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 ...

The SJ equation is a slightly more accurate equation than that derived from CMJ data. This equation should be used in the determination of peak power in place of the formulas developed by both Harman et al. and Lewis. Separate equations for males and females are unnecessary.

The benefits of exercise and physical activity, im- No. 2, pp. 197-203, 1993. It is widely acknowledged that musculoskeletal injuries occur as a result public health officials in the United States to promote of vigorous physical activity and exercise, but little quantitative greater activity and fitness levels in the population as documentation exists on the incidence of or risk factors for these major health objectives for the nation (32).injuries. This study was conducted to assess the incidence, types, and risk factors for training-related injuries among young men undergoing For some populations, such as the military, however, Army infantry basic training. Prior to training we evaluated 303 men there is a strong need to know not oniy the mcnefits.(median age 19 yr), utilizing questionnaires and measurements of but also the short-term risks of exercise. Even relatively physical fitness. Subjects were followed over 12 wk of training. Physical training was documented on a daily basis, and injuries were benign injuries, such as sprained ankles, can be costly ascertained by review of medical records for every trainee. We perin terms of lost training time and reduced "combat formed univariate and multivariate analyses of the data. Cumulative readiness" of soldiers. Because physical fitness is conincidence of subjects with one or more lower extremity trainingrelated injury was 37% (80% of all injuries). The most common sidered to be an essential element of readiness. the injuries were muscle strains, sprains, and overuse knee conditions. A Army places great emphasis on physical training. As a number of risk factors were identified, including: older age, smoking.

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Lower-body power output, estimated from vertical jump height and body mass, is a sensitive and field expedient measure that can be used to assess the influence of caloric deficit on physical performance after 8 wk of U.S. Army Ranger training. With severe weight loss (>or=13% of body mass), IGF-I and cortisol correlate more closely with soft-tissue tissue adaptations than does testosterone.

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.

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