Wayne E. Sinning

Reproductive hormonal profiles of endurance-trained and untrained males

This study compares the resting reproductive hormonal profiles of untrained (N = 11) and endurance-trained (N = 11) males. Testosterone, free testosterone, estradiol, luteinizing hormone (LH), prolactin, and cortisol were measured by radioimmunoassay in resting blood samples (8 h fast) collected every 60 min for 4 h. The endurance-trained group had been active for (mean +/- SE) 12.4 +/- 6.7 yr, 6.6 +/- 0.2 d.wk-1, 68.5 +/- 4.4 min.d-1, while the untrained group was sedentary. Neither group had histories of hypothalamic-pituitary-testicular disorders. The overall 4 h mean testosterone and free testosterone levels were significantly (P less than 0.05) lower in the trained group (4.99 +/- 0.46 vs 7.25 +/- 0.67 ng.ml-1, and 17.2 +/- 1.4 vs 23.6 +/- 0.6 pg.ml-1, for the trained and untrained groups, respectively). The LH of the endurance-trained group was higher (15.3 +/- 1.9 vs 11.7 +/- 1.2 mIU.ml-1, P = 0.06); however, LH pulse frequency and amplitude did not differ between groups. An enhanced estradiol feedback to the hypothalamus-pituitary could not account for the elevated LH, as estradiol levels were similar in the groups. Prolactin and cortisol levels were normal and did not differ between groups. The results suggested normal hypothalamic-pituitary function existed in the trained subjects, and prolactin and cortisol were not causative factors in the lowered resting testosterone and free testosterone levels. The findings indicate that chronic endurance training lowers testosterone and free testosterone in males possibly by impairing testicular function.

Validity of “Generalized” Equations for Body Composition Analysis in Women Athletes

Abstract Equations by Jackson, Pollock, and Ward (1980) and by Durnin and Womersly (1974) for estimating body density (BD) from skinfolds (SF) purportedly overcome the criticism of “population specificity” by taking into account age and the curvilinear relationship between SFs and BD. Selected equations were validated on 79 women athletes against %fat and fat(kg) measured by underwater weighing. Equations by Sloan, Burt, and Blyth (1962), Wilmore and Behnke (1970), and Katch and McArdle (1973) were also evaluated to compare the newer equations to older ones. The mean estimate of %fat by one equation by Jackson et al. utilizing the sum of triceps, abdomen, suprailiac and thigh SF was the same as the true value (20.1%) and correlated .795 (SEE ± 3.27 total error 3.23). Regression analysis showed it to have acceptable accuracy over the range of sample values (10.3–34.0%). The Durnin-Womersly equations overestimated %fat by 3.9 to 4.4% and were not acceptable. For the older equations, the mean Sloan et al. es...

Body composition and menstrual function in athletes.

SummaryThe problem of menstrual dysfunction in athletes was recognised at about the same time as a theory was developed that a critical fat level was necessary for the onset and maintenance of menstrual function (17% and 22% of bodyweight, respectively). This theory was acceptable because of the frequency of leanness in athletes experiencing menstrual dysfunction and because of the role of adipose tissue in the intraconversion of hormones which could affect hypothalamic and pituitary regulatory centres. Research on this topic has been hampered by the extensive use of surveys, confining sampling to specific sports, use of inaccurate methods of body composition assessment, and lack of data on hormonal changes. Studies using appropriate body composition measures do not support the critical fat theory, but they do not exclude a role for body composition changes in the regulation of menstrual function. The probability of finding menstrual dysfunction in very lean athletes is high, but not absolute, and there is no assurance that dysfunction will improve merely by increasing body weight. Perhaps of more concern, however, is recent research on very lean, long term amenorrhoeic athletes who train intensely and show a loss of bone mineral, apparently related to low oestrogen levels. This mineral deficiency is apparently a factor in stress fractures. The bone mineral content of these athletes is similar to that of post-menopausal women susceptible to osteoporosis. Although the loss of bone due to short term amenorrhoea may be reversible, the prognosis for a long term deficiency is not presently known.

Muscle Stiffness in Down Syndrome and Other Mentally Handicapped Subjects: A Research Note

An attempt was made to determine the effects of strength training on elbow flexor stiffness of Down syndrome, non-Down syndrome mentally handicapped, and nonhandicapped subjects. It was hypothesized that stiffness would be affected by the training. Results showed that only half of the individual subjects increased their maximum voluntary contraction (MVC) level as a result of the training and that premeasures and postmeasures of MVC were not significantly different for any of the three groups. As expected, for both premeasures and postmeasures, nonhandicapped subjects had a significantly higher MVC than the other groups who were not significantly different. An important finding was that measures of stiffness (slopes of the IEMG × Torque) were not significantly different for the three groups. This finding is consistant with recent studies (Davis & Kelso, 1982; Shumway-Cook & Woollacott, in press) but raises serious doubts about the popularly held opinion that Down syndrome individuals are hypotonic. It was also found that both the Down syndrome and other mentally handicapped subjects produced significantly less torque at the maximum level than the nonhandicapped subjects. These findings suggest that deficits in mentally handicapping conditions result from a decrease in the range of a primary motor control parameter λ (see Feldman, 1986).

Effects of resistance training and protein supplementation on bone turnover in young adult women.

BackgroundThe strength of aging bone depends on the balance between the resorption and formation phases of the remodeling process. The purpose of this study was to examine the interaction of two factors with the potential to exert opposing influences on bone turnover, resistance exercise training and high dietary protein intake. It was hypothesized that resistance training by young, healthy, untrained women with protein intakes near recommended levels (0.8 g·kg-1·d-1) would promote bone formation and/or inhibit bone resorption, and that subsequent supplementation to provide 2.4 g protein·kg-1·d-1 would reverse these effects.MethodsBone formation was assessed with serum bone-specific alkaline phosphatase (BAP) and osteocalcin (OC), and bone resorption with urinary calcium and deoxypyridinoline (DPD). Biochemical, strength, anthropometric, dietary, and physical activity data were obtained from 24 healthy, untrained, eumenorrheic women (18–29y) at baseline, after eight weeks of resistance training (3 d·wk-1, ~1 hr·d-1; 3 sets, 6–10 repetitions, 13 exercises, 75–85% maximum voluntary contraction), and after 12 weeks of resistance training and 10 days of protein/placebo supplementation. Subjects were randomized (double-blind) to either a high protein (HP) or training control (TC) group and, during the final 10 days, consumed either enough purified whey protein to bring daily protein intake to 2.4 g·kg-1·d-1, or an equivalent dose of isoenergetic, carbohydrate placebo.ResultsStrength, lean tissue mass, and DPD increased significantly in both groups over time, while percent body fat and BAP decreased (repeated measures ANOVA, p ≤ 0.05, Bonferroni correction). No significant changes were observed for serum OC or urinary calcium, and no significant group (TC, HP) × time (baseline, week 8, week 12) interactions emerged for any of the biochemical measures.Conclusion(1) Twelve weeks of high-intensity resistance training did not appear to enhance bone formation or inhibit bone resorption in young adult women, as assessed by biochemical markers of bone metabolism. (2) Subsequent maintenance of a high protein intake for 10 days in these regularly-training, calcium-replete women also showed no effects on bone metabolism.

Monitoring hemodialysis changes with bioimpedance : what do we really measure ?

Changes in electrical resistance (delta R), water (delta H2O), and blood variables (Na+, K+, Cl-, protein [Pr], osmolality [Osmo], hemoglobin [Hb], and hematocrit [Hct]) were monitored during hemodialysis in 20 subjects. Average delta H2O was 1.69 +/- 0.91 liters. Blood, R, and circumferences (C) were measured for the upper limb (UL), lower limb (LL), and total body (TB) before, midway, and at the end of dialysis. Segmental volumes (V) and specific resistivity (rho) were computed. delta Hct and delta Pr were stronger predictors of delta H2O than delta R. Forward stepwise regression analysis using delta R at 5, 50, and 548 kHz, delta Pr, and delta Hct showed that delta Hct and delta Pr alone accounted for 77% of the variance in delta TBW. Adding delta R increased this at most to 81%. Both the UL and LL had significant increases in rho. The volumetric change of the UL was nonsignificant, whereas that of the LL accounted for over one half of the delta H2O. Single frequency bioimpedance cannot be used to monitor dialytic delta H2O unless one accounts for fluid composition changes. Monitoring bioimpedance changes over only a single body segment is also questioned.

Exercise and temperature effects on human sperm production and testosterone levels.

Five subjects exercised at an ambient temperature of 6.2 degrees C, five exercised at 37.7 degrees C, and five served as non-exercise controls. Each subject in the exercise groups performed one 45-min treadmill run a day for five consecutive days at heart rates that represented 80% of their maximum capacity. Sperm production was quantified the week preceding treatment and from 6-10 wk post-treatment. Plasma testosterone levels (PTL) were measured before each exercise test and immediately, 30 min, and 60 min after the first and fifth tests. The initial pre-exercise sample was taken immediately preceding the first test. Rectal temperature (Tre) and heart rate were monitored during all tests. No significant differences were found for sperm production. Plasma testosterone levels were 32.9% greater on the fourth and fifth day of testing than they were on day one (P less than 0.018). The 6.2 degrees C group (1202.7 ng%) had higher resting PTL than either the 37.7 degrees C (897.3 ng%) or the control (968.8 ng%) groups throughout the exercise period (P less than 0.001); PTL were 46.6% greater on day 5 than they were on day 1 for the 6.2 degrees C group (P less than 0.021). The change in Tre attributed to exercise was significantly greater in the 37.7 degrees C group (2.5 degrees C) when compared to the 6.2 degrees C group (1.1 degrees C; P less than 0.001). In summary, the changes in PTL and Tre that occurred as a result of 5 d of heavy exercise did not affect sperm production rates in humans.

Body Composition and Somatotype of Male and Female Nordic Skiers.

Abstract Body composition and somatotype characteristics were determined from measurements taken on 11 men and 5 women who were members of the U. S. Nordic Ski Team and in summer training during the summer of 1975. Mean body composition characteristics for men were height, 179.0 cm; weight, 71.8 kg; density, 1.085 g/ml; relative fat, 7.2%; and lean body weight (LBW), 67.1 kg. Respective means for women were 164.5 cm, 56.9 kg, 1.062 g/ml, 16.1%, and 48.6 kg. Both groups were very lean in comparison with nonathletic populations and were comparable to the leanest athletes of both sexes. Anthropometric measurements for both sexes showed small values for measures of variance (SD, range, coefficient of variation) suggesting that the subjects represented a select body type. Mean somatotypes (Heath-Carter anthropometric method) for men and women were 1.95-4.45-3.00 (ectomorphic mesomorph) and 3.5-4.3-2.3 (endomorphic mesomorph). Somatotypes for each sex were confined to a small area of the somatochart, again sugg...

The Effects of Body Position on Bioimpedance Spectroscopy

Bioimpedance spectroscopy (BIS), which measures the resistance (R) and reactance (Xc) to a low amperage current over a predetermined range of frequencies, expands the application of bioimpedance technology. By using appropriate modeling procedures, it is possible to estimate the R of the extracellular (Recf) and intracellular (Ricf) fluids as well as other parameters describing cell characteristics.1 Kanai et al.1 have demonstrated the application of BIS to study fluid shifts during exercise and hemodialysis.

The Effects of Resistance Training and Protein Supplementation on Bone Turnover in Young Adult Women.

BACKGROUND The strength of aging bone depends on the balance between the resorption and formation phases of the remodeling process. The purpose of this study was to examine the interaction of two factors with the potential to exert opposing influences on bone turnover, resistance exercise training and high dietary protein intake. It was hypothesized that resistance training by young, healthy, untrained women with protein intakes near recommended levels (0.8 g.kg(-1).d(-1)) would promote bone formation and/or inhibit bone resorption, and that subsequent supplementation to provide 2.4 g protein.kg(-1).d(-1) would reverse these effects. METHODS Bone formation was assessed with serum bone-specific alkaline phosphatase (BAP) and osteocalcin (OC), and bone resorption with urinary calcium and deoxypyridinoline (DPD). Biochemical, strength, anthropometric, dietary, and physical activity data were obtained from 24 healthy, untrained, eumenorrheic women (18-29 y) at baseline, after eight weeks of resistance training (3 d.wk(-1), approximately 1 hr.d(-1); 3 sets, 6-10 repetitions, 13 exercises, 75-85% maximum voluntary contraction), and after 12 weeks of resistance training and 10 days of protein/placebo supplementation. Subjects were randomized (double-blind) to either a high protein (HP) or training control (TC) group and, during the final 10 days, consumed either enough purified whey protein to bring daily protein intake to 2.4 g.kg(-1).d(-1), or an equivalent dose of isoenergetic, carbohydrate placebo. RESULTS Strength, lean tissue mass, and DPD increased significantly in both groups over time, while percent body fat and BAP decreased (repeated measures ANOVA, p < or = 0.05, Bonferroni correction). No significant changes were observed for serum OC or urinary calcium, and no significant group (TC, HP) x time (baseline, week 8, week 12) interactions emerged for any of the biochemical measures. CONCLUSION (1) Twelve weeks of high-intensity resistance training did not appear to enhance bone formation or inhibit bone resorption in young adult women, as assessed by biochemical markers of bone metabolism. (2) Subsequent maintenance of a high protein intake for 10 days in these regularly-training, calcium-replete women also showed no effects on bone metabolism.