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.

A Comparison of Three Different Warm-Ups on 800-Meter Running Performance in Elite Division I Track Athletes - A Pilot Study.

Track and Field athletes perform different types of warm-ups at varying levels of volume and/or intensity prior to competition. Theoretically, this prepares sport specific muscles for activity by increasing muscle temperature, thus mitigating the chance for injury. There is a paucity of information regarding the optimum level for warm-ups regarding maximizing performance in middle distance events. The aim of this study was to examine the effects of three different warm-ups on 800-meter performance. Thirteen Division I student-athletes (seven males and six females) from the Southeastern Conference (SEC) who were middle distance runners participated in this study. We utilized a randomized, cross-over study design to test low, medium, and high-volume warm-up protocols on 800-meter performance. Trials were conducted over a span of three weeks on a SEC University outdoor track. We used a 2 (Sex) x 3 (Warm-Up Protocol) mixed-factor ANOVA, and our results show a main effect of warm-up volume that is not moderated by sex. Post-hoc tests reveal a high-volume warm-up yields superior results for the 800-meter run in comparison to a medium volume warm-up, which provides better results than a low-volume warm-up. These findings may be of value in providing information in program design for coaches on the most effective warm-up protocols for 800-meter runners. Identifying the best warm-up protocol to prime an 800-meter runner for peak performance may not only assist in preventing injury, but enhance performance thus leading to an increased of achievement, and confidence in personal ability.

Effects of Supplemental Citrulline-Malate Ingestion on Blood Lactate, Cardiovascular Dynamics, and Resistance Exercise Performance in Trained Males.

Citrulline-malate (CM) has been proposed to provide an ergogenic effect during resistance exercise; however, there is a paucity of research investigating these claims. Therefore, we investigated the impact that CM supplementation would have on repeated bouts of resistance exercise. Fourteen resistance-trained males participated in a randomized, counterbalanced, double-blind study. Subjects were randomly assigned to placebo (PL) or CM (8 g) and performed three sets each of chin-ups, reverse chin-ups, and push-ups to failure. One week later, subjects ingested the other supplement and performed the same protocol. Blood lactate (BLa), heart rate (HR), and blood pressure (BP) were measured preexercise, with BLa measured a second time immediately following the last set, while HR and BP were measured 5 and 10 min postexercise. Citrulline-malate ingestion significantly increased the amount of repetitions performed for each exercise (chin-ups: PL = 28.4 ± 7.1, CM = 32.2 ± 5.6, p = .003; reverse chin-ups: PL = 26.6 ± 5.6, CM = 32.1 ± 7.1, p = .017; push-ups: PL = 89.1 ± 37.4, CM = 97.7 ± 36.1, p < .001). Blood lactate data indicated a time effect (p < .001), but no treatment differences (p = .935). Systolic BP data did not show differences for time (p = .078) or treatment (p = .119). Diastolic BP data did not show differences for time (p = .069), but indicated treatment differences (p = .014) for subjects ingesting CM. Collectively, these findings suggests that CM increased upper-body resistance performance in trained college-age males.

Effects of supplemental citrulline malate ingestion during repeated bouts of lower-body exercise in advanced weightlifters.

The purpose of this investigation was to test the efficacy of citrulline malate supplementation on exercise performance, blood lactate, heart rate, and blood pressure during lower-body dynamic resistance exercise. We hypothesized that citrulline malate ingestion before performing submaximal repeated bouts of multiple lower-body resistance exercises would improve performance. Twelve advanced resistance-trained male subjects participated in a randomized, counterbalanced, double-blind study. Subjects were randomly assigned to placebo (PL) or citrulline malate (8 g) groups and then performed repeated bouts of multiple lower-body resistance exercise. Specifically, subjects performed 5 sequential sets (60% 1 repetition maximum) to failure on the leg press, hack squat, and leg extension machines. Blood lactate, heart rate, systolic blood pressure, and diastolic blood pressure were determined before and after exercise. The exercise protocol resulted in sequential significant (p ≤ 0.05) decrease in the number of repetitions in all 3 exercises. However, subjects in the citrulline malate group performed significantly (p ≤ 0.05) higher number of repetitions during all 3 exercises compared with PL group. Blood lactate and heart rate were significantly increased (p ≤ 0.05) after exercise compared with before exercise but were not significantly different between citrulline malate and PL (p > 0.05). No significant (p > 0.05) differences were detected for blood pressure measurements. In conclusion, our results suggest that citrulline malate supplementation may be beneficial in improving exercise performance during lower-body multiple-bout resistance exercise in advanced resistance-trained men.

Effects of supplemental GAKIC ingestion on resistance training performance in trained men.

PURPOSE: Glycine-arginine-alpha-ketoisocaproic acid (GAKIC) is a relatively new supplement that athletes and fitness enthusiasts ingest to enhance performance during anaerobic exercise. Therefore, the purpose of this study was to investigate the potential ergogenic effects of GAKIC ingestion during multiple bouts of resistance exercise. METHOD: Seven resistance-trained men participated in a randomized, counterbalanced, double-blind study. Participants were randomly assigned to placebo or GAKIC (10.2 g) and performed 5 sets of 75% of 1-repetition maximum leg press to failure. Total load volume was calculated by multiplying the 75% of 1-repetition maximum mass lifted by the sum of repetitions to failure. One week later, participants ingested the other supplement (placebo or GAKIC) and the same exercise protocol was performed (i.e., crossover). Blood lactate, glucose, and heart rate were determined preexercise and immediately postexercise. RESULTS: GAKIC supplementation significantly increased leg-press total load volume (GAKIC = 31,564 +/- 9,132 kg; placebo = 25,763 +/- 6,595 kg, p < .05). Heart rate and blood lactate were significantly increased (p < .05) postexercise compared with preexercise but were not significantly different between GAKIC and placebo. No significant changes (p > .05) were detected for one-repetition maximum and blood glucose. CONCLUSIONS: These novel findings suggest that GAKIC increases total work performed during repeated bouts of lower-body resistance exercise. Thus, our data suggest that GAKIC ingestion before weight training may increase the training volume of athletes and resistance-trained individuals.

Effects of supplemental carbohydrate ingestion during superimposed electromyostimulation exercise in elite weightlifters.

The purpose of this investigation was to test the effects of carbohydrate supplementation on blood parameters and force output during superimposed electromyostimulation (SEMS) single-leg isometric contractions. We hypothesized that carbohydrate ingestion before and during muscle contractions would lead to greater glucose availability and greater total force output for the session. Six elite resistance trained male subjects participated in a randomized, counterbalanced, double-blind study. The subjects were randomly assigned to placebo (PL) or carbohydrate (CHO). The subjects in CHO consumed 1 g of carbohydrate per kilogram of body mass loading dose and 0.17 g of carbohydrate · per kilogram of body mass every 6 minutes during the exercise protocol. The PL received an equal volume of a solution made of saccharin and aspartame. The exercise protocol consisted of repeated 20-second isometric contractions of quadriceps muscle at 50% maximal voluntary contraction followed by 40 seconds of rest until failure occurred. Importantly, quadriceps maximal voluntary contraction with SEMS was performed in the beginning and then every 5 minutes during the last 3 seconds of isometric contractions throughout the exercise protocol. Venous blood samples were taken preexercise, immediately postexercise, and at 5 minutes postexercise and analyzed for glucose, nonesterified fatty acids, and glycerol. Our results indicate that CHO ingestion increased (p < 0.05) plasma glucose, but no significant differences (p > 0.05) were detected for nonesterified fatty acids or glycerol. Importantly, total force output during exercise protocol was higher (p < 0.05) in CHO compared with that in PL. Therefore, our data suggest that CHO supplementation before and during exercise may be beneficial for individuals performing high-volume resistance training.

Effects of glycine-arginine-α-ketoisocaproic acid supplementation in college-age trained females during multi-bouts of resistance exercise.

Glycine-arginine-α-ketoisocaproic acid (GAKIC) has been proposed to increase anaerobic high-intensity exercise performance in male subjects. However, the effects of GAKIC ingestion in female subjects have not been studied. Therefore, the purpose of this study was to investigate the effects of GAKIC supplementation on total load volume (i.e., mass lifted) and metabolic parameters during repeated bouts of submaximal leg extensions in college-age females. Nine resistance-trained females participated in a randomized, counterbalanced, double blind study. Subjects were randomly assigned to placebo or GAKIC (10.2 g) and performed six sets of 50% of one repetition maximum leg extensions (two legs simultaneously) to failure. One week later, subjects ingested the other supplement and performed the same exercise protocol. Furthermore, blood lactic acid, blood glucose, and heart rate were also measured preexercise and 5 s after the completion of the exercise protocol (postexercise). GAKIC supplementation significantly increased leg extension total load volume (GAKIC = 1721.7 ± 479.9 kg; placebo = 1479.1 ± 396.8 kg, p < .01). Heart rate and blood lactic acid were significantly increased (p < .01 for both measures) postexercise compared to preexercise, but were not significantly different between GAKIC and placebo (p = .40 for heart rate; p = .88 for lactic acid). Blood glucose was significantly decreased (p = .03) postexercise compared to preexercise, but was not significantly different (p = .78) between GAKIC and placebo. Collectively, these findings suggest that GAKIC increased lower body resistance performance in trained college-age females; however, these findings are not necessarily generalizable.

Aerobic fitness affects cortisol responses to concurrent challenges.

PURPOSE: Studies have demonstrated that a combination of mental and physical challenge can elicit exacerbated state anxiety, effort sense, and cortisol responses above that of a single stimulus. However, an analysis of the effects of aerobic fitness on the responses of cortisol to concurrent mental and physical stress between below average and above average fitness individuals has not been conducted. This study examined the effects of a combination of acute mental challenges and physical stress on psychological and cortisol responses between eight individuals of below average fitness (low fit (LF), VO2max = 36.58 ± 3.36 mL·kg(-1)·min(-1)) and eight individuals of above average fitness (high fit (HF), VO2max = 51.18 ± 2.09 mL·kg(-1)·min). METHODS: All participants completed two experimental conditions. An exercise-alone condition (EAC) consisted of cycling at 60% VO2max for 37 min, and a dual-challenge condition (DCC) included concurrent participation in a mental challenge for 20 min while cycling. RESULTS: The DCC resulted in increases in state anxiety (P = 0.018), perceived overall workload (P = 0.001), and exacerbated cortisol responses (P = 0.04). Furthermore, LF participants had a greater overall cortisol response in the DCC compared with the EAC (DCC = 346.83 ± 226.92; EAC = -267.46 ± 132.32; t7 = 2.49, P = 0.04), whereas HF participants demonstrated no difference between conditions (DCC = 38.91 ± 147.01; EAC = -324.60 ± 182.78; t7 = 1.68, P = 0.14). DISCUSSION: LF individuals seem to demonstrate unnecessary and unfavorable responses to the DCC compared with HF individuals, particularly concerning cortisol. The exacerbated cortisol responses in LF individuals have implications for harmful consequences such as increased risk of cardiovascular disease.

Effects of carbohydrate supplementation on force output and time to exhaustion during static leg contractions superimposed with electromyostimulation.

The purpose of this study was to investigate the effects of carbohydrate ingestion on force output and time to exhaustion using single leg static contractions superimposed with brief periods of electromyostimulation. Six trained male subjects participated in a randomized, counterbalanced, double-blind study. The subjects were randomly assigned to placebo (PL) or carbohydrate (CHO). The subjects in CHO consumed 1 g of carbohydrate per kilogram of body mass loading dose and 0.17 g of carbohydrate per kilogram of body mass every 6 minutes during the exercise protocol. The PL received an equal volume of a solution made of saccharin and aspartame. The exercise protocol consisted of repeated 20-second static contractions of quadriceps muscle at 50% maximal voluntary contraction followed by 40-second rest until failure occurred. Importantly, the force output during quadriceps maximal voluntary contraction strength with superimposed electromyostimulation was measured in the beginning and every 5 minutes during the last 3 seconds of static contractions throughout the exercise protocol. Venous blood samples were taken preexercise, immediately postexercise, and at 5 minutes postexercise and analyzed for blood lactate. Our results indicate that time to exhaustion (PL = 16.0 ± 8.1 minutes; CHO = 29.0 ± 13.1 minutes) and force output (PL = 3,638.7 ± 524.5 N; CHO = 5,540.1 ± 726.1 N) were significantly higher (p < 0.05) in CHO compared with that in PL. Data suggest that carbohydrate ingestion before and during static muscle contractions can increase force output and increase time to exhaustion. Therefore, our data suggest that carbohydrate supplementation before and during resistance exercise might help increase the training volume of athletes.

Acute L-arginine alpha ketoglutarate supplementation fails to improve muscular performance in resistance trained and untrained men.

BACKGROUND: Dietary supplements containing L-arginine are marketed to improve exercise performance, but the efficacy of such supplements is not clear. Therefore, this study examined the efficacy of acute ingestion of L-arginine alpha-ketoglutarate (AAKG) muscular strength and endurance in resistance trained and untrained men. METHODS: Eight resistance trained and eight untrained healthy males ingested either 3000mg of AAKG or a placebo 45 minutes prior to a resistance exercise protocol in a randomized, double-blind crossover design. One-repetition maximum (1RM) on the standard barbell bench press and leg press were obtained. Upon determination of 1RM, subjects completed repetitions to failure at 60% 1RM on both the standard barbell bench press and leg press. Heart rate was measured pre and post exercise. One week later, subjects ingested the other supplement and performed the identical resistance exercise protocol. RESULTS: Our data showed statistical significant differences (p<0.05) between resistance trained and untrained males for both 1RM and total load volume (TLV; multiply 60% of 1RM times the number of repetitions to failure) for the upper body. However, 1RM and TLV were not statistically different (p>0.05) between supplementation conditions for either resistance trained or untrained men in the bench press or leg press exercises. Heart rate was similar at the end of the upper and lower body bouts of resistance exercise with AAKG vs. placebo. CONCLUSION: The results from our study indicate that acute AAKG supplementation provides no ergogenic benefit on 1RM or TLV as measured by the standard barbell bench press and leg press, regardless of the subjects training status.