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Purpose: The purpose of this case study was to determine the effects of 15 wk of resistance exercise and creatine (Cr) supplementation on body composition, training volume, peak strength, and complete blood chemistry in a patient with myasthenia gravis (MG)., Methods: The patient was a 26-yr-old man who was taking prednisone and azathioprine for his condition. The patient self-administered 5 g of Cr per day in addition to resistance exercise 3 times per week. Fasting blood samples were obtained and body weight (BW) and fat free mass (FFM; via hydrostatic weighing) were measured before and after training and Cr supplementation. In addition, isokinetic (Cybex II) peak strength for leg extension (LE), leg flexion (LF), and volume load (repetition x mass lifted) for the first and last resistance training session were determined., Results: After Cr supplementation and training, the results demonstrated increases in BW (6.8%), FFM (4.3%), upper body volume load (37.0%), lower body volume load (15.0%), and peak strength for LE (37.0%) and LF (12.5%). Moreover, blood chemistry values remained within normal limits for the duration of the 15-wk study., Conclusion: These data suggest that resistance exercise plus Cr supplementation may promote gains in strength and FFM in patients with MG.

The present study examined the validity of bioelectrical impedence (BIA) equations for estimating fat-free weight (FFW) in female gymnasts by comparing the values to those obtained from underwater weighing (UWW). Ninety-seven female Caucasian high school gymnasts (mean age +/- SD = 15.7 +/- 1.1 yr) participated in the study. FFW from UWW was calculated from percent fat using the revised formula of Brozek et al. (mean FFW +/- SD = 43.8 +/- 4.5 kg) and the age-specific constants of Lohman (mean FFW +/- SD = 44.8 +/- 4.6 kg). Cross-validation analyses included examination of the constant error (CE), SEE, r, and total error (TE). The results indicated similar trends between equations when based on either the Brozek or Lohman conversions; however, the CE, SEE, and TE values were consistently lower for the majority of the equations using the revised formula of Brozek et al. Based upon the results of the cross-validation analyses, the equation of Houtkooper et al. and the interlaboratory equations of Van Loan et al. and Lohman, which resulted in identical TE values of 2.4 kg are recommended for use with young high school gymnasts.

The purpose of the present investigation was to examine the mechanomyographic (MMG) responses to maximal eccentric isokinetic muscle actions. Eight adult male volunteers [age 22 +/- 2 (SD) yr] performed maximal eccentric muscle actions of the leg extensors at 60, 90, 120, and 180 degrees /s on a Cybex 6000 isokinetic dynamometer. MMG was detected by a piezoelectric crystal contact sensor placed over the vastus lateralis muscle. Test-retest intraclass correlations ranged from R = 0.88 to 0.97 for peak torque and from R = 0.97 to 0.98 for root mean square MMG amplitude values. There was no significant (P > 0.05) velocity-related change in eccentric peak torque; however, there was a significant (P < 0.05) increase in MMG between 60 [119 +/- 44 (SE) mV] and 180 degrees/s (302 +/- 128 mV). These findings indicated a velocity-related dissociation between MMG and peak torque for maximal eccentric isokinetic muscle actions.

A preseason estimation of body composition may be useful for assigning a safe minimal body weight for female gymnasts. The present investigation examined the validity of 11 skinfold equations for predicting percent body fat (%fat) in high school female gymnasts (X age +/- SD = 15.7 +/- 1.2 yr) by comparing the values with those obtained from underwater weighing. Seventy-three gymnasts (X %fat +/- SD = 18.6 +/- 4.5%fat) volunteered to serve as subjects. The statistical analyses included examination of the constant error (CE), standard error of estimate (SEE), correlation coefficient (r), and total error (TE). The results of this investigation indicated that 7 of the 11 equations resulted in TE values that were < or = 3.9%fat (range, 3.3-3.9%fat). Of these, the quadratic sum-of-three skinfold equation of Thorland et al. (37) satisfies the most cross-validation criteria and, therefore, is recommended for estimating body composition and minimal body weight in high school female gymnasts. The other six equations with TE values of < or = 3.9%fat should be considered acceptable alternatives.

The purpose of this study was to examine the covariate influence of fat-free weight (FFW) on age-related increases in isokinetic peak torque for leg flexion and extension in high school female gymnasts. Seventy-two gymnasts (X age +/- SD = 15 7 +/- 1.2 yr) volunteered to be measured for isokinetic leg flexion and extension strength using a calibrated Cybex II dynamometer at 30, 180, and 300 degrees*s(-1) as well as for body composition from underwater weighing. The results indicated that there were significant (P < 0.05) zero-order correlations for age versus leg flexion (r = 0.36-0.47) and extension (r = 0.51-0.57) peak torque, as well as FFW versus leg flexion (r = 0.50-0.66) and extension (r = 0.620.73) peak torque. There were also significant (P < 0.05) first-order partial correlations between age and peak torque (covaried for FFW) for leg extension at 30 (r = 0.25), 180 (r = 0.36-0.39), and 300 degrees*s(-1) (r = 0.25-0.28) but not for leg flexion. These findings indicated that for the high school female gymnasts in the present study, there were age-related increases in strength that could not be accounted for by changes in FFW. It is possible that factors such as an increase in muscle mass per unit of FFW and/or neural maturation contribute to strength increases during adolescence in female athletes.

The present study examined the validity of selected bioelectrical impedance (BIA) equations for estimating percent fat (% fat) in males and compared their validity with that of a commonly used skinfold equation (Sum3). One-hundred twenty-two Caucasian males (X +/- SD = 12.5 +/- 5.8% fat, as determined by underwater weighing) served as subjects. Selection of the BIA equations was dependent upon meeting at least one of three criteria: 1) developed from a previous interlaboratory investigation, 2) derived on a large sample size (> 200), or 3) previously been shown to accurately estimate body composition when cross-validated against a criterion method. Cross-validation analyses included examination of the constant error, standard error of estimate (SEE), r, and total error (TE). The Sum3 equation which resulted in the lowest SEE and TE values (2.6% fat and 3.4% fat, respectively) and the highest validity coefficient (r = 0.90, P < 0.001), most accurately estimated % fat and, therefore, was recommended over BIA equations for estimating body composition in Caucasian males with lean to average body fatness. The fat-specific interlaboratory BIA equation of Segal et al. for males < or = 20% fat (N = 107) which resulted in a TE value of 3.6% fat and the generalized equation of Guo et al. (TE = 4.1% fat) may, however, be considered as acceptable alternatives.

The present investigation examined the validity of 16 skinfold equations for predicting body density (BD) in youth wrestlers (mean age +/- SD = 11.0 +/- 1.3 yr) by comparing the values to those obtained from underwater weighing. Forty-eight members of youth wrestling clubs (mean BD +/- SD = 1.0634 +/- 0.0125 g.cm-3) volunteered to serve as subjects. The statistical analyses included examination of the constant error (CE), standard error of estimate (SEE), correlation coefficient (r), and total error (TE). The results of this investigation indicated that all of the equations resulted in TE values that were > or = 0.0106 g.cm-3 (range = 0.0106-0.0229 g.cm-3) which corresponded to > or = 4.9% body fat. The TE values were too large to provide accurate estimates of body composition in the present sample of youth wrestlers. Future studies should use the CE values from the present investigation to adjust the intercepts of the skinfold equations in the present study and cross-validate the modified equations on young male athletes.

The purpose of this investigation was to derive and validate circumference and skinfold equations for estimating the anatomical cross-sectional area (CSA) of the quadriceps, hamstrings, and total thigh muscles. Forty-three adult male (mean age +/- SD = 25 +/- 5 yr) volunteers underwent magnetic resonance imaging (MRI) to determine the CSA of the thigh muscles at the midfemur level as well as midthigh circumference and anterior thigh skinfold assessment. Multiple regression analyses were used to derive equations for predicting quadriceps, hamstrings, and total thigh muscle CSA of the dominant limb from the anthropometric dimensions on a random sample of 30 of the subjects. Cross-validation (CV) analyses were performed for each equation on: (a) the nondominant thigh of the derivation group (N = 30); (b) the dominant thigh of the CV group (N = 13); and (c) the nondominant thigh of the CV group (N = 13). The CV total error values for the quadriceps, hamstrings, and total thigh muscle CSA ranged from 5.4 to 14.4, 3.3 to 5.5, and 10.0 to 25.4 cm2, respectively. The anthropometric equations are recommended for one-time estimates of muscle CSA values in healthy, well-nourished young adult males when more sophisticated procedures are not available.

The present investigation examined the validity of selected skinfold (Sum3), near-infrared interactance (F5000 and F1000), and bioelectrical impedance (BIA) equations for estimating percent body fat (% fat) in young adult males (mean age +/- SD = 22 +/- 3 yr) by comparing the estimates with values obtained from underwater weighing. Fifty-seven Caucasian male (mean % fat +/- SD = 15.1 +/- 6.2) volunteers served as subjects. The statistical analyses included examination of constant error (CE), standard error of estimate (SEE), r, and total error (TE). The results indicated that the Sum3 equation had the lowest SEE (2.7% fat) and TE (3.6% fat) as well as the highest validity coefficient (r = 0.90). The F5000, however, had the lowest CE (-1.0% fat). Based on these findings, the Sum3 equation is recommended over the F5000 (TE = 4.2% fat), F1000 (TE = 6.1% fat), and BIA (TE = 5.0% fat) equations for estimating % fat in young adult males.