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We examined the associations between levels of accelerometer-based physical activity and the mismatch of physiological fall risk and fear of falling (FOF) in community-dwelling older adults. We assessed 123 participants who received 7-day wrist-worn accelerometry. Physiological fall risk was assessed using the portable BTrackS™ balance system and FOF was assessed using a short version of the Falls Efficacy Scale-International. Participants were categorized into four groups: rational (low FOF/normal balance), irrational (high FOF/normal balance), incongruent (low FOF/poor balance), and congruent (high FOF/poor balance). One third of older adults had a mismatch between their FOF and actual fall risk. Accelerometer-based moderate to vigorous physical activity (MVPA) was significantly different in the irrational group compared to the rational group (p = 0.023) and the congruent group compared to the rational group (p = 0.032). Encouraging older adults to improve MVPA may prevent them from shifting from rational to irrational or congruent groups, thereby reducing the risk of injurious falls. [Journal of Gerontological Nursing, 49(6), 41–49.], One third to two thirds of community-dwelling older adults have a discrepancy between physiological fall risk and fear of falling (FOF), known as mal-adaptive fall risk appraisal (FRA) (Ng et [...]

Boffey, D, DiPrima, JA, Kendall, KL, Hill, EC, Stout, JR, and Fukuda, DH. Influence of body composition, load-velocity profiles, and sex-related differences on army combat fitness test performance. J Strength Cond Res37(12): 2467–2476, 2023—The Army Combat Fitness Test (ACFT) became the U.S. Army's mandatory physical fitness test in April of 2022. The purpose of this study was to determine the relationship between ACFT performance and both body composition and velocity profiles and to determine sex differences for these variables. Data were collected at 2 timepoints 4 months apart, from male (n= 55) and female (n= 17) Army Reserve Officers' Training Corps (ROTC) cadets. Body composition was assessed with a bioelectrical impedance spectroscopy device, and cadets completed a hex bar deadlift load-velocity profile (LVP) and ACFT on separate days. Stepwise multiple regressions were used to explain the amount of variance in ACFT total score and individual event performance. Significance for statistical tests was defined as an alpha level of p≤ 0.05. Muscle mass and body fat percentage accounted for 49% of shared variance of total ACFT score, and deadlift maximal power and maximal velocity accounted for 67% of shared variance of total ACFT score. The 3 repetition maximum deadlift, standing power throw, hand-release push-up, and sprint-drag-carry events favored cadets with more muscle mass, whereas the leg tuck was influenced by the body fat percentage and the 2-mile run was affected by fat mass. Sex had greater predictive capability for the 2-mile run than body composition. Men outperformed women on all individual events, with the greatest differences on standing power throw and sprint-drag-carry. It is recommended that Army ROTC cadets taking the ACFT maximize lower-body power production and increase muscle mass.

This study aimed to determine the test-retest reliability and efficacy of the Drift protocol. Thirteen male Division I Baseball pitchers (18–35 years.) completed four testing visits where a single leg hopping protocol on the stride and trail legs was completed with and without an arm swing. Jump contact time and flight time demonstrated “moderate to good” relative reliability (ICC= 0.633–0.847) and acceptable absolute reliability (CV= 3.6%–14.1%). The stride leg, compared to the trail leg, displayed greater relative and absolute reliability for contact time, flight time as well as jump power (ICC= 0.692–0.847; CV= 3.6%–14.1%). Arm swing trials demonstrated more acceptable relative and absolute reliability than trials without an arm swing for contact and flight time, jump height and jump power (ICC= 0.574–0.837; CV= 3.6%–9.3%). Significant main effects for arm swing were found for jump height, power, contact and flight time, and the average area covered (P< 0.001). Significant main effects were also found in asymmetry variables regarding arm swing for the variables jump height, power and flight time (P< 0.05). The current data suggest that, when assessing single leg vertical jumps in baseball pitchers with the Drift protocol, jump height, power, contact and flight time may be more reliable than average drift and total area covered.

This article examines the beneficial effects of creatine supplementation and a fifteen-week isometric exercise protocol on the fitness level of a man with myasthenia gravis, a neuromuscular disease. Findings indicate that the combination of physical training and creatine supplementation resulted in significant increases in muscle strength and fat free mass.

A one-group pre/posttest study was conducted to examine the feasibility and effect size of an 8-week physio-feedback and exercise program (PEER) on improving balance, muscle strength, and fall risk. Nineteen participants (mean age = 76 years) received the intervention, which included visual physio-feedback by the BTrackS™ Assess Balance System, cognitive reframing, and a combined group- and home-based exercise program by a trained peer coach. Pre- and post-measurement outcomes were evaluated for balance, handgrip strength, and fall risk. Feasibility was assessed by dropout rate, safety, and adherence to exercise. Significant improvements were noted in dynamic balance (Sit-to-Stand, Timed Up & Go tests), handgrip strength, and fall risk. Participants' attendance was 87.5%, with no fall incidence. The physio-feedback, cognitive reframing, and peer coaching facilitate older adults to align their perceived fall risk with physiological fall risk and motivate them to stay active. PEER intervention is feasible; safe; improves balance, muscle strength, and fall risk; and may enhance activity engagement.Targets:Community-dwelling older adults.Intervention Description:Provide visual physio-feedback and cognitive reframing based on the fall risk appraisal matrix and participate in combined group- and home-based exercises by a trained peer coach.Mechanism of Action:Align perceived and physiological fall risk, peer coaching to exercise.Outcomes:Balance, handgrip strength, fall risk, and activity engagement.[[Research in Gerontological Nursing, 13(6), 289–296.]

The current study aimed to categorize fall risk appraisal and quantify discrepancies between perceived fall risk measured subjectively using the short Fall Efficacy Scale-International and physiological fall risk measured objectively using the portable BTrackS™ Assess Balance System. One hundred two community-dwelling older adults were evaluated in this cross-sectional study. Approximately 40% of participants had maladaptive fall risk appraisals, which were either irrational (high perceived risk despite low physiological fall risk) or incongruent (low perceived risk but high physiological fall risk). The remaining 60% of participants had adaptive fall risk appraisals, which were either rational (low perceived risk aligned with low physiological fall risk) or congruent (high perceived risk aligned with high physiological fall risk). Among participants with rational, congruent, irrational, and incongruent appraisals, 21.7%, 66.7%, 28%, and 18.8%, respectively, reported having a history of falls (The current study aimed to categorize fall risk appraisal and quantify discrepancies between perceived fall risk measured subjectively using the short Fall Efficacy Scale-International and physiological fall risk measured objectively using the portable BTrackS™ Assess Balance System. One hundred two community-dwelling older adults were evaluated in this cross-sectional study. Approximately 40% of participants had maladaptive fall risk appraisals, which were either irrational (high perceived risk despite low physiological fall risk) or incongruent (low perceived risk but high physiological fall risk). The remaining 60% of participants had adaptive fall risk appraisals, which were either rational (low perceived risk aligned with low physiological fall risk) or congruent (high perceived risk aligned with high physiological fall risk). Among participants with rational, congruent, irrational, and incongruent appraisals, 21.7%, 66.7%, 28%, and 18.8%, respectively, reported having a history of falls (p< 0.01). Using technology to identify discrepancies in perceived and physiological fall risks can potentially increase the success of fall risk screening and guide fall interventions to target perceived or physiological components of balance. [Journal of Gerontological Nursing, 46(4), 41–47.]

AbstractObjective:The present study evaluated the effects of repeated-sprint training in normobaric hypoxia and β-alanine supplementation (BA) on aerobic and anaerobic performance in recreationally active men.Methods:Participants were randomly assigned to one of the following groups: normoxia/β-alanine (NB, n = 11), normoxia/placebo (NP, n = 8), normobaric hypoxia/β-alanine (HB, n = 10) and normobaric hypoxia/placebo (HP, n = 9). All participants completed 8 training sessions over 4 weeks on a cycle ergometer either in normobaric hypoxia (oxygen fraction: FiO2 = 14.2%) or normoxia (FiO2 = 20.9%). Participants were instructed to consume a daily dosage of 6.4 g of BA or placebo. Changes in performance in a graded exercise test, repeated-sprint test (RST), and 3-minute all-out test (3MT) were examined before and after training and supplementation.Results:No between-group differences were observed for training volume or supplementation compliance. Anthropometric and hematological measures remained unchanged before and after intervention in all groups. A main effect of training condition was shown for oxygen consumption and power output at respiratory compensation point, average power output during the last sprint of the RST, heart rate recovery following the RST, and total work during the 3MT. These measures in the normobaric hypoxia groups were significantly (p < 0.05) higher than the normoxia groups, except for the heart rate recovery following the RST. A main effect of supplement was detected in anaerobic working capacity, with postintervention values in the BA groups being significantly (p < 0.05) higher than the placebo groups.Conclusions:Repeated-sprint training in hypoxia improved aerobic performance, exercise tolerance, cardiovascular recovery, and overall working capacity, while BA maintained the anaerobic working capacity. However, BA did not provide additional benefits with respect to attenuating fatigue or enhancing repeated-sprint performance.

ABSTRACTObjective: β-alanine (BA) is a nonproteogenic amino acid that combines with histidine to form carnosine. The amount taken orally in individual doses, however, is limited due to symptoms of paresthesia that are associated with higher doses. The use of a sustained-release formulation has been reported to reduce the symptoms of paresthesia, suggesting that a greater daily dose may be possible. The purpose of the present study was to determine whether increasing the daily dose of BA can result in a similar increase in muscle carnosine in a reduced time.Methods: Eighteen men and twelve women were randomized into either a placebo (PLC), 6-g BA (6G), or 12-g BA (12G) groups. PLC and 6G were supplemented for 4 weeks, while 12G was supplemented for 2 weeks. A resting blood draw and muscle biopsy were obtained prior to (PRE) and following (POST) supplementation. Plasma and muscle metabolites were measured by high-performance liquid chromatography. The loss in peak torque (ΔPT) was calculated from maximal isometric contractions before and after 250 isokinetic kicks at 180°·sec−1PRE and POST.Results: Both 12G (p = 0.026) and 6G (p = 0.004) increased muscle carnosine compared to PLC. Plasma histidine was decreased from PRE to POST in 12G compared to PLC (p = 0.002) and 6G (p = 0.001), but no group x time interaction (p = 0.662) was observed for muscle histidine. No differences were observed for any hematological measure (e.g., complete blood counts) or in symptoms of paresthesia among the groups. Although no interaction was noted in ΔPT, a trend (p = 0.073) was observed.Conclusion: Results of this investigation indicate that a BA supplementation protocol of 12 g/d−1, using a sustained-release formulation, can accelerate the increase in carnosine content in skeletal muscle while attenuating paresthesia.

Objective: The objective of this study was to compare the chronic effects of different whey protein forms on body composition and performance when supplemented with resistance training.Methods: Resistance-trained men (N= 56, 21.4 ± 0.4 years, 79.5 ± 1.0 kg) participated in an 8-week resistance training regimen (2 upper-body sessions and 2 lower-body sessions per week) and received one of 4 double-blinded treatments: 30 g/serving carbohydrate placebo (PLA) or 30 g/serving protein from either (a) 80% whey protein concentrate (WPC), (b) high-lactoferrin-containing WPC (WPC-L), or (c) extensively hydrolyzed WPC (WPH). All subjects consumed 2 servings of treatment per day; specifically, once immediately before and after training and between meals on nontraining days. Blood collection, one repetition maximum (1RM) testing for bench press and hack squat, and body composition assessment using dual-energy x-ray absorptiometry (DXA) occurred prior to training and 48 hours following the last training session.Results: Total body skeletal muscle mass increased in all groups (p< 0.0125). There were similar between-group increases in upper-body (4%–7%, analysis of covariance [ANCOVA] interaction p= 0.73) and lower-body (24%–35%, ANCOVA interaction p= 0.85) 1RM strength following the intervention. Remarkably, WPH reduced fat mass (−6%), which was significantly different from PLA (+4.4%, p< 0.0125). No time or between-group differences were present for serum markers of health, metabolism, or muscle damage, with the exception of blood urea nitrogen being significantly lower for WPH than WPC (p< 0.05) following the intervention.Conclusions: WPH may augment fat loss but did not provide any other advantages when used in combination with resistance training. More mechanistic research is needed to examine how WPH affects adipose tissue physiology.

Objective:To examine the efficacy of l-alanyl-l-glutamine ingestion with a commercially available sports drink compared to the sports drink only on time to exhaustion and physiological measures during prolonged endurance exercise.Methods:Twelve endurance-trained men (23.5 ± 3.7 years; 175.5 ± 5.4 cm; 70.7 ± 7.6 kg) performed 4 trials, each consisting of a 1-hour treadmill run at 75% VO2peakfollowed by a run to exhaustion at 90% VO2peak. One trial consisted of no hydration (NHY), another required ingestion of only a sports drink (ED), and 2 trials required ingestion of a low dose (LD; 300 mg·500 ml−1) and high dose (HD) of l-alanyl-l-glutamine (1 g·500 ml−1) added to the sports drink. During the fluid ingestion trials, 250 ml was consumed every 15 minutes. Plasma glutamine, glucose, electrolytes, and osmolality were measured prior to the run (PRE) and at 30, 45, and 60 minutes. VO2, respiratory quotient (RQ), and heart rate (HR) were measured every 15 minutes.Results:Time to exhaustion was significantly longer during the LD and HD trials compared to NHY. No differences were noted in time to exhaustion between ED and NHY. Plasma glutamine concentrations were significantly elevated at 45 minutes in LD and HD trials and remained elevated at 60 minutes during HD. Sodium concentrations increased from the beginning of exercise and remained stable for the duration of the 1-hour run. At 60 minutes, plasma sodium was significantly lower in all trials compared to NHY.Conclusions:Results indicated that ingestion of the alanine-glutamine dipeptide at either the low or high dose significantly improved time to exhaustion during high-intensity exercise compared to a no-hydration trial.

Context:Professional basketball players have demanding schedules that, in combination with certain underlying physical characteristics and side-to-side strength and power imbalances, may make them vulnerable to lower extremity injuries.Objective:To examine the relationship among skeletal muscle architecture, lower body power, and games missed because of lower extremity injury (MISS) in professional basketball players.Design:Cross-sectional study.Setting:Human Performance Laboratory.Patients or Other Participants:Nine players under contract for Orlando Magic were assessed. We compared athletes who were injured (n 4, height 203.2 ± 5.5 cm, mass 105 ± 7.5 kg, age 25.0 ± 2.8 years) and those who remained healthy (n 5, height 200.2 ± 12.2 cm, mass 100.1 ± 16.6 kg, age 22.4 ± 1.9 years) during the season.Main Outcome Measure(s):Bilateral ultrasonographic measurements of muscle thickness, pennation angle, echo intensity, and cross-sectional area of the rectus femoris and vastus lateralis were collected before regular-season play. Subsequently, muscle thickness and pennation angle were used to compute fascicle length. Along with unilateral jumping power, inferences were made upon the magnitude of the relationship between the percentage bilateral difference in these measures and MISS, as well as between injured and healthy athletes.Results:The data indicated likely relationships between MISS and age (r 0.772), and between MISS and bilateral differences in rectus femoris cross-sectional area (7.8 ± 6.4; r 0.657) and vastus lateralis cross-sectional area (6.2 ± 4.8; r 0.521), as well as a possible relationship with vastus lateralis muscle thickness (7.9 ± 8.9; r 0.444). Echo-intensity differences in the vastus lateralis were greater in injured (8.0 ± 2.4) versus healthy athletes (3.2 ± 2.0). Although a 2-fold difference in mean jumping power was observed between injured (26.3 ± 14.9 W) and healthy athletes (13.6 ± 8.7 W), these differences were not statistically significant (P .20).Conclusions:In the present sample, lower extremity side-to-side differences may be related to an increased risk for lower extremity injury. Future researchers using larger sample sizes need to identify normal versus at-risk ranges for bilateral differences in muscle structure and power of the lower extremities of professional basketball players and athletes in other sports.

-Alanine is rapidly developing as one of the most popular sport supplements used by strengthpower athletes worldwide. The popularity of -alanine stems from its unique ability to enhance intramuscular buffering capacity and thereby attenuating fatigue. This review will provide an overview of the physiology that underlies the mechanisms of action behind -alanine, examine dosing schemes, and examine the studies that have been conducted on the efficacy of this supplement. In addition, the effect that -alanine has on body mass changes or whether it can stimulate changes in aerobic capacity also will be discussed. The review also will begin to explore the potential health benefits that -alanine may have on older adult populations. Discussion will examine the potential adverse effects associated with this supplement as well as the added benefits of combining -alanine with creatine.

The purpose of this study was to evaluate the use of critical velocity (CV) and isoperformance curves as an alternative to the Army Physical Fitness Test (APFT) two-mile running test. Seventy-eight men and women (mean +/- SE; age: 22.1 +/- 0.34 years; VO2(MAX): 46.1 +/- 0.82 mL/kg/min) volunteered to participate in this study. A VO2(MAX) test and four treadmill running bouts to exhaustion at varying intensities were completed. The relationship between total distance and time-to-exhaustion was tracked for each exhaustive run to determine CV and anaerobic running capacity. A VO2(MAX) prediction equation (Coefficient of determination: 0.805; Standard error of the estimate: 3.2377 mL/kg/min) was developed using these variables. Isoperformance curves were constructed for men and women to correspond with two-mile run times from APFT standards. Individual CV and anaerobic running capacity values were plotted and compared to isoperformance curves for APFT 2-mile run scores. Fifty-four individuals were determined to receive passing scores from this assessment. Physiological profiles identified from this procedure can be used to assess specific aerobic or anaerobic training needs. With the use of time-to-exhaustion as opposed to a time-trial format used in the two-mile run test, pacing strategies may be limited. The combination of variables from the CV test and isoperformance curves provides an alternative to standardized time-trial testing.

JUDO TRAINING IS AN INTERMITTENT METABOLICALLY DEMANDING ACTIVITY THAT HAS HISTORICALLY BEEN CONNECTED TO PHYSICAL EDUCATION AND DEVELOPMENT. THE HEALTH IMPACT OF PRACTICING THIS OLYMPIC SPORT AND MARTIAL ART HIGHLIGHTS THE BENEFITS OF COMBAT SPORTS FOR CHILDREN AND ADOLESCENTS. VARIOUS PHYSIOLOGICAL IMPROVEMENTS, INCLUDING THOSE IN THE AREAS OF BODY COMPOSITION, STRENGTH, AND ENDURANCE, AS WELL AS ENHANCED COGNITIVE PERFORMANCE AND LIFE SATISFACTION HAVE SHOWN TO RESULT FROM PARTICIPATION IN JUDO BY YOUNG PEOPLE.

PHOSPHATE LOADING HAS BEEN SHOWN TO INCREASE 2,3-DIPHOSPHOGLYCERATE (2,3-DPG). ELEVATED 2,3-DPG LEVELS LEAD TO A LOWERED AFFINITY FOR OXYGEN BY HEMOGLOBIN. WITH MORE OXYGEN AVAILABLE TO THE MUSCLE, INCREASES IN EXERCISE PERFORMANCE WOULD BE EXPECTED. THE PURPOSE OF THIS REVIEW IS TO DISCUSS PREVIOUS RESEARCH AND OFFER PRACTICAL APPLICATIONS.

Creatine is a nutraceutical that has gained popularity in both well-trained and casual athletes for its performance-enhancing or ergogenic properties. The major disadvantages of creatine monohydrate formulations are poor solubility and oral bioavailability. In the present study, creatine transport was examined using Caco-2 monolayers as an in vitro model for intestinal absorption. Confluent monolayers of Caco-2 cells (passage 25–35) were used for the permeability studies. Monolayers were placed in side-by-side diffusion chambers. ¹⁴C-Creatine (0.1–0.5 μCi/mL) was added to either the apical or basolateral side, and the transport of the creatine across the Caco-2 monolayer was measured over a 90-min period. The apical to basolateral transport of ¹⁴C-creatine was small, ranging from 0.2–3% of the original amount appearing on the receiver side in a 90-min period. Interestingly, the basolateral to apical permeability of radiolabeled creatine was substantially greater than that observed in the apical to basolateral direction. Studies with drug efflux transport inhibitors indicate that neither the P-glycoprotein nor multidrug resistance-associated protein is involved in the enhanced basolateral to apical transport of creatine. © 2001 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 90:1593–1598, 2001

Creatine is a nutraceutical that has gained popularity in both well‐trained and casual athletes for its performance‐enhancing or ergogenic properties. The major disadvantages of creatine monohydrate formulations are poor solubility and oral bioavailability. In the present study, creatine transport was examined using Caco‐2 monolayers as an in vitromodel for intestinal absorption. Confluent monolayers of Caco‐2 cells (passage 25–35) were used for the permeability studies. Monolayers were placed in side‐by‐side diffusion chambers. 14C‐Creatine (0.1–0.5 μCi/mL) was added to either the apical or basolateral side, and the transport of the creatine across the Caco‐2 monolayer was measured over a 90‐min period. The apical to basolateral transport of 14C‐creatine was small, ranging from 0.2–3% of the original amount appearing on the receiver side in a 90‐min period. Interestingly, the basolateral to apical permeability of radiolabeled creatine was substantially greater than that observed in the apical to basolateral direction. Studies with drug efflux transport inhibitors indicate that neither the P‐glycoprotein nor multidrug resistance‐associated protein is involved in the enhanced basolateral to apical transport of creatine. © 2001 Wiley‐Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 90:1593–1598, 2001

The purpose of this investigation was to compare the thresholds of neuromuscular fatigue determined simultaneously from the vastus lateralis (VL), vastus medialis (VM) and rectus femoris (RF) muscles using the electromyographic fatigue threshold (EMGFT) test, Eight adult volunteers [mean (SD) age, 33 (10) years] served as subjects for this investigation. The results of a one-way repeated measured ANOVA indicated that there was a significant (P < 0.05) difference among the mean EMGFT values for the VL [248(31)W], VM [223(43)W] and RF [220(30)W] muscles. Tukey post-hoc comparisons indicated that the EMGFT for the RF was significantly (P < 0.05) lower than that of the VL. These findings suggested that during cycle ergometry there is a dissociation in neuromuscular fatigue characteristics of the superficial muscles of the quadriceps femoris group.

The present study examined the validity of bioelectrical impedance (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 (X 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. (5)(X FFW± SD = 43.8 ± 4.5 kg) and the age-specific constants of Lohman(28)(X 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. (5). Based upon the results of the cross-validation analyses, the equation of Houtkooper et al. (22)and the interlaboratory equations of Van Loan et al. (50)and Lohman(29), which resulted in identical TE values of 2.4 kg are recommended for use with young high school gymnasts.

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 ([horizontal bar over]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. (26)for males ≤ 20% fat (N= 107) which resulted in a TE value of 3.6% fat and the generalized equation of Guo et al. (10)(TE = 4.1% fat) may, however, be considered as acceptable alternatives.

HOUSH, D. J., T. J. HOUSH, J. P. WEIR, L. L. WEIR, G. O. JOHNSON, and J. R. STOUT. Anthropometric estimation of (high muscle cross-sectional area. Med. Sci. Sports Exerc., Vol. 27, No. 5, pp. 784–791, 1995. 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 (X 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 purpose of this study was to examine the covariate influence of fat-free weight (FFW) on agerelated increases in isokinetic peak torque for leg flexion and extension in high school female gymnasts. Seventy-two gymnasts([horizontal bar over]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°·s-1as 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 = 0.62-0.73) 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°·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 athlets.

The present investigation examined the validity of 16 skinfold equations for predicting body density (BD) in youth wrestlers ( age ± SD = 11.0 ± 1.3 yr) by comparing the values to those obtained from underwater weighing. Forty-eight members of youth wrestling clubs ( 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 ≥0.0 106 g·cm−1(range = 0.0106–0.0229 g·cm−1) which corresponded to ≥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.

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 ([horizontal bar over]X age ± SD= 15.7 ± 1.2 yr) by comparing the values with those obtained from underwater weighing. Seventy-three gymnasts ([horizontal bar over]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 ≤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 ≤3.9%fat should be considered acceptable alternatives.

STOUT, J. R., J. M. ECKERSON, T. J. HOUSH, G. O. JOHNSON, and N. M. BETTS. Validity of percent body fat estimations in males. Med. Sci. Sports Exerc., Vol. 26, No. 5, pp. 632–636,1994. 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 ( age ± SD = 22 ± 3 yr) by comparing the estimates with values obtained from underwater weighing. Fifty-seven Caucasian male ( 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.

Smith, Douglas B., Terry J. Housh, Jeffrey R. Stout, Glen O. Johnson, Tammy K. Evetovich, and Kyle T. Ebersole.Mechanomyographic responses to maximal eccentric isokinetic muscle actions. J. Appl. Physiol.82(3): 1003–1007, 1997.—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°/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 fromR= 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°/s (302 ± 128 mV). These findings indicated a velocity-related dissociation between MMG and peak torque for maximal eccentric isokinetic muscle actions.

The purpose of this study was twofold: (1) to determine the effect of increasing the duration of the workbout at each power output during the physical working capacity at fatigue threshold (PWCFT) test from 2 to 3 or 4 min, and (2) to examine the time to exhaustion during continuous workbouts at the PWCFT. Twelve adult males (χ¯± SD = 22.4 ± 3.0 years) volunteered to perform three PWCFT tests using workbout durations of 2, 3, and 4 min. Following the determination of the PWCFT values, nine of the subjects performed continuous workbouts at PWCFT2 and PWCFT4 for as long as possible. The mean PWCFT value using 4-min workbouts (PWCFT4 = 168.8 ± 45.1 W) was significantly less (p<0.05, 19 1%) than that using 2-min workbouts (PWCFT2 = 208.9 ± 59.0W). However, only two subjects were able to complete 60 min at PWCFT4 and none of the subjects were able to complete 60min at PWCFT2. Therefore, although increasing the duration of the workbout at each power output resulted in a lower PWCFT4, these findings do not support a recommendation for a change in the PWCFT test protocol.

The purpose of this investigation was to examine the effects of velocity of contraction on the mechanomyographic (MMG) responses to maximal concentric isokinetic leg extension movements. Eight adult males [mean (SD) age, 22.3 (1.3) years] performed maximal leg extensions on a calibrated Cybex 6000 dynamometer at velocities of 60, 120, 180, 240, 300, and 360°?·?s -1. MMG responses were detected by a piezoelectric recording device placed over the vastus lateralis muscle. Intraclass reliability correlations ranged from R?=?0.84 to 0.97 and from 0.90 to 0.99 for peak torque and MMG amplitude values, respectively, with no significant differences ( P?>?0.05) between the mean values for test versus retest at any contraction velocity. There were significant differences ( P?-1 [115 (37) Nm]. The mean MMG amplitude at 60°?·?s -1 [61 (67) mV] was significantly less ( P?-1 [452 (451) mV]. These results indicate a velocity-related dissociation between MMG amplitude and peak torque. Furthermore, it was hypothesized that the increases in MMG amplitude were due to velocity-related decreases in muscle stiffness which allowed for greater muscle fiber oscillations.

Beta-alanine supplementation (3.2-6.4 g/d) may elevate skeletal muscle carnosine levels and enhance exercise performance in untrained subjects. Future studies need to examine whether beta-ala-nine supplementation can increase skeletal muscle carnosine levels and exercise performance in trained athletes, as well as to determine the combined effect of beta-alanine supplementation and training on performance.