Hormonal Responses and Adaptations to Resistance Exercise and Training

Testosterone

  • Acute Responses:
    • Resistance exercise increases testosterone concentrations.
    • Influenced by muscle mass, intensity, volume, nutrition, and training experience.
    • Large muscle exercises (Olympic lifts, deadlifts) yield greater elevations.
  • Chronic Changes:
    • Inconsistent changes in resting concentrations during resistance training.
    • Elevations or reductions may occur based on training volume and intensity.
  • Androgen Receptor (AR) Content:
    • Resistance training modulates AR content.
    • AR content related to muscle fiber type and testosterone concentrations.
    • High-volume exercise down-regulates AR content.
  • Luteinizing Hormone (LH):
    • Resistance exercise does not acutely induce LH secretion.
    • LH is the primary regulator of testosterone secretion.
  • Testosterone Precursors:
    • Low doses of DHEA do not increase testosterone.
    • Adrenal androgens may play a more significant role in women.
  • Sex Hormone-Binding Globulin (SHBG):
    • SHBG binds to androgens and influences free testosterone concentrations.

Growth Hormone (GH) Super Family

  • Acute Response:

    • Resistance exercise elevates GH variants.
    • Dependent on exercise selection, muscle mass, intensity, and volume.
    • Acidosis produced by lactic may be the primary factor influencing GH release.

  • Chronic Changes:

    • Traditional resistance training does not typically affect resting GH concentrations.

  • GH Binding Protein:

    • GHBP is elevated with acute resistance exercise.

Cortisol

  • Acute Response:

    • Resistance exercise elevates cortisol and ACTH.
    • The greatest cortisol response is seen in programmes that also elicit the greatest acute GH and lactate response.

  • Chronic Adaptations:

    • Inconsistent changes in resting concentrations of cortisol occur with resistance training.
    • Chronic changes may be involved with tissue homeostasis involving protein metabolism

  • Testosterone/Cortisol Ratio:

    • Indirect measure of the anabolic/catabolic properties of skeletal muscle.

  • Glucocorticoid Receptor:

    • Down-regulation of the glucocorticoid receptor may reduce the catabolic influence on skeletal muscle tissue.
    • Eccentric resistance exercise up-regulates glucocorticoid receptor content and myofibrillar proteolysis.

Insulin-Like Growth Factors (IGFs)

  • Acute IGF-1 Response:

    • Little change in IGF-1 during or immediately following resistance exercise has been found in most studies
    • It appears that IGF-1 elevation following an acute bout of resistance exercise may be delayed until GH-stimulated synthesis and secretion from the liver can take place.

  • Chronic Circulating IGF-1 Adaptations:

    • No change in resting concentrations of IGF-1 have been reported during normal short-term resistance training.

  • Muscle Isoforms of IGF-1:

    • Muscle isoforms of insulin-like growth factor appears promiment during tissue remodelling.

  • IGF Binding Proteins:

    • Regulate IGF availability and prolong IGF circulation.

Insulin

  • Insulin affects muscle protein synthesis when amino acids are available.
  • Serum insulin concentrations mirror blood glucose.

Catecholamines

  • Increase force production and energy availability.
  • Epinephrine, norepinephrine, and dopamine increase.
  • Anticipatory rise