The effect of exercise duration on serum cholesterol and triglycerides in women.
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Adult↗
Biomedical subjects
G O Johnson
Publications and source records attributed to G O Johnson.
Midwest wrestling study: prediction of minimal weight for high school wrestlers.
This study determined the validity of previously published or newly derived equations to predict fat-free body mass (FFB) in high school wrestlers from the midwestern United States. Five laboratories participated in the data-pooling study (total sample of 860 subjects). Measures included body composition by underwater weighing and anthropometric measurements of body mass, stature, and selected circumferences, diameters, and skinfolds. Cross-validation of selected equations to predict FFB revealed the lowest levels of error from the equations of Lohman, Thorland et al., Katch and McArdle, and Behnke and Wilmore. Modification of the constants in these equations or generation of new equations did not substantially reduce prediction error. Overall, total error for these top equations ranged from 2.44 to 2.59 kg. However, based on observed trends, this error was of lower magnitude with the younger and lighter subjects and of higher magnitude with the older and heavier subjects. We conclude that these equations could be used singularly or collectively to determine FFB, and a minimal weight could then be derived and assigned to a scholastic wrestler.
Adolescent↗
The accuracy of coaches' estimates of minimal wrestling weight.
The purpose of this study was to compare estimations of minimal wrestling weight (MWW) from experienced high school wrestling coaches and anthropometric equations with those from underwater weighing. Eighty-two wrestlers (X age +/- SD = 16.54 +/- 1.05 yr) volunteered to be assessed via anthropometry and underwater weighing, with percent body fat calculated from body density (BD) using both the conversion constants of Lohman [percent body fat = [5.03/BD) - 4.59) x 100] and Brozek [percent body fat = [4.57/BD) - 4.142) x 100]. In addition, five head coaches, who had between 5 and 24 yr of experience, were asked to estimate within 1 lb the MWW for each of their athletes. The validity of four selected anthropometric equations and the coaches' estimates were compared with the actual MWW from underwater weighing by examining the constant error (CE), r, SEE, and total error (TE) values. The results indicated that the skinfold equation (EQ1) of Lohman provided the most accurate estimates of MWW (TE = 1.90-2.09 kg) and is therefore recommended over the subjective estimates of high school coaches.
Adipose Tissue↗
The effect of glycogen depletion and supercompensation on the physical working capacity at the fatigue threshold.
The purpose of this investigation was to determine the effect of glycogen depletion and supercompensation on the physical working capacity at the fatigue threshold (PWCFT). Ten adult males (mean age 23 years, SD 3) volunteered as subjects for this study. During the first laboratory visit the subjects performed a maximal bicycle ergometer test for the determination of maximum oxygen consumption (VO2max). Between 48 and 72 h later, the subjects pedaled to exhaustion at a power output which corresponded to a mean of 76% of VO2max (range, 72-80%) for the purpose of glycogen depletion. For the next 3 days, the subjects were fed a 10.5 MJ.day-1 low carbohydrate diet which consisted of 7.5% carbohydrates, 22.0% protein and 70.5% fat. The subjects then performed an incremental cycle ergometer test to the onset of fatigue or PWCFT, which was estimated from integrated electromyographic voltages of the vastus lateralis muscle. For the next 3 days the subjects were fed a 10.5 MJ high carbohydrate diet which consisted of 72.2% carbohydrates, 12.4% protein and 15.4% fats for the purpose of glycogen supercompensation. The subjects then performed a second PWCFT test. A paired t-test indicated that there was no significant (p greater than 0.05) difference between the means of the PWCFT values (depletion 246 W, SD 30; supercompensation 265 W, SD 28) and they were highly correlated at r = 0.884. The results of this investigation suggested that the methods commonly used to affect glycogen depletion or supercompensation had no effect on PWCFT.
Adaptation, Physiological↗
Factors affecting the estimation of physical working capacity at the fatigue threshold.
The purpose of this study was to investigate potential improvements in the methodology associated with the Physical Working Capacity at the Fatigue Threshold (PWCFT) test including: (1) the use of a continuous test protocol; (2) the use of a treadmill; (3) the use of a bipolar EMG lead system for noisy electronic environments; and (4) the potential for residual fatigue from tests repeated 24 hours apart. The results of the continuous test protocol (mean +/- S.D. = 210 +/- 73 watts) correlated well (r = 0.856) with the original discontinuous technique (222 +/- 83 watts) and there was no significant (p greater than 0.05) difference between the mean values (t = 1.146). Treadmill testing required a bipolar lead system to counteract the electrical noise generated by the treadmill motor. The heart rate values which corresponded to PWCFT on the treadmill (mean +/- s.d. = 164 +/- b.p.m.) and bicycle ergometer (153 +/- 18 b.p.m.) were highly correlated (r = 0.833) and there was no significant (p greater than 0.05) difference between the mean values (t = 2.22). The use of a bipolar lead EMG system on the bicycle ergometer resulted in significantly (p less than 0.05) smaller voltage for any given power output, and the PWCFT exhibited a low to moderate correlation (r = 0.60) with PWCFT derived from a unipolar arrangement. The test-retest results of discontinuous PWCFT measurements performed 24 hours apart on the bicycle ergometer were correlated at r = 0.812 with no significant (p greater than 0.05) difference (t = 0.52) between the mean values (test = 198 +/- 60; retest = 191 +/- 63 watts).(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
The effects of age and body weight on anthropometric estimations of minimal wrestling weight in high school wrestlers.
The purpose of this study was to determine the effects of age and body weight on anthropometric estimations of minimal wrestling weight (MWW) in high school wrestlers. Five hundred and twenty-two high school wrestlers (M age +/- SD = 16.45 +/- 1.03 years) volunteered as subjects for this study. The total sample (N = 522) was dichotomized by age (less than 16 years, n = 171; greater than or equal to 16 years, n = 351) and body weight (less than or equal to 62.60 kg, n = 252; greater than 62.60 kg, n = 270). Cross-validation analyses included examination of the constant error (CE), standard error of estimate (SEE), r, and total error (TE). The results indicated that the quadratic skinfold equation of Lohman (EQ1; Table 2) most accurately estimated MWW in each group. Furthermore, it was recommended that MWW be calculated from EQ1 using the conversion constants of Lohman ([(5.03/BD)-4.59] x 100) to estimate relative fat from body density.
Adolescent↗
A physiological comparison of female body builders and power lifters.
Ten female body builders (FBB) (X age +/- SD = 30.40 +/- 8.22 years) and ten female power lifters (FPL) (X age +/- SD = 25.20 +/- 6.01 years) were studied to determine group differences in body composition, strength and anaerobic characteristics. All subjects had been training a minimum of two years and twelve of the subjects had competed nationally while the remainder had participated in regional or local events. Measures of body build and body composition were obtained via hydrostatic weighing, skinfolds (sum of 7), circumferences (sum of 13) and diameters (sum of 9). Flexion and extension strength of the dominant forearm and leg were measured with a Cybex II dynamometer at 60 degrees/second. Anaerobic power and capacity were determined using the Wingate Anaerobic Test. Independent t-tests indicated the FPL had significantly greater body weight (X +/- SD = 68.60 +/- 3.60 vs 56.47 +/- 0.85 kg), relative fat (21.47 +/- 1.29 vs 13.51 +/- 1.46%), sum of skinfolds (120.76 +/- 7.55 vs 71.46 +/- 7.02 mm), sum of diameters (177.57 +/- 2.97 vs 168.17 +/- 2.55 cm), and sum of circumferences (594.93 +/- 13.10 vs 551.24 +/- 3.17). No significant differences were found for fat-free weight, strength or anaerobic power and capacity. These results demonstrate subtle but specific differences between well-trained FBB and FPL reflecting the leaner physiques and smaller skeletal structures of the FBB necessary for the definition and symmetry demanded by the sport. The lack of differences in strength and anaerobic characteristics reflect the similarity of the groups in basic training techniques.
Adult↗
The effect of exercise intensity on serum lipoprotein responses.
The purpose of this study was to determine the effect of exercise intensity on lipoprotein responses. Eleven normolipidemic male volunteers (X +/- SD = 23.1 +/- 2.4) participated in the study. The subjects were assessed for VO2max and ventilatory threshold (VT), matched for VO2max and then randomly assigned to one of two groups: Group A, which exercised for 12 minutes at an intensity 15% below VT (n = 5), and Group B, which exercised for 12 minutes at an intensity 15% above VT (n = 6). The lipoprotein measures HDL-C, LDL-C, total cholesterol (TC), and triglycerides (TG) were assessed from blood samples taken pre-exercise and immediately post-exercise as well as one, 24, and 48 hours post-exercise. A 2 X 5 split plot ANCOVA (controlling for pre-exercise values), revealed no significant differences between groups for HDL-C, TC or LDL-C. However, when means were collapsed across groups, TC levels measured immediately post-exercise were significantly higher than those taken 24 and 48 hours post-exercise (168.0, 159.1, and 159.9 mg.dl-1, respectively; p less than 0.05). A significant interaction was found for the TG measurements. For Group A, TG levels were elevated immediately post-exercise, but decreased significantly at the 1 and 24 hours post-exercise sampling, before returning to baseline levels at the 48 hour post-exercise measurement (93.2 +/- 3.1, 69.5 +/- 4.2, 66.8 +/- 6.7 and 99.5 +/- 2.1 mg.dl-1, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Validity of anthropometric estimations of body composition in high school wrestlers.
The purpose of this study was to determine the validity of 23 anthropometric equations for estimating body composition and minimal wrestling weight in high school wrestlers. A total of 409 high school wrestlers (M age +/- SD = 16.42 +/- 1.03 yrs) volunteered for this study. Twenty-three anthropometric measures including eight skinfolds, nine circumferences, and six diameters were obtained from each subject. The mean body density, determined from underwater weighing, was 1.0748 +/- 0.0100 g.cm-3. The crossvalidation analyses indicated that the quadratic skinfold equation of Lohman resulted in the most accurate estimation of body density. The total error, constant error, standard error of estimate, and r for this equation were 0.0077 g.cm-3, -0.0003 g.cm-3, 0.0076 g.cm-3 and .65, respectively. Furthermore, the results of this investigation indicated that the minimal wrestling weight equations of Tcheng and Tipton resulted in total error values (5.54 to 6.06 kg) which were too large to be of practical use for high school wrestlers.
Adolescent↗
Isokinetic strength and body composition of high school wrestlers across age.
The purpose of this study was to determine the changes in body composition as well as absolute and relative isokinetic forearm and leg strength of high school wrestlers across age. One hundred ninety-five wrestlers (means age +/- SD = 16.36 +/- 1.12 yr) volunteered to be measured for strength using a Cybex II dynamometer at 30, 180, and 300 degrees.s-1. In addition, underwater weighing was used to determine body composition characteristics. The subjects were divided into four age groups: group 1 (G1) = 14.17-15.00 yr (N = 20); group 2 (G2) = 15.01-16.00 yr (N = 60); group 3 (G3) = 16.01-17.00 yr (N = 52); and group 4 (G4) = 17.01-18.50 yr (N = 63). One-way ANOVA or ANCOVA with Tukey post hoc comparisons indicated significant (P less than 0.05) changes across age for height, body weight, and fat-free weight, as well as absolute and relative forearm and leg strength. The results of this study indicated that, while a large portion of the improvements in strength across age were associated with increases in lean tissue, there was an additional "age effect" which could not be accounted for by changes in fat-free weight. Although the mechanism responsible for the "age effect" is unclear, it is possible that neural development contributed to the strength increases across age.
Adolescent↗
Validity of anthropometric equations for determination of changes in body composition in adult males during training.
Twenty-six males (26.5 +/- 6.0 yr; X +/- SD) were studied before and after a fourteen week endurance training program to determine the validity of anthropometric equations for estimating changes in body composition (BC). Anthropometric measures included skinfolds (SF), circumferences, and diameters. Body density (BD) was determined by underwater weighing corrected for residual lung volume. Training resulted in an increase in BD (1.061 +/- 0.002 to 1.067 +/- 0.002 g/ml; X +/- SEM) and decreases in body weight (73.0 +/- 2.1 to 71.4 +/- 2.0 kg), relative fat (16.6 +/- 0.9 to 14.1 +/- 0.8%), fat weight (12.4 +/- 1.0 to 10.2 +/- 0.8 kg), and seventeen of the anthropometric measures (p less than 0.05). Cross-validation of twenty-four equations revealed validity coefficients (r2) and total error in relative fat (RFE) of r2 = 0.40-0.77 and RFE = 2.60-10.15% before training and r2 = 0.14-0.61 and RFE = 2.62-9.45% after training. Linear and base 10 logarithmic (log10) equations using primarily SF measures tended to have higher r2 and lower RFE than equations based on quadratic and natural logarithmic (loge) models and other anthropometric measures. Paired t-tests revealed that of these equations with higher r2 and lower RFE, only the linear equation by Forsyth & Sinning (BD = 1.10647--0.00162(scapSF)--0.00144(abdSF)--0.00077(triSF++ +) + 0.00071(midaxSF] was a stable predictor of BD during training. These results suggest that many existing equations may not be accurate predictors of changes in BC during training.
Adult↗
The effect of a competitive season on the body composition of university female athletes.
Fifty-six NCAA Division I female athletes (age +/- SD = 19.82 +/- 0.59 years) from the swimming (SW), track (TR), volleyball (VB), gymnastics (GYM) and basketball (BB) teams were measured preseason and postseason to determine the effects of a season's training on their body composition. Body density (BD), relative fat (RF), fat-weight (FW), and fat-free weight (FFW) were obtained via hydrostatic weighing. The TR and GYM athletes showed significant increases and the VB players significant decreases in BD and FFW across season, respectively. No significant changes were found for the SW and BB teams. Preseason comparisons showed greater BD for TR than for BB, VB or SW. The GYM and VB had lower BD values than SW. Fat-free weight was higher in BB and VB teams, while TR and SW teams had greater FFW than GM. The BB, VB and SW teams had greater preseason FW than the TR and GYM groups. Postseason comparisons showed greater BD in TR and GYM than in the other three groups. Although FW differences were consistent with preseason data, all groups differed significantly in FFW with BB players having the greatest amount followed by VB, SW, TR and GYM.
Adipose Tissue↗
Validity and intertester error of anthropometric estimations of body density.
The purposes of this study were to evaluate the intertester error in anthropometry and its effect on estimations of actual body density (ABD), as well as to assess the validity of predicted body density (PBD) from selected anthropometric equation. Sixteen adult males X +/- SD = 21.98 +/- 1.65 years) volunteered to be measured by three experienced and reliable testers at eight circumference, two diameter, and eight skinfold sites as well as by underwater weighing. Eighteen commonly used anthropometric equations which predict body density were selected for evaluation. Repeated measures ANOVA with Tukey post-hoc comparisons were used to determine differences between testers for each anthropometric measure and the PBD values, as well as between the PBD values and ABD. There were significant (p less than 0.01) differences between testers for all anthropometric measures except bi-iliac diameter and hips circumference. However, the magnitude of the differences between testers were considered to be quite small and of no practical concern. There were significant differences among the PBD values and ABD for all equations except the base 10 logarithmic transformations of Durnin and Womersley. Seven of the equations, however, resulted in a constant error of less than or equal to 0.0085 g.ml-1. Overall, there was no single anthropometric equation which satisfied all of the cross-validation criteria suggested by previous investigators, however the linear equation of Forsyth and Sinning which included the scapular and abdominal skinfolds, as well as the bitrochanteric diameter resulted in an extremely small constant error (0.0024 g.ml-1) and an appropriate standard deviation of the PBD values (0.0127 g.ml-1).
Adult↗
A comparison between methods of measuring anaerobic work capacity.
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Adult↗
Estimation of minimal wrestling weight using measures of body build and body composition.
This study evaluated field methods for establishing minimal body weight in wrestlers based upon estimates of fat-free body weight (FFB): 239 high school wrestlers were measured for height, weight, 13 diameters, 24 circumferences, and 7 skinfolds, as well as for underwater weight to determine body density and resultant FFB. To estimate FFB, anthropometric models were used which were based upon diameters, circumferences, and/or skinfolds. Correlations between actual and predicted FFB were high, ranging from r = 0.89 to 0.92 for the models employing diameters and r = 0.96 for those employing circumferences, which respectively increased to r = 0.96 and r = 0.97 when body weight was included in theses models. The skinfold-based and mixed model estimates of FFB were r = 0.97 and r = 0.91 to 0.97, respectively. The corresponding total error (TE) in these estimates for the diameter-based models ranged from 6.54 to 3.80 kg (inclusion of body weight further reduced TE to 2.77 kg). Among the circumference models, TE ranged from 2.50 to 2.33 kg, with inclusion of body weight accounting for the lower value. Skinfold-based estimates of FFB demonstrated a TE level ranging from 2.48 to 2.33 kg. The lowest TE (2.32 kg) was demonstrated by a mixed model which included skinfolds, diameter, height, and body weight. Cross-validation of these new equations revealed the lowest TE values (less than 2.2 kg) for the skinfold and the mixed model equations, thereby identifying highly valid field techniques for determining the present level of FFB, which can serve as the basis upon which minimal body weight estimates can be made.
Adipose Tissue↗
Strength and anaerobic responses of elite young female sprint and distance runners.
The purpose of this study was to assess the strength and anaerobic responses of elite young female runners, in order to determine the relationship of these characteristics to age and high proficiency in sprint events. Thirty-one national junior-level sprint and middle distance runners were evaluated for isokinetic peak torque for leg extension at velocities ranging for 30 degrees to 300 degrees X s-1, anaerobic power and capacity based on the Wingate test, and body composition based on underwater weighing. Age-related and event-related differences were noted for both the peak torque and anaerobic response measures. Peak torques were greater for the older (greater than 11.67 yr) runners and greater for the sprinters when measured at the higher testing velocities. Anaerobic power and capacity were also greater for the older runners, but event-related differences only appeared when anaerobic power was adjusted for fat-free weight (adjusted anaerobic power was greater in the older sprinters). These results indicate that both age and fat-free weight influence strength and anaerobic responses in young female runners and that exceptional levels of such characteristics only appear for sprinters within the upper age groups of youth competition.
Adolescent↗
The effect of endurance training on metabolic responses and the prediction of distance running performance.
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Adult↗
Body composition and body build variables as predictors of middle distance running performance.
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Adolescent↗