Creatine is one of the most studied and popular ergogenic aids for athletes and recreational weightlifters seeking to improve sport and exercise performance, augment exercise training adaptations, and mitigate recovery time. Studies consistently reveal that creatine supplementation exerts positive ergogenic effects on single and multiple bouts of short-duration, high-intensity exercise activities, in addition to potentiating exercise training adaptations. In this respect, supplementation consistently demonstrates the ability to enlarge the pool of intracellular creatine, leading to an amplification of the cell’s ability to resynthesize adenosine triphosphate. This intracellular expansion is associated with several performance outcomes, including increases in maximal strength (low-speed strength), maximal work output, power production (high-speed strength), sprint performance, and fat-free mass. Additionally, creatine supplementation may speed up recovery time between bouts of intense exercise by mitigating muscle damage and promoting the faster recovery of lost force-production potential. Conversely, contradictory findings exist in the literature regarding the potential ergogenic benefits of creatine during intermittent and continuous endurance-type exercise, as well as in those athletic tasks where an increase in body mass may hinder enhanced performance. The purpose of this review was to summarize the existing literature surrounding the efficacy of creatine supplementation on exercise and sports performance, along with recovery factors in healthy populations.

Purpose. Many strength and conditioning professionals propose that postactivation potentiation (PAP) warm-ups enhance power performance although there are few studies conducted in this regard on sprinting. Therefore, the purpose of this study was to determine the effects of a PAP warm-up on sprint performance. Methods. Twenty-four men and women completed a 40-yard (yd) sprint pretest on four nonconsecutive days followed by a PAP warm-up that included a sled resistance sprint at either 0%, 10%, 20%, or 30% of their body mass and concluded with a 40-yd dash posttest. Each resistance sprint was recorded for kinematic analysis. Results. A 2 × 2 × 4 factorial mixed ANOVA revealed a statistically significant difference between sexes in 40-yd dash times (p < 0.001). A significant main effect was found in pre-and post-40-yd dash measures regardless of sex (p < 0.001). The results indicated no significant differences in the post-40-yd dash times between sled loads and the load by time interaction. The participants' 40-yd dash times improved 1.2% on average after the 10% load. Improvements in dash time for the 0%, 20%, and 30% loads were greater than 2%. Sprint kinematics analysis demonstrated statistically significant differences between lighter and heavier loads. Conclusions. Regardless of the significant disruptions in sprint mechanics, there appears to be a potential for heavier sled resistances to affect acute improvements in 40-yd sprint performance. However, it is unclear whether heavier sleds loads may provide greater benefit than warming up with 0% resistance.

Lyons, BC, Mayo, JJ, Tucker, WS, Wax, B, and Hendrix, RC. Electromyographical comparison of muscle activation patterns across 3 commonly performed kettlebell exercises. J Strength Cond Res 31(9): 2363-2370, 2017-The purpose of this study was to compare the muscle activation patterns of 3 different kettlebell (KB) exercises using electromyography (EMG). Fourteen resistance-trained subjects completed a 1-arm swing (Swing), 1-arm swing style snatch (Snatch), and a 1-arm clean (Clean) using a self-selected 8 to 10 repetition maximum load for each exercise. Trial sessions consisted of subjects performing 5 repetitions of each KB exercise. Mean EMG was used to assess the muscle activation of the biceps brachii, anterior deltoid, posterior deltoid, erector spinae (ES), vastus lateralis (VL), biceps femoris, contralateral external oblique (EO), and gluteus maximus during each lift using surface electrodes. The mean EMG was normalized using maximal voluntary contractions obtained from manual muscle testing. Repeated-measures analysis of variance revealed a significant difference in the muscle activation patterns of the ES (Swing > Snatch), EO (Snatch, Clean > Swing), and VL (Swing > Clean) across the 3 KB exercises. We conclude that although the KB Swing, Snatch, and Clean are total body exercises, they place different demands on the ES, contralateral EO, and the VL. Therefore, KBs represent an authentic alternative for lifters, and the Swing, Snatch, and Clean are not redundant exercises.

Purpose. Complex training (CT) involves the coupling of two exercises ostensibly to enhance the effect of the second exercise. Typically, the first exercise is a strength exercise and the second exercise is a power exercise involving similar muscles. In most cases, CT is designed to enhance power. The purpose of this study was twofold. First, this study was designed to determine if lower body power could be enhanced using complex training protocols. Second, this study investigated whether the inclusion of a power exercise instead of a strength exercise as the first exercise in CT would produce differences in lower body power. Methods. Thirty-six recreationally-trained men and women aged 20 to 29 years attending a college physical education course were randomly assigned to one of three groups: squat and countermovement squat jumps (SSJ), kettlebell swings and countermovement squat jumps (KSJ), and a control (CON). Training involving CT lasted 6 weeks. All participants were pre-and posttested for vertical jump performance in order to assess lower body power. Results. Vertical jump scores improved for all groups (p < 0.01). The results also indicated that there were no statistically significant differences between group scores across time (p = 0.215). The statistical power for this analysis was low (0.312), most likely due to the small sample size. However, the results did reveal a trend suggesting that the training improvements were greater for both the SSJ and KSJ groups compared with the CON (by 171% and 107%, respectively) although significance was not reached. Conclusions. Due to the observed trend, a replication of this study with a greater number of participants over a longer period of time is warranted.

Bat velocity is considered to be an important factor for successful hitting. The relationship between grip strength and bat velocity has not been conclusively established. The purposes of this study were to determine the relationship of grip strength to bat velocity and to ascertain whether the performance of resistance training exercises designed to specifically target the forearms and grip would significantly alter bat velocity. The subjects for this study were 23 male members (mean +/- SD, age = 19.7 +/- 1.3 years, height = 182.5 +/- 5.9 cm, weight = 85.4 +/- 15.5 kg, experience = 14.4 +/- 1.7 years) of a varsity baseball team at a National Collegiate Athletic Association Division II school. The Jamar hand dynamometer was used to test grip strength, and the SETPRO Rookie was used to measure instantaneous bat velocity at the point of contact with the ball. Subjects were randomly divided into an experimental group and a control group. For 6 weeks, both groups participated in their usual baseball practice sessions, but the experimental group also performed extra forearm and grip strengthening exercises, whereas the control group did not. Pretest and posttest correlations between grip strength and bat velocity revealed no significant relationship between grip strength and bat velocity (pretest r = 0.054, p = 0.807; posttest r = 0.315, p = 0.145). A dependent t-test performed on all subjects revealed that a significant (p = 0.001) increase in bat velocity did occur over the course of the study. A covariate analysis, employing pretest bat velocity as the covariate, revealed no significant difference (p = 0.795) in posttest bat velocity scores between the experimental and control groups. Thus, increases in bat velocity occurred, but the differences were similar for both the experimental and control groups. The findings of this study suggest that grip strength and bat velocity are not significantly related, and that the allocation of time and energy for added training of the forearms in order to improve grip strength for the purpose of increasing bat velocity may not be warranted.

Context:Rehabilitation specialists should understand cardiovascular responses to different movement patterns.Objective:To investigate physiological responses to forward- (FM), backward- (BM), and lateral-motion (LM) exercise at self-selected intensities.Design:Within-subjects design to test independent variable, movement pattern; repeated-measures ANOVA to analyze oxygen consumption (VO2), heart rate (HR), respiratory-exchange ratio (RER), and ratings of perceived exertion (RPE).Participants:10 healthy women.Results:VO2and HR were significantly higher during LM than during FM and BM exercise. The respective VO2(ml · kg · min–1) and HR (beats/min) values for each condition were FM 25.19 ± 3.6, 142 ± 11; BM 24.24 ± 2.7, 145 ± 12; and LM 30.5 ± 4.6, 160 ± 13. No differences were observed for RER or RPE.Conclusions:At self-selected intensities all 3 modes met criteria for maintaining cardiovascular fitness. Practitioners can use these results to develop rehabilitation programs based on clients’ perception and level of discomfort

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Introduction: The aim of this study was to investigate the potential ergogenic properties of citrulline malate (CM) during a 300-yard shuttle run. Methods:  Thirty-two recreationally active subjects (M=24; F=8) participated in a randomized, placebo-controlled, double-blind study. Participants completed baseline testing which consisted of two 300-yard shuttle runs for time. Immediately post-exercise blood lactate was taken via a finger stick. An average of the two trials (time in seconds and blood lactate in mmols/L) were recorded and used for analysis. One week later, participants were randomly assigned to one of four groups (control, placebo, 4 grams CM, or 8 grams of CM) and repeated the same exercise protocol. Data were analyzed using a two-way repeated measures analysis of variance. Results: No main effect for shuttle-run time (F=0.149; p=0.702) or shuttle run time by group interaction was observed (F=0.672; p=0.576). There was a main effect for blood lactate (F=17.079; p<0.001) with lactate accumulation during the pre-test (11.64±2.83 mmol/L) being significantly greater compared to the post-treatment lactate levels (9.65±1.94 mmol/L). There was no blood lactate by group interaction (F=0.867; p=0.47). Conclusions: These results indicated that acute CM supplementation did not   improve anaerobic performance in healthy, young adults.