All hormones are directly correlated with effort and inversely correlated
with excess volume! Cortisol is directly correlated with volume, and GH and
Testosterone are both inversely correlated with volume.Overtraining( excess
volume) reduces the pituitary output of GH in addition to inversely
affecting testosterone , insulin and cortisol.(Urhausen A, Gabriel
H,Kinderman .Blood Hormones as Markers of Training Stress and
Overtraining.Sports Med 1995;20:251) There are certainly other factors that
would affect the production of these hormones but the principles here
remain the same .It's simplicity is whats appealing, and as for
generalization, science backs it up quite well!
George Carvajal