Elevated endogenous testosterone concentrations potentiate muscle androgen receptor responses to resistance exercise |
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Authors: | Barry A Spiering William J Kraemer Jakob L Vingren Nicholas A Ratamess Jeffrey M Anderson Lawrence E Armstrong Bradley C Nindl Jeff S Volek Keijo Hkkinen Carl M Maresh |
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Institution: | aDepartment of Kinesiology, University of Connecticut, Storrs, CT 06269, USA;bDepartment of Health and Exercise Science, The College of New Jersey, Ewing, NJ 08628, USA;cMilitary Performance Division, U.S. Army Research Institute of Environmental Medicine, Natick, MA 01760, USA;dDepartment of Biology of Physical Activity & Neuromuscular Research Center, University of Jyväskylä, Jyväskylä, Finland |
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Abstract: | The purpose of this study was to determine the influence of endogenous circulating testosterone (T) on muscle androgen receptor (AR) responses to acute resistance exercise (RE). Six healthy men (26 ± 4 years; 176 ± 5 cm; 75.8 ± 11.4 kg) performed a knee extension exercise protocol on two occasions separated by 1–3 weeks. Rest preceded one trial (i.e., control CON] trial) and a high-volume upper-body RE protocol designed to increase circulating T preceded the other trial (i.e., high T HT] trial). Serial blood samples were obtained throughout each trial to determine circulating T concentrations. Biopsies of the vastus lateralis were obtained pre-RE (REST), 10-min post-RE (+10), and 180-min post-RE (+180) to determine muscle AR content. Circulating T concentrations remained stable during CON. Alternately, HT significantly (p ≤ 0.05) increased T concentrations above resting values (+16%). Testosterone area-under-the-time curve during HT exceeded CON by 14%. AR content remained stable from REST to +10 in both trials. Compared to the corresponding +10 value, muscle AR content at +180 tended to decrease during CON (−33%; p = 0.10) but remained stable during HT (+40%; p = 0.17). Muscle AR content at +180 during the HT trial exceeded the corresponding CON value. In conclusion, acute elevations in circulating T potentiated muscle AR content following RE. |
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Keywords: | Anabolic Androgen Endocrine Hormone Steroids |
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