Exercise Mode And Volume Differentially Affect Growth Hormone And Luteinizing Hormone Secretion Patterns

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Growth hormone (GH) and luteinizing hormone (LH) availability is known to be altered by exercise; however, few studies have compared different volumes of aerobic and resistance exercise. Due to the pulsatility of GH and LH, multiple-time point sampling is needed to fully characterize lasting changes in secretion following exercise. PURPOSE To evaluate the impact of different volumes of aerobic versus resistance exercise on GH and LH concentration and secretion patterns. METHODS 8 untrained men (24±5 y; 182±6 cm; 87±9 kg; 21±5 %BF) randomly performed each of 5 conditions separated by at least one month: no exercise control (C), high volume resistance exercise (HR), moderate volume resistance exercise (MR), high volume aerobic exercise (HA), and moderate volume aerobic exercise (MA). Blood samples were obtained every 20 min starting at 1700 h (immediately following the exercise bouts) for 20 h. GH and LH concentration and secretion patterns were calculated via cluster and deconvolution analysis, respectively. RESULTS GH total area under the curve (C: 1064.28±147.22 ng·m1−1·min-1; HA: 2303.10±357.89 ng·m1−1·min−1; MA: 1659.64±158.19 ng·m1−1·min−1) was significantly increased only after aerobic exercise as compared to C. HA increased GH burst area (C: 4.39±0.69 ng·m1−1; HA: 7.36±1.16 ng·m1−1), amplitude of bursts (C: 0.17±0.03 ng·m1−1·min−1; HA: 0.28±0.04 ng·m1−1·min−1), and total pulsatile secretion (C: 32.89±4.35 ng·m1−1·20 h−1; HA: 61.77±13.54 ng·m1−1·20 h−1). LH total area under the curve (C: 3483.95±255.73 IU·1−1·min−1; HA: 3074.20±345.98 IU·−11·min−1) was significantly decreased only after HA when compared to C. HA decreased LH burst area (C: 3.24±0.33 IU·1−1; HA: 2.63±0.38 IU·1−1), and amplitude of bursts (C: 0.13±0.01 IU·1−1·min−1; HA: 0.10±0.02 IU·1−1·min−1), HA and MR decreased total pulsatile secretion of LH (C: 40.34±3.54 IU·1−1·19h−1; HA: 32.35±5.27 IU·1−1·19h−1; MR: 32.57±2.86 IU·1−1·19h−1) (All changes P<0.05). HR did not alter any of the measured parameters. CONCLUSIONS We observed a volume and mode effect of exercise with HA increasing GH and decreasing LH secretion more than the other conditions when compared to control possibly due to the required energy expenditure. Secretion patterns of GH and LH were not altered by HR.