ripheral blood concentrations of testosterone in males FLECK. Hormonal and growth factor responses to heavy resist-(9, 13, 19, 29). Furthermore, it has been suggested that ance exercise protocols. J. Appl, Physiol. 69(4): 1442-1450, training may influence resting values of testosterone (14-1990.-To examine endogenous anabolic hormone and growth training m a i lun ingivale t estosterone (14-factor responses to various heavy resistance exercise protocols 16). Limited data also indicate that human growth hor-(HREPs), nine male subjects performed each of six randomly mone may increase in response to an acute bout of assigned HREPs, which consisted of identically ordered exer-resistance exercise (25, 29, 33). VanHelder et al. (33) cises carefully designed to control for load [5 vs. 10 repetitions have demonstrated that human growth hormone elevamaximum (RM)], rest period length (1 vs. 3 min), and total tions may be dependent on specific exercise characteriswork effects. Serum human growth hormone (hGH), testoster-tics such as the load utilized and frequency of lifting one (T), somatomedin-C (SM-C), glucose, and whole blood exercise. To our knowledge, no data exist regarding solactate (HLa) concentrations were determined preexercise, matomedin-C responses to heavy resistance exercise promidexercise (i.e., after 4 of 8 exercises), and at 0, 5, 15, 30, 60, tocols. The purpose of this investigation was to deter-90, and 120 min postexercise. All HREPs produced significant mine the impact of load, rest period length, and total (P < 0.05) temporal increases in serum T concentrations, min te ima toftload, rest p rod th andmtota although the magnitude and time point of occurrence above work on serum testosterone, human growth hormone, resting values varied across HREPs. No differences were ob-and somatomedin-C response patterns during and after served for T when integrated areas under the curve (AUCs) different heavy resistance exercise protocols. were compared. Although not all HREPs produced increases in serum hGH, the highest responses were observed consequent METHODS to the H10/1 exercise protocol (high total work, 1 min rest, 10-RM load) for both temporal and time integrated (AUC) reNine healthy male subjects gave informed written consponses. The pattern of SM-C increases varied among HREPs sent to participate in this investigation. The physical and did not consistently follow hGH changes. Whereas tem-characteristics of the subjects were the following: age, poral changes were observed, no integrated time (A T "-) differ-24.66 ± 4.27 (SD) yr; height, 178.41 ± 7.77 cm; body ences between exercise protocols occurred. These data indicate that the release patterns (temporal or time integrated) observed mass, 81.08 l 12.03 kg; maximal oxygen consumption, are complex functions of the type of HREPs utilized and the 54.17 ±4.63 ml.kg-min-; and body fat 1596+4.18%. physiological mechanisms involved with determining periph-All subjects had recreational experience with resistance era] circulatory concentrations (e.g., clearance ...

We tested the hypothesis that key endocrine responses to semistarvation would be attenuated by changing only the food intake in a multistressor environment that also included sustained workload, inadequate sleep, and thermal strain. Serum hormones were compared within and between two groups of healthy young male volunteers participating in the 8-wk US Army Ranger course, with four repeated cycles of restricted energy intakes and refeeding: group 1 (n = 49) and group 2 (n = 48); energy deficits averaged 1,200 and 1,000 kcal/day, respectively. After 8 wk, most of group 1 achieved a minimum body fat, serum 3,5,3'-triiodothyronine (T(3)) was below normal (78 +/- 20 ng/dl), testosterone (T) approached castrate levels (4.5 +/- 3.9 nmol/l), insulin-like growth factor I (IGF-I) declined by one-half (75 +/- 25 microg/l), and cholesterol rose from 158 +/- 31 to 217 +/- 39 mg/dl. Bioavailable T(3) and T were further reduced by increases in their specific binding proteins in response to declining insulin. Refeeding, even with continuation of the other stressors, produced prompt recovery of T(3), T, and IGF-I. Higher energy intakes in group 2 attenuated the subclinical hypothyroidism and hypercholesterolemia, whereas consistent luteinizing hormone suppression indicated centrally mediated threshold effects on gonadal hormone suppression. We conclude that low T, T(3), and IGF-I remained reliable markers of acute energy deficits in the presence of other stressors; elevated cholesterol and cortisol provided information about chronic status, corresponding to diminishing body fat stores.

To examine endogenous anabolic hormonal responses to two different types of heavy resistance exercise protocols (HREPs), eight male and eight female subjects performed two randomly assigned protocols (i.e. P-1 and P-2) on separate days. Each protocol consisted of eight identically ordered exercises carefully designed to control for load, rest period length, and total work (J) effects. P-1 utilized a 5 RM load, 3-min rest periods and had lower total work than P-2. P-2 utilized a 10 RM load, 1-min rest periods and had a higher total work than P-1. Whole blood lactate and serum glucose, human growth hormone (hGH), testosterone (T), and somatomedin-C [SM-C] (i.e. insulin-like growth factor 1, IGF-1) were determined pre-exercise, mid-exercise (i.e. after 4 of the 8 exercises), and at 0, 5, 15, 30, and 60 min post-exercise. Males demonstrated significant (p less than 0.05) increases above rest in serum T values, and all serum concentrations were greater than corresponding female values. Growth hormone increases in both males and females following the P-2 HREP were significantly greater at all time points than corresponding P-1 values. Females exhibited significantly higher pre-exercise hGH levels compared to males. The P-1 exercise protocol did not result in any hGH increases in females. SM-C demonstrated random significant increases above rest in both males and females in response to both HREPs.(ABSTRACT TRUNCATED AT 250 WORDS)

Previous studies have demonstrated that full recovery from weight loss may take months or years. The present investigation examined short-term recovery (5 wks "post") of physical performance (muscular strength, muscular power, vertical jump), body composition, metabolic hormones (testosterone, luteinizing hormone, sex hormone binding globulin, insulin-like growth factor-1, triiodothyronine, thyroxine, thyroid binding globulin, and thyroid-stimulating hormone) and metabolic markers (transferrin, ferritin, prealbumin, glycerol, nonesterified fatty acids, high-density lipoproteins, and lactate) in 10 healthy young men after an 8-week Army course with an energy deficit (1000 kcal/d) and loss of body mass (-12%). Subjects ate ad libitum after the course ended ("post"). Body composition was determined by dual-energy X-ray absorptiometry; strength from a simulated power clean, power from body mass and jump height, and metabolic hormones were measured in morning-fasted blood by radioimmunoassay. With the exception of transferrin and glycerol, all study parameters were significantly (p<.05) altered by the training course. At 5 weeks post fat-free mass along with all physical performance measures returned to initial levels; however, fat mass had significantly (p<.05) increased over initial levels. Also, with the exception of lactate, all measured hormones and markers were close to initial levels and within normal ranges. Reported complications during recovery included sleep irregularities, diarrhea, loss of motivation and feelings of fatigue. While the long range effect of this energy deprivation experience is uncertain, these data do suggest that severe weight loss does not result in lasting alterations of the contractile and metabolic properties of skeletal muscle in young, lean, healthy men.