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Physiologic Responses to Motorized and Non-Motorized Locomotion Utilizing the International Space Station TreadmillTreadmill locomotion is used onboard the International Space Station (ISS) as a countermeasure to the effects of prolonged weightlessness. The treadmill operates in two modes: motorized (T-M) and non-motorized (T-NM). Little is known about the potential physiologic differences between modes which may affect countermeasure exercise prescription. PURPOSE: To quantify heart rate (HR), oxygen consumption (VO2), perceived exertion (RPE), and blood lactate (BLa) during T-M and T-NM locomotion at 2 and 4 mph in normal ambulatory subjects. METHODS: Twenty subjects (10 men, 10 women; 31+/-5 yr, 172+/-10 cm, 68+/-13 kg, mean SD) with a treadmill peakVO2 of 45.5+/-5.4 ml/kg/min (mean+/-SD) exercised on the ground-based ISS treadmill. Following a familiarization session in each mode, subjects completed two data collection sessions, T-M and T-NM in random order, at 2 and 4 mph. Subjects attempted to complete 5 min of exercise at each speed; if they could not maintain the speed, the trial was discontinued. At least 5 minutes of rest separated each speed trial, and at least 48 hrs separated each session. VO2 was measured continuously (metabolic gas analysis), while HR (HR monitor) and RPE (Borg Chart, 6-20 scale) were recorded each min. Not all subjects completed 5 min during each condition, therefore the mean of the min 3 and 4 was taken as representative of steady-state. BLa was measured (finger stick) within 2 min post-exercise. Paired t-tests were used to test for differences (p<0.05) between treadmill modes within the same speed. RESULTS: All twenty subjects completed at least 4 min of exercise during all conditions, except T-NM 4 mph when only 11 subjects completed the minimum exercise duration. VO2, HR, RPE and BLa were significantly higher during T-NM locomotion at both speeds.
Document ID
20080026195
Acquisition Source
Johnson Space Center
Document Type
Conference Paper
Authors
Smith, Cassie (JES Tech Houston, TX, United States)
Lee, Stuart MC (Wyle Labs., Inc. Houston, TX, United States)
Laughlin, Mitzi (Wyle Labs., Inc. Houston, TX, United States)
Loehr, James (Wyle Labs., Inc. Houston, TX, United States)
Norcross, Jason (Wyle Labs., Inc. Houston, TX, United States)
DeWitt, John (Bergalia Engineering Services United States)
Hagan, R. D. (NASA Johnson Space Center Houston, TX, United States)
Date Acquired
August 24, 2013
Publication Date
May 31, 2006
Subject Category
Aerospace Medicine
Meeting Information
Meeting: American College of Sports Medicine Meeting
Location: Denver, Co
Country: United States
Start Date: May 31, 2006
End Date: June 3, 2006
Distribution Limits
Public
Copyright
Public Use Permitted.

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