Creatine for Exercise and Sports Performance, with Recovery Considerations for Healthy Populations

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.

Electromyographical Comparison of Muscle Activation Patterns Across Three Commonly Performed Kettlebell Exercises

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.

Effect of grip strength and grip strengthening exercises on instantaneous bat velocity of collegiate baseball players

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.