; 50(9):1961-80.

Miller CA, Kofman IS, Brady RR, May-Phillips TR, Batson CD, Lawrence EL, Taylor LC, Peters BT, Mulavara AP, Feiveson AH, Reschke MF, and Bloomberg JJ. Functional task and balance performance in bed rest subjects and astronauts. Aerospace Medicine and Human Performance. 2018. September; 89(9):805-15.

Ataxia

Cardiovascular deconditioning

Muscular atrophy

Bed rest

Task performance and analysis

Activity board time

Blood volume

Diastolic blood pressure, difference

Diastolic blood pressure, fall recovery prone

Diastolic blood pressure, stand