NASA LogoNTRSNTRS - NASA Technical Reports ServerSearchmore_vertCollectionsAboutNewsHelpLogin Back to ResultsCycle-Powered Short Radius (1.9 m) Centrifuge: Effect of Exercise Versus Passive Acceleration on Heart Rate in HumansIn addition to extensive use of lower extremity physical exercise training as a countermeasure for the work capacity component of spaceflight deconditioning, some form of additional head-to-foot (+Gz) gravitational (orthostatic) stress may be required to further attenuate or prevent the signs and symptoms (nausea, vertigo, instability, fatigue) of the general reentry syndrome (GRS) that can reduce astronaut performance during landing. Orthostatic (head-to-foot) stress can be induced by standing, by lower body negative pressure, and by +Gz acceleration. One important question is whether acceleration training alone or with concurrent leg exercise would provide sufficient additive stimulation to attenuate the GRS. Use of a new human-powered centrifuge may be the answer. Thus, the purpose for this study was to compare heart rate (HR), i.e., a stress response during human-powered acceleration, in four men (35-62 yr) and two women (30-31 yr) during exercise acceleration versus passive acceleration (by an off-board operator) at 100% (maximal acceleration = A(max)), and at 25%, 50%, and 75% of A(max). Mean (+/-SE) A(max) was 43.7 +/- 1.3 rpm (+3.9 +/- 0.2Gz). Mean HR at exercise A(max) was 189 +/- 13 b/min (50-70 sec run time), and 142 +/- 22 b/min at passive A(max) (40-70 sec run time). Regression of mean HR on the various +Gz levels indicated explained variance (correlations squared) of r(exp 2) = 0.88 (exercise) and r(exp 2) = 0.96 (passive): exercise HR of 107 +/- 4 (25%) to 189 +/- 13 (100%) b/min were 43-50 b/min higher (p less than 0.05) than comparable passive HR of 64 +/- 2 to 142 +/- 22 b/min. Thus, exercise adds significant physiological stress during +Gz acceleration. Inflight use of this combined exercise and acceleration countermeasure may maintain work capacity as well as normalize acceleration and orthostatic tolerances which could attenuate or perhaps eliminate the GRS.Document ID19970011171Acquisition SourceAmes Research CenterDocument TypeTechnical Memorandum (TM)AuthorsGreenleaf, J. E.*(NASA Ames Research Center Moffett Field, CA United States)*Gundo, D. P.*(NASA Ames Research Center Moffett Field, CA United States)*Watenpaugh, D. E.*(NASA Ames Research Center Moffett Field, CA United States)*Mulenburg, G. M.*(NASA Ames Research Center Moffett Field, CA United States)*Mckenzie, M. A.*(NASA Ames Research Center Moffett Field, CA United States)*Looft-Wilson, R.*(NASA Ames Research Center Moffett Field, CA United States)*Hargens, A. R.*(NASA Ames Research Center Moffett Field, CA United States)*Date AcquiredSeptember 6, 2013Publication DateFebruary 1, 1997Subject CategoryLife Sciences (General)Report/Patent NumberNAS 1.15:110433NASA-TM-110433A-975618Accession Number97N16183Funding Number(s)PROJECT: RTOP 199-21-12-07Distribution LimitsPublicCopyrightWork of the US Gov. Public Use Permitted.Available DownloadsNameType19970011171.pdfSTIcloud_downloadcontent_copyvisibilityRelated RecordsThere are no records associated with this record.visibility_offNo Preview Available
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