Weight loss and wrestling training: effects on nutrition, growth, maturation, body composition, and strength.

Adolescent wrestlers (n = 9, 15.4 yr) and recreationally active control adolescent males (n = 7, 15.7 yr) were measured before, at the end (late season), and 3.5-4 mo after a wrestling season to assess the influence of dietary restriction on growth, maturation, body composition, protein nutrition, and muscular strength. Controls consumed adequate amounts of energy, carbohydrate (CHO), protein, and fat, and demonstrated normal gains in weight, fat mass (FM) and fat-free mass (FFM). Wrestlers consumed a high-CHO (61 +/- 2% kcal), low-fat (24 +/- 2% kcal) diet during the season but did not consume adequate energy (24.7 +/- 3.5 kcal.kg-1.day-1) or protein (0.9 g.kg-1.day-1). Deficient dietary intake reduced prealbumin levels (26.0 +/- 1.9 vs. 20.2 +/- 0.9 mg/dl) and slowed the accrual of lean arm and thigh cross-sectional muscle areas (AXSECT, TXSECT, respectively). For wrestlers, dietary deficiency also decreased weight (60.3 +/- 3.5 to 58.0 +/- 3.3 kg), relative fat (9.9 +/- 0.5 to 8.0 +/- 0.7%), and FM (6.0 +/- 0.5 to 4.7 +/- 0.6 kg). Postseason, wrestlers and controls consumed similar diets, and wrestlers had significant increases in prealbumin, AXSECT, and TXSECT. Wrestlers also increased their weight (6.1 +/- 0.6 kg), FFM (3.0 +/- 0.6 kg), and FM (3.2 +/- 0.5 kg) postseason. Rates of bone maturation and segmental growth were not different between the groups. The wrestlers had reductions in elbow and knee strength from preseason to late season but increases postseason. Lean tissue changes were associated with the changes in strength and power (r = 0.72-0.91, P < 0.001). After covariance for FFM or limb-specific cross section, few significant changes remained. In conclusion, dietary restriction reduced protein nutrition and muscular performance but produced little effect on linear growth and maturation. Prealbumin levels and the rate of lean tissue accrual were positively related (r = 0.43, P < or = 0.05).

Weight loss and wrestling training: effects on growth-related hormones.

Adolescent wrestlers (n = 9, 15.4 yr) and recreationally active control males (n = 7, 15.7 yr) were measured before, at the end of, and 3.5-4 mo after a competitive wrestling season to assess the influence of dietary restriction on growth-related hormones. Wrestlers had significant elevations preseason to late season for morning serum concentrations (mean of 8 serial samples) of growth hormone (GH; 2.9 +/- 0.7 vs. 6.5 +/- 1.4 ng/ml) and sex hormone-binding globulin (SHBG; 16.1 +/- 2.3 vs. 27.9 +/- 6.9 nmol/l) and significant reductions in GH-binding protein (GHBP; 178 +/- 19 vs. 109 +/- 17 pmol/l), insulin-like growth factor I (IGF-I; 332 +/- 30 vs. 267 +/- 34 ng/ml), testosterone (T; 4.9 +/- 0.4 vs. 3.6 +/- 0.4 ng/ml), and free testosterone (Free-T; 22.4 +/- 3.6 vs. 15.7 +/- 2.8 pg/ml). Wrestlers had significant postseason reductions in GH (3.44 +/- 1.30 ng/ml) and SHBG (10.43 +/- 4.13 nmol/l) but elevations in GHBP (66.7 +/- 23.8 pmol/l), IGF-I (72.9 +/- 25.1 ng/ml), T (2.10 +/- 0.46 ng/ml), and Free-T (9.76 +/- 3.01 pg/ml). Concentrations of luteinizing hormone (LH), estradiol, prolactin, cortisol, insulin, and thyroid hormones did not differ because of exercise-dietary practices of wrestlers. In-season elevations in GH, with concomitant reductions in GHBP and IGF-I, that were reversed during the postseason suggest a reduction in GH receptor number and partial GH resistance during the season. Nonelevated LH with reduced T levels suggests a central hypothalamic-pituitary-gonadal (H-P-G) axis impairment. In conclusion, undernutrition may lead to altered H-P-G and GH-IGF-I axes function in adolescent wrestlers. However, only the wrestlers' late-season Free-T concentrations were outside the normal range, and the hormone axis impairments were quickly reversed. The present data do not address hormonal axis responses to several years of wrestling and weight loss.

Cardiovascular and peak VO2 responses to supine exercise: effects of age and training status.

Although stroke volume during exercise is affected by aging and posture, few studies have carefully examined the heart rate, blood pressure, and peak oxygen uptake (VO2) responses of older subjects to supine exercise. The present study examined these responses during graded supine cycling in younger (21-30 yr) and older (51-62 yr) untrained (Treadmill VO2max = 47.0 vs 32.3 ml.kg-1.min-1) and endurance-trained (66.3 vs 52.7 ml.kg-1.min-1) men (N = 6/group). All subjects had lower (P < 0.05) peak VO2 (ml.min-1) and peak heart rate responses during supine cycling compared with treadmill exercise. Additionally, the age-related reduction in peak VO2 (approximately 20-30%) was similar for supine compared with treadmill testing, even when normalized to fat-free leg volume and fat-free mass, respectively. However, at given absolute intensities (VO2) of supine exercise, heart rates were 10-15 beats.min-1 less (P < 0.05) in both older groups. Across relative supine work intensities (% of peak), systolic pressure increased most rapidly in the younger trained and older untrained groups. These findings suggest that the effects of aging on peak VO2 are similar during treadmill and supine exercise in both endurance-trained and untrained men. These data also indicate that the heart rate response to supine exercise is attenuated in healthy older men and contributes to their reduced peak VO2.

Sport-seasonal changes in body composition, growth, power and strength of adolescent wrestlers.

Changes in body composition, somatic growth, power and strength of high school wrestlers (W, n = 8, 15.9 +/- 0.3 yrs) and controls (C, n = 6, 16.1 +/- 0.2 yrs) were studied early, mid-, late-, and 3.5-months post-season. Elbow flexion peak power (FPP), peak torque (FPT), extension peak power (EPP), and peak torque (EPT) were measured on an isokinetic dynamometer. C demonstrated normal rates of somatic growth and gains in strength and power. However, for W, significant (p < 0.05) decreases were found in: weight (WT, 61.6 +/- 2.8 to 59.2 +/- 2.8 kg), relative fat (%BF) (7.8 +/- 0.7 to 6.1 +/- 0.7 %), FPT (33.3 +/- 2.3 to 29.9 +/- 2.7 Nm), FPP (125.8 +/- 0.3 to 107.8 +/- 8.4 W), EPT (37.5 +/- 2.5 to 36.2 +/- 3.8 Nm), and EPP (132.7 +/- 8.4 to 126.7 +/- 12.3 W), between early-season and late-season and significant increases in WT (5.4 +/- 0.4 kg), fat-free mass (FFM, 4.4 +/- 0.7 kg), FPT (9.4 +/- 1.7 Nm), FPP (38.8 +/- 8.8 W), EPT (6.5 +/- 1.0 Nm), and EPP (24.4 +/- 4.7 W), between late-season and post-season. Compared to C, W had significantly (p < 0.05) smaller increases in mid-arm girth and flexed mid-arm cross-sectional muscle area (X-SECT) during the wrestling season and larger increases in shoulder girth, abdominal girth, and mid-arm girth, X-SECT, and biacromial, biilium, and anterior-posterior chest breadths during the post-season. Power and strength measures were significantly correlated with FFM, lean upper limb volume (ULV), and X-SECT (r = 0.74 to 0.93, p <0.0001). When covaried for FFM, ULV or X-SECT seasonal declines in strength and power were no longer significant while post-seasonal increases remained. In conclusion, pre- to late- season W demonstrated a lack of lean tissue accretion and reductions in strength. At post-season these variables returned to, or were above, pre-season levels. Results of analysis of covariance indicated that lean tissue changes were associated with the changes in strength and power.

Oxidative capacity of human muscle fiber types: effects of age and training status.

Morphometry and oxidative capacity of slow-twitch (type I) and fast-twitch (type IIa and IIb) muscle fibers obtained from vastus lateralis needle biopsies were compared between younger (21-30 yr) and older (51-62 yr) normal fit (maximal O2 uptake = 47.0 vs. 32.3 ml.kg-1.min-1) and endurance-trained (66.3 vs. 52.7 ml.kg-1.min-1) men (n = 6/group). The older groups had smaller type IIa (31%) and IIb (40%) fiber areas and fewer capillaries surrounding these fibers than did younger groups. The reduced type II fiber areas and capillary contacts associated with aging were also observed in the older trained men. However, the capillary supply per unit type II fiber area was not affected by age but was enhanced by training. Additionally, on the basis of quantitative histochemical analysis, succinate dehydrogenase activities of type IIa fibers in the older trained men [4.07 +/- 0.68 (SD) mmol.min-1.l-1] were similar to those observed in younger trained men (4.00 +/- 0.48 mmol.min-1.l-1) and twofold higher than in older normal fit men (2.01 +/- 0.65 mmol.min-1.l-1; age x fitness interaction, P < 0.05). Type I muscle fibers were unaffected by age but were larger and had more capillary contacts and higher succinate dehydrogenase activities in the trained groups. The findings of this study suggest that aging results in a decrease in type II fiber size and oxidative capacity in healthy men and that this latter effect can be prevented by endurance training. Conclusions regarding the effects of age and training status on muscle capillarization depend largely on how these data are expressed.

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.

Hypothalamic-pituitary-testicular axis function in endurance-trained males.

The hypothalamic-pituitary-testicular (H-P-T) axis was evaluated in groups of endurance-trained (TRG) and untrained (UNT) males. Each group was subjected to: 1) a 4-h resting hormonal profile [testosterone (T), free-testosterone (FT), estradiol (E2), luteinizing hormone (LH), prolactin (PRL), and cortisol (C)], 2) a dopamine antagonist (DA; 10 micrograms.kg-1 body weight) challenge to the pituitary-testes, and 3) a gonadotropin-releasing hormone (GnRH; 120 micrograms.kg-1 body weight) challenge to the pituitary-testes. Compared to UNT, the TRG resting T (4.8 +/- 0.7 vs 7.1 +/- 1.2 ng.ml-1, p = 0.05) and PRL (3.3 +/- 1.4 vs 7.0 +/- 2.3 ng.ml-1, p = 0.09) were lower while LH was elevated (15.0 +/- 1.8 vs 11.8 +/- 1.5 mIU.ml-1, p = 0.06). The DA challenge produced a greater integrated PRL response in the TRG (2962.7 +/- 265.1 ng +/- ml-1.min) than in the UNT (1735.3 +/- 282.0 ng.ml-1.min; p = 0.01). No significant changes were observed in T following the DA-induced PRL rise. The TRG had a blunted LH response (817.2 +/- 111.6 mIU.ml-1.min) following the GnRH injection as compared to the UNT (1493.7 +/- 213.4 mIU.ml-1.min; P less than 0.02). T levels were significantly (p less than 0.03) increased in both groups by the LH rise after the GnRH challenge (TRG = 9.9 +/- 5.0%; UNT = 8.6 +/- 9.9%, respectively), but no significant between group differences were observed. Results suggest endurance training produces an enhanced PRL and attenuated LH release by the pituitary.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

Body composition and menstrual function in athletes.

The 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 bodyweight. 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.

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).

Kinematic effects of heel lift use to correct lower limb length differences*.

The effect of the heel lift to correct a limb length difference was studied by electrogoniometry (elgons) in four male subjects with a limb length inequality between 3/~6 inch (0.48 cm) and 3h inch (0.95 cm). Six elgons were attached to bilateral hip, knee, and ankle joints as the subject walked (3 mph) and jogged (6 mph) on the treadmill twice, once with the heel lift and once without. Recordings from the elgons examined maximal flexion and extension during support and swing phase, amplitude of movement (ROM), duration of each movement, and angular velocity of each joint. Within the limitations of the study, the following conclusions were drawn: 1) the addition of a heel lift did not appear to significantly affect biomechanical measures of gait; and 2) insertion of a heel lift did tend to cause more symmetrical movement for the maximum angle of hip extension and ROM of the swing plantarflexion phase of the ankle but more asymmetrical ROM of the swing flexion phase of the knee. J Orthop Sports Phys Ther 1986;7(4):173-179.

Validity of "generalized" equations for body composition analysis in male athletes.

Equations by Durnin and Womersley [(D-W), Br. J. Nutr. 32:77, 1974], Jackson and Pollock [(J-P), Br. J. Nutr. 40:497, 1978], and Lohman [(L), Human Biol., 53:181, 1981] for estimating body density (BD) purportedly overcome the problem of specificity by accounting for age and/or the curvilinear relationship between skinfolds (SF) and BD. Their equations were validated on 265 male athletes against percent fat measured by underwater weighing [(UWW); mean +/- SD = 9.2 +/- 4.4%]. Equations by Sloan [(S), J. Appl. Physiol. 23:311, 1967], Katch and McArdle [(K-M), Human. Biol. 45:445, 1973], and Forsyth and Sinning [(F-S), Med. Sci. Sports 5:174, 1973] were included as "linear regression models" to compare to the curvilinear models of J-P, D-W, and L. Differences between UWW and estimated mean values ranged from -1.1 to +5.9%; correlations ranged from 0.58 to 0.85; SEE ranged from +/- 2.41 to +/- 3.61% and total error (E) ranged from 2.38 to 6.97%. The seven D-W equations overestimated mean percent fat by from 3.9 to 5.9%. The K-M, S, and L equations overestimated by 1.3, 0.5, and 1.7%, respectively. The F-S equations overestimated by 2.4 to 3.8%. Of the 21 equations evaluated, only 3 by J-P gave estimates not significantly different from UWW percent fat. Regression analyses of the relationship between UWW (y) and estimated (x) percent fat values from those equations were: y = 1.037x - 0.08 +/- 2.38, E = 2.38, r = 0.84; 0.869x + 1.36 +/- 2.45, E = 2.51, r = 0.83; 1.107x - 1.14 +/- 2.51, E = 2.53, r = 0.82.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

Anaerobic and aerobic responses of males and females to rope skipping.

Six male and six female subjects performed maximal bicycle ergometer work and skipped rope at selected rates. Measures included oxygen uptake (VO2), oxygen debt (VO2 debt), blood lactate, and heart rate (HR). Mean values for males for the maximum test and while skipping at 120, 140, and 160 turns . min-1 were, respectively: VO2-50.2, 38.3, 39.7, and 44.3 ml . kg-1 . min-1; HR-185, 166, 168, and 178 beats . min-1; VO2 debt--5.70, 3.65, 3.50, and 4.04 liter; and lactate--12.7, 7.4, 7.6, and 9.2 mM . 1(-1). For females: VO2--42.8, 39.8, 39.4, and 39.4 ml . kg-1 . min-1; HR--185, 181, 181, and 181 beats . min-1; VO2 debt--4.71, 4.27, 4.22, and 4.15 liter; and lactate--11.5, 11.5, 12.2, and 11.9 mM . l-1. No significant differences were found between treatments for females for any measure. Rope skipping placed high demands on both aerobic (females, 92% VO2max, males, 76-88%) and anaerobic capacities (females, 100-106% lactate values after maximum bicycle exercise; males, 58-72%). In males, who did not reach VO2max during rope skipping, it was verified that the VO2 requirement does not increase with skipping rate over a relatively wide range, but that extremely high rates do require more energy from both aerobic and anaerobic sources. Differences in tolerance of males and females to rope skipping were attributed to the lower aerobic power and higher body fat of females.

The effect of rope skipping rate on energy expenditure of males and females.

The purpose was to study the effects of skipping rate on energy expenditure and sex differences in response to rope skipping. Responses of 19 males and 11 females were measured while skipping for 5 min at 125, 135 and 145 skips . min-1. Expired air was routed through a hollow handle to collection bags to provide uninterrupted exercise. Values at the respective rates for the total sample were: VO2 (l . min-1) 2.79, 2.83, 2.85; VO2 (ml . kg-1 . min-1) 41.1, 42.0 42.5; HR (beats . min-1) 176, 177, 177; VE (l . min) 102.2, 103.5, 106.3; R 1.09, 1.07, 1.05; energy expenditure (kj . min-1) 58.6, 59.4, 60.3. Sex differences were found in that females had significantly lower VO2 both in l . min-1 and ml . kg-1 . min-1 but higher HR values than males. Comparison of VO2 values of the females to VO2max values reported for females in the literature suggested that they may have been exercising close to their maximum. There were no differences in any of the values due to skipping rate nor was there interaction between sex and rate. Retrospective cinematographic analysis on two subjects suggested that the failure to find significant differences due to rate may be due to a decrease in vertical displacement resulting in a relatively constant work output as skipping rate increased. Average MET values at the different rates ranged from 11.7 to 12.5, which supported findings from other studies that rope skipping is very strenuous exercise.

Anthropometric estimation of body density, fat, and lean body weight in women gymnasts.

Measurements from 44 highly skilled women gymnasts were used to evaluate previously derived equations for estimating body composition and to develop new equations by step-wise linear regression. True composition values were computed from body density (DB). Measures were taken of skeletal diameters (D), circumferences (C) and skin-folds (SF). Equations evaluated were those by Sloan et al. (23), F. Katch and Michael (15), Wilmore and Behnke (28), F. Katch and McArdle (18) and Weltman and V. Katch (26). With exception of the Weltman-Katch equation, correlations between true and estimated LBW's were high (.91 to .95) but underestimated true LBW 1.13 to 3.88 kg. Regression analysis suggested adjustment of ordinate values would give these equations acceptable accuracy for use with women gymnasts. New equations were derived from variables that had been selected by using factor analysis to minimize shared variance. Equations derived were DB - 1.024620 + .002024 Neck C--.001435 Supra-iliac SF--.001039 Juxta-um-bilicus SF (R.806, +/- .0061); Fat = .3798--.5809 Neck C + .3253 Abdominal C + .3007 Supra-iliac SF + .2047 Juxta-umbilicus SF, (R .891, +/- 1.29) and LBW = .3973 Height + .8357 Neck C + .4317 Shoulder C--87.203 (R .923, +/- 1.75).