Catecholamine release, growth hormone secretion, and energy expenditure during exercise vs. recovery in men

We examined the relationship between energy expenditure (in kcal) and epine phrine (Epi), norepinephrine (NE), and growth hormone (GH) release. Ten men [age, 26 yr; height, 178 cm; weight, 81 kg; O-2 uptake at lactate threshol d (LT), 36.3 ml.kg(-1).min(-1); peak O-2 uptake, 49.5 ml.kg(-1).min(-1)] we re tested on six randomly ordered occasions [control, 5 exercise: at 25 and 75% of the difference between LT and rest (0.25LT, 0.75LT), at LT, and at 25 and 75% of the difference between LT and peak (1.25LT, 1.75LT) (0900-093 0)]. From 0700 to 1300, blood was sampled and assayed for GH, Epi, and NE. Carbohydrate (CHO) expenditure during exercise and fat expenditure during r ecovery rose proportionately to increasing exercise intensity (P = 0.002). Fat expenditure during exercise and CHO expenditure during recovery were no t affected by exercise intensity. The relationship between exercise intensi ty and CHO expenditure during exercise could not be explained by either Epi (P = 1.00) or NE (P = 0.922), whereas fat expenditure during recovery incr eased with Epi and GH independently of exercise intensity (P = 0.028). When Epi and GH were regressed against fat expenditure during recovery, only GH remained statistically significant (P < 0.05). We conclude that a positive relationship exists between exercise intensity and both CHO expenditure du ring exercise and fat expenditure during recovery and that the increase in fat expenditure during recovery with higher exercise intensities is related to GH release.