Abstract: Effect of Resistance Exercise on Muscle Steroidogenesis

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Relevant to previous discussions:

Effect of Resistance Exercise on Muscle Steroidogenesis

J Appl Physiol (October 2, 2008). doi:10.1152/japplphysiol.91235.2008

Jakob L. Vingren1, J. Kraemer1*, Disa L. Hatfield1,

M. 1, Jeff S. Volek1, A. Ratamess2, Gwendolyn A.

1, Jen Y. Ho1, Maren S. Fragala1, and Carl M. Maresh1

Circulating testosterone is elevated acutely following resistance

exercise (RE) and is an important anabolic hormone for muscle

adaptations to resistance training.

The purpose of this study was to examine the acute effect of heavy RE

on intracrine muscle testosterone production in young resistance

trained men and women.

15 young highly resistance trained men (n=8; 21±1 years, 175.3±6.7

cm, 90.8±11.6 kg) and women (n=7; 24±5 years, 164.6±6.7 cm, 76.4±15.6

kg) completed 6 sets of 10 repetitions of 's machine squats with

80% of their 1-repetition maximum. Before RE, and 10 min and 70 min

after RE, muscle biopsies were obtained from the vastus lateralis.

Before RE, after 3 and 6 sets of squats, and 5, 15, 30 and 70 min

into recovery from RE blood samples were obtained using venipuncture

from an anticubital vein. Muscle samples were analyzed for

testosterone, 17 -hydroxysteroid dehydrogenase (HSD) type 3, and 3 -

HSD type 1-2 content. Blood samples were analyzed for the glucose and

lactate concentrations. No changes were found for muscle

testosterone, 3 -HSD1-2, and 17 -HSD3 concentrations. However, a

change in protein migration in the Bis-Tris gel was observed for 17 -

HSD3 post-exercise; this change in migration indicated ~2.8 kd

increase in molecular weight. These findings indicate that species

differences in muscle testosterone production may exist between rats

and humans.

In humans, muscle testosterone concentrations do not appear to be

affected by RE. This study expands on the current knowledge obtained

from animal studies by examining resting and post-exercise

concentrations of muscle testosterone and steroidogenic enzymes in

humans.

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Carruthers

Wakefield, UK