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Purpose: This study compared the relative peak torque and normalized electromyographic (EMG) mean frequency (MNF) responses during fatiguing isokinetic muscle actions for men versus women. Method: Twenty men M[subscript age] ± SD = 22 ± 2 years) and 20 women M[subscript age] ± SD = 22 ± 1 years) performed 50 maximal concentric isokinetic muscle actions of the leg extensors at a velocity of 180°/s while surface EMG signals were detected from the vastus lateralis, rectus femoris, and vastus medialis. The dependent variables were initial, final, and average peak torque; percent decline; the estimated percentage of fast-twitch fibers for the vastus lateralis; and the linear slope coefficients and y-intercepts for normalized EMG MNF versus repetition number. The data were analyzed with independent-samples "t" tests and 2-way mixed-factorial analyses of variance. Results: The mean initial, final, and average peak torque values for men were greater than those for women. There were no mean differences for percent decline and the estimated percentage of fast-twitch fibers for the vastus lateralis. There were also no sex differences for the linear slope coefficients, but there were differences among the muscles (vastus medialis>vastus lateralis>rectus femoris). The mean y-intercept for the vastus lateralis for men was greater than that for women. Conclusions: Men demonstrated greater peak torque values than those for women, but the declines in peak torque and normalized EMG MNF were similar between the sexes. The vastus medialis was more fatigue-resistant than both the vastus lateralis and rectus femoris.

DeFreitas, JM, Beck, TW, Stock, MS, Dillon, MA, Sherk, VD, Stout, JR, and Cramer, JT. A comparison of techniques for estimating training-induced changes in muscle cross-sectional area. J Strength Cond Res 24(9): 2383-2389, 2010--The ability to accurately estimate changes in muscle cross-sectional area (CSA) could be a useful tool for strength and conditioning practitioners to assess the effectiveness of a resistance training program. The purpose of this study was twofold: (a) to compare the reliability of 2 separate anthropometric-based field estimations of thigh muscle CSA with that of a more accurate, sophisticated imaging technique (peripheral quantitative computed tomography [pQCT] scanner) and (b) to determine if the field methods would be sensitive enough to detect changes in CSA during a resistance training program. Twenty-five healthy, untrained men completed 8 weeks of resistance training. Cross-sectional area testing occurred twice before the start of training, for reliability and again every 2 weeks during the study. Testing consisted of a pQCT scan of the right thigh followed by circumference and skinfold measurements. Two separate equations (Moritani and deVries [M + D] and Housh multiple regression [HMR]) were used to estimate CSA from the anthropometric data. The M + D and HMR methods demonstrated intraclass correlations of 0.983 and 0.961, respectively, but both significantly underestimated thigh muscle CSA when compared to the pQCT. This error was consistent, however, and consequently, the field methods were able to demonstrate increases in muscle CSA with a pattern similar to those from the pQCT. Thus, these equations can be useful tools to evaluate an athlete's progress toward the goal of increasing muscle CSA. It is the authors' hope that the present study will increase awareness among practitioners of these useful field methods for estimating training-induced changes in muscle CSA. KEY WORDS anthropometry; pQCT, hypertrophy

The present study examined the effects of adding leucine to pre and postexercise carbohydrate beverages on selected markers of muscle damage, delayed-onset muscle soreness (DOMS), and squat performance for up to 72 hours after lower-body resistance training. Seventeen resistance trained men (mean [+ or -] SD age 22.9 [+ or -] 2.9 years) and 3 resistance trained women (mean [+ or -] SD age 21.6 [+ or -] 2.6 years) performed 6 sets of squats to fatigue using 75[degrees]/o of the 1 repetition maximum. Each subject consumed a carbohydrate beverage 30 minutes before and immediately after exercise with or without the addition of 22.5 mg x [kg.sup.-1] (45 mg x [kg.sup.-1] total) of leucine in a randomized, double-blind fashion. Serum creatine kinase (CK), lactate dehydrogenase (LDH), and DOMS were analyzed immediately before (TIME1), 24 (TIME2), 48 (TIME3), and 72 (TIME4) hours after exercise. The subjects repeated the squat protocol at TIME4 to test recovery. No differences were observed between groups for squat performance, defined as the total number of repetitions performed during 6 sets of squats, for both TIME1 and TIME4. The addition of leucine did not significantly decrease CK and LDH activity or DOMS. These results suggested that adding leucine to carbohydrate beverages did not affect acute muscle recovery and squat performance during both initial testing and during a subsequent exercise bout 72 hours later in resistance trained subjects. KEY WORDS amino acids, eccentric, delayed-onset muscle soreness

Creatine (Cr) loading consists of short-term, high-dosage Cr supplementation and has been shown to increase intramuscular total Or content. Increases in body weight (BW) have been shown to result from Cr loading, with differences by gender, and increased BW may impact weight-bearing exercise. The critical velocity (CV) test is used to quantify the relationship between total running distance and time to exhaustion. The CV test provides the variable, anaerobic running capacity (ARC), which is an estimate of the anaerobic energy reserves in muscle. The purpose of this study was to examine the effects of gender and Cr loading on ARC. Fifty moderately trained men and women volunteered to participate in this randomized, double-blinded, placebo (PL)controlled, repeated-measures study. After a familiarization session, a 3-day testing procedure was conducted. A maximal oxygen consumption test ([[??]o.sub.2]max) on a treadmill was performed on day 1 to establish the maximum velocity (Vmax) at [[??]o.sub.2]max and to record BW. Days 2 and 3 involved treadmill running at varying percentages of Vmax. Participants were randomly assigned to either the Cr or PL group and received 20 packets of the Cr supplement (1 packet = 5 g Cr citrate, 18 g dextrose) or 20 packets of the PL (1 packet = 18 g dextrose). After consuming 4 packets daily for 5 consecutive days, the 3-day testing procedure was repeated. The male Cr loading group exhibited a 23O/o higher (p = 0.003) ARC compared to the PL group. Nonsignificant BW increases were found for the Cr groups. These findings suggest that Cr loading may be an effective strategy for improving ARC in men, but not in women, and revealed only nonsignificant increases in BW. Creatine loading may be used before competition by athletes to provide improvements in high-intensity, short-duration activities. KEY WORDS ergogenic aids, treadmill running, sprint performance, body weight, high-intensity activity, critical velocity

The purpose of the present study was to examine the linearity and reliability of the mechanomyographic (MMG) amplitude versus concentric dynamic constant external resistance (DCER) relationships for the bench press exercise. Twenty-one resistance-trained men (mean [+ or -] SD age = 23.5 [+ or -] 2.7 yr; 1 repetition maximum [1RM] bench press = 125.4 [+ or -] 18.4 kg) volunteered to perform submaximal bench press muscle actions as explosively as possible from 10% to 90% of the 1 RM on 2 separate occasions. During each muscle action, surface MMG signals were detected from both the right and left pectoralis major and triceps brachii, and the concentric portion of the range of motion was selected for analysis. The coefficients of determination for the MMG amplitude versus concentric DCER relationships ranged from [r.sup.2] = 0.010 to 0.980 for the right pectoralis major, [r.sup.2] = 0.010 to 0.943 for the left pectoralis major, [r.sup.2] = 0.010 to 0.920 for the right triceps brachii, and [r.sup.2] = 0.020 to 0.915 for the left triceps brachii, thus indicating a wide range of linearity between subjects. The intraclass correlation coefficients (ICC) and corresponding standard error of measurements (SEM) for the linear slope coefficients for these relationships were 0.592 (39.3% of the mean value), 0.537 (41.9% of the mean value), 0.625 (42.0% of the mean value), and 0.460 (60.2% of the mean value) for the right pectoralis major, the left pectoralis major, the right triceps brachii, and the left triceps brachii, respectively. These data demonstrated that these relationships were neither linear nor reliable enough to be used for assessing issues such as the neural versus hypertrophic contributions to training-induced strength gains and the mechanisms underlying cross-education. KEY WORDS efficiency of electrical activity, mechanomyogram, intraclass correlation coefficient

J Strength Cond Res 24(1): 109-113, 2010--The submaximal electromyographic fatigue threshold test ([EMG.sub.FT]) has been shown to be highly correlated to ventilatory threshold (VT) as determined from maximal graded exercise tests (GXTs). Recently, a prediction equation was developed using the [EMG.sub.FT] value to predict VT. The aim of this study, therefore, was to determine if this new equation could accurately track changes in VT after high-intensity interval training (HILT). Eighteen recreationally trained men (mean [+ or -] SD; age 22.4 [+ or -] 3.2 years) performed a GXT to determine maximal oxygen consumption rate ([Vo.sub.2]peak) and VT using breath-by-breath spirometry. Participants also completed a discontinuous incremental cycle ergometer test to determine their [EMG.sub.FT] value. A total of four 2-minute work bouts were completed to obtain 15-second averages of the electromyographic amplitude. The resulting slopes from each successive work bout were used to calculate [EMG.sub.FT]. The [EMG.sub.FT] value from each participant was used to estimate VT from the recently developed equation. All participants trained 3 days a week for 6 weeks. Training consisted of 5 sets of 2-minute work bouts with 1 minute of rest in between. Repeated-measures analysis of variance indicated no significant difference between actual and predicted VT values after 3 weeks of training. However, there was a significant difference between the actual and predicted VT values after 6 weeks of training. These findings suggest that the EMGFT may be useful when tracking changes in VT after 3 weeks of HIIT in recreationally trained individuals. However, the use of [EMG.sub.FT] to predict VT does not seem to be valid for tracking changes after 6 weeks of HILT. At this time, it is not recommended that [EMG.sub.FT] be used to predict and track changes in VT. KEY WORDS cardiorespiratory fitness, muscle fatigue, interval training, cycling