The effects of creatine supplementation on repeated upper- and lower-body Wingate performance.

Nineteen physically active men supplemented their diet with 20 g per day creatine monohydrate (Cr group) or placebo (PI group) for 6 days. Before and after supplementation, subjects performed 3 arm Wingates (AW1, AW2, and AW3) and 3 leg Wingates (LW1, LW2, and LW3) on consecutive days. Wingates were separated by 2 minutes each. Mean power (MP), peak power (PP), and percent decrease (%D) were compared between and within groups. MP did not change significantly for arms or legs. PP did not change significantly for legs. PP increased significantly in the Cr group (AW1) and for the P1 group (AW1 and AW3). MP and PP were not significantly different between groups. The %D increased significantly in the P1 group (AW1, AW3, and LW3). For the Cr group, %D decreased significantly (pre vs. post) and was significantly lower than for the P1 group (LW2-post). Results suggest that short-term Cr supplementation does not enhance MP and PP during repeated upper- and lower-body Wingate tests when not accompanied by an increase in body weight. However, changes in %D suggest possible ergogenic effects.

Effects of carbohydrate-electrolyte content of beverages on voluntary hydration in a simulated industrial environment.

This study examined the effects of ingesting beverages of varying electrolyte-carbohydrate (ECHO) composition on hydration, sensory response, physiological function, and work performance during 4 hours of simulated industrial work for subjects wearing impermeable protective clothing (PC). Male subjects (N=18) completed four separate work sessions. Each session consisted of 30 min of treadmill walking with intermittent arm curls at 300 kcal per hour (moderate work rate), followed by 30 min of rest, for a total of 4 hours at 33 degrees C wet-bulb globe temperature. Excessive physiological strain prevented only four subjects from completing the 4-hour protocol. A different beverage was provided for consumption ad libitum for each work trial in a repeated measures, double-blind design. The beverages included lime colored water (W), lemon-lime placebo (P), lemon-lime ECHO with 18 mEq/L NaCl (ECHO18), and lemon-lime ECHO with 36 mEq/L NaCl (ECHO36). There was no difference in sweat production among the four trials (p = 0.61). Mean (standard deviation [SD]) fluid consumption was significantly greater for the ECHO36 [771 (+/-264) mL per hour] as compared with the W [630.6 (+/-234) mL per hour] and the P [655.2 (+/-228) mL per hour] (p<0.05), but not significantly greater than the ECHO18 [740.4 (+/-198) mL per hour]. Also, consumption of the ECHO18 was significantly greater than the W. Mean (SD) weight change, expressed as a percentage of total body weight (pre minus post), was -0.55(+/-0.8) for W, -0.31(+/-1.0) for P, -0.01(+/-1.1) for ECHO18, and +0.11(+/-1.1) for ECHO36 (p = 0.06). Subjects drank less and tended to experience greater weight loss in trials in which W or P were provided compared with trials in which either ECHO was provided. Thus, ECHO beverages, when provided ad libitum to workers wearing PC in a hot environment, produced better hydration than water.

Comparison of leg length inequality measurement methods as estimators of the femur head height difference on standing X-ray.

OBJECTIVE: To assess the validity and reliability of prone and supine measurements of leg length inequality and to determine the potential use of measurements at the iliac crests and patient demographics as predictors to estimate standing leg length differential. DESIGN: Repeated prone and supine measurements of leg length inequality were made by an experienced chiropractor and compared with iliac crest and femur head measurements made on X-rays of standing patients. Multiple regression analysis was performed. SETTING: Private chiropractic practice. PARTICIPANTS: The first 50 new patients with low back pain that were X-rayed were included in the study. RESULTS: Intraexaminer reliability was excellent for the prone measurements. The supine tests were less reliable. The prone measurements were highly correlated with the standing X-ray femur head measurement. The supine measurements were poorly correlated. Measurements of deficiency at the iliac crests on X-ray were most highly correlated with X-ray measurements of discrepancy. In multiple regression, the prone measurements and duration of problem were the only significant predictors of standing X-ray difference. CONCLUSIONS: In this study, crest measurements were made on X-ray; the degree of accuracy with which millimeter differences can be measured clinically on patients is unknown. In a few cases, the supine measurements were more accurate than the prone; however, the supine test validity was poor when compared with the standing X-ray measurements, and reliability was less than expected. Supine measurements should not be used to estimate standing leg length discrepancy in new low back pain patients but perhaps can be used in other clinically meaningful ways. Intraexaminer reliability of the prone measurements was higher, but further investigations need to focus on interexaminer reliability. The prone measurement as a predictor holds promise, but new measurement tools must be developed.

The validity of the prone leg check as an estimate of standing leg length inequality measured by X-ray.

OBJECTIVE: To determine if prone leg length measurements for inequality are valid to estimate standing X-ray measured differences. DESIGN: Leg length inequality (LLI) was measured, in millimeters, with each patient prone and with a standing X-ray, by an experienced chiropractor. Correlation between the two was calculated, and dependent t test performed. SETTING: Private chiropractic practice. PARTICIPANTS: The first 50 new patients with low back pain (LBP) who were X-rayed were included in the study. RESULTS: Correlation between the two variables was 0.71. Standard error of estimation was 5.4 mm. In 54% of subjects, the prone measurement was within 3 mm of the X-ray LLI; in 12%, however, opposite legs were identified as being "shorter" between the two methods. In 76% of patients, prone measurements were within 6 mm of X-ray, but there was 12-mm difference between the two measurement methods in 8% of the comparisons. CONCLUSIONS: Despite positive correlation, prone leg length measurements for inequality are not entirely valid estimates of standing X-ray differences. Large differences between prone and X-ray measurements in some cases indicate that one should be cautious when using the prone method alone to estimate leg length discrepancy. Additional research is needed to determine the causes of measurement differences between the two methods. Other methods for estimating standing leg length differential must be developed and evaluated for validity.

Exercise intensity increased by addition of handheld weights to rebounding exercise.

PURPOSE: Researchers who studied the effects of rebound exercise on fitness have concluded that the intensity of rebound exercise elicited only minimal improvements in fitness. This study determined how the addition of arm pumping with handheld weights (HHW) would increase exercise intensity while rebounding. METHODS: Fifteen male subjects (20 to 43 years) ran in place on a mini-trampoline at a stride frequency of 120 foot strikes per minute, with the sole of the foot 15 cm above the rebounder rim. Oxygen uptake (VO2) and heart rate (HR) were measured while rebounding alone, and also while pumping 0.45 kg, 0.91 kg, and 1.36 kg HHW to heights of 61 and 91 cm. RESULTS: All combinations of weights and pumping levels resulted in significantly (P < .05) higher VO2 and HR than rebounding alone. The estimated mean increase in VO2 was 3.2 mL/kg/min when the weight was increased from 0.91 kg to 1.36 kg at the 91 cm pumping height. The corresponding HR increase was 10.1 bpm. Similarly, when 1.36 kg weights were pumped at 91 cm instead of 61 cm, the mean increase in VO2 and HR was 6.2 mL/kg/min and 11.4 bpm, respectively. CONCLUSIONS: The addition of HHW exercise to rebounding substantially increases exercise intensity. Because rebounding without weights results in a relatively low intensity, the addition of HHW should be considered in the use of rebounding for cardiovascular training.

Strength, muscle symmetry, and flexibility in young female idiopathic scoliotics.

Application of previous findings regarding muscle strength and function in scoliotics suggests that curvature might result from unbalanced pull of spinal muscles oriented transversely. This study investigated the role of muscle strength and strength symmetry in 48 young female scoliotics and 48 age-matched controls. The subjects were divided into three age levels: 11 and 12, 13, and 14 and 15 years of age. Scoliotics were weaker than the nonscoliotics only for shoulder strength in the two older age levels. For all subjects combined, as well as each group and age level, the dominant versus nondominant strength differences were significantly greater than zero; however, the magnitudes of the differences were not different between any of the groups. Nonscoliotics displayed significantly greater trunk flexibility than scoliotics. J Orthop Sports Phys Ther 1991;14(4):144-148.

Validation of body composition models for high school wrestlers.

This study investigates the utility of two equations for predicting minimum wrestling weight and three equations for predicting body density for the population of high school wrestlers. A sample of 54 wrestlers was assessed for body density by underwater weighing, residual volume by helium dilution, and selected anthropometric measures. The differences between observed and predicted responses were analyzed for the five models. Four statistical tests were used to validate the equations, including tests for the mean of differences, proportion of positive differences, equality of standard errors from regression, and equivalence of regression coefficients between original and second sample data. The Michael and Katch equation and two Forsyth and Sinning equations (FS1 and FS21) for body density did not predict as well as expected. The Michael and Katch equation tends to overpredict body density while FS1 underpredicts. The FS2 equation, consisting of a constant adjustment to FS1, predicts well near the mean but not at the ends of the sample range. The two Tcheng and Tipton equations produce estimates which slightly but consistently overpredict minimum wrestling weight, the long form equation by 2.5 pounds and the short form by 3.8 pounds. As a result the proportion of positive differences is less than would be expected. But based on the tests for the standard errors and regression coefficients, the evidence does not uniformly reject these two equations.

Body composition prediction in university football players.

This study was intended to determine if previously-developed body composition prediction equations were valid for use with a Division I university football team. A sample of 68 Division I football players with a mean age of 19.7 yr, was assessed for body density (BD) by underwater weighing (UWW), residual volume by helium dilution, and 26 selected anthropometric measures. A predicted BD was obtained by using two sets of equations developed from college football players and from three generalized equations. The differences between predicted and observed body densities were analyzed. Seven of the nine models examined failed to accurately predict the BD for this population of university football players. One sport-specific equation of White, Mayhew, and Piper for individuals in the backfield and a generalized model of Jackson and Pollock (JP) containing two circumferences performed well when considering the mean of differences and the magnitude of total error relative to the published standard error. However, both of these models overestimate body density for players with low BD and underestimate BD when actual BD is high. Using the JP model for a player whose actual BD is near the sample mean of 1.070, the estimated mean is very close at 1.069. However, for players with actual BD of 1.050, the estimated mean is 1.054, and if actual BD is 1.085, the JP estimated mean is 1.078. The bias is linear between these points.