Muscle Fiber Composition and Respiratory Capacity in Triathletes
- 1 December 1987
- journal article
- research article
- Published by Georg Thieme Verlag KG in International Journal of Sports Medicine
- Vol. 08 (06), 383-386
- https://doi.org/10.1055/s-2008-1025690
Abstract
In an effort to describe the skeletal muscle characteristics of trained triathletes, biopsies were obtained from the gastrocnemius, vastus lateralis, and posterior deltoid muscles of 11 triathletes and 4 normally active controls. Each specimen was analyzed for muscle fiber composition, respiratory capacity (QO2), and citrate synthase activity. The mean (.+-. SE) percentage of type I fibers for the triathletes was 59 (4.0), 63 (3.3), and 60 (2.8) in the gastrocnemius, vastus lateralis, and deltoid, respectively (P > 0.05). The mean (.+-. SE) QO2 values in the gastrocnemius (4.4 .+-. 0.3 ml O2 .cntdot. min-1 .cntdot. g-1) and the vastus lateralis (4.1 .+-. 0.2) were not significantly different while the QO2 values of the deltoid (3.6 .+-. 0.2) were significantly lower than the gastrocnemius (P < 0.05). The mean citrate synthase activity of the deltoid (27.7 .+-. 1.7 .mu.mol .cntdot. min-1 .cntdot. g-1) was significantly lower than both the vastus lateralis (36.0 .+-. 3.2) and the gastrocnemius (45.8 .+-. 2.1) (P < 0.05). There was a high correlation between the percentage of type I fibers and the citrate synthase activity within the vastus lateralis (r = .760) and deltoid (r = .610) (P < 0.05) but not the gastrocnemius (r = .200). No significant relationships were observed between skeletal muscle characteristics and .ovrhdot.VO2 max nor between skeletal muscle charcteristics and performance. The results of this study demonstrate that: (1) these triathletes have a high percentage of type I fibers in all three muscle groups; (2) skeletal muscle characteristics were not highly related to laboratory or competitive performance; (3) despite a similar fiber composition, the deltoid appears to have a lower oxidative potential than the leg muscles, possibly due to the lesser use of the deltoid in normal daily activity.This publication has 9 references indexed in Scilit:
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