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The purpose of this study was to validate the Physical Working Capacity at the Heart Rate Threshold ([PWC.sub.HRT]) and Physical Working Capacity at the Oxygen Consumption Threshold (PWC [Vo.sub.2]) tests by 1) using individual power vs. duration relationships to estimate the times to exhaustion (ETTE) at the [PWC.sub.HRT] and PWC [Vo.sub.2], and 2) comparing the power outputs and ETTE values of the [PWC.sub.HRT] and PWC [Vo.sub.2] with those of the ventilatory threshold (VT). Ten adults (mean age [+ or -] SD = 23 [+ or -] 1 years) performed an incremental test to exhaustion on a cycle ergometer for the determination of [Vo.sub.2]peak and VT. The subjects also performed four randomly ordered workbouts to exhaustion at different power outputs (ranging from 98 to 246 W) to determine the PWC [Vo.sub.2], [PWC.sub.HRT], and power vs. duration relationship. Power curve analyses (y = [ax.sup.b]) were used to define the hyperbolic power vs. duration relationship for each subject and to determine the ETTE at the PWC [Vo.sub.2], [PWC.sub.HRT], and VT. Two separate one-way repeated-measures analyses of variance indicated that there were significant differences among the fatigue thresholds (PWC [Vo.sub.2] > [PWC.sub.HRT]) and ETTE values ([PWC.sub.HRT] > PWC [Vo.sub.2]): PWC [Vo.sub.2] (mean [+ or -] SD = 147 [+ or -] 43 W; ETTE = 21 [+ or -] 3 minutes), [PWC.sub.HRT] (136 [+ or -] 37 W; ETTE = 29 [+ or -] 6 minutes), and VT (143 [+ or -] 44 W; ETTE = 27 [+ or -] 11 minutes). These findings were consistent with previous studies that indicated that the [PWC.sub.HRT] occurred at a lower power output than the PWC [Vo.sub.2]. Furthermore, the [PWC.sub.HRT] was maintained for a mean of 29 minutes, whereas the PWC [Vo.sub.2] and VT were maintained for 21 and 27 minutes, respectively. These findings indicate that the ETTE values for the PWC [Vo.sub.2] and [PWC.sub.HRT] were substantially less than those suggested in previous studies. KEY WORDS fatigue threshold, PWC [Vo.sub.2], [PWC.sub.HRT], VT

The purposes of this study were to 1) compare the patterns of responses for plasma ammonia concentration ([N[H.sub.3]]) during moderate- vs. heavy-intensity cycle ergometry, and 2) examine the relationship between the [Vo.sub.2] slow component ([Vo.sub.2SC]) and plasma [N[H.sub.3]]. Thirteen healthy, untrained men (mean [+ or -] SEM age = 24.8 [+ or -] 0.6 years) performed a total of eight constant power output exercises (7 minutes in duration) at two different intensities (moderate, 60% gas exchange threshold [GET] = 60% of the gas exchange threshold; and heavy, [DELTA]50% = 50% of the difference between GET and [Vo.sub.2]max). Blood was collected from an antecubital vein before the exercise, during the last 3 minutes of the 6-minute warm-up, and during each minute of the 7-minute constant power output workbout. The time course of changes in plasma [N[H.sub.3]] and [Vo.sub.2] during the two constant power output exercise intensities were assessed separately using 2 (intensity) x 7 (time) repeated-measures analyses of variance. For 60% GET, there were no significant differences in the mean normalized plasma [N[H.sub.3]] during the 7-minute workbout. For [DELTA]50%, there was a significant increase in the mean normalized plasma [N[H.sub.3]] during the 7-minute workbout. These findings suggest a potential relationship between exercise-induced hyperammonemia and the [Vo.sub.2SC] during heavy-intensity exercise. KEY WORDS ammonia concentration, AMP deaminase, bioenergetics, muscle energetics, oxygen uptake kinetics

The purpose of the present study was to examine the acute effects of a caffeine-containing supplement (SUPP) on one-repetition maximum (1-RM) bench press strength and time to running exhaustion (TRE) at a velocity that corresponded to 85% of the peak oxygen uptake (V[O.sub.2]peak). The study used a double-blinded, placebo-controlled, crossover design. Thirty-one men (mean [+ or -] SD age = 23.0 [+ or -] 2.6 years) were randomly assigned to take either the SUPP or placebo (PLAC) first. The SUPP contained 201 mg of caffeine, and the PLAC was microcrystalline cellulose. All subjects were tested for 1-RM bench press strength and TRE at 45 minutes after taking either the SUPP or PLAC. After 1 week of rest, the subjects returned to the laboratory and ingested the opposite substance (SUPP or PLAC) from what was taken during the previous visit. The 1-RM bench press and TRE tests were then performed in the same manner as before. The results indicated that the SUPP had no effect on 1-RM bench press strength or TRE at 85% V[O.sub.2]peak. It is possible that the acute effects of caffeine are affected by differences in training status and/or the relative intensity of the exercise task. Future studies should examine these issues, in addition to testing the acute effects of various caffeine doses on performance during maximal strength, power, and aerobic activities. These findings do not, however, support the use of caffeine as an ergogenic aid in untrained to moderately trained individuals.

The purpose of the present study was to use ratings of perceived exertion (RPE) from the Borg (6-20) and OMNI-Leg (0-10) scales to determine the Physical Working Capacity at the Borg and OMNI thresholds ([PWC.sub.BORG] and [PWC.sub.OMNI]). [PWC.sub.BORG] and [PW.subC.oMNI] were compared with other fatigue thresholds determined from the measurement of heart rate (the Physical Working Capacity at the Heart Rate Threshold: [PWC.sub.HRT]), and oxygen consumption (the Physical Working Capacity at the Oxygen Consumption Threshold, [MATHEMATICAL NOT REPRODUCIBLE IN ASCII.]), as well as the ventilatory threshold (VT). Fifteen men and women volunteers (mean age [+ or -] SD = 22 [+ or -] 1 years) performed an incremental test to exhaustion on an electronically braked ergometer for the determination of V[O.sub.2 peak] and VT. The subjects also performed 4 randomly ordered workbouts to exhaustion at different power outputs (ranging from 60 to 206W) for the determination of [PWC.sub.BORG], [PWC.sub.OMNI], [PWC.sub.HRT], and [MATHEMATICAL EXPRESSION NOR REPRODUCIBLE IN ASCII.] The results indicated that there were no significant mean differences among the fatigue thresholds: [PWC.sub.BORG] (mean [+ or -] SD = 133 [+ or -] 37W; 67 [+ or -] 8% of V[O.sub.2 peak]), [PWC.sub.OMNI] (137 [+ or -] 44W; 68 [+ or -] 9% of V[O.sub.2] peak), [PW.sub.CHRT] (135 [+ or -] 36W; 68 [+ or -] 8% of V[O.sub.2 peak]), [MATHEMATICAL EXPRESSION NOR REPRODUCIBLE IN ASCCI.],(145 [+ or -] 41W; 72 [+ or -] 7% of V[O.sub.2 peak]) and VT (131 [+ or -] 45W; 66 [+ or -] 8% of V[O.sub.2 peak]). The results of this study indicated that the mathematical model used to estimate [PW.sub.CHRT] and [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII.], can be applied to ratings of perceived exertion to determine [PWC.sub.BORG] and [PWC.sub.OMNI] during cycle ergometry. Salient features of the [PWC.sub.BORG] and [PWC.sub.OMNI] tests are that they are simple to administer and require the use of only an RPE scale, a stopwatch, and a cycle ergometer. Furthermore, the power outputs at the [PWC.sub.BORG] and [PWC.sub.OMNI] may be useful to estimate the VT noninvasively and without the need for expired gas analysis. KEY WORDS fatigue threshold, Borg scale, OMNI-leg scale

The purpose of this study was to examine the effects of a drink containing creatine, amino acids, and protein vs. a carbohydrate placebo on body composition, strength, muscular endurance, and anaerobic performance before and after 10 weeks of resistance training. Fifty-one men (mean [+ or -] SD; age: 21.8 [+ or -] 2.9 years) were randomly assigned to either the test drink (TEST; n = 23) or the placebo (PLAC; n = 28) and performed two 30-second Wingate Anaerobic Tests for determination of peak power (PP) and mean power (MP), were weighed underwater for percent body fat (%fat) and fat-free mass (FFM), and were tested for 1 repetition maximum (1RM) dynamic constant external resistance strength and muscular endurance (END; number of repetitions performed with 80% of 1RM) on the bilateral leg extension (LE) and free-weight bench press (BP) exercises. The testing was conducted before (PRE) and after (POST) 10 weeks of resistance training (3 sets of 10 repetitions with 80% of the subject's 1RM performed 3 times per week) on the LE and BP exercises. Body weight, FFM, LE 1RM, LE END, BP 1RM, and BP END increased (p < 0.05), whereas %fat decreased (p < 0.05) from PRE to POST for both the TEST and PLAC groups. Peak power and MP, however, increased for the TEST group, but not for the PLAC group. These results suggested that the creatine-, amino acid-, and protein-containing drink provided no additional benefits when compared with carbohydrates alone for eliciting changes in body composition, strength, and muscular endurance after a 10-week resistance training period. The TEST drink was, however, more effective than carbohydrates alone for improving anaerobic power production. KEY WORDS. anaerobic power, nutritional supplement, bench press, leg extension

The purpose of this investigation was to determine the validity of the non-exercise-based equations of Davis et al. (13), Jones et al. (20), and Neder et al. (30) for estimating the ventilatory threshold (VT) in samples of aerobically trained men and women. One hundred and forty-four aerobically trained men (mean [+ or -] SD age, 41.0 [+ or -] 11.6 years; N = 83) and women (37.1 [+ or -] 9.0 years, N = 61) performed a maximal incremental test to determine [VO.sub.2]max and observed VT on a cycle ergometer. The observed VT was determined by gas exchange measurements using the V-slope method ([VO.sub.2]/[VO.sub.2]) in conjunction with analyses of the ventilatory equivalents (i.e., minute ventilation [V.sub.E]/[VO.sub.2] and [V.sub.E]/[VO.sub.2]) and end-tidal gas tensions (i.e., ([P.sub.ET][O.sub.2] and [P.sub.ET]C[O.sub.2]) for oxygen and carbon dioxide. The predicted VT values from 14 equations were compared to the observed VT values by examining the constant error (CE), standard error of estimate (SEE), Pearson correlation coefficient (r), and total error (TE). The results of this investigation indicated that all 14 equations resulted in significant (p < 0.008) CE values ranging from 1.13 to 1.72 L*[min.sup.-1] for the men and from 0.58 to 1.12 L*[min.sup.-1] for the women. Furthermore, the SEE, r, and TE values ranged from 0.37 to 0.54, from 0.36 to 0.53, and from 0.68 to 1.81 L*[min.sup.-1], respectively. The lowest TE values for the men and women represented 45 and 36% of the mean of the observed VT values, respectively. The results of this study indicated that the errors associated with all 14 equations were too large to be of practical value for estimating VT in aerobically trained men and women. KEY WORDS. endurance-trained, regression analysis, statistics, V-slope method

The purpose of this investigation was to examine the effects of 3 days of velocity-specific isokinetic training on peak torque (PT) and the electromyographic (EMG) signal. Thirty adult women were randomly assigned to a slow-velocity training (SVT), fast-velocity training (FVT), or control (CON) group. All subjects performed maximal, concentric, isokinetic leg extension muscle actions at 30 and 270[degrees] x [s.sup.-1] for the determination of PT on visits 1 (pretest) and 5 (posttest). Electromyographic signals were recorded from the vastus lateralis, rectus femoris, and vastus medialis muscles during each test. The training groups performed 4 sets of 10 maximal repetitions at 30[degrees] x [s.sup.-1] (SVT group) or 270[degrees] x [s.sup.-1] (FVT group) on visits 2, 3, and 4. For the SVT group, PT increased from pretest to posttest at 30 and 270[degrees] x [s.sup.-1]. The increase in PT at 30[degrees] x [s.sup.-1] was greater than at 270[degrees] x [s.sup.-1]. For the FVT group, PT increased at 270[degrees] x [s.sup.-1] only. For the CON group, there were no changes in PT at either velocity. There were no pretest to posttest changes in EMG amplitude or mean power frequency (MPF) for any group at any velocity, with the exception of an increase in EMG MPF from the vastus medialis muscle at 270[degrees] x [s.sup.-1] for the FVT group. The results indicated that 3 sessions of slow velocity (30[degrees] x [s.sup.-1]) isokinetic training resulted in an increase in PT at slow and fast velocities (30 and 270[degrees] x [s.sup.-1]), whereas training at the fast velocity (270[degrees] x [s.sup.-1]) increased PT only at 270[degrees] x [s.sup.-1]. The lack of consistent increases in EMG amplitude or MPF suggested that the training-induced increases in leg extension PT were not caused by increased activation of the superficial muscles of the quadriceps femoris. The important implication for coaches, trainers, and physical therapists is that significant muscular performance gains may be achieved even after very short training periods, but determination of the specific physiological adaptation(s) underlying these performance gains requires further investigation. KEY WORDS. strength, resistance training, electromyography, coactivation

The purpose of this study was to examine the effects of daily administration of a supplement that contained caffeine in conjunction with 8 weeks of aerobic training on [Vo.sub.2]peak, time to running exhaustion at 90% [Vo.sub.2]peak, body weight, and body composition. Thirty-six college students (14 men and 22 women; mean [+ or -] SD, age 22.4 [+ or -] 2.9 years) volunteered for this investigation and were randomized into either a placebo (n = 18) or supplement group (n = 18). The subjects ingested 1 dose (3 pills = 201 mg of caffeine) of the placebo or supplement per day during the study period. In addition, the subjects performed treadmill running for 45 minutes at 75% of the heart rate at [Vo.sub.2]peak, three times per week for 8 weeks. All subjects were tested pretraining and posttraining for [Vo.sub.2]peak, time to running exhaustion (TRE) at 90% [Vo.sub.2]peak, body weight (BW), percentage body fat (%FAT), fat weight (FW), and fat-free weight (FFW). The results indicated that there were equivalent training-induced increases (p < 0.05) in [Vo.sub.2]peak and TRE for the supplement and placebo groups, but no changes (p > 0.05) in BW, %FAT, FW, or FFW for either group. These findings indicated that chronic use of the caffeine-containing supplement in the present study, in conjunction with aerobic training, provided no ergogenic effects as measured by [Vo.sub.2]peak and TRE, and the supplement was of no benefit for altering body weight or body composition. KEY WORDS. aerobic power, maximal oxygen uptake, nutrition, supplements, treadmill exercise

The purpose of this study was to examine the acute effects of a caffeine-containing supplement on upper- and lower-body strength and muscular endurance as well as anaerobic capabilities. Thirty-seven resistance-trained men (mean [+ or -] SD, age: 21 [+ or -] 2 years) volunteered to participate in this study. On the first laboratory visit, the subjects performed 2 Wingate Anaerobic Tests (WAnTs) to determine peak power (PP) and mean power (MP), as well as tests for I repetition maximum (1RM), dynamic constant external resistance strength, and muscular endurance (TOTV; total volume of weight lifted during an endurance test with 80% of the 1RM) on the bilateral leg extension (LE) and free-weight bench press (BP) exercises. Following a minimum of 48 hours of rest, the subjects returned to the laboratory for the second testing session and were randomly assigned to I of 2 groups: a supplement group (SUPP; n = 17), which ingested a caffeine-containing supplement, or a placebo group (PLAC; n = 20), which ingested a cellulose placebo. One hour after ingesting either the caffeine-containing supplement or the placebo, the subjects performed 2 WAnTs and were tested for 1RM strength and muscular endurance on the LE and BP exercises. The results indicated that there was a significant (p < 0.05) increase in BP 1RM for the SUPP group, but not for the PLAC group. The caffeine-containing supplement had no effect, however, on LE 1RM, LE TOTV, BP TOTV, PP, and MP. Thus, the caffeine-containing supplement may be an effective supplement for increasing upper-body strength and, therefore, could be useful for competitive and recreational athletes who perform resistance training. Key Words. ergogenic aid, performance, sports nutrition

The purpose of this study was to determine the effects of resistance training in combination with a leucine and whey protein supplement or a carbohydrate placebo on strength and muscle cross-sectional area (CSA). Thirty-three men (mean age [+ or -] SD = 22.4 [+ or -] 2.4 years) were assigned to 1 of 3 groups: (1) supplementation group (SUPP), (2) placebo group (PL), or (3) control group (CON). The SUPP and PL performed unilateral training of the leg extensor muscles with the nondominant limb for 8 weeks. The strength of each limb, muscle CSA of the quadriceps femoris (QF), and body composition were assessed pre-training and posttraining. The results indicated significant increases in strength for both limbs in the SUPP but only the trained limb in the PL. The increase in strength for the trained limb of the SUPP was greater than that for the trained limb of the PL. There was no significant increase in strength for either limb in the CON. There were significant increases in the CSA of all muscles of the QF of the trained limb for the SUPP and PL, and of the vastus lateralis of the untrained limb for the SUPP. The increases in QF CSA did not differ between the SUPP and PL. No significant CSA changes were found for either limb in the CON. There were no significant changes in body composition for the SUPP, PL, or CON. The current findings suggest that leucine and whey protein supplementation may provide an ergogenic effect which enhances the acquisition of strength beyond that achieved with resistance training and a carbohydrate placebo. KEY WORDS. amino acids, muscular strength, quadriceps femoris, strength training, cross-training, cross-education

Beck, T.W., T.J. Housh, G.O. Johnson, J.P. Weir, J.T. Cramer, J.W. Coburn, and M.H. Malek. Mechanomyographic and electromyographic responses during submaximal to maximal eccentric isokinetic muscle actions of the biceps brachii. J. Strength Cond. Res. 20(1):184-191. 2006.--The purpose of this investigation was to determine the mechanomyography (MMG) and electromyography (EMG) amplitude and mean power frequency (MPF) vs. eccentric isokinetic torque relationships for the biceps brachii muscle. Nine adults (mean [+ or -] SD age = 23.1 [+ or -] 2.9 years) performed submaximal to maximal eccentric isokinetic muscle actions of the dominant forearm flexors. After determination of isokinetic peak torque (PT), the subjects randomly performed submaximal step muscle actions in 10% increments from 10 to 90% PT. Polynomial regression analyses indicated that the MMG amplitude vs. eccentric isokinetic torque relationship was best fit with a quadratic model ([R.sup.2] = 0.951), where MMG amplitude increased from 10 to 60% PT and then plateaued from 60 to 100% PT. There were linear increases in MMG MPF ([r.sup.2] = 0.751) and EMG amplitude ([r.sup.2] = 0.988) with increases in eccentric isokinetic torque, but there was no significant change in EMG MPF from 10 to 100% PT. The results suggested that for the biceps brachii, eccentric isokinetic torque was increased to approximately 60% PT through concurrent modulation of the number of active motor units and their firing rates, whereas additional torque above 60% PT was produced only by increases in firing rates. These findings contribute to current knowledge of motor-control strategies during eccentric isokinetic muscle actions and could be useful in the design of training programs. KEY WORDS. mechanomyography, electromyography, motor-control strategies, eccentric isokinetic torque

The purposes of this study were to (a) determine if the mathematical model used to estimate the physical working capacity at the oxygen consumption threshold (PW[C.sub.vo2]) and physical working capacity at the heart rate threshold (PW[C.sub.HRT]) for cycle ergometry could be applied to treadmill running; (b) propose new fatigue thresholds called the running velocity at the oxygen uptake threshold (R[V.sub.vo2]) and running velocity at the heart rate threshold (R[V.sub.HRT]) for treadmill exercise; and (c) statistically compare the velocities at the R[V.sub.vo2], R[V.sub.HRT], and ventilatory threshold (VT). Seven aerobically trained adult volunteers (mean [+ or -] SD: age 24.0 [+ or -] 3.9 years, [Vo.sub.2] max 56.7 [+ or -] 7.1 ml*[kg.sup.1*[min.sup.-1]) performed a maximal treadmill test to determine [Vo.sub.2] peak and VT as well as four 8-minute submaximal workbouts for the determination of R[V.sub.vo2] and R[V.sub.HRT]. One-way repeated-measures analysis of variance indicated that there were no significant (p > 0.05) mean differences among the running velocities for the R[V.sub.vo2], R[V.sub.HRT], and VT. The results of this study indicated that the mathematical model used to estimate PW[C.sub.vo2] and PW[C.sub.HRT] for cycle ergometry could be applied to treadmill running. Furthermore, the RV[Vo.sub.2] and R[V.sub.HRT] test may provide submaximal techniques for estimating the VT. Key Words. cardiovascular response, cardiorespiratory, exercise, treadmill exercise, fatigue thresholds

The purposes of the present study were to (a) modify previously published [Vo.sub.2]max equations using the constant error (CE = mean difference between actual and predicted [Vo.sub.2]max) values from Malek et al. (28); (b) cross-validate the modified equations to determine their accuracy for estimating [Vo.sub.2]max in aerobically trained men; (c) derive a new non-exercise-based equation for estimating [Vo.sub.2]max in aerobically trained men if the modified equations are not found to be accurate; and (d) cross-validate the new [Vo.sub.2]max equation using the predicted residual sum of squares (PRESS) statistic and an independent sample of aerobically trained men. One hundred and fifty-two aerobically trained men ([Vo.sub.2]max mean [+ or -] SD = 4,154 [+ or -] 629 ml*[min.sup.-1]) performed a maximal incremental test on a cycle ergometer to determine actual [Vo.sub.2]max. An aerobically trained man was defined as someone who had participated in continuous aerobic exercise 3 or more sessions per week for a minimum of I hour per session for at least the past 18 months. Nine previously published [Vo.sub.2]max equations were modified for use with aerobically trained men. The predicted [Vo.sub.2]max values from the 9 modified equations were compared to actual [Vo.sub.2]max by examining the CE, standard error of estimate (SEE), validity coefficient (r), and total error (TE). Cross-validation of the modified non-exercise-based equations on a random subsample of 50 subjects resulted in a %TE [greater than or equal to] 13% of the mean of actual [Vo.sub.2]max. Therefore, the following non-exercise-based [Vo.sub.2]max equation was derived from a random subsample of 112 subjects: [Vo.sub.2]max (ml*[min.sup.-1]) = 27.387(weight in kg) + 26.634(height in cm) 27.572(age in years) + 26.161(h*[wk.sup.-1] of training) + 114.904(intensity of training using the Borg 6-20 scale) + 506.752(natural log of years of training) 4,609.791 (R = 0.82, [R.sup.2] adjusted = 0.65, and SEE - 378 ml*[min.sup.-1]). Cross-validation of this equation on the remaining sample of 40 subjects resulted in a %TE of 10%. Therefore, the non-exercise-based equation derived in the present study is recommended for estimating [Vo.sub.2]max in aerobically trained men. Key Words. maximal aerobic power, cardiorespiratory fitness, cross-validation, PRESS statistic, reference values

The purpose of this study was to examine the patterns for the mechanomyographic (MMG) and electromyographic (EMG) amplitude and mean power frequency (MPF) vs. torque relationships during submaximal to maximal isometric and isokinetic muscle actions. Seven men (mean [+ or -] SD age, 22.4 [+ or -] 1.3 years) volunteered to perform isometric and concentric isokinetic leg extension muscle actions at 20, 40, 60, 80, and 100% of maximal voluntary contraction (MVC) and peak torque (PT) on a Cybex II dynamometer. A piezoelectric MMG recording sensor was placed between bipolar surface EMG electrodes on the vastus medialis. Polynomial regression and separate 1-way repeated-measures analysis of variance were used to analyze the EMG amplitude, MMG amplitude, EMG MPF, and MMG MPF data for the isometric and isokinetic muscle actions. For the isometric muscle actions, EMG amplitude ([R.sup.2] - 0.999) and MMG MPF ([R.sup.2] = 0.946) increased to MVC, mean MMG amplitude increased to 60% MVC and then plateaued, and mean EMG MPF did not change (p > 0.05) across torque levels. For the isokinetic muscle actions, EMG amplitude ([R.sup.2] = 0.988) and MMG amplitude ([R.sup.2] = 0.933) increased to PT, but there were no significant mean changes with torque for EMG MPF or MMG MPF. The different torque-related responses for EMG and MMG amplitude and MPF may reflect differences in the motor control strategies that modulate torque production for isometric vs. dynamic muscle actions. These results support the findings of others and suggest that isometric torque production was modulated by a combination of recruitment and firing rate, whereas dynamic torque production was modulated primarily through recruitment. KEY WORDS. electromyography, mechanomyography, phonomyography, acoustic myography, quadriceps

This article investigates fitness trainers' knowledge of nutrition, health screening, and exercise techniques. An examination of the trainers' experience, training, and overall knowledge is presented.