Effects of oral creatine supplementation on high intensity, intermittent exercise performance in competitive squash players

The purpose of this study was to determine the effects of oral creatine supplementation on high intensity, intermittent exercise performance in competitive squash players. Nine squash players (mean ± SEM V˙O2max = 61.9 ± 2.1ml · kg-1 · min-1; body mass = 73 ± 3 kg) performed an on-court “ghosting” routine that involved 10 sets of 2 repetitions of simulated positional play, each set interspersed with 30 s passive recovery. A double blind, crossover design was utilised whereby experimental and control groups supplemented 4 times daily for 5 d with 0.075 g · kg-1 body mass of creatine monohydrate and maltodextrine, respectively, and a 4 wk washout period separated the crossover of treatments. The experimental group improved mean set sprint time by 3.2 ± 0.8 % over and above the changes noted for the control group (P = 0.004 and 95 % Cl = 1.4 to 5.1 %). Sets 2 to 10 were completed in a significantly shorter time following creatine supplementation compared to the placebo condition (P < 0.05). In conclusion, these data support existing evidence that creatine supplementation improves high intensity, intermittent exercise performance. In addition, the present study provides new evidence that oral creatine supplementation improves exercise performance in competitive squash players

Effects of creatine monohydrate supplementation on simulated soccer performance

Purpose: To determine the effects of acute short-term creatine (Cr) supplementation on physical performance during a 90-min soccer-specific performance test. Methods: A double-blind, placebo-controlled experimental design was adopted during which 16 male amateur soccer players were required to consume 20 g/d Cr for 7 d or a placebo. A Ball-Sport Endurance and Speed Test (BEAST) comprising measures of aerobic (circuit time), speed (12- and 20-m sprint), and explosive-power (vertical jump) abilities performed over 90 min was performed presupplementation and postsupplementation. Results: Performance measures during the BEAST deteriorated during the second half relative to the first for both Cr (1.2–2.3%) and placebo (1.0–2.2%) groups, indicating a fatigue effect associated with the BEAST. However, no significant differences existed between groups, suggesting that Cr had no performance-enhancing effect or ability to offset fatigue. When effect sizes were considered, some measures (12-m sprint, –0.53 ± 0.69; 20-m sprint, –0.39 ± 0.59) showed a negative tendency, indicating chances of harm were greater than chances of benefit. Conclusions: Acute short-term Cr supplementation has no beneficial effect on physical measures obtained during a 90-min soccer-simulation test, thus bringing into question its potential as an effective ergogenic aid for soccer players

Effects of long-term creatine monohydrate supplementation on anaerobic performance of trained young adults

O objetivo do presente estudo foi investigar o impacto de oito semanas de suplementação de creatina mono-hidratada (Crm) sobre o desempenho anaeróbio de adultos jovens treinados. Vinte e seis estudantes de educação física, do sexo masculino, saudáveis, foram divididos aleatoriamente em grupo creatina (GCr, n = 13; 22,5 ± 2,7 anos; 74,9 ± 6,8kg, 178,5 ± 4,8cm) e grupo placebo (GPl, n = 13; 22,9 ± 3,2 anos, 71,9 ± 11,3kg, 178,6 ± 4,0cm). Os indivíduos ingeriram em sistema duplo-cego doses de Crm ou placebo-maltodextrina (20 g.d-1 por 5 dias e 3 g.d-1 por 51 dias subsequentes). Ambos os grupos tiveram seus hábitos alimentares e os níveis de aptidão física controlados anteriormente. O teste anaeróbio de Wingate (TW) foi usado para avaliar o desempenho anaeróbio antes e após o período de ingestão de Crm ou placebo. Os índices de desempenho analisados foram: potência pico relativa (PPR), potência média relativa (PMR), trabalho total relativo (TTR) e índice de fadiga (IF). Para tratamento estatístico foi utilizado ANOVA, seguido pelo teste de post hoc Tukey, quando P<0,05. Não foram observadas diferenças significantes nos índices PPR, PMR, TTR e IF após o período de suplementação de Crm (P<0,05). Os resultados do presente estudo sugerem que a suplementação de Crm não parece ser um recurso ergogênico eficiente em esforços físicos de alta intensidade e curta duração que envolve uma única série.The objective of the present study was to investigate the impact of eight weeks of creatine monohydrate (Crm) supplementation on the anaerobic performance of young trained adults. Twenty-six healthy male physical education students were randomly divided in creatine group (CrG, n = 13; 22.5 ± 2.7 years; 74.9 ± 6.8 kg; 178.5 ± 4.8 cm) and placebo group (PlG, n = 13; 22.9 ± 3.2 years; 71.9 ± 11.3 kg; 178.6 ± 4.0 cm). The subjects received in a double-blind system a Crm or placebo-maltodextrin dose (20 g.d-1 for 5 days and 3 g.d-1 for 51 subsequent days). Both groups had their eating habits and levels of physical fitness previously controlled. The Wingate anaerobic test (WT) was used to evaluate the anaerobic performance before and after the ingestion period of Crm or placebo. The performance indexes assessed were: relative peak power (RPP), relative mean power (RMP), relative total work (RTW) and index of fatigue (IF). ANOVA followed by Tukey post hoc test were used when P<0.05 for statistical treatment. No significant difference in RPP, RMP, RTW or IF was observed after the period of supplementation of Crm (P>0.05). The results of the present study suggest that Crm supplementation does not seem to be an efficient ergogenic resource in high-intensity and short-duration efforts involving a single set.FapespCNPqCoordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES

The effect of combined supplementation of carbohydrates and creatine on anaerobic performance.

The purpose of the study was to examine the effect of creatine (Cr) supplementation on anaerobic performance when ingesting creatine and carbohydrates (CHO) together. Twenty male physical education students comprised the two experimental (CR and CRCHO) and one control (CON) groups of the study. All groups performed three 30 s anaerobic Wingate tests (AWTs) interspersed with 6 minutes of recovery. The CR group (n = 7) ingested 5 g of Cr 5 times per day for 4 days. Subjects in the CRCHO group (n = 6) ingested the same quantity but additionally after each 5 g dose of Cr consumed 500 ml of a commercially available energy drink containing 100 g of simple sugars. Over all three AWTs average mean power improved significantly compared to baseline for the CR group (5.51%) but not for the CRCHO group (3.06%). Mean power for the second AWT was improved following the acute loading for the CR group only (4.54%) and for the third AWT for both CR (8.49%) and CRCHO (5.75%) groups. Over all three AWTs a significant change was recorded in average peak power following the acute loading for the CR group (8.26%) but not for the CRCHO group (4.11%). Peak power was significantly improved following the loading only for the CR group during the third AWT (19.79%). No changes in AWT performance were recorded for the CON group after intervention. The findings of the present study suggest that ingesting creatine together with carbohydrates will not further improve performance compared to the ingestion of creatine only

Effects of creatine loading on electromyographic fatigue threshold during cycle ergometry in college-aged women

This is the publisher's version, also found at http://www.jissn.com/content/4/1/20The purpose of this study was to examine the effects of 5 days of Creatine (Cr) loading on the electromyographic fatigue threshold (EMGFT) in college-aged women. Fifteen healthy college-aged women (mean ± SD = 22.3 ± 1.7 yrs) volunteered to participate in this double-blind, placebocontrolled study and were randomly placed into either placebo (PL – 10 g of flavored dextrose powder; n = 8) or creatine (Cr – 5 g di-creatine citrate plus 10 g of flavored dextrose powder; n = 7; Creatine Edge, FSI Nutrition) loading groups. Each group ingested one packet 4 times per day (total of 20 g/day) for 5 days. Prior to and following supplementation, each subject performed a discontinuous incremental cycle ergometer test to determine their EMGFT value, using bipolar surface electrodes placed on the longitudinal axis of the right vastus lateralis. Subjects completed a total of four, 60 second work bouts (ranging from 100–350 W). The EMG amplitude was averaged over 10 second intervals and plotted over the 60 second work bout. The resulting slopes from each successive work bouts were used to calculate EMGFT. A two-way ANOVA (group [Cr vs. PL] × time [pre vs. post]) resulted in a significant (p = 0.031) interaction. Furthermore, a dependent samples t-test showed a 14.5% ± 3.5% increase in EMGFT from pre- to post-supplementation with Cr (p = 0.009), but no change for the PL treatment (-2.2 ± 5.8%; p = 0.732). In addition, a significant increase (1.0 ± 0.34 kg; p = 0.049) in weight (kg) was observed in the Cr group but no change for PL (-0.2 kg ± 0.2 kg). These findings suggest that 5 days of Cr loading in women may be an effective strategy for delaying the onset of neuromuscular fatigue during cycle ergometry

Effect of creatine malate supplementation on physical performance, body composition and selected hormone levels in spinters and long-distance runners

Purpose The aim of the study was to determine whether creatine malate (CML) supplementation results in similar ergogenic effect in sprinters and long-distance runners. The other goal was to compare changes in body composition, physical performance and hormone levels after six-week training in athletes, divided into subgroups supplemented with creatine malate or taking placebo. Results Six-week supplementation combined with physical training induced different effects in athletes. Significantly higher increases in relative and absolute peak power and total work (p < 0.05) were found in sprinters compared to other groups. Except for growth hormone, post-exercise venous blood serum hormone levels exhibited no statistically significant differences in athletes. After CML loading period, a significant increase in growth hormone was found in the group of sprinters. Conclusions A significant ergogenic effect was found in sprinters, which was reflected by the increase in anaerobic exercise indices and morphological indices and elevated growth hormone level, after graded exercise testing. The significant increase in the distance covered during graded test was only observed in supplemented long-distance runners, whereas no significant changes in maximal oxygen uptake, relative peak power and relative total work were noticed. This could be caused by later anaerobic threshold appearance in exercise test to exhaustion

The effect of oral creatine supplementation on one hour cycling performance and metabolism

The effect of oral creatine (Cr) supplementation with 20 g/day for 7 days on one-hour cycling performance and metabolism was investigated in a double-blind placebo controlled study. Twenty endurance-trained male cyclists volunteered for the study that was approved by the University of Cape Town ethics committee. The subjects' peak sustained power output was measured and they underwent a familiarization one-hour cycle on a cycle ergometer. Five days later subjects had a muscle biopsy and an indwelling cannula was inserted into a forearm vein before performing a maximal one-hour cycle (T1) during which blood samples were taken at regular intervals. Following the cycle, the subjects each received either Cr or placebo tablets to be ingested four times per day for the following week. After the loading week the subjects again reported to the laboratory, had a muscle biopsy and underwent and the same test routine (T2) with blood sampling as the previous week. Resting muscle total Cr measured by HPLC increased significantly (p<0.001) in the Cr group from 123.0 ± 3.8 mmol/kg dry wt to 159.8 ± 7.9 mmol/ kg dry wt, but was unchanged in the placebo group. The extent of Cr loading was not related to baseline Cr levels (r=0.46, NS). No differences were noted in the resting levels of adenine nucleotides in either group. Analyses of the plasma samples indicated no change in plasma lactate concentration, but a significant lowering of indicators of adenine nucleotide degradation including concentrations of plasma ammonia (p<0.05) and hypoxanthine (p<0.01) in the Cr group from T1 to T2. Plasma urate concentration was significantly lowered (p<0.01) from T1 to T2 but there were no differences between groups. Cr supplementation did not significantly improve performance in the one-hour trial (Cr group: 39.1 ± 0.9 km vs 39.8 ± 0.8 km and placebo group: 39.3 ± 0.8 km vs 39.2 ± 1.1 km). We hypothesised that Cr supplementation affects the purine nucleotide cycle through improved maintenance of low intracellular ADP during exercise as a result of enhanced efficiency of the Cr-PCr shuttle. Cr supplementation had no effect on lactate and carbohydrate metabolism and did not improve performance significantly during a one-hour cycle trial

The effects of creatine pyruvate and creatine citrate on performance during high intensity exercise

<p>Abstract</p> <p>Background</p> <p>A double-blind, placebo-controlled, randomized study was performed to evaluate the effect of oral creatine pyruvate (Cr-Pyr) and creatine citrate (Cr-Cit) supplementation on exercise performance in healthy young athletes.</p> <p>Methods</p> <p>Performance during intermittent handgrip exercise of maximal intensity was evaluated before (pretest) and after (posttest) 28 days of Cr-Pyr (5 g/d, n = 16), Cr-Cit (5 g/d, n = 16) or placebo (pla, 5 g/d, n = 17) intake. Subjects performed ten 15-sec exercise intervals, each followed by 45 sec rest periods.</p> <p>Results</p> <p>Cr-Pyr (p < 0.001) and Cr-Cit (p < 0.01) significantly increased mean power over all intervals. Cr-Cit increased force during the first and second interval (p < 0.01) compared to placebo. The effect of Cr-Cit on force decreased over time and the improvement was not significant at the sixth and ninth interval, whereas Cr-Pyr significantly increased force during all intervals (p < 0.001). Cr-Pyr (p < 0.001) and Cr-Cit (p < 0.01) resulted in an increase in contraction velocity, whereas only Cr-Pyr intake significantly (p < 0.01) increased relaxation velocity. Oxygen consumption measured during rest periods significantly increased with Cr-Pyr (p < 0.05), whereas Cr-Cit and placebo intake did not result in significant improvements.</p> <p>Conclusion</p> <p>It is concluded that four weeks of Cr-Pyr and Cr-Cit intake significantly improves performance during intermittent handgrip exercise of maximal intensity and that Cr-Pyr might benefit endurance, due to enhanced activity of the aerobic metabolism.</p

Influence of Creatine Supplementation on the Parameters of the “All-Out Critical Power Test”

We tested the hypotheses that creatine loading would result in no alteration in critical power (CP) or the total work done > CP (W) as estimated from a novel 3-minute all-out cycling protocol. Seven habitually active male subjects completed 3-minute all-out tests against fixed resistance on an electrically-braked cycle ergometer after a 5-day dietary supplementation with 20 g·d−1 of a glucose placebo (PL) and the same dose of creatine monohydrate (CR). The CP was estimated from the mean power output over the final 30 seconds of the test and the W was estimated as the power-time integral above the end-test power output. Creatine supplementation resulted in a significant increase in body mass (from 80.4 ± 9.2 kg to 81.5 ± 9.5 kg; p < 0.05), whereas the body mass was not different after placebo supplementation (80.3 ± 9.3 kg; p > 0.05). There were no differences in the power outputs measured during the 3-minute all-out tests following PL and CR supplementation (CP—PL: 252 ± 30 W vs. CR: 255 ± 28 W, p > 0.05; W—PL: 19.4 ± 3.5 kJ vs. CR: 19.2 ± 3.4 kJ, p > 0.05; total work done—PL: 64.8 ± 4.9 kJ vs. CR: 65.0 ± 4.9 kJ, p > 0.05). Creatine loading had no ergogenic effect on the CP measured using the novel all-out protocol. In contrast to earlier studies which established the power- duration relationship using the conventional protocol, the finite work capacity > CP (W) for all-out exercise was not enhanced by creatine loading