Endocrine responses during overnight recovery from exercise: impact of nutrition and relationships with muscle protein synthesis.

J.A. Betts, M. Beelen, K.A. Stokes, W.H. Saris, L.J.C. van Loon

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Abstract

Nocturnal endocrine responses to exercise performed in the evening and the potential role of nutrition are poorly understood. To gain novel insight, 10 healthy men ingested carbohydrate with (C+P) and without (C) protein in a randomized order and double-blind manner during 2 hr of interval cycling followed by resistance type exercise and into early postexercise recovery. Blood samples were obtained hourly throughout 9 hr of postexercise overnight recovery for analysis of key hormones. Muscle samples were taken from the vastus lateralis before and after exercise and then again the next morning (7 a.m.) to calculate mixed-muscle protein fractional synthetic rate (FSR). Overnight plasma hormone concentrations were converted into overall responses (expressed as area under the concentration curve) and did not differ between treatments for either growth hormone (1,464 +/- 257 vs. 1,432 +/- 164 pg/ml . 540 min) or total testosterone (18.3 +/- 1.2 vs. 17.9 +/- 1.2 nmol/L . 540 min, C and C+P, respectively). In contrast, the overnight cortisol response was higher with C+P (102 +/- 11 nmol/L . 540 min) than with C (81 +/- 8 nmol/L . 540 min; p = .02). Mixed-muscle FSR did not differ between C and C+P during overnight recovery (0.062% +/- 0.006% and 0.062% +/- 0.009%/hr, respectively) and correlated significantly with the plasma total testosterone response (r = .7, p < .01). No correlations with FSR were apparent for the response of growth hormone (r = -.2, p = .4), cortisol (r = .1, p = .6), or the ratio of testosterone to cortisol (r = .2, p = .5). In conclusion, protein ingestion during and shortly after exercise does not modulate the endocrine response or muscle protein synthesis during overnight recovery.
Original languageEnglish
Pages (from-to)398-409
Number of pages12
JournalInternational Journal of Sport Nutrition and Exercise Metabolism
Volume21
Issue number5
DOIs
Publication statusPublished - Oct 2011

Keywords

  • carbohydrate
  • growth hormone
  • cortisol
  • testosterone
  • AMINO-ACID INGESTION
  • GROWTH-HORMONE RELEASE
  • RESISTANCE EXERCISE
  • SKELETAL-MUSCLE
  • ENDURANCE EXERCISE
  • ENERGY-EXPENDITURE
  • ANABOLIC HORMONES
  • DAYTIME EXERCISE
  • UNTRAINED MEN
  • SINGLE BOUT

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