HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Free Full Text (PDF) Free All Versions of this Article: 95/6/2576    most recent 00298.2003v1 Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Web of Science (4) Citing Articles via Google Scholar Google Scholar Articles by Mattern, C. O. Articles by Devor, S. T. Search for Related Content PubMed PubMed Citation Articles by Mattern, C. O. Articles by Devor, S. T.

Maximal lactate steady state declines during the aging process

¹Sport and Exercise Science Program, ²Department of Family Medicine, and ³Department of Veterinary Clinical Sciences, The Ohio State University, Columbus, Ohio 43210-1284

Submitted 24 March 2003 ; accepted in final form 22 August 2003

Increased participation of aged individuals in athletics warrants basic research focused on delineating age-related changes in performance variables. On the basis of potential age-related declines in aerobic enzyme activities and a shift in the expression of myosin heavy chain (MHC) isoforms, we hypothesized that maximal lactate steady-state (MLSS) exercise intensity would be altered as a function of age. Three age groups [young athletes (YA), 25.9 ± 1.0 yr, middle-age athletes (MA), 43.2 ± 1.0 yr, and older athletes (OA), 64.6 ± 2.7 yr] of male, competitive cyclists and triathletes matched for training intensity and duration were studied. Subjects performed a maximal O₂ consumption (O_{2 max}) test followed by a series of 30-min exercise trials to determine MLSS. A muscle biopsy of the vastus lateralis was procured on a separate visit. There were differences (P < 0.05) in O_{2 max} among all age groups (YA = 67.7 ± 1.2 ml · kg^-1 · min^-1, MA = 56.0 ± 2.6 ml · kg^-1 · min^-1, OA = 47.0 ± 2.6 ml · kg^-1 · min^-1). When expressed as a percentage of O_{2 max}, there was also an age-related decrease (P < 0.05) in the relative MLSS exercise intensity (YA = 80.8 ± 0.9%, MA = 76.1 ± 1.4%, OA = 69.9 ± 1.5%). There were no significant age-related changes in citrate synthase activity or MHC isoform profile. The hypothesis is supported as there is an age-related decline in MLSS exercise intensity in athletes matched for training intensity and duration. Although type I MHC isoform, combined with age, is helpful in predicting (r = 0.76, P < 0.05) relative MLSS intensity, it does not explain the age-related decline in MLSS.

exercise; masters athlete; citrate synthase; myosin heavy chain