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The involvement of youth in the sport of weightlifting and the use of weightlifting methods as part of training for youth sport performance appears to be increasing. Weightlifting for children and adolescents has been criticized in some circles and is a controversial aspect of resistance training for young people. Although injuries can occur during weightlifting and related activities, the incidence and rate of injury appear to be relatively low and severe injury is uncommon. A number of performance, physical, and physiological variables, such as body composition, strength, and power, are improved by weightlifting training in children, adolescents, and young athletes. Manipulating program variables, when appropriate, can have a substantial and profound influence on the psychological, physiological, physical, and performance aspects of weightlifters. An understanding of the sport, scientific training principles, and musculoskeletal growth development is necessary to properly construct a reasonable and appropriate training program. A scientific background aids in providing an evidenced basis and sound rationale in selecting appropriate methods and directing adaptations toward more specific goals and enables the coach to make choices about training and competition that might not otherwise be possible. If weightlifting training and competition are age group appropriate and are properly supervised, the sport can be substantially safe and efficacious.

The purpose of the present investigation was to examine the acute effects of whole body vibration (WBV) on isometric mid-thigh pull force&ndash, time curve (FTC) characteristics. Eleven recreationally trained subjects were randomly assigned to three treatment conditions: sham no vibration protocol (T1), vibration protocol 30 Hz 2&ndash, 4 mm amplitude (T2), and vibration protocol 30 Hz 2&ndash, 4 mm (T3). After completing a standardized warm-up, the subject stood on a vibration platform with the knee at a 120&deg, angle and performed one of the three interventions. Each treatment condition required the subject to stand on the platform for thirty-second treatments, each separated by thirty seconds of recovery. Five minutes after the completion of the treatment conditions, the subjects performed the isometric mid-thigh pull. All FTCs were analyzed with standardized procedures for peak force (PF) and peak rate of force development (PRFD). A 1 &times, 3 repeated measures analysis of variance (ANOVA) was used to compare the three treatments. Additionally, coefficients of variance (CV), as well as intraclass and interclass correlations, were performed. There were no significant differences (p &gt, 0.05) for any of the FTC analyses performed in this investigation. The CV and the 95% confidence interval (CI) indicate that the WBV protocol resulted in trivial changes in PF and beneficial changes in PRFD. A 30 Hz 2&ndash, 4 mm amplitude WBV does not result in a significant increase in isometric mid-thigh pull performance.

Travis, SK, Pritchard, HJ, Mujika, I, Gentles, JA, Stone, MH, and Bazyler, CD. Characterizing the tapering practices of United States and Canadian raw powerlifters. J Strength Cond Res 35(12S): S26-S35, 2021-The purpose of this study was to characterize the tapering practices used by North American powerlifters. A total of 364 powerlifters completed a 41-item survey encompassing demographics, general training, general tapering, and specific tapering practices. Nonparametric statistics were used to assess sex (male and female), competition level (regional/provincial, national, and international), and competition lift (squat, bench press, and deadlift). The highest training volume most frequently took place 5-8 weeks before competition, whereas the highest training intensity was completed 2 weeks before competition. A step taper was primarily used over 7-10 days while decreasing the training volume by 41-50% with varied intensity. The final heavy (>85% 1 repetition maximum [1RM]) back squat and deadlift sessions were completed 7-10 days before competition, whereas the final heavy bench press session was completed

The block periodization training paradigm has been shown to produce enhanced gains in strength and power. The purpose of this study is to assess resistance training induced alterations in lean body mass and cross-sectional area using a block periodization training model among individuals (n = 15) of three differing strength levels (high, moderate and low) based on one repetition maximum back squat relative to body weight. A 3 × 5 mixed-design ANOVA was used to examine within-and between-subject changes in cross-sectional area (CSA), lean body mass (LBM), lean body mass adjusted (LBMadjusted) and total body water (TBW) over an 11-week resistance training program. LBMadjusted is total body water subtracted from lean body mass. The ANOVA revealed no statistically significant between-group differences in any independent variable (p &gt, 0.05). Within-group effects showed statistically significant increases in cross-sectional area (p &lt, 0.001), lean body mass (p &lt, 0.001), lean body mass adjusted (p ˂ 0.001) and total body water (p &lt, 0.001) from baseline to post intervention: CSA: 32.7 cm2 ± 8.6, 36.3 cm2 ± 7.2, LBM: 68.0 kg ± 9.5, 70.6 kg ± 9.4, LBMadjusted: 20.4 kg ± 3.1, 21.0 kg ± 3.3 and TBW: 49.8 kg ± 6.9, 51.7 kg ± 6.9. In conclusion, the results of this study suggest subjects experienced an increase in both lean body mass and total body water, regardless of strength level, over the course of the 11-week block periodized program. Gains in lean body mass and cross-sectional area may be due to edema at the early onset of training.

Some controversy exists as to the most efficacious method of training to achieve enhanced levels of sport performance. Controversy concerning the efficacy of periodization and especially block periodization (BP) likely stems from the use of poorly or untrained subjects versus trained who may differ in their responses to a stimulus. The purpose of this study was to investigate the effect of training status on performance outcomes resulting from 11 weeks of BP training. Fifteen males were recruited for this study and placed into strong (age = 24.3 &plusmn, 1.9 years., body mass (BM) = 87.7 &plusmn, 8.7 kg, squat: body mass = 1.96 &plusmn, 0.16), moderate (age = 25.3 &plusmn, 2.7 years., body mass = 100.2 &plusmn, 15.5 kg, squat: body mass = 1.46 &plusmn, 0.14), or weak (age = 23.2 &plusmn, 3.9 yrs., body mass = 83.5 &plusmn, 17.1 kg, squat: body mass = 1.17 &plusmn, 0.07) groups based on relative strength. Testing was completed at baseline, and after each block which consisted of 1 repetition maximum (1RM) squat, 0 kg static jump (SJ), 0 kg countermovement jump (CMJ), 20 kg SJ, and 20 kg CMJ. Absolute and relative strength were strongly correlated with rates of improvement for absolute strength, relative strength, 0 kg, and 20 kg vertical jumps. All subjects substantially improved back squat (p &lt, 0.001), relative back squat (p &lt, 0.001) with large&ndash, very large effect sizes between groups for percent change favoring the weak group over the moderate and strong group for all performance variables. All subjects showed statistically significant improvements in 0 kg SJ (p &lt, 0.001), 0 kg CMJ (p &lt, 0.001), 20 kg SJ (p = 0.002), and 20 kg CMJ (p &lt, 0.001). Statistically significant between group differences were noted for both 20 kg SJ (p = 0.01) and 20 kg CMJ (p = 0.043) with the strong group statistically greater jump heights than the weak group. The results of this study indicate BP training is effective in improving strength and explosive ability. Additionally, training status may substantially alter the response to a resistance training program.

Sams, ML, Wagle, JP, Sato, K, DeWeese, BH, Sayers, AL, and Stone, MH. Using the session rating of perceived exertion to quantify training load in a men's college soccer team. J Strength Cond Res 34(10): 2793-2799, 2020-The purpose of this study was to examine the training load (TL) programming of 3 training groups of a National Collegiate Athletic Association Division I men's college soccer team across a season. Thirty athletes were classified as starters (S), substitutes (NS), or redshirts (RS) based on the percentage of possible minutes played during the season. Training load was quantified at the season, phasic, and weekly levels by the session rating of perceived exertion. Between-group differences were observed at the season level (p < 0.001), and group-by-time interactions for average weekly TL were found at both the phasic (p = 0.04) and weekly levels (p < 0.001). In general, S accumulated greater TL than NS (effect size range for all analyses: -0.59 < d < 1.91) and RS (0.17 < d < 3.67), and NS accumulated greater TL than RS (-0.54 < d < 2.34). Within-group variation at the phasic level was less apparent (-0.35 < d < 1.44); however, all 3 groups displayed training variation at the weekly level (-1.80 < d < 3.24). The session rating of perceived exertion can serve as a low-cost, valid means of quantifying TL in men's college soccer athletes. Practitioners should be especially aware of the possibility of insufficient loading in NS.

Cytokine and hormone concentrations can be linked to the manipulation of training variables and to subsequent alterations in performance. Subjects: Nine D-1 collegiate throwers and 4 control subjects participated in this preliminary and exploratory report. Methods: Hormone (testosterone (T) and cortisol (C)) and adipokine (adiponectin, leptin, and resistin) measurements were taken at weeks 1, 7, and 11 for the throwers and weeks 1 and 11 for the control group. The throwers participated in an 11-week periodized resistance training and throws program during the fall preparatory period. Volume load was recorded throughout the study. Results: Hormone values did not exhibit statistically significant changes across time; however, there were notable changes for C, the testosterone to cortisol ratio (T:C), and adiponectin. Conclusions: T:C was increased as volume load decreased, and adiponectin increased in concert with decreases in C and increases in the T:C, possibly suggesting a lesser degree of obesity-related inflammation and a higher degree of “fitness” and preparedness.

Bazyler, CD, Mizuguchi, S, Zourdos, MC, Sato, K, Kavanaugh, AA, DeWeese, BH, Breuel, KF, and Stone, MH. Characteristics of a national level female weightlifter peaking for competition: A case study. J Strength Cond Res 32(11): 3029-3038, 2018-This study investigated physiological and performance changes of a national-level 69 kg female weightlifter after 3 competition phases over a 28-week training period. The athlete first trained for a regional championship (weeks 1-12), followed by a local competition (weeks 13-23) and the national championship (weeks 24-28). Body mass, vastus lateralis cross-sectional area (CSA), and unloaded and loaded squat jump performance were assessed weekly during each 4-week competition phase. Serum biomarkers and dynamic midthigh pulls were assessed before and after each competition phase. Weightlifting performance goals were met for the regional championship (total = 200 kg) and the local competition (total = 193 kg), but not the national championship (total = 196 kg). She lost more body mass in preparation for Nationals (-6.0 kg) compared with regionals (-2.5 kg) and the local competition (+2.2 kg). Vastus lateralis CSA very likely decreased after Nationals (precision = 99%, effect size = 2.08). Her testosterone:cortisol ratio likely increased (88%, 2.64), whereas interleukin-6 (79%, 2.47) and tumor necrosis factor-alpha (81%, 3.59) likely decreased after Nationals. Serum myostatin (99%, 1.95) and decorin (99%, 1.96) very likely decreased after the local competition. Unloaded squat jump height likely increased the week of regionals (89%, 0.95) and the local competition (99%, 1.83), whereas unloaded and loaded squat jump height possibly (69%, 0.99) and likely (82%, 1.52) decreased the week of Nationals. Dynamic midthigh pull vertical displacement likely increased after regionals (93%, 0.84) and likely decreased after Nationals (94%, 0.87). These findings indicate that biomarkers of stress, inflammation, and hypertrophy are related to changes in training volume-load; however, performance measures are needed to assess competition preparedness. Considering the reductions in muscle CSA corresponding with the large reductions in body mass and underperformance at the national championship, sport scientists, and coaches should instruct weightlifters to not attempt large losses in body mass (e.g., >3 kg) close to competition (e.g.

Kavanaugh, AA, Mizuguchi, S, Sands, WA, Ramsey, MW, and Stone, MH. Long-term changes in jump performance and maximum strength in a cohort of NCAA division I women's volleyball Athletes. J Strength Cond Res 32(1): 66-75, 2018-The purpose of this investigation was to quantify the magnitude of change in maximal strength and jumping abilities over approximately 1, 2, and 3 years of supervised sport and resistance training in National Collegiate Athletic Association (NCAA) division I women's volleyball athletes. This was an exploratory study on a cohort of women's volleyball athletes (n = 29) split into 3 groups based on the length of the time spent in a supervised resistance training program: group 1 (n = 11): 0.7 ± 0.3 years, group 2 (n = 9): 1.6 ± 0.2 years, and group 3 (n = 9): 2.4 ± 0.6 years. Monitoring tests consisted of standing height (cm), body mass (kg), body fat (%), static jump height (SJH) and countermovement JH (CMJH) with 0-, 11-, and 20-kg loads (cm), and midthigh clean pull isometric peak force (IPF) and allometrically scaled IPF (IPFa) (N·kg). Increasing trends were observed for all variables from groups 1 to 2 to 3. Statistically greater improvements (p ≤ 0.05) with moderate to large effect sizes were found between groups 1 and 3 for SJH 0 (19.7%, d = 1.35), SJH 11 (23.8%, d = 1.23), SJH 20 (30.6%, d = 1.20), CMJH 11 (22.6%, d = 1.18), IPF (44.4%, d = 1.22), and IPFa (41.2%, d = 1.32). A combination of traditional resistance training exercises and weightlifting variations at various loads, in addition to volleyball practice, seem to be effective at increasing maximal strength by 44% and vertical JH by 20-30% in NCAA division I women's volleyball athletes after about 2.5 years of training. Furthermore, these characteristics can be improved in the absence of additional plyometric training outside normal volleyball-specific practice.

Resistance training of healthy young men typically results in muscle hypertrophy and a shift in vastus lateralis composition away from type IIx fibers to an increase in IIa fiber content. Our previous studies of 8 wk of resistance training found that many metabolic syndrome men and women paradoxically increased IIx fibers with a decrease in IIa fibers. To confirm the hypothesis that obese subjects might have muscle remodeling after resistance training very different from healthy lean subjects, we subjected a group of nine obese male volunteers to progressive resistance training for a total of 16 wk. In these studies, weight loss was discouraged so that muscle changes would be attributed to the training alone. Detailed assessments included comparisons of histological examinations of needle biopsies of vastus lateralis muscle pretraining and at 8 and 16 wk. Prolonging the training from 8 to 16 wk resulted in increased strength, improved body composition, and more muscle fiber hypertrophy, but euglycemic clamp-quantified insulin responsiveness did not improve. Similar to prior studies, muscle fiber composition shifted toward more fast-twitch type IIx fibers (23 to 42%). Eight weeks of resistance training increased the muscle expression of phosphorylated Akt2 and mTOR. Muscle GLUT4 expression increased, although insulin receptor and IRS-1 expression did not change. We conclude that resistance training of prediabetic obese subjects is effective at changing muscle, resulting in fiber hypertrophy and increased type IIx fiber content, and these changes continue up to 16 wk of training.NEW & NOTEWORTHY Obese, insulin-resistant men responded to 16 wk of progressive resistance training with muscle hypertrophy and increased strength and a shift in muscle fiber composition toward fast-twitch, type IIx fibers. Activation of muscle mTOR was increased by 8 wk but did not increase further at 16 wk despite continued augmentation of peak power and rate of force generation.

There is a need for reliable analysis techniques for kinetic data for coaches and sport scientists who employ athlete monitoring practices. The purpose of the study was: (1) to determine intra- and inter-rater reliability within a manual-based kinetic analysis program; and (2) to determine test-retest reliability of an algorithm-based kinetic analysis program. Five independent raters used a manual analysis program to analyse 100 isometric mid-thigh pull (IMTP) trials obtained from previously collected data. Each trial was analysed three times. The same IMTP trials were analysed using an algorithm-based analysis software. Variables measured were peak force, rate of force development from 0 to 50 ms (RFD50) and RFD from 0 to 200 ms (RFD200). Intraclass correlation coefficients (ICC) and coefficient of variation (CV) were used to assess intra- and inter-rater reliability. Nearly perfect reliability was observed for the manual-based (ICC 0.92). However, poor intra- and inter-rater CV was observed for RFD (CV 16.25% and CV 32.27%, respectively). The algorithm-based method resulted in perfect reliability in all measurements (ICC = 1.0, CV = 0%). While manual methods of kinetic analysis may provide sufficient reliability, the perfect reliability observed within the algorithm-based method in the current study suggest it is a superior method for use in athlete monitoring programs.

Gleason, BH, Sams, M, Salley, JT, Pustina, A, and Stone, MH. Global positioning system analysis of a high school football scrimmage. J Strength Cond Res 31(8): 2183-2188, 2017-The purpose of this study was to examine the physical demands of a high school American football scrimmage. Male high school football players (N = 25) participated in a spring scrimmage. Global positioning system data and game film were recorded throughout the entirety of the scrimmage to determine the total distance covered, the distance covered in different velocity bands, the number of accelerations and decelerations performed, and the work-to-rest ratio of the scrimmage. The athletes were divided into 2 groups: linemen (L) (N = 7) vs. nonlinemen (NL) (N = 8) for statistical analysis, and independent T-tests with Holm's sequential Bonferroni adjustment were used to determine differences in movement characteristics between the L and NL groups. Average play duration was 5.7 ± 2.1 seconds, whereas the rest interval was 33.4 ± 13.6 seconds between plays, for an overall exercise-to-rest ratio of 1:5.9. Total distance, standing and walking distance, running distance, striding distance, sprinting distance, and total high-speed running distance covered by NL was greater than L (statistically significant at p ≤ 0.05). Distances traveled in each velocity band by position and by play are also included to provide context of our findings. Data from the present study add to the pool of support for the use of position-specific training in preparing high school football players for competition.

Stuart, CA, Lee, ML, South, MA, Howell, MEA, Cartwright, BM, Ramsey, MW, and Stone, MH. Pre-training muscle characteristics of subjects who are obese determine how well exercise training will improve their insulin responsiveness. J Strength Cond Res 31(3): 798-808, 2017-Only half of prediabetic subjects who are obese who underwent exercise training without weight loss increased their insulin responsiveness. We hypothesized that those who improved their insulin responsiveness might have pretraining characteristics favoring a positive response to exercise training. Thirty nondiabetic subjects who were obese volunteered for 8 weeks of either strength training or endurance training. During training, subjects increased their caloric intake to prevent weight loss. Insulin responsiveness by euglycemic clamps and muscle fiber composition, and expression of muscle key biochemical pathways were quantified. Positive responders initially had 52% higher intermediate muscle fibers (fiber type IIa) with 27% lower slow-twitch fibers (type I) and 23% lower expression of muscle insulin receptors. Whether after weight training or stationary bike training, positive responders' fiber type shifted away from type I and type IIa fibers to an increased proportion of type IIx fibers (fast twitch). Muscle insulin receptor expression and glucose transporter type 4 (GLUT4) expression increased in all trained subjects, but these moderate changes did not consistently translate to improvement in whole-body insulin responsiveness. Exercise training of previously sedentary subjects who are obese can result in muscle remodeling and increased expression of key elements of the insulin pathway, but in the absence of weight loss, insulin sensitivity improvement was modest and limited to about half of the participants. Our data suggest rather than responders being more fit, they may have been less fit, only catching up to the other half of subjects who are obese whose insulin responsiveness did not increase beyond their pretraining baseline.

The purpose of this study was to investigate the kinetic and morphological adaptations that occur during distinct phases of a block periodized training cycle in weightlifters. Athlete monitoring data from nine experienced collegiate weightlifters was used. Isometric mid-thigh pull (IMTP) and ultrasonography (US) results were compared to examine the effects of three specific phases of a training cycle leading up to a competition. During the high volume strength-endurance phase (SE) small depressions in rate of force development (RFD) but statistically significant (p &le, 0.05) increases in vastus lateralis cross-sectional area (CSA), and body mass (BM) were observed. The lower volume higher intensity strength-power phase (SP) caused RFD to rebound above pre-training cycle values despite statistically significant reductions in CSA. Small to moderate increases only in the earlier RFD time bands (&lt, 150 ms) occurred during the peak/taper phase (PT) while CSA and BM were maintained. Changes in IMTP RFD and CSA from US reflected the expected adaptations of block periodized training phases. Changes in early (&lt, 100 ms) and late (&ge, 150 ms) RFD time bands may not occur proportionally throughout different training phases. Small increases in RFD and CSA can be expected in well-trained weightlifters throughout a single block periodized training cycle.

The purpose of this investigation was to elucidate the changes in cf-DNA as it relates to fluctuations in resistance training workloads and intensities. The relationship between cell free DNA (cf-DNA), C-reactive protein (CRP), creatine kinase (CK), testosterone (T), cortisol (C), testosterone-cortisol ratio (T:C), body mass and body composition were also examined. Eight weightlifters (5 males and 3 females, age = 25 ± 3.5 yr, body mass = 88.3 ± 22.7 kg, height = 173.8 ±8.4 cm) volunteered to participate in this study. Venous blood samples, body mass and body composition were taken six times, each corresponding to the end of a training phase. CK (p = 0.018, η² = 0.409) and CK %Δ (p < 0.001, η² = 0.594) were the only biochemical variables to reach statistical significance at any point. A number of statistically significant correlations were found among variables. VLD4wk was related to CK %Δ (r = 0.86), VLD4wk %Δ was related CK %Δ (r = 0.86) and TID1wk was related to CRP (r = 0.83). cf-DNA %Δ was correlated with CRP and CRP %Δ (r = 0.83 and 0.86, respectively). CRP and CRP %Δ were correlated with BF % (r = 0.94 and 0.92, respectively). CK and CK %Δ were both related to T:C (r = 0.94 and 0.89, respectively) and T:C %Δ (r = 0.87 and 0.86, respectively). The correlation between cf-DNA and CRP suggests that cf-DNA may be a valuable indicator of inflammation in weightlifters.

The purpose of this study was to compare 4 methods that assess the lower-body stretch-shortening cycle (SSC) utilization of athletes. Eighty-six National Collegiate Athletic Association Division I athletes from 6 different sports performed 2 squat jumps and 2 countermovement jumps on a force platform. Pre-stretch augmentation percentage (PSAP), eccentric utilization ratio (EUR), and reactive strength (RS) for jump height (JH) and peak power (PP) magnitudes, and reactive strength index-modified (RSImod) were calculated for each team. A series of one-way analyses of variance with a Holm-Bonferroni sequential adjustment were used to compare differences in PSAP, EUR, RS, and RSImod between teams. Statistical differences in RSImod (p0.001) existed between teams, whereas no statistical differences in PSAP-JH (p = 0.150), PSAP-PP (p = 0.200), EUR-JH (p = 0.150), EUR-PP (p = 0.200), RS-JH (p = 0.031), or RS-PP (p = 0.381) were present. The relationships between PSAP, EUR, and RS measures were all statistically significant and ranged from strong to nearly perfect (r = 0.569-1.000), while most of the relationships between PSAP, EUR, and RS measures and RSImod were trivial to small (r = 0.192-0.282). Pre-stretch augmentation percentage and EUR, RS, and RSImod values indicate that women's tennis, men's soccer, and men's soccer teams may use the SSC most effectively, respectively. Pre-stretch augmentation percentage, EUR, RS, and RSImod values may show vastly different results when comparing an individual's and a team's ability to use the SSC. Practitioners should consider using RSImod to monitor the SSC utilization of athletes due to its timing component.

Seventeen strength and power athletes (n = 11 males, 6 females, height: 177.5 &plusmn, 7.0 cm, 165.8 &plusmn, 11.4 cm, body mass: 90.0 &plusmn, 14.1 kg, 66.4 &plusmn, 13.9 kg, age: 30.6 &plusmn, 10.4 years, 30.8 &plusmn, 8.7 years), who regularly performed weightlifting movements during their resistance training programs, were recruited to examine the effect of altering body posture and barbell position on the between-session reliability of force-time characteristics generated in the isometric mid-thigh pull (IMTP). After participants were familiarised with the testing protocol, they undertook two testing sessions which were separated by seven days. In each session, the participants performed three maximal IMTP trials in each of the four testing positions examined, with the order of testing randomized. In each position, no significant differences were found between sessions for all force-time characteristics (p = &gt, 0.05). Peak force (PF), time-specific force (F50, F90, F150, F200, F250) and IMP time-bands (0&ndash, 50, 0&ndash, 90, 0&ndash, 150, 0&ndash, 200, 0&ndash, 250 ms) were reliable across each of the four testing positions (ICC &ge, 0.7, CV &le, 15%). Time to peak force, peak RFD, RFD time-bands (0&ndash, 250 ms) and peak IMP were unreliable regardless of the testing position used (ICC = &lt, 0.7, CV = &gt, 15%). Overall, the use of body postures and barbell positions during the IMTP that do not correspond to the second pull of the clean have no adverse effect on the reliability of the force-time characteristics generated.

Wagle, JP, Carroll, KM, Cunanan, AJ, Wetmore, A, Taber, CB, DeWeese, BH, Sato, K, Stuart, CA, and Stone, MH. Preliminary investigation into the effect of ACTN3 and ACE polymorphisms on muscle and performance characteristics. J Strength Cond Res 35(3): 688-694, 2021-The purpose of this investigation was to explore the phenotypic and performance outcomes associated with ACTN3 and ACE polymorphisms. Ten trained men (age = 25.8 ± 3.0 years, height = 183.3 ± 4.1 cm, body mass = 92.3 ± 9.3 kg, and back squat to body mass ratio = 1.8 ± 0.3) participated. Blood samples were analyzed to determine ACTN3 and ACE polymorphisms. Standing ultrasonography images of the vastus lateralis (VL) were collected to determine whole muscle cross-sectional area (CSA-M), and a percutaneous muscle biopsy of the VL was collected to determine type I-specific CSA (CSA-T1), type II-specific CSA (CSA-T2), and type II to type I CSA ratio (CSA-R). Isometric squats were performed on force platforms with data used to determine peak force (IPF), allometrically scaled peak force (IPFa), and rate of force development (RFD) at various timepoints. One repetition maximum back squats were performed, whereby allometrically scaled dynamic strength (DSa) was determined. Cohen's d effect sizes revealed ACTN3 RR and ACE DD tended to result in greater CSA-M but differ in how they contribute to performance. ACTN3 RR's influence seems to be in the type II fibers, altering maximal strength, and ACE DD may influence RFD capabilities through a favorable CSA-R. Although the findings of the current investigation are limited by the sample size, the findings demonstrate the potential influence of ACTN3 and ACE polymorphisms on isometric and dynamic strength testing. This study may serve as a framework to generate hypotheses regarding the effect of genetics on performance.

The purpose of this study was to examine the force-time differences between concentric-only half-squats (COHS) performed with ballistic (BAL) or non-ballistic (NBAL) intent across a range of loads. Eighteen resistance-trained men performed either BAL or NBAL COHS at 30%, 50%, 70%, and 90% of their one repetition maximum (1RM) COHS. Relative peak force (PF) and relative impulse from 0&ndash, 50 ms (Imp50), 0&ndash, 90 ms (Imp90), 0&ndash, 200 ms (Imp200), and 0&ndash, 250 ms (Imp250) were compared using a series of 2 &times, 4 (intent &times, load) repeated measures ANOVAs with Bonferroni post hoc tests. Cohen&rsquo, s d effect sizes were calculated to provide measures of practical significance between the BAL and NBAL COHS and each load. BAL COHS produced statistically greater PF than NBAL COHS at 30% (d = 3.37), 50% (d = 2.88), 70% (d = 2.29), and 90% 1RM (d = 1.19) (all p &lt, 0.001). Statistically significant main effect differences were found between load-averaged BAL and NBAL COHS for Imp90 (p = 0.006, d = 0.25), Imp200 (p = 0.001, d = 0.36), and Imp250 (p &lt, 0.001, d = 0.41), but not for Imp50 (p = 0.018, d = 0.21). Considering the greater PF and impulse observed during the BAL condition, performing COHS with BAL intent may provide a favorable training stimulus compared to COHS performed with NBAL intent.

The purpose of this study was to examine the effects of a recovery supplement compared with a placebo on muscle morphology in trained weightlifters. Vastus lateralis and muscle fiber cross sectional area of type I and type II fibers were compared between groups using a series of 2 × 2 (group × time) repeated measure ANOVAs. Both groups on average improved cross-sectional area of the vastus lateralis, type I and type II muscle fibers from pre-to-post but individual response varied within both groups. Greater magnitude of changes in type I and type II muscle fibers were observed for the placebo group but not for vastus lateralis cross sectional area. Additionally, subjects were divided into large and small fiber groups based on combined fiber size at the start of the investigation. These findings indicate that the recovery supplement utilized provided no greater effect compared with a placebo in a 12-week block periodization protocol in trained weightlifters. The primary determinate of fiber size changes in the study was determined to be the initial fiber size of muscle fibers with larger practical changes observed in the small fiber group compared with the large fiber group in type I, II, and ultrasound cross-sectional area (CSA).

The purposes of this investigation were to: (1) assess kinetic characteristics of overload, (2) examine eccentric and concentric muscle activations and (3) explore velocity measurement as a method of intensity prescription in inertial flywheel squat training. A series of two experiments were performed: one assessing kinetic and muscle activation characteristics of flywheel squat training using three progressive inertial loads. The second experiment assessed inertial load-velocity relationships using six progressive inertial loads. Peak force, net impulse, positive-negative impulse ratio and positive-negative impulse duration ratio were each statistically significant between all three load conditions (

Athlete recovery-adaptation is crucial to the progress and performance of highly trained athletes. The purpose of this study was to assess peristaltic pulse dynamic compression (PPDC) in reducing short-term pressure-to-pain threshold (PPT) among Olympic Training Center athletes after morning training. Muscular tenderness and stiffness are common symptoms of fatigue and exercise-induced muscle microtrauma and edema. Twenty-four highly trained athletes (men = 12 and women = 12) volunteered to participate in this study. The athletes were randomly assigned to experimental (n = 12) and control (n = 12) groups. Pressure-to-pain threshold measurements were conducted with a manual algometer on 3 lower extremity muscles. Experimental group athletes underwent PPDC on both legs through computer-controlled circumferential inflated leggings that used a peristaltic-like pressure pattern from feet to groin. Pressures in each cell were set to factory defaults. Treatment time was 15 minutes. The control group performed the same procedures except that the inflation pump to the leggings was off. The experimental timeline included a morning training session, followed by a PPT pretest, treatment application (PPDC or control), an immediate post-test (PPT), and a delayed post-test (PPT) after the afternoon practice session. Difference score results showed that the experimental group's PPT threshold improved after PPDC treatment immediately and persisted the remainder of the day after afternoon practice. The control group showed no statistical change. We conclude that PPDC is a promising means of accelerating and enhancing recovery after the normal aggressive training that occurs in Olympic and aspiring Olympic athletes.

Daily undulating periodization (DUP), using daily alterations in repetitions, has been advocated as a superior method of resistance training, while traditional forms of programming for periodization (Block) have been questioned. Nineteen Division I track and field athletes were assigned to either a 10-week Block or DUP training group. Year and event were controlled. Over the course of the study, there were four testing sessions, which were used to evaluate a variety of strength characteristics, including maximum isometric strength, rate of force development, and one repetition maximum (1RM). Although, performance trends favored the Block group for strength and rate of force development, no statistical differences were found between the two groups. However, different (p ≤ 0.05) estimated volumes of work (VL) and amounts of improvement per VL were found between groups. Based upon calculated training efficiency scores, these data indicate that a Block training model is more efficient in producing strength gains than a DUP model. Additionally, alterations in testosterone (T), cortisol (C) and the T:C ratio were measured. Although there were no statistically (p ≤ 0.05) different hormone alterations between groups, relationships between training variables and hormone concentrations including the T:C ratio, indicate that Block may be more efficacious in terms of fatigue management.

Objectives: This study investigated chronic changes in cell free DNA (cf-DNA) throughout a collegiate soccer season. The relationship between cf-DNA, C-reactive protein (CRP), creatine kinase (CK), testosterone (T), cortisol (C), testosterone-cortisol ratio (T:C), body mass and body composition were also examined. Design: Longitudinal study design with repeated measures and group comparisons. Methods: Twenty three NCAA Division I male soccer players were divided into two groups. Starters were placed in Group 1 (G1) and non-starters were placed in Group 2 (G2). cf-DNA, CRP, CK, T, C, T:C, body mass and body composition were taken three times, corresponding to pre-season, approximately mid-season and immediately after the concluding the season. Results: In G1, cf-DNA, CRP, CK, cf-DNA %∆, CRP %∆ and, CK %∆ were all statistically higher at T2 and T3 than T1. In G2, CRP %∆ was statistically higher at T2 than T1. In G2, cf-DNA %∆, CRP %∆ and CK %∆ were higher at T2 and T3 than T1. Conclusions: This suggests that cf-DNA may be a useful marker that can reflect accumulated soccer training and competitive stressors. (Journal of Trainology 2015;4:25-31)

The purpose of the current study was (1) to examine the differences between standing and lying measures of vastus lateralis (VL), muscle thickness (MT), pennation angle (PA), and cross-sectional area (CSA) using ultrasonography; and (2) to explore the relationships between lying and standing measures with isometric and dynamic assessments of force production—specifically peak force, rate of force development (RFD), impulse, and one-repetition maximum back squat. Fourteen resistance-trained subjects (age = 26.8 ± 4.0 years, height = 181.4 ± 6.0 cm, body mass = 89.8 ± 10.7 kg, back squat to body mass ratio = 1.84 ± 0.34) agreed to participate. Lying and standing ultrasonography images of the right VL were collected following 48 hours of rest. Isometric squat assessments followed ultrasonography, and were performed on force platforms with data used to determine isometric peak force (IPF), as well as RFD and impulse at various time points. Forty-eight hours later, one-repetition maximum back squats were performed by each subject. Paired-samples t-tests revealed statistically significant differences between standing and lying measurements of MT (p < 0.001), PA (p < 0.001), and CSA (p ≤ 0.05), with standing values larger in all cases. Further, standing measures were correlated more strongly and abundantly to isometric and dynamic performance. These results suggest that if practitioners intend to gain insight into strength-power potential based on ultrasonography measurements, performing the measurement collection with the athlete in a standing posture may be preferred.

Purpose: To determine if jumping-performance changes during a peaking phase differed among returners and new players on a female collegiate volleyball team and to determine which variables best explained the variation in performance changes. Methods: Fourteen volleyball players were divided into 2 groups—returners (n = 7) and new players (n = 7)—who completed a 5-wk peaking phase prior to conference championships. Players were tested at baseline before the preseason on measures of the vastus lateralis cross-sectional area using ultrasonography, estimated back-squat 1-repetition maximum, countermovement jump height (JH), and relative peak power on a force platform. Jumping performance, rating of perceived exertion training load, and sets played were recorded weekly during the peaking phase. Results: There were moderate to very large (P P = .07, Δ = 1.09) differences in JH and relative peak power changes in favor of returners over new players, respectively, during the peaking phase. Irrespective of group, 7 of 14 players achieved peak JH 2 wk after the initial overreach. The number of sets played (r = .78, P r = .54, P = .05) were the strongest correlates of JH changes during the peaking phase. Conclusions: Returners achieved greater improvements in jumping performance during the peaking phase compared with new players, which may be explained by the returners’ greater relative maximal strength, time spent competing, and training experience. Thus, volleyball and strength coaches should consider these factors when prescribing training during a peaking phase to ensure their players are prepared for important competitions.

The purpose of the current study was two-fold: (1) To examine the variation in velocity and power with increasing intensity in the back squat among subjects; and (2) To explore individual subject characteristics as possible explanations for variations of velocity in the back squat. Fourteen recreationally trained male subjects with experience in the back squat agreed to participate in the study (age = 25.0 ± 2.6 years, height = 178.9 ± 8.1 cm, body mass = 88.2 ± 15.8 kg). One-repetition maximums (1RM) were performed for each subject on force platforms with four linear position transducers attached to the barbell. The 1RM assessment was immediately preceded by warm-up sets at 65%, 75%, 85%, and 95% of estimated 1RM for 5, 3, 2, and 1 repetitions, respectively. Mean concentric velocity (MCV) and mean power were recorded for each intensity condition and were analyzed using Pearson correlation to determine the relationship between each variable and relative intensity (%1RM). Statistically significant negative relationships existed between %1RM and MCV (r = -0.892) and mean power (r = -0.604). Between-subject coefficient of variation tended to increase as %1RM increased for both MCV and mean power. These results suggest that MCV is superior to mean power as an indicator of relative intensity in the back squat. Additionally, the between-subject variation observed at higher intensities for MCV and mean power support the use of velocity ranges by strength and conditioning coaches.

Sands, WA, Murray, MB, Murray, SR, McNeal, JR, Mizuguchi, S, Sato, K, and Stone, MH. Peristaltic pulse dynamic compression of the lower extremity enhances flexibility. J Strength Cond Res 28(4): 1058‐1064, 2014—This study investigated the effects of peristaltic pulse dynamic compression (PPDC) on range-ofmotion (ROM) changes in forward splits. Serious stretching usually involves discomfort and large time investments. Tissue structural changes and stretch tolerance have heretofore been considered the primary mechanisms of enhanced ROM. The PPDC treatment was computer controlled. Circumferential and segmented inflation pressures were induced by feet to hip leggings. Nine subjects, experienced in stretching and a forward split position, volunteered. The subjects were familiarized with the protocol and randomly assigned to an initial condition: experimental (PPDC), or control (CONT). The study involved a crossover design. Second conditions were tested within 1‐5 days. All tests were 2 trials of right and left forward splits. Split flexibility was assessed by measuring the height of the anterior superior iliac spine of the rear leg from the floor. Pelvic posture was controlled by rear leg position. The PPDC treatment was 15 minutes of seated PPDC. The control condition was the same except that leggings were not inflated. Pressures of 5 cells in the leggings were set at factory defaults, 70 mm Hg sequentially. Difference score results indicated statistically significant (p # 0.05) differences by condition and the condition by leg interaction. The rapid acute changes in ROM (PPDC: right 25.3%, left 33.3%; CONT: right 12.2%, left 1.0%) support the premise that changes in ROM were dependent on mechanisms other than tissue structural changes and/or stretch tolerance. PPDC provides a means of rapidly enhancing acute ROM requiring less discomfort and time.

The current manuscript has been adapted from the official position statement of the UK Strength and Conditioning Association on youth resistance training. It has subsequently been reviewed and endorsed by leading professional organisations within the fields of sports medicine, exercise science and paediatrics. The authorship team for this article was selected from the fields of paediatric exercise science, paediatric medicine, physical education, strength and conditioning and sports medicine.

South, MA, Layne, AS, Stuart, CA, Triplett, NT, Ramsey, MW, Howell, ME, Sands, WA, Mizuguchi, S, Hornsby, WG, Kavanaugh, AA, and Stone, MH. Effects of short-term free-weight and semiblock periodization resistance training on metabolic syndrome. J Strength Cond Res 30(10): 2682-2696, 2016-The effects of short-term resistance training on performance and health variables associated with prolonged sedentary lifestyle and metabolic syndrome (MS) were investigated. Resistance training may alter a number of health-related, physiological, and performance variables. As a result, resistance training can be used as a valuable tool in ameliorating the effects of a sedentary lifestyle including those associated with MS. Nineteen previously sedentary subjects (10 with MS and 9 with nonmetabolic syndrome [NMS]) underwent 8 weeks of supervised resistance training. Maximum strength was measured using an isometric midthigh pull and resulting force-time curve. Vertical jump height (JH) and power were measured using a force plate. The muscle cross-sectional area (CSA) and type were examined using muscle biopsy and standard analysis techniques. Aerobic power was measured on a cycle ergometer using a ParvoMedics 2400 Metabolic system. Endurance was measured as time to exhaustion on a cycle ergometer. After training, maximum isometric strength, JH, jump power, and V[Combining Dot Above]O2peak increased by approximately 10% (or more) in both the metabolic and NMS groups (both male and female subjects). Over 8 weeks of training, body mass did not change statistically, but percent body fat decreased in subjects with the MS and in women, and lean body mass increased in all groups (p ≤ 0.05). Few alterations were noted in the fiber type. Men had larger CSAs compared those of with women, and there was a fiber-specific trend toward hypertrophy over time. In summary, 8 weeks of semiblock free-weight resistance training improved several performance variables and some cardiovascular factors associated with MS.

bench press and deadlift. For each event, the ultimate goal is to lift as much weight as is possible. In the deadlift, a lifter lifts the barbell off of the floor until standing upright. The lift is finished upon extending the knees and hips with scapula retracted. Two styles of the deadlift are used in competition. The sumo style uses a wide foot stance, upright posture, and a grip width that is narrower than the feet.1 Conversely, the conventional style deadlift uses a narrow foot stance, generally a more bent-over posture, and a grip outside of the legs. Three key phases have been identified in the literature for the conventional deadlift.2-4 The first phase, or lift-off, occurs when the lifter first applies force to the bar and the bar rises off of the floor. The second phase, knee passing, occurs when the bar moves from below to above the knee. The third phase, or lift completion, occurs when the lifter transitions into a full upright position. While these specific regions of the deadlift are known, little has been done to examine how each position might contribute to deadlift performance. The most disadvantageous position represents a limiting factor in overall performance, thus identification of this position may lead to better training prescriptions. To the authors’ knowledge, no literature exists that assesses the force generation capabilities of lifters in these phases of the deadlift, however in a number of studies examining the isometric mid thigh pull (MTP), a weightlifting-specific position, a variety of athletes produced high levels of peak forces.5-7 Peak force measured in these studies showed moderate to strong relationships with dynamic mid-thigh pulls, jumps and a number of other dynamic measures. Therefore, since little is known about the force generation capabilities of lifters in the key phases of the deadlift, the purpose of the study was to evaluate the isometric maximum strength of powerlifters in bar positions corresponding to key phases of the deadlift and also to compare those positions to the MTP, given the strong relationship the MTP shares with a variety of dynamic measures.

Currently, whole-body vibration is being used to promote enhanced performance. Many coaches and athletes believe that it can acutely enhance explosive performance and power output. However, the scientific literature is unclear as to whether this enhancement occurs. The purpose of this study was to examine the acute effects of whole-body vibration on static jump performance, including jump height, peak force, rate of force development, and peak power. Fourteen recreationally active individuals (5 females, 9 males) participated in three separate randomized treatment sessions. Treatment 1 consisted of no vibration while treatment 2 and treatment 3 incorporated whole-body vibration. The whole-body vibration protocol consisted of three 30-s bouts of vibration performed at 30 Hz and low amplitude (~3 mm) with a 30-s rest between bouts. Treatment 1 was identical in duration to both treatments 2 and 3, but did not contain any vibration. Five minutes after each treatment, the participants performed the st...

Small chemical hand and foot warmers are used by many winter sport athletes and other outdoor enthusiasts. The purpose of this study was to characterize the thermal behaviors of 14 commercially available hand and foot warmers.Both types of warmers were instrumented with a fast-responding thermistor. One of each pair of warmers was placed in a boot or glove. Temperature was recorded in a data logger for a period of hours to more than a day until the heat output of the devices ceased and returned to room temperature. Thermal behaviors were characterized and graphed, including peak temperature, time to peak temperature, and duration of temperature greater than 30 degrees C. Reliability was determined by comparing thermal behavior of 2 hand or foot warmers of the same type and from the same manufacturer. Comparisons were also made between package claims and measured behaviors.Measured outcomes were most noteworthy in their variability within and between manufacturers and types of warmers. A strong correlation was found between the masses of the warmers and their duration of heat production.Although there is a paucity of research information on these types of warmers, this experiment showed that some of the devices exceeded packaging claims while others fell short; that the thermal behavior over time of the devices was variable; and that there appears to be a simple but strong relationship between the mass of the devices and the duration of their heat production.

THE INTRODUCTION OF NOVEL TRAINING STIMULI PLAYS A CRUCIAL ROLE IN INDUCING SPECIFIC TRAINING ADAPTATIONS. ONE METHOD THAT CAN BE EMPLOYED TO INTRODUCE A NOVEL STIMULUS TO THE TRAINING PROGRAM WHILE MAXIMIZING THE VELOCITY AND POWER OUTPUT OF THE TRAINING EXERCISE IS THE INCLUSION OF THE CLUSTER SET CONFIGURATION. THE CURRENT REVIEW PRESENTS THE THEORETICAL AND RESEARCH FOUNDATION FOR THE USE OF THE CLUSTER SET IN PERIODIZED TRAINING PROGRAMS AND OFFERS EXAMPLES OF PRACTICAL APPLICATIONS THAT CAN BE USED IN THE PREPARATION OF ATHLETES IN A VARIETY OF SPORTS.

The objective of this study was to examine different motivational factors, leading mothers to commit neonaticidal, infanticidal or filicidal acts. This study was based on data gathered through a retrospective chart review of all filicidal women admitted to the Mid-Hudson Forensic Psychiatric Hospital in New York State (MHFPC) between 1976 and 2000 (n=57). Because our sample was drawn from MHFPC records it excludes filicidal mothers who went directly to prison. Our women were either found not competent to stand trial, or found not guilty by reason of insanity, or were convicted offenders who were seriously mentally ill and were not sent to prison. Fourteen percent committed neonaticide, meaning that they killed their child within the first day of its life; 21% killed the child after the first day but before it reached its first birthday (infanticide); and 65% committed filicide by murdering a child older than one. Two groups of women could be identified as having different motivational profiles: The neonaticidal mothers were mostly troubled by psychosis and social problems while the filicidal women were defined as severely depressed, with a history of self-directed violence and a high rate of suicide attempts following the filicidal offense.

Glaister, M., M.H. Stone, A.M. Stewart, M.G. Hughes, G.L. Moir. Aerobic and anaerobic correlates of multiple sprint cycling performance. J. Strength Cond. Res. 20(4):792- 798. 2006.-The aims of this study were to examine (a) the relationship between maximal oxygen uptake ( O2max) and several performance indices of multiple sprint cycling; (b) the relationship between maximal accumulated oxygen deficit (MAOD) and those same performance indices; and (c) the influence of recovery duration on the magnitude of those relationships. Twenty-five physically active men completed a O2max test, a MAOD test, and 2 maximal intermittent (20 × 5 seconds) sprint cycling tests with contrasting recovery periods (10 seconds or 30 seconds). Mean ± SD for age, height, and body mass were 20.6 ± 1.5 years, 177.2 ± 5.4 cm, and 78.2 ± 8.2 kg, respectively. All tests were conducted on a friction-braked cycle ergometer with subsequent data normalized for body mass. Moderate (0.3 r < 0.5) positive correlations were observed between power output data and MAOD (range, 0.31-0.46; 95% confidence limits, ?0.10 to 0.72). Moderate to large positive correlations also were observed between power output data and O2max, the magnitude of which increased as values were averaged across all sprints (range, 0.45-0.67; 95% confidence limits 0.07-0.84). Correlations between fatigue and O2max were greater in the intermittent protocol with 30-second recovery periods (r = ?0.34; 95% confidence limits, 0.06 to ?0.65). The results of this study reflect the complex energetics associated with multiple sprint work. Though the findings add support to the idea that multiple sprint sports demand a combination of speed and endurance, further longitudinal research is required to confirm the relative importance of these parameters.

The primary objective of this study was to analyze the relationship between testosterone levels and vertical jumping performance in elite men and women athletes. The secondary objective was to verify whether testosterone levels and vertical jumping performance were different in men and women athletes and if those measurements were different between different athletic groups. Seventy (22 women and 48 men) elite athletes in track and field (sprinters), handball, volleyball, and soccer competing at national and international levels participated in the study. After 10 hours of fasting and 1 day of rest, blood samples were drawn from the antecubital vein for determining testosterone levels. Vertical jumping tests consisted of countermovement jumps conducted on a resistive platform connected to a digital timer. Resting testosterone levels in women were 9.5% of those of the men (respectively 0.62 +/- 0.06 ng.ml(-1) and 6.49 +/- 0.37 ng.ml(-1); p < 0.001). Countermovement jump performance was significantly different between women and men athletes, with women's jumping ability 86.3% of that of men (p < 0.001). A significant positive relationship was identified between testosterone levels and vertical jump performance when all data where considered (r = 0.61, p < 0.001, n = 70).

The aim of this study was to characterize sprint ability, anthropometry, and lower extremity power in the US National Team Skeleton athletes. Fourteen athletes (male n = 7; mean ± SD: height 1.794 ...

Objectives: Pre-participation examination, screening and health surveillance are part of the job specification for many roles within Sports Medicine. The type and scope of this activity varies enormously, with little consensus as to best evidence-based practice. The purpose of this work was to explore and understand the practical approaches to pre-participation examination, screening and health surveillance in two contrasting sport scenarios. Data Source: Team physicians for British Triathlon and Manchester United Football Club. Data synthesis/Methods: Information was gathered under the headings: why screen, screening objectives, practical issues and constraints? Results: The systems evolved within these two sports reflect their respective opportunities and constraints. Different systems, each with merit, have evolved with some generalizable concepts across sport. Conclusions: A perfect system for pre-participation examination, screening and health surveillance across all sport does not exist, however, within specific sport scenarios examples of good practice are demonstrated.

In order to stimulate further adaptation toward a specific training goal(s), progression in the type of resistance training protocol used is necessary. The optimal characteristics of strength-specific programs include the use of both concentric and eccentric muscle actions and the performance of both single- and multiple-joint exercises. It is also recommended that the strength program sequence exercises to optimize the quality of the exercise intensity (large before small muscle group exercises, multiple-joint exercises before single-joint exercises, and higher intensity before lower intensity exercises). For initial resistances, it is recommended that loads corresponding to 8-12 repetition maximum (RM) be used in novice training. For intermediate to advanced training, it is recommended that individuals use a wider loading range, from 1-12 RM in a periodized fashion, with eventual emphasis on heavy loading (1-6 RM) using at least 3-min rest periods between sets performed at a moderate contraction velocity (1-2 s concentric, 1-2 s eccentric). When training at a specific RM load, it is recommended that 2-10% increase in load be applied when the individual can perform the current workload for one to two repetitions over the desired number. The recommendation for training frequency is 2-3 d x wk(-1) for novice and intermediate training and 4-5 d x wk(-1) for advanced training. Similar program designs are recommended for hypertrophy training with respect to exercise selection and frequency. For loading, it is recommended that loads corresponding to 1-12 RM be used in periodized fashion, with emphasis on the 6-12 RM zone using 1- to 2-min rest periods between sets at a moderate velocity. Higher volume, multiple-set programs are recommended for maximizing hypertrophy. Progression in power training entails two general loading strategies: 1) strength training, and 2) use of light loads (30-60% of 1 RM) performed at a fast contraction velocity with 2-3 min of rest between sets for multiple sets per exercise. It is also recommended that emphasis be placed on multiple-joint exercises, especially those involving the total body. For local muscular endurance training, it is recommended that light to moderate loads (40-60% of 1 RM) be performed for high repetitions (> 15) using short rest periods (< 90 s). In the interpretation of this position stand, as with prior ones, the recommendations should be viewed in context of the individual's target goals, physical capacity, and training status.

Current information and evidence indicate that for most activities free weight training can produce superior results compared to training with machines, particularly when the free weight training involves complex, multi-joint exercises. A number of reasons can account for the superiority of free weights; the major factor deals with mechanical specificity. Mechanical specificity is concerned with appropriate movement patterns, force application and velocity of movement. Considering the available evidence that adherence to the concept of specificity of exercise and training can result in a greater transfer of training effect then free weights should produce a more effective training transfer. Therefore, the majority of resistance exercises making up a training programme should include of free weight exercises with emphasis on mechanical specificity (i.e. large muscle mass exercises, appropriate velocity, contraction type etc.). Generally, machines should be used as an adjunct to free weight training and, depending upon the sport, can be used to a greater or lesser extent during various phases of the training period (preparation, pre-competition, competition).

The purpose of this investigation was to study the efficacy of two dietary supplements on measures of body mass, body composition, and performance in 42 American football players. Group CM (n = 9) received creatine monohy-drate, Group P (n = 11) received calcium pyruvate. Group COM (n = 11) received a combination of calcium pyruvate (60%) and creatine (40%), and Group PL received a placebo. Tests were performed before (Tl) and after (T2) the 5-week supplementation period, during which the subjects continued their normal training schedules. Compared to P and PL. CM and COM showed significantly greater increases for body mass, lean body mass, 1 repetition maximum (RM) bench press, combined 1 RM squat and bench press, and static vertical jump (SVJ) power output. Peak rate of force development for SVJ was significantly greater for CM compared to P and PL. Creatine and the combination supplement enhanced training adaptations associated with body mass/composition, maximum strength, and SVJ; however, pyruvate supplementation alone was ineffective.