Godfrey, R., Whyte, G. P., & Head, T. (2004). Acute human growth hormone response in elite rowers after 12- weeks of training. Medicine and Science in Sports and Exercise, 36(5), Supplement abstract 2084.

A number of studies have examined the hGH response to a chronic exercise stimulus. Under a varying range of circumstances with sub-elite populations results have been mixed, with findings of an increase, decrease and no change being demonstrated. However, no studies exist which compare the exercise induced hGH response (EIGR) in elite rowers before and after a period of concentrated endurance training (p. S303). This study compared the acute hGH response to a standardized graded exercise stimulus in members of the GB heavyweight male rowing squad (N = 8; Olympic Gold medalists). Ss completed an incremental rowing exercise test in January and again in April. This comprised 5 4-minute stages (25 W/stage increment) and a sixth and final 4-minute maximal paced effort. Capillary (earlobe) blood samples for lactate and hGH determination were taken at -10, 4, 8.5, 13, 17.5, 22, 28.5, 38.5, 48.5 and 58.5 minutes. Oxygen consumption, heart rate, and power output were measured continuously throughout exercise. During 12-weeks of training, 80% of weekly hours comprised aerobic work and 20% was a combination of strength training, lactate threshold training, and high intensity efforts.

There was no significant difference between January and April for peak power, power at lactate threshold, O2peak, hGH at lactate threshold, and hGH at peak exercise. Only the performance measure, distance covered during the sixth 4-minute effort, demonstrated a significant difference increasing from 1,327.05m in January to 1,346.47m in April.

Implication. No change was seen in the exercise induced hGH response in rowers who exhibited few physiological changes after four months of endurance training. The performance change could be attributed to improvement in technique. This finding is consistent with out-of-season training for elite athletes where maintenance of physiological condition is key whilst technical improvements are sought.

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