אימונים Myocellular Basis for Tapering in Competitive Distance Runners.

[Mike Bikov]

J Appl Physiol. 2010 Mar 18. [Epub ahead of print]
Myocellular Basis for Tapering in Competitive Distance Runners.

Luden N, Hayes E, Galpin AJ, Minchev K, Jemiolo B, Raue U, Trappe TA, Harber MP, Bowers T, Trappe SW.

Ball State University.

The purpose of this study was to examine the effects of a 3-wk taper on the physiology of competitive distance runners. We studied seven collegiate distance runners (20 +/- 1 yr, 66 +/- 1 kg) before and after a 3-wk taper. The primary measures included 8-km cross-country race performance, gastrocnemius single muscle fiber size and function (peak force, shortening velocity, and power), baseline and exercise-induced gene expression 4 hrs after a standardized 8-km run, citrate synthase activity, and maximal and submaximal cardiovascular physiology (Vo2, VE, HR, and RER). Race performance improved by 3% following taper (P<0.05). MHC IIa fiber diameter (+7%, P<0.05), peak force (+11%, P=0.06), and absolute power (+9%, P<0.05) increased following taper. In addition to the MHC IIa adaptations, taper elicited a distinct post-exercise gene response. Specifically, the induction of MuRF-1 was attenuated following taper, whereas MRF4, HSP 72, and MT-2A displayed an exaggerated response (P<0.05). No changes were observed in MHC I size or function, baseline gene expression, citrate synthase activity, or cardiovascular function. Our findings show that tapered training in competitive runners promoted MHC IIa fiber remodeling and an altered transcriptional response following the same exercise perturbation, with no adverse affects on aerobic fitness. Together, these results provide a myocellular basis for distance runners to taper in preparation for peak performance. Key words: cross country performance, contractile properties, taper, aerobic capacity.​

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