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Sex-based comparisons of myofibrillar protein synthesis after resistance exercise in the fed state.
J Appl Physiol (1985). 2012 Jun; 112(11):1805-13.JA

Abstract

We made sex-based comparisons of rates of myofibrillar protein synthesis (MPS) and anabolic signaling after a single bout of high-intensity resistance exercise. Eight men (20 ± 10 yr, BMI = 24.3 ± 2.4) and eight women (22 ± 1.8 yr, BMI = 23.0 ± 1.9) underwent primed constant infusions of l-[ring-(13)C(6)]phenylalanine on consecutive days with serial muscle biopsies. Biopsies were taken from the vastus lateralis at rest and 1, 3, 5, 24, 26, and 28 h after exercise. Twenty-five grams of whey protein was ingested immediately and 26 h after exercise. We also measured exercise-induced serum testosterone because it is purported to contribute to increases in myofibrillar protein synthesis (MPS) postexercise and its absence has been hypothesized to attenuate adaptative responses to resistance exercise in women. The exercise-induced area under the testosterone curve was 45-fold greater in men than women in the early (1 h) recovery period following exercise (P < 0.001). MPS was elevated similarly in men and women (2.3- and 2.7-fold, respectively) 1-5 h postexercise and after protein ingestion following 24 h recovery. Phosphorylation of mTOR(Ser2448) was elevated to a greater extent in men than women acutely after exercise (P = 0.003), whereas increased phosphorylation of p70S6K1(Thr389) was not different between sexes. Androgen receptor content was greater in men (main effect for sex, P = 0.049). Atrogin-1 mRNA abundance was decreased after 5 h recovery in both men and women (P < 0.001), and MuRF-1 expression was elevated in men after protein ingestion following 24 h recovery (P = 0.003). These results demonstrate minor sex-based differences in signaling responses and no difference in the MPS response to resistance exercise in the fed state. Interestingly, our data demonstrate that exercise-induced increases in MPS are dissociated from postexercise testosteronemia and that stimulation of MPS occurs effectively with low systemic testosterone concentrations in women.

Authors+Show Affiliations

Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

22383503

Citation

West, Daniel W D., et al. "Sex-based Comparisons of Myofibrillar Protein Synthesis After Resistance Exercise in the Fed State." Journal of Applied Physiology (Bethesda, Md. : 1985), vol. 112, no. 11, 2012, pp. 1805-13.
West DW, Burd NA, Churchward-Venne TA, et al. Sex-based comparisons of myofibrillar protein synthesis after resistance exercise in the fed state. J Appl Physiol (1985). 2012;112(11):1805-13.
West, D. W., Burd, N. A., Churchward-Venne, T. A., Camera, D. M., Mitchell, C. J., Baker, S. K., Hawley, J. A., Coffey, V. G., & Phillips, S. M. (2012). Sex-based comparisons of myofibrillar protein synthesis after resistance exercise in the fed state. Journal of Applied Physiology (Bethesda, Md. : 1985), 112(11), 1805-13. https://doi.org/10.1152/japplphysiol.00170.2012
West DW, et al. Sex-based Comparisons of Myofibrillar Protein Synthesis After Resistance Exercise in the Fed State. J Appl Physiol (1985). 2012;112(11):1805-13. PubMed PMID: 22383503.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Sex-based comparisons of myofibrillar protein synthesis after resistance exercise in the fed state. AU - West,Daniel W D, AU - Burd,Nicholas A, AU - Churchward-Venne,Tyler A, AU - Camera,Donny M, AU - Mitchell,Cameron J, AU - Baker,Steven K, AU - Hawley,John A, AU - Coffey,Vernon G, AU - Phillips,Stuart M, Y1 - 2012/03/01/ PY - 2012/3/3/entrez PY - 2012/3/3/pubmed PY - 2013/4/2/medline SP - 1805 EP - 13 JF - Journal of applied physiology (Bethesda, Md. : 1985) JO - J Appl Physiol (1985) VL - 112 IS - 11 N2 - We made sex-based comparisons of rates of myofibrillar protein synthesis (MPS) and anabolic signaling after a single bout of high-intensity resistance exercise. Eight men (20 ± 10 yr, BMI = 24.3 ± 2.4) and eight women (22 ± 1.8 yr, BMI = 23.0 ± 1.9) underwent primed constant infusions of l-[ring-(13)C(6)]phenylalanine on consecutive days with serial muscle biopsies. Biopsies were taken from the vastus lateralis at rest and 1, 3, 5, 24, 26, and 28 h after exercise. Twenty-five grams of whey protein was ingested immediately and 26 h after exercise. We also measured exercise-induced serum testosterone because it is purported to contribute to increases in myofibrillar protein synthesis (MPS) postexercise and its absence has been hypothesized to attenuate adaptative responses to resistance exercise in women. The exercise-induced area under the testosterone curve was 45-fold greater in men than women in the early (1 h) recovery period following exercise (P < 0.001). MPS was elevated similarly in men and women (2.3- and 2.7-fold, respectively) 1-5 h postexercise and after protein ingestion following 24 h recovery. Phosphorylation of mTOR(Ser2448) was elevated to a greater extent in men than women acutely after exercise (P = 0.003), whereas increased phosphorylation of p70S6K1(Thr389) was not different between sexes. Androgen receptor content was greater in men (main effect for sex, P = 0.049). Atrogin-1 mRNA abundance was decreased after 5 h recovery in both men and women (P < 0.001), and MuRF-1 expression was elevated in men after protein ingestion following 24 h recovery (P = 0.003). These results demonstrate minor sex-based differences in signaling responses and no difference in the MPS response to resistance exercise in the fed state. Interestingly, our data demonstrate that exercise-induced increases in MPS are dissociated from postexercise testosteronemia and that stimulation of MPS occurs effectively with low systemic testosterone concentrations in women. SN - 1522-1601 UR - https://www.unboundmedicine.com/medline/citation/22383503/Sex_based_comparisons_of_myofibrillar_protein_synthesis_after_resistance_exercise_in_the_fed_state_ L2 - https://journals.physiology.org/doi/10.1152/japplphysiol.00170.2012?url_ver=Z39.88-2003&amp;rfr_id=ori:rid:crossref.org&amp;rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -