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Response of Testosterone and Cortisol Concentrations to High-Intensity Resistance Exercise Following Creatine Supplementation
Abstract
This study investigated the influence of oral creatine monohydrate supplementation on hormone responses to high-intensity resistance exercise in 13 healthy, normally active men. Subjects were randomly assigned in double-blind fashion to either a creatine or placebo group. Both groups performed bench press and jump squat exercise protocols before (T1) and after (T1) ingesting either 25 g creatine monohydrate or placebo per day for 7 days. Blood samples were obtained pre- and 5 min postexercise to determine serum lactate, testosterone, and cortisol concentrations. Creatine ingestion resulted in a significant (p < 0.05) increase in body mass but no changes in skinfold thickness. Serum lactate concentrations were significantly higher at 5 min postexercise in both groups compared to resting values. From T1 to T2 there were no significant differences in postexercise lactate concentration during both exercise protocols in the placebo group, but the creatine group had significantly higher lactate concentrations after the bench press and a trend toward lower concentrations during the jump squat at T2. There were significant increases in testosterone concentration postexercise after the jump squat, but not the bench press, for both groups; 5-min postexercise cortisol concentrations did not differ significantly from preexercise values for both groups for either protocol. Creatine supplementation may increase body mass; however, test-osterone and cortisol may not mediate this initial effect.
(C) 1997 National Strength and Conditioning Association
... Preparation increases the body weight without any significant effects on brain. At the other hand, L-arginine and glycine as the primary substrates for the creatine biosynthesis with extremely high doses of the creatine monohydrate are relatively effective [34,40]. ...
... CrM supplementation up regulates genes mRNA with a vital role in osmosensing specially during the earlier phase of cell swelling, by promoting cell adhesion to the extracellular matrix and inducing intracellular signal transduction [39,40]. Among the modulated genes are those involved in transmembrane signaling systems of hormonal regulation of adenylate cyclase in response to β-adrenergic stimuli [41,42] and also genes involved in sensing extracellular calcium concentration that assists in maintainin calcium homeostasis [43]. ...
... One of the potentially most beneficial effects of Cr supplementation in power athletes is an increase of the amount of work performed during a series of maximal effort muscle contraction. Volek et al. [40] reported that Cr supplementation (25 g/day for 7 days) resulted in significant improvement in exercise performance during five sets of bench press and jump squats in comparison to a placebo group. Cr supplementation resulted in a significant increase in repetitions performed during bench press for set 2, while peak power output significantly increased in the jump squat during set 5. The authors concluded that increase in exercise performance and body mass (1.3 kg) associated with one week of Cr supplementation are not due to any measurable alteration in circulating concentrations of steroid hormones, as preand post-exercise testosterone and cortisol values did not differ significantly between groups. ...
... Creatine supplementation as a nutritional supplement positively affects strength development (Kraemer, et al., 2007Kraemer, et al., , 2006Gotshalk, et al., 2008;Rawson & Volek, 2003). This supplementation also increases the lean muscle mass, total work performed and muscular power; alters body composition and hydration status (Volek, Boetes, Bush, 1997;Rawson & Persky, 2007;Rawson & Volek, 2003). The coordinated function of metabolically connected nutrients (such as creatine supplementation) and physiologically active ingredients may be pivotal in enhancing hormonal responses and enhancing performance. ...
... However, there have been few studies investigating the effects of short-term creatine supplementation on anabolic hormones and these have produced confl icting results. For example,Volek, et al. (1997)assessed testosterone and cortisol immediately post-exercise (5 sets of bench presses and jump squats) in creatine (25 g/d for 7 days) and placebo-supplemented participants, and found no effect of creatine on the endocrine status.Schedel, et al. (2000), however, found increased growth hormone levels (83%) in response to a 20 g oral creatine bolus. Despite this, Op't Eijnde and Hespel (2001) reported that creatine supplementation (20 g/day for 5 days) did not alter cortisol and growth hormone responses to a single bout of heavy resistance exercise. ...
... Therefore, an increase of muscle mass may be instigated by these hormones (Hansen, et al., 2001). Despite of our data,Volek, et al. (1997)and/or Op'tEijnde and Hespel (2001)found no measurable alteration in endocrine status after creatine supplementation to resistance exercise. As the improvement in exercise volume seems to be refl ected in the hormonal response to the exercise protocol, the difference in the improvement of the total volume of exercise between this study and their researches may explain, in part, these discrepancies in hormonal responses. ...
The purpose of this study was to determine the influence of short-term creatine supplementation on hormonal responses to resistance exercise. 27 trained men were randomly divided into a creatine supplementation group [the CR group (n=15), taking 4×5 g creatine monohydrate/day] or a placebo supplementation group [the PL group (n=12), taking 4×7.5 g maltodextrin/day]. A double-blind research design was employed for a 7-day supplementation period. After this period, the participants performed exercise testing. Blood tests occurred on day 1 prior to supplementation loading (1Pre) and after this period [on the exercise testing day: pre-exercise (Pre), immediately post-exercise (IP), and 15 (15P) and 30 (30P) minutes post-exercise] for the measurement of the serum growth hormone and testosterone concentrations. Significant differences in the number of repetitions and volume were seen with CR (7.2±1.3 repetitions, 1560±386 kg) compared to PL (5.6±2 repetitions, 1089±341 kg) at set 5 of the exercise protocol (p=.01). Serum growth hormone and testosterone were significantly higher at 15P in CR (6.1±1.8 ng/ml, 70.1±19 pmol/L) compared to PL (4.1±1.7 ng/ml, 44.8±16 pmol/L) [(p=.02), (p=.01)]. The enhanced exercise performance resulted in a significantly greater increase in both the growth hormone and testosterone concentrations, indicating an augmented anabolic hormone response to creatine supplementation.
... Creatine supplementation as a nutritional supplement positively affects strength development (Kraemer, et al., , 2006Gotshalk, et al., 2008;Rawson & Volek, 2003). This supplementation also increases the lean muscle mass, total work performed and muscular power; alters body composition and hydration status (Volek, Boetes, Bush, 1997;Rawson & Persky, 2007;Rawson & Volek, 2003). The coordinated function of metabolically connected nutrients (such as creatine supplementation) and physiologically active ingredients may be pivotal in enhancing hormonal responses and enhancing performance. ...
... However, there have been few studies investigating the effects of short-term creatine supplementation on anabolic hormones and these have produced confl icting results. For example, Volek, et al. (1997) assessed testosterone and cortisol immediately post-exercise (5 sets of bench presses and jump squats) in creatine (25 g/d for 7 days) and placebo-supplemented participants, and found no effect of creatine on the endocrine status. Schedel, et al. (2000), however, found increased growth hormone levels (83%) in response to a 20 g oral creatine bolus. ...
... Therefore, an increase of muscle mass may be instigated by these hormones (Hansen, et al., 2001). Despite of our data, Volek, et al. (1997) and/or Op't Eijnde andHespel (2001) found no measurable alteration in endocrine status after creatine supplementation to resistance exercise. As the improvement in exercise volume seems to be refl ected in the hormonal response to the exercise protocol, the difference in the improvement of the total volume of exercise between this study and their researches may explain, in part, these discrepancies in hormonal responses. ...
The purpose of this study was to determine the influence of short-term creatine supplementation on hormonal responses to resistance exercise. 27 trained men were randomly divided into a creatine supplementation group [the CR group (n=15), taking 4×5 g creatine monohydrate/day] or a placebo supplementation group [the PL group (n=12), taking 4×7.5 g maltodextrin/day]. A double-blind research design was employed for a 7-day supplementation period. After this period, the participants performed exercise testing. Blood tests occurred on day 1 prior to supplementation loading (1Pre) and after this period [on the exercise testing day: pre-exercise (Pre), immediately post-exercise (IP), and 15 (15P) and 30 (30P) minutes post-exercise] for the measurement of the serum growth hormone and testosterone concentrations. Significant differences in the number of repetitions and volume were seen with CR (7.2±1.3 repetitions, 1560±386 kg) compared to PL (5.6±2 repetitions, 1089±341 kg) at set 5 of the exercise protocol (p=.01). Serum growth hormone and testosterone were significantly higher at 15P in CR (6.1±1.8 ng/ml, 70.1±19 pmol/L) compared to PL (4.1±1.7 ng/ml, 44.8±16 pmol/L) [(p=.02), (p=.01)]. The enhanced exercise performance resulted in a significantly greater increase in both the growth hormone and testosterone concentrations, indicating an augmented anabolic hormone response to creatine supplementation.
... Few studies have reported the short-term (Ͻ1 wk) effects of Cr supplementation on dynamic and constant resistance exercise (3). For instance, Volek et al. (37) showed that shortterm Cr supplementation resulted in a significant improvement in the highest recorded peak power output achieved for a single repetition during all 5 sets of jump squats and a significant improvement in the number of repetitions during bench presses. To the authors' knowledge, no studies have reported the short-term (Ͻ1 wk) effects of Cr supplementation on the power output generated during maximal repetitive muscle contractions of the lower-and upper-extremity muscles in two resistance exercises with training loads typically undertaken by athletes (i.e., bench-press and halfsquat exercises; 60 -70% of 1RM). ...
... The present study demonstrated that in trained subjects Cr supplementation significantly enhanced maximal repetitive power production during sets of bench-press and half-squat resistance exercises. This confirms the finding of Volek et al. (37) with jump squats and Greenhaff et al. (11) with isokinetic knee-extension contractions that short-term Cr supplementation may improve muscle power output during repetitive bouts of resistance exercise (39). Although muscle creatine concentration was not measured in the present study, the increased ability of the Cr group to perform a greater total lifting volume and generate more total average muscle power suggests that creatine loading appears to enhance muscular performance during intermittent resistance exercise. ...
... With few exceptions, the majority of studies have reported increases in body mass of 0.5-3.0 kg after short-term Cr supplementation (4,24,27,33,37). A possible mechanism underlying shortterm Cr-induced increase in body mass are increases in water retention in the intramuscular space (16) as a result of the cellular transport of Cr with Na ϩ (16). ...
To determine the effects of creatine (Cr) supplementation (20 g x d(-1) during 5 d) on maximal strength, muscle power production during repetitive high-power-output exercise bouts (MRPB), repeated running sprints, and endurance in handball players.
Nineteen trained male handball players were randomly assigned in a double-blind fashion to either creatine (N = 9) or placebo (N = 10) group. Before and after supplementation, subjects performed one-repetition maximum half-squat (1RM(HS) and bench press (1RM(BP)), 2 sets of MRPB consisting of one set of 10 continuous repetitions (R10) followed by 1 set until exhaustion (R(max)), with exactly 2-min rest periods between each set, during bench-press and half-squat protocols with a resistance equal to 60 and 70% of the subjects' 1RM, respectively. In addition, a countermovement jumping test (CMJ) interspersed before and after the MRPB half-squat exercise bouts and a repeated sprint running test and a maximal multistage discontinuous incremental running test (MDRT) were performed.
Cr supplementation significantly increased body mass (from 79.4 +/- 8 to 80 +/- 8 kg; P < 0.05), number of repetitions performed to fatigue, and total average power output values in the R(max) set of MRPB during bench press (21% and 17%, respectively) and half-squat (33% and 20%, respectively), the 1RM(HS) (11%), as well as the CMJ values after the MRPB half-squat (5%), and the average running times during the first 5 m of the six repeated 15-m sprints (3%). No changes were observed in the strength, running velocity, or body mass measures in the placebo group during the experimental period.
Short-term Cr supplementation leads to significant improvements in lower-body maximal strength, maximal repetitive upper- and lower-body high-power exercise bouts, and total repetitions performed to fatigue in the R(max) set of MRPB, as well as enhanced repeated sprint performance and attenuated decline in jumping ability after MRPB in highly trained handball players. Cr supplementation did not result in any improvement in upper-body maximal strength and in endurance running performance.
... Resistance training programs have been shown to increase muscle mass and strength in older men and women (Fiatarone and Evans 1993;Fiatarone et al. 1994;Frontera et al. 1991;Grimsby 1986;Häkkinen 1994;Treuth et al. 1994). A number of studies on creatine supplementation have demonstrated increased dynamic muscular strength and power in young men (Krieder et al. 1997;Volek et al. 1997Volek et al. , 1999, and young women (GreenhaV et al. 1993;GrindstaV et al. 1997;Vanderberghe et al. 1997). A few studies have examined the eVects of creatine supplementation on muscle mass, strength and power in older adults, with varying results. ...
... Failure to detect a statistically signiWcant eVect of creatine supplementation on performance in older adults may partially be attributed to insuYcient reliability of testing protocols (Bermon et al. 1998). Several (Wve or more) familiarization sessions are critical to establish a control for day-to-day variability and the reliability of maximal eVort performances in order to detect statistically signiWcant eVects of a particular intervention (Gotshalk et al. 2002), especially regarding creatine supplementation because the increases are typically 5-10% (GreenhaV et al. 1993;Volek et al. 1997). Only the Gotshalk et al. (2002) study has attempted to assess how increases in maximal exercise performance after creatine supplementation translate into performance of activities of day-to-day living. ...
... Compared with a PL group having similar physical characteristics, the CR group showed small, but signiWcant, increases in upper-and lower-body dynamic strength and mean explosive power as well as lower extremity functional capacity. These outcomes are similar to those found in our previous study of older men (Gotschalk et al. 2002) and responses reported in younger men and women (Volek et al. 1997(Volek et al. , 1999Balsom et al. 1992;Birch et al. 1994;GreenhaV et al. 1994). This study is the Wrst to demonstrate that in older women, short-term creatine supplementation increases overall body strength and power. ...
Muscle power and strength decrease with age leading to reduced independence and increased health risk from falls. Creatine supplementation can increase muscle power and strength. The purpose of this study was to examine the effects of 7 days of creatine supplementation on body composition, muscular strength, and lower-body motor functional performance in older women. Thirty 58-71 year old women performed three test sessions (T1-T3) each separated by one week. Each session consisted of one repetition maximum tests for bench press and leg press, and isometric hand-grip, tandem gait, upper-body ergometer, and lower-body ergometer tests. Following T2, subjects were assigned to a creatine monohydrate (0.3 g kg body mass(-1) for 7 days) (CR: 63.31 +/- 1.22 year, 160.00 +/- 1.58 cm, 67.11 +/- 4.38 kg) or a placebo (PL: 62.98 +/- 1.11 year, 162.25 +/- 2.09 cm, 67.84 +/- 3.90 kg) supplementation group. CR significantly (P < 0.05) increased bench press (1.7 +/- 0.4 kg), leg press (5.2 +/- 1.8 kg), body mass (0.49 +/- 0.04 kg) and fat free mass (0.52 +/- 0.05) and decreased completion time on the functional tandem gait tests from T2-T3. No significant changes were found for PL on any of the measured variables. No adverse side-effects were reported by either group. Short-term creatine supplementation resulted in an increase in strength, power, and lower-body motor functional performance in older women without any adverse side effects.
... Few studies evaluating the effects of creatine supplementation on performance have, however, included additional analysis of hormonal responses on consecutive days and these have produced conflicting results. Volek et al. (1997) assessed circulating testosterone and cortisol concentrations immediately post-exercise (five sets of bench presses and jump squats) in creatine (25 g/d for seven days) and placebo supplemented subjects and found no effect. Schedel et al. (2000), however, found increased serum growth hormone (GH) concentrations (83%) in response to a 20 g oral creatine bolus. ...
... For example, Op't Eijnde and Hespel (2001) found that creatine supplementation (20 g/day for five days) could not alter cortisol and GH responses to a single bout of heavy resistance exercise. Moreover, Volek et al. (1997) assessed testosterone and cortisol immediately post-exercise (five sets of bench presses and jump squats) in creatine (25g/day for seven days) and placebo-supplemented subjects, and found no effect of creatine on testosterone and cortisol hormones status. Results of this study and previous data indicate that it is unlikely that creatine supplementation is hormonally mediated. ...
THE EFFECTS OF CREATINE SUPPLEMENTATION ON SPRINT
RUNNING PERFORMANCE AND SELECTED HORMONAL RESPONSES
Hassan FARAJI*, Hamid ARAZI**, Dariush SHEIKHOLESLAMI VATANI ***
& Mehdi HAKIMI**
* Department of Physical Education & Sport Science, Islamic Azad University Marivan
Branch, Marivan, Iran
**Faculty of Physical Education and Sport Science, University of Guilan, Rasht, Iran
***Department of Physical Education & Sport Science, University of Kurdistan,
Sanandaj, Iran
ABSTRACT
The purpose of this study was to determine the influence of short-term creatine
supplementation on sprint running performance (100 and 200 m) and circulating
hormone [growth hormone (GH), testosterone and cortisol] concentrations. Twenty
amateur male runners were randomly divided into a creatine supplementation
group, or placebo group. Subjects were provided with capsules containing either
creatine monohydrate or identical powdered cellulose placebo. Daily creatine
monohydrate supplementation was 20 g/day parceled into three equal dosages to be
consumed with each major meal. Subjects were tested for performance and resting
blood hormone concentrations before and after six days. A double-blind research
design was employed in this study. After this creatine loading, the mean running
performance time of the creatine supplementation group decreased significantly in
the 100 m, but not the 200 m. Serum GH, testosterone, and cortisol concentrations
were not affected by creatine supplementation. It can therefore be concluded that
although short-term creatine supplementation was found to improve sprint
performance in the 100 m in amateur runners, this performance improvement did not
appear to be hormonally mediated.
Key words: Sprint performance; Creatine supplementation; Hormonal
responses; Creatine loading.
... Few studies evaluating the effects of creatine supplementation on performance have, however, included additional analysis of hormonal responses on consecutive days and these have produced conflicting results. Volek et al. (1997) assessed circulating testosterone and cortisol concentrations immediately post-exercise (five sets of bench presses and jump squats) in creatine (25 g/d for seven days) and placebo supplemented subjects and found no effect. Schedel et al. (2000), however, found increased serum growth hormone (GH) concentrations (83%) in response to a 20 g oral creatine bolus. ...
... For example, Op't Eijnde and Hespel (2001) found that creatine supplementation (20 g/day for five days) could not alter cortisol and GH responses to a single bout of heavy resistance exercise. Moreover, Volek et al. (1997) assessed testosterone and cortisol immediately post-exercise (five sets of bench presses and jump squats) in creatine (25g/day for seven days) and placebo-supplemented subjects, and found no effect of creatine on testosterone and cortisol hormones status. Results of this study and previous data indicate that it is unlikely that creatine supplementation is hormonally mediated. ...
The purpose of this study was to determine the influence of short-term creatine supplementation on sprint running performance (100 and 200 m) and circulating hormone [growth hormone (GH), testosterone and cortisol] concentrations. Twenty amateur male runners were randomly divided into a creatine supplementation group, or placebo group. Subjects were provided with capsules containing either creatine monohydrate or identical powdered cellulose placebo. Daily creatine monohydrate supplementation was 20 g/day parceled into three equal dosages to be consumed with each major meal. Subjects were tested for performance and resting blood hormone concentrations before and after six days. A double-blind research design was employed in this study. After this creatine loading, the mean running performance time of the creatine supplementation group decreased significantly in the 100 m, but not the 200 m. Serum GH, testosterone, and cortisol concentrations were not affected by creatine supplementation. It can therefore be concluded that although short-term creatine supplementation was found to improve sprint performance in the 100 m in amateur runners, this performance improvement did not appear to be hormonally mediated.
... To our knowledge, few studies investigated the effects of short term (e.g., 5 and 7 days) Cr supplementation on anabolic and catabolic hormones. For example, Volek et al. [3] compared testosterone and cortisol concentrations between Cr and placebo groups and found no Cr effect on endocrine status at immediately after-resistance exercise. ...
... The increase of testosterone secretion and decrease of cortisol secretion according to results of current investigation are not in agreement with previous authors who examined effects of Cr supplementation on hormonal responses. Volek et al. [3] found no significant alteration in endocrine status after Cr supplementation to resistance exercise. The reason of this discrepancy could be differing in blood sampling. ...
Introduction: The purpose of this study was to examine the effects of 3, 5 and 7 days of creatine loading coupled with resistance exercise on resting testosterone and cortisol concentrations, systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), heart rate and rate pressure product (RPP). These measures were compared to those in placebo group. Summary of facts: Twenty active males were randomly assigned to either a creatine group (Cr) or placebo group (Pl). Participants performed resistance exercises at day 3, 5, and 7; and also tested at day 4, 6, and 8. Subjects of the Cr group showed significant increases in testosterone concentrations and decreases in cortisol concentrations, in comparison with Pl and baseline, after 5 and 7 days of Cr loading (P< 0.05). There were no significant changes in heart rate, SBP, DBP, MAP, and RPP for both groups at all times (P > 0.05). Conclusion: Results of the present study suggest that more than 5 days of creatine supplementation, associated with resistance exercises is sufficient for increasing testosterone concentrations and decrement in cortisol concentrations.
... However, creatine possibly binds to intracellular components, which may further facilitate muscle creatine retention (Walker, 1979). Creatine is an osmotically active substance; thus an increase in intracellular creatine concentration induces the influx of water into cells (Volek et al, 1997). ...
... Another study by Volek et al (1997), on 13 healthy resistance trained men, reported a 1.3kg ...
... Creatine is an osmotically active substrate; thus an increase in intracellular total creatine concentration as free creatine and phosphocreatine may induce the influx of water into the cell, increasing intracellular water and, concomitantly, body mass (Volek et al. 1997a(Volek et al. , 1997b. ...
... Moreover, some research suggests that increased cellular hydration and/or increased phosphocreatine may stimulate protein synthesis or decrease protein degradation, possibly increasing fat free mass (Volek and Kraemer 1996;Clark 1997;Volek et al. 1997aVolek et al. , 1997b. ...
... La creatina es una molécula osmóticamente activa. Como se ha indicado anteriormente, ello significa que si la ingestión de creatina se acompaña de un aumento significativo de la concentración muscular de creatina, se puede esperar que este aumento provocará un paso de agua al interior de la célula muscular, aumentando el volumen de líquido intracelular del organismo y, por lo tanto, provocando un aumento del peso corporal 45 . En los siguientes párrafos se analizarán los trabajos que han estudiado los efectos de la administración de creatina en el peso corporal. ...
... Sin embargo, la retención de agua no puede explicar completamente el aumento del peso corporal. Algunos autores sugieren que la ingestión aguda de creatina podría estimular la síntesis diaria de cerca de 1 gramo de proteina por Kg de peso muscular 4,106 , y favorecer el aumento de la fuerza 45 . Este aumento de la síntesis proteica no parece estar asociado con una mayor producción de testosterona (hormona anabolizante) 78,121 , aunque podría estar asociado con una mayor producción de la hormona de crecimiento en las horas posteriores a la ingestión de creatina 122,123 , o con un aumento de la concentración muscular de la hormona IGF-I 124 . ...
... Creatine is an osmotically active substrate; thus an increase in intracellular total creatine concentration as free creatine and phosphocreatine may induce the influx of water into the cell, increasing intracellular water and, concomitantly, body mass (Volek et al. 1997a(Volek et al. , 1997b. ...
... Moreover, some research suggests that increased cellular hydration and/or increased phosphocreatine may stimulate protein synthesis or decrease protein degradation, possibly increasing fat free mass (Volek and Kraemer 1996;Clark 1997;Volek et al. 1997aVolek et al. , 1997b. ...
A variety of studies using both humans and animals have shown that the rate of protein synthesis is generally depressed during exercise. After exercise, protein synthesis increases for periods up to 48 hours before declining to baseline values. Human muscle can oxidize at least seven amino acids. Of these amino acids, however, oxidation of only the branched chain amino acids (leucine, isoleucine, and valine) appears to be increased during catabolic states such as exercise. Recent scientific studies indicate that for physically active individuals the recommended daily protein intake should be as high as 1.6-1.8 gkg-1. However, testimonials from athletes who believe that their success depends on consumption of large amounts of protein and energy suggest that additional research is necessary before the question of protein need in those attempting to increase lean mass is settled. Despite recommended protein requirements, special protein supplementation is unnecessary for most who consume a varied diet containing complete protein foods, assuming energy intake is sufficient to match the additional expenditures of training and competition. There is evidence that ingestion of oral essential amino acids results in a change from net muscle protein degradation to net muscle protein synthesis after heavy resistance exercise in humans similar to that seen when the amino acids were infused. Moreover, there is some evidence that the response of net muscle protein synthesis to consumption of an oral essential amino-acid carbohydrate solution immediately before exercise is greater than when the solution is consumed after exercise.
... Considering that creatine supplementation is thought to improve the quality of the workout, it may have important implications to endocrine function and influence on muscle remodeling. Although limited research has indicated that creatine supplementation does not influence the acute responses to an exercise stress (26,37), its' ability to change resting hormonal concentrations is less understood. Volek and colleagues have indicated that alterations in resting hormonal concentrations are unable to explain performance and body composition changes during a 4 wk resistance training program (39). ...
... No significant changes were seen during the 10 wk training program in any of the power performance measures for C, CA, or P. Although creatine supplementation has been shown to significantly enhance power performance (4,8,17,37), in most of those studies the power performance measures were often part of the subjects' normal training regimen. One study (4) has shown significant improvements in a power assessment (Wingate Anaerobic Power Test) when that exercise was not part of the training program. ...
The effects of creatine and creatine plus beta-alanine on strength, power, body composition, and endocrine changes were examined during a 10-wk resistance training program in collegiate football players. Thirty-three male subjects were randomly assigned to either a placebo (P), creatine (C), or creatine plus beta-alanine (CA) group. During each testing session subjects were assessed for strength (maximum bench press and squat), power (Wingate anaerobic power test, 20-jump test), and body composition. Resting blood samples were analyzed for total testosterone, cortisol, growth hormone, IGF-1, and sex hormone binding globulin. Changes in lean body mass and percent body fat were greater (P < 0.05) in CA compared to C or P. Significantly greater strength improvements were seen in CA and C compared to P. Resting testosterone concentrations were elevated in C, however, no other significant endocrine changes were noted. Results of this study demonstrate the efficacy of creatine and creatine plus beta-alanine on strength performance. Creatine plus beta-alanine supplementation appeared to have the greatest effect on lean tissue accruement and body fat composition.
... Our results support previous research that reported a significant elevation in resting testosterone concentration [45,46] after Cr loading and no alteration following BA supplementation [21]. In contrast, some studies have shown that Cr loading did not change hormonal status [47,48]. Furthermore, the implications of a small rise in endogenous levels of testosterone on muscle adaptations are controversial and may only play a minor role [49]. ...
The purpose was to investigate the effects of a 7-day creatine (Cr) loading protocol at
the end of four weeks of β-alanine supplementation (BA) on physical performance, blood lactate,
cognitive performance, and resting hormonal concentrations compared to BA alone. Twenty male
military personnel (age: 21.5 ± 1.5 yrs; height: 1.78 ± 0.05 m; body mass: 78.5 ± 7.0 kg; BMI:
23.7 ± 1.64 kg/m2
) were recruited and randomized into two groups: BA + Cr or BA + placebo (PL).
Participants in each group (n = 10 per group) were supplemented with 6.4 g/day of BA for 28 days.
After the third week, the BA + Cr group participants were also supplemented with Cr (0.3 g/kg/day),
while the BA + PL group ingested an isocaloric placebo for 7 days. Before and after supplementation,
each participant performed a battery of physical and cognitive tests and provided a venous blood
sample to determine resting testosterone, cortisol, and IGF-1. Furthermore, immediately after the
last physical test, blood lactate was assessed. There was a significant improvement in physical
performance and mathematical processing in the BA + Cr group over time (p < 0.05), while there
was no change in the BA + PL group. Vertical jump performance and testosterone were significantly
higher in the BA + Cr group compared to BA + PL. These results indicate that Cr loading during the
final week of BA supplementation (28 days) enhanced muscular power and appears to be superior
for muscular strength and cognitive performance compared to BA supplementation alone.
... Over the 28-day period of the study, there were no significant within group or between group changes in sAA or cortisol. The lack of an impact on the stress hormones tested is in line with earlier published research examining similar parameters [18,32]. One study did find that providing 20 grams of creatine monohydrate daily along with exercise may have an impact on cortisol levels, however, the current study used a dose that was 25% that of the tested dose [33]. ...
Creatine monohydrate is a popular ergogenic aid used by athletes, adolescents and older individuals. There are various forms of creatine supplements that are on the market, however, creatine monohydrate is the most popular. Creatine itself is considered as less stable in solution when left in solution over time. Advances in product development and science may allow for a more stable aqueous solution of creatine. One major concern of ready-to-drink creatine supplements is the potential adverse gastrointestinal effects. In this randomized, double-blind, placebo-controlled design, the potential gastrointestinal effects of stabilized creatine (CreaBev®) as compared to standard creatine monohydrate versus control was tested. Subjects were randomly assigned to receive the CreaBev® supplement, creatine monohydrate supplement or no supplement (control). Subjects were instructed to consume one serving of the supplement (delivering 5 gm creatine) on a daily basis for 28 days. Subjects underwent baseline testing and end of study testing. The Severity of Dyspepsia Analysis (SODA) questionnaire and National Institutes of Health (NIH) Cognitive Test Toolbox were used to evaluate GI effects and cognition. Additional testing included body composition analysis (including fluid balance), and exploratory measurement of the stress biomarkers, salivary alpha amylase and cortisol. Following the consumption of CreaBev, no adverse gas-trointestinal side effects were reported. Cognition via the Dimension Change Test significantly improved (pre: 104 ± 14 to post: 116 ± 14; p = 0.0017) in the CreaBev group. There was no observed differences in total body fluid status over the 28 days between the groups (p > 0.05) No significant differences in levels of salivary alpha amylase, cortisol and anthropometrics were observed. The use of CreaBev did not cause any adverse GI effects and improved cognitive performance on the Dimension Change Test.
... In addition, the results of Cooke et al. [13] showed that consuming creatine monohydrate and carbohydrates does not significantly change IGF-1 and testosterone levels in older men. In contrast, the results of Volek et al. [39] did not show any significant changes in the status of endocrine hormones after taking creatine supplement with RT. The reason for these differences may be different blood sampling methods, as well as the training status of the subjects, which slows down the rate of changes in the anabolic hormones. ...
Study aim: The aim of this study to determine whether creatine ethyl ester (CEE) supplementation combined with resistance training (RT) is effective for improving hormonal changes, body composition and muscle strength in underweight non-athlete men.
Materials and methods: Sixteen underweight non-athlete men participated in this double-blind study and were randomly assigned to one of two groups: RT with placebo (RT + PL, n = 8) and RT with CEE supplementation (RT + CEE, n = 8). The participants performed 6 weeks of RT (60–80% 1RM) combined with CEE or PL. 48 hours before and after the training period, muscle strength (1RM for leg press and bench press), body composition (percentage of body fat, circumference measurements of the arm and thigh), serum levels of testosterone, cortisol, and growth hormone (GH) of the participant were measurements.
Results: Significant increases were observed for weight, muscle strength and muscle mass, serum levels of testosterone and GH between pre and post-test in the RT + CEE group (p < 0.05). In addition, cortisol level was significantly decreased in the post-test in the RT+CEE group. The decrease in fat percent was greater in the RT + PL group than in the RT + CEE group (%change = –6.78 vs. –0.76, respectively). Weight and leg strength changes in the RT + CEE group were significant compared to the RT + PL group (p < 0.001, p = 0.05, p = 0.001; respectively). However, in other variables, despite the increase of GH and testosterone levels and lower levels of cortisol in the RT + CEE group, no significant differences were observed between the two groups (p < 0.05).
Conclusion: It seems that the consumption of CEE combined with RT can have significant effects on body weight and leg strength in underweight non-athlete men. This supplement may provide a potential nutritional intervention to promote body weight in underweight men.
... transport [90]. In addition, a plethora of studies were published in the 1990s and beyond examining the ergogenic effects of creatine supplementation on muscle performance [91][92][93]. ...
The history of resistance training research began with anecdotal ideas and a slow growth of research from the late 1890s through the 1970s. The mid-1970s were a nexus point when resistance training studies evolved from just strength assessments to importance in physiological systems, physical health, and physical performance capabilities for individuals interested in physical fitness through to those seeking elite athletic performances. The pursuit of understanding program design and what mediated successful programs continues today as new findings, replication of old concepts, and new visions with the latest technologies fuel both our understanding and interest in this modality. This brief review highlights some of the important scientific contributions to the evolution of our scientific study of resistance training and provides a literature base analysis for greater quantification of the origins and expanse of such investigations.
... Tomando-se como base que 95% dos estoques da creatina total são encontrados no músculo esquelético, sendo 60 -70% depositados na forma de CP, a retenção de água intramuscular pode representar a maior parte do aumento da MCM (HAUSSINGER et al, 1993;VOLEK et al, 1997ae VOLEK et al, 1997bZIEGENFUSS et al, 1997;PODEWILS et al, 1998). Apesar da discussão sobre a suplementação aguda (a curto prazo) alterar a MCT e MCM ainda não estar totalmente definida, ganhos de massa muscular podem ser ergogênicos para alguns grupos, como levantadores de peso e idosos (CHRUSCH et al, 2001;GOTSHALK et al, 2002), mas contraproducentes (ergolíticos) para outros, como corredores de distância, lutadores e ciclistas (MUJIKA et al, 1996;MISZKO et al, 1998;SMART et al, 1998) exploring the role of the creatine kinase/phosphocreatine system in human muscle. ...
The aim of the present study was to investigate the effect of a high dose,
short-duration oral creatine supplementation on anaerobic power and morfofunctional
profile of 20 (n=20) male off-road cyclists. A double-blind design was used and the
athletes were randomly assigned into 2 groups: placebo (PLA = 10) and creatine
(CRE = 10). The tests were split in two days. On the first day, subjects performed two
tests, heart rate variability and aerobic power output. On the second day they were
submitted to anthropometric evaluation, underwater weighing and Wingate Anaerobic
Test. The oral supplements (creatine and malthodextrine) were taken in sweetened
vehicle, during 7 days, in three equal doses per day (0, 1 g/kg body mass/dose).
After seven-day period, the athletes returned to the laboratory to post-treatment tests
(PÓS). Student t-test showed significant differences on skinfold sum between PRÉ
and PÓS tests (P<0,05), without differences between groups. Total body mass
(MCT) and lean tissue mass (MCM) increased in CRE group (0,5% and 1,1%), while
the PLA group showed decreases (-0,7% and -1,1%). The percentual of fat
(GORD%) and fat mass (GORD) decreased for both groups (CRE, 9,2% and 15,4%)
and (PLA, 4,0% and 10,1%). The CRE group showed increases for power output
(P<0,01) and decreases for fatigue index (P<0,05) between PRÉ and PÓS tests,
however, no significant differences were observed between groups for power output,
mean power and fatigue index. The only variable that differs between groups was the
peak power moment (P<0, 01). The results of the present study indicates that the
short-term creatine supplementation leads to significant improvements on power
output (CRE, PRÉ 11,26 ± 0,46 / PÓS 11,69 ± 0,51 ∆% =3,81) and (PLA, PRÉ 11,28
± 0,74 /11,27 ± 0,51 ∆% =-1,24%), fatigue index (CRE, PRÉ 36,06± 6,53/ PÓS 33,33
± 7,52 ∆% = -7,57%) and (PLA, PRÉ 36,71 ± 5,41/ 36,61 ± 6,06 ∆% = -0,27) and
peak power moment in off-road cyclists. Attention must be paid to the high values for
both aerobic and anaerobic power as well as for anaerobic threshold obtained by
these athletes
... Creatine is produced in amounts sufficient for the body by the liver, kidneys and pancreas (10). It facilitates the conversion of adenosine diphosphate (ADP) to adenosine triphosphate (ATP), thus increasing the free energy available for muscle activity (43), increases strength and power (7,36,51); increases sprint and high intensity performance (68), increases fat free mass (16), improves recovery (53), prevents muscle damage (6), and decreases oxidative stress induced by exercise (21), but numerous studies suggest that is has no benefits at all (11,23,24,27,29,46). However, the use of this supplement has stipulated concerns about its safety, especially kidney function (38) and increased oxidative stress (54). ...
Introduction: The purpose of the study was to determine the prevalence of dietary supplement use, types of physical activities, and aims of supplements users and non-users, knowledge about their side effects, and changes reported due to dietary supplements use in the suburbs of Beirut, Lebanon. Methods: 220 male participants between the ages of 15 and 53 completed a questionnaire on the ingestion of dietary supplements and knowledge about their benefits and side effects. The study population was drawn from seven health and fitness clubs located in the suburbs of Beirut city. Results: Out of the 220 participants, 109 (49.5%) reported taking supplements; protein shakes were the most consumed (49.5%). Participants mainly engaged in strength exercises (56.7%), and users of dietary supplements were found to practice more than non-users (2.8 vs 2.18 d/wk; 1.29 vs 1.13 hr/d). Users of dietary supplements mainly performed physical activity to build muscles while non-user aims were mainly to improve fitness and performance and to lose weight. Participants sought knowledge regarding dietary supplement use from the internet (24.6%), friends (21.1%), or coaches and personal trainers (24.6%), and rarely from licensed dietitians (1.8%). The greatest difference reported after the use of supplements was improved performance and muscle growth (12.8%). Knowledge about supplements was rated to be low and inaccurate, as 57.8% believed supplements have no side effects and 16.5% did not know what the side effects were. Conclusion: There is limited data on dietary supplement use from males in Beirut, Lebanon. This study provides data to contribute to the awareness on the use of dietary supplements specific to this population.
... This effect, however, was not related to an increase in body weight. Although several groups reported that creatine induces body weight gain in humans (Harris, 1992;Volek et al., 1997a;Engelhardt et al., 1998;Peeters et al., 1999;Kelly and Jenkins, 1998;Mihic et al., 2000;Volek et al., 1999;Mujika et al., 2000;Volek et al., 2001), others did not show any significant change in body mass in humans (Redondo et al., 1996) or Sprague-Dawley rats (Brannon et al., 1997;McKenna et al., 1999;McMillen, 2001). These discrepancies may result from protocol differences, doses of creatine, type and duration of the exercise. ...
Creatine has been shown to increase the total muscle mass. In this study, we investigated the effect of oral creatine monohydrate supplementation on cross-sectional area of type I, IIA and IIB fibers of gastrocnemius, extensor digitorum longus - EDL and soleus muscles from male Wistar rats subjected to swimming training for 33 days. Four groups were set up: sedentary with no supplementation (CON), sedentary with creatine supplementation (3.3 mg creatine per g chow) (CR), exercised with no supplementation (EX) and exercised with supplementation (CREX). The rats performed in a special swimming pool and swam five times a week for 1 hour each day, with a extra lead weight corresponding to 15% of their body weight. At the end of 33 days, skeletal muscles of the animals were dissected and the samples got immediately frozen using liquid nitrogen. Muscle samples were allocated to slices of 10 μm by a cryostat at -20°C, which was followed by histochemical analysis in order to identify fiber types of the muscles, and morphometrical analysis to calculate the muscle fiber areas. All groups gained body weight at the end of 33 days but there was no statistical difference among them. The EX and CREX rats had a larger food intake than the sedentary groups (CON and CR), and the CREX group had a larger food intake than CR rats. The cross-sectional area of type I and IIA fibers of the soleus muscle, type IIA and IIB fibers of EDL muscle and type IIA and IIB fibers of the white portion of gastrocnemius muscle were greater in the EX and CREX groups in comparison to sedentary rats. In addition, these fibers were greater in the CREX rats than in the EX group. There was no change in the cross sectional area of type I fibers in EDL muscle among all groups studied. Our results suggest that creatine supplementation enhances the exercise related muscle fiber hypertrophy in rodents.
... First, the loading dose (20 g·day -1 for 4-d) may not be adequate to achieve maximal increase in TCr concentrations. Majority of research report loading phases of 20-30 g·day -1 for 5- 7-d (Hultman et al., 1996; Volek et al., 1997a; Snow et al., 1998; Francaux and Poortmans, 1999; Finn et al., 2001; Wilder et al., 2001; Louis et al., 2003). Secondly, the subjects undertook no dietary control. ...
During the past decade, the nutritional supplement creatine monohydrate has been gaining popularity exponentially. Introduced to the general public in the early 1990s, shortly after the Barcelona Olympic Games, creatine (Cr) has become one of the most widely used nutritional supplements or ergogenic aids, with loading doses as high as 20-30 g·day(-1) for 5-7 days typical among athletes. This paper reviews the available research that has examined the potential ergogenic value of creatine supplementation (CrS) on exercise performance and training adaptations. Short-term CrS has been reported to improve maximal power/strength, work performed during sets of maximal effort muscle contractions, single-effort sprint performance, and work performed during repetitive sprint performance. During training CrS has been reported to promote significantly greater gains in strength, fat free mass, and exercise performance primarily of high intensity tasks. However, not all studies demonstrate a beneficial effect on exercise performance, as CrS does not appear to be effective in improving running and swimming performance. CrS appears to pose no serious health risks when taken at doses described in the literature and may enhance exercise performance in individuals that require maximal single effort and/or repetitive sprint bouts.
... Because of the critical functions of hormones, study has investigated various plans to enhance the exercise-endocrine interaction. Volek et al. [18] tested testosterone and cortisol levels immediately after-exercise (five sets of bench presses and jump squats) in creatine (25 g/d for 7 d) and placebo-supplemented subjects, and found no effect of creatine on endocrine status. Schedel et al. [19], however, found increased growth hormone levels (83%) in response to a 20 g oral creatine bolus. ...
Objectifs
Le but de cette étude était de déterminer l’influence à court terme d’une supplémentation en créatine sur la performance lors de sprints en natation (50 et 100 m) et sur les réponses hormonales (hormone de croissance, testostérone et le cortisol).
Méthodes
Vingt nageurs amateurs ont ingéré du monohydrate de créatine (CR) ou un placebo (PL) pendant six jours pendant lesquels ils ont poursuivi leur entraînement de natation. Les performances et les réponses hormonales ont été enregistrées le jour précédent et après cette période de charge orale en créatine.
Résultats
Le temps de nage moyen du groupe CR sur 50 m était significativement diminué (53,1 ± 3,73 secondes avant charge vs 50,7 ± 2,84 secondes après supplémentation). L’hormone de croissance et le cortisol n’ont pas été affectés par cette charge en créatine. En revanche, la concentration de testostérone était significativement plus élevée dans CR par rapport à PL après la période de supplémentation (p < 0,05).
Conclusion
Nos résultats suggèrent qu’une supplémentation de courte durée en créatine a amélioré de manière significative la performance lors de sprints sur 50 m chez des nageurs amateurs sans que l’on puisse imputer de manière objective une médiation hormonale.
... Results also became available showing that dietary nutrients (Volek et al. 1997b), a protein-carbohydrate supplement consumed 2 h before (Kraemer, W.J. et al. 1998b) or post-exercise nutrition (Bloomer et al. 2000) may influence the testosterone pattern in resistance training session or during the 24 h of recovery. Amino acid supplementation (Fry et al. 1993) or the administration of either creatine (Volek et al. 1997a;Op'Teijnde & Hespel 2001) or ginseng (Youl et al. 2002) failed to alter testosterone responses. ...
... However, there have been few studies investigating the effects of short-term creatine supplementation on anabolic hormones and these have produced confl icting results. For example, Volek, et al. (1997) assessed testosterone and cortisol immediately post-exercise (5 sets of bench presses and jump squats) in creatine (25 g/d for 7 days) and placebo-supplemented participants, and found no effect of creatine on the endocrine status. Schedel, et al. (2000), however, found increased growth hormone levels (83%) in response to a 20 g oral creatine bolus. ...
The purpose of this study was to determine the influence of short-term creatine supplementation on hormonal responses to resistance exercise. 27 trained men were randomly divided into a creatine supplementation group [the CR group (n=15), taking 4×5 g creatine monohydrate/day] or a placebo supplementation group [the PL group (n=12), taking 4×7.5 g maltodextrin/day]. A double-blind research design was employed for a 7-day supplementation period. After this period, the participants performed exercise testing. Blood tests occurred on day 1 prior to supplementation loading (1Pre) and after this period [on the exercise testing day: pre-exercise (Pre), immediately post-exercise (IP), and 15 (15P) and 30 (30P) minutes post-exercise] for the measurement of the serum growth hormone and testosterone concentrations. Significant differences in the number of repetitions and volume were seen with CR (7.2±1.3 repetitions, 1560±386 kg) compared to PL (5.6±2 repetitions, 1089±341 kg) at set 5 of the exercise protocol (p=.01). Serum growth hormone and testosterone were significantly higher at 15P in CR (6.1±1.8 ng/ml, 70.1±19 pmol/L) compared to PL (4.1±1.7 ng/ml, 44.8±16 pmol/L) [(p=.02), (p=.01)]. The enhanced exercise performance resulted in a significantly greater increase in both the growth hormone and testosterone concentrations, indicating an augmented anabolic hormone response to creatine supplementation.
... Tomando-se como base que 95% dos estoques da creatina total são encontrados no músculo esquelético, sendo 60 -70% depositados na forma de CP, a retenção de água intramuscular pode representar a maior parte do aumento da MCM (HAUSSINGER et al, 1993;VOLEK et al, 1997ae VOLEK et al, 1997bZIEGENFUSS et al, 1997;PODEWILS et al, 1998). Apesar da discussão sobre a suplementação aguda (a curto prazo) alterar a MCT e MCM ainda não estar totalmente definida, ganhos de massa muscular podem ser ergogênicos para alguns grupos, como levantadores de peso e idosos (CHRUSCH et al, 2001;GOTSHALK et al, 2002), mas contraproducentes (ergolíticos) para outros, como corredores de distância, lutadores e ciclistas (MUJIKA et al, 1996;MISZKO et al, 1998;SMART et al, 1998) exploring the role of the creatine kinase/phosphocreatine system in human muscle. ...
Com o objetivo de investigar os efeitos da suplementação aguda com creatina no desempenho da potência anaeróbia de atletas de elite do mountain bike, 20 atletas em período básico do macrociclo de treinamento foram distribuídos aleatoriamente (duplo-cego) em dois grupos: placebo (PLA, n = 10) e creatina (CRE, n = 10). Foram avaliados quanto à composição corporal (pesagem hidrostática) e potência anaeróbia (teste de Wingate - TW) antes (PRÉ) e depois (PÓS) de sete dias de suplementação. A creatina ou maltodextrina foi usada em três doses diárias de 0,3g/kg de massa corporal diluídos em meio líquido adoçado. Não foram observadas diferenças significativas nas variáveis morfológicas após sete dias de suplementação (PRÉ x PÓS), e os grupos não diferiram apesar da variação percentual (Δ%) contrária (positiva para o grupo CRE e negativa para o PLA). A potência anaeróbia pico (PP) e o instante da potência pico (IPP) aumentaram e o índice de fadiga diminuiu do PRÉ para o PÓS-testes no grupo CRE, enquanto que o grupo PLA não apresentou diferenças significantes. A PP apresentou forte tendência em ser maior e o IPP foi maior no grupo CRE comparado com o PLA. Conclui-se que existem evidências de que a suplementação com creatina (0,3g/kg) em curto prazo (sete dias) pode retardar o IPP (CRE 3,0 ± 0,5/3,6 ± 0,8 Δ%= 20%) no teste de Wingate em atletas de elite do mountain bike, sugerindo que a suplementação com creatina pode melhorar o desempenho físico quanto à potência anaeróbia durante o trabalho de alta intensidade e curta duração.
... Plasma cortisol concentrations increased significantly from rest in the present study in both groups, indicating similar glucoregulatory responses at the level of the adrenal gland under both conditions. Creatine supplementation did not have any effect on the cortisol response to cycle exercise in the heat, which is consistent with our prior study demonstrating no effect of creatine supplementation on the cortisol or testosterone response to heavy resistance exercise (36). Improved power output during repeated all-out cycling (Ͻ30 s) after short-term creatine supplementation is consistent with the findings of many (2,5,9) but not all (4,6,7) creatine studies. ...
This investigation was designed to examine the influence of creatine (Cr) supplementation on acute cardiovascular, renal, temperature, and fluid-regulatory hormonal responses to exercise for 35 min in the heat.
Twenty healthy men were matched and then randomly assigned to consume 0.3 g.kg(-1) Cr monohydrate (N = 10) or placebo (N = 10) for 7 d in a double-blind fashion. Before and after supplementation, both groups cycled for 30 min at 60-70% VO2(peak) immediately followed by three 10-s sprints in an environmental chamber at 37 degrees C and 80% relative humidity.
Body mass was significantly increased (0.75 kg) in Cr subjects. Heart rate, blood pressure, and sweat rate responses to exercise were not significantly different between groups. There were no differences in rectal temperature responses in either group. Sodium, potassium, and creatinine excretion rates obtained from 24-h and exercise urine collection periods were not significantly altered in either group. Serum creatinine was elevated in the Cr group but within normal ranges. There were significant exercise-induced increases in cortisol, aldosterone, renin, angiotensin I and II, atrial peptide, and arginine vasopressin. The aldosterone response was slightly greater in the Cr (263%) compared with placebo (224%) group. Peak power was greater in the Cr group during all three 10-s sprints after supplementation and unchanged in the placebo group. There were no reports of adverse symptoms, including muscle cramping during supplementation or exercise.
Cr supplementation augments repeated sprint cycle performance in the heat without altering thermoregulatory responses.
... In addition, these exercises have elicited the greatest acute hormonal responses (67). Deadlifts (25), squat jumps (105), and Olympic lifts (67) have produced greater acute 22-kDa growth hormone and testosterone responses compared with exercises such as the bench press and seated shoulder press. Thus, the amount of muscle mass involved in a movement significantly impacts the acute metabolic demands and anabolic hormonal response, which have direct implications for resistance training programs targeting improvements in local muscle endurance, lean body mass, and reductions in body fat. ...
Progression in resistance training is a dynamic process that requires an exercise prescription process, evaluation of training progress, and careful development of target goals. The process starts with the determination of individual needs and training goals. This involves decisions regarding questions as to what muscles must be trained, injury prevention sites, metabolic demands of target training goals, etc. The single workout must then be designed reflecting these targeted program goals including the choice of exercises, order of exercise, amount of rest used between sets and exercises, number of repetitions and sets used for each exercise, and the intensity of each exercise. For progression, these variables must then be varied over time and the exercise prescription altered to maintain or advance specific training goals and to avoid overtraining. A careful system of goal targeting, exercise testing, proper exercise technique, supervision, and optimal exercise prescription all contribute to the successful implementation of a resistance training program.
Creatine has become increasingly popular as a nutritional supplement among athletes both on a competitive and recreational level due to its potential "ergogenic" effects. This paper reviews the biochemical and scientific aspects of the creatine supplementation. Over the past several years many studies have suggested an improvement in performance during repetitive maximal and submaximal activities. On the contrary only few studies support the ability to improve performance measurably during competition. Recommendations for athletes considering creatine supplementation are described in a survey. Both clinicians and athletes should be aware thet the long term effects of creatine supplementation are unknown. At present, creatine is not listed as a banned substance by the International Olympic Committee (IOC).
The purpose of this study is to investigate how effects creatine dosage has on the improvement of rowing athletes` performance ability. Rowing athletes were administered with creatine, through which to examine the change of athletic performance ability, blood fatigue substances, and muscular activity. The subjects (participants) of this Study consisted of 12 male rowing athletes at P University, with at least 5 years of rowing experiences, which divided into two groups - creatine dosing group of 6 persons and control group of 6 persons - for random sampling measurement. Enzymatic-colorimetric method using lacrate oxidase and 4-aminoantipyrine was performed for blood lactate level analysis, and wireless EMG system (QEMG-4: Lxtha Korea) for muscular activity analysis, with 4 channels set for data analysis. As body parts to be measured, two muscular parts - latissimus dorsi and lumbar spinel - were chosen. Then, on the 5th day from the date of administering them with creatine (that is, 4 days after dosing them with creatine), rowing movement with the highest level of activity was calculated as peak value, which was measured twice. The test data used for this Study were SPSS/PC 18.0, pre-movement and post-movement two-way ANOVA for repeated measurement for comparative analysis of each muscle, with significant level at .05. As a result, the change of blood lactate level was significantly higher in creatine dosing group than in non-dosing group (p
Male infertility is caused by a variety of factors including anatomical and genetic abnormalities, but it is estimated that over 30 % of male infertility is of an unknown cause. The most likely contributors to idiopathic male infertility are life style and environmental factors such as poor diet, insufficient physical activity, exposure to toxins, and tobacco, alcohol and other substance abuse. This chapter describes the effects of common recreational and performance enhancing substance abuse such as marijuana, opioids, methamphetamine and ecstasy, cocaine, and creatine and steroids on male fertility. These drugs affect the testes, spermatozoa, and male fertility by negatively interfering with the hormones that are responsible for the proper regulation of the male reproductive system such as gonadotropin releasing hormone, luteinizing hormone, follicle stimulating hormone, and testosterone. Some of these drugs also interfere with spermatogenesis via direct testicular influence. It is therefore important to know, especially to those of the reproductive age wishing to have children, that abuse of these drugs and substances contribute to male infertility.
Creatine is an endogenous compound synthesized from arginine, glycine and methionine. This dietary supplement can be acquired from food sources such as meat and fish, along with athlete supplement powders. Since the majority of creatine is stored in skeletal muscle, dietary creatine supplementation has traditionally been important for athletes and bodybuilders to increase the power, strength, and mass of the skeletal muscle. However, new uses for creatine have emerged suggesting that it may be important in preventing or delaying the onset of neurodegenerative diseases associated with aging. On average, 30% of muscle mass is lost by age 80, while muscular weakness remains a vital cause for loss of independence in the elderly population. In light of these new roles of creatine, the dietary supplement's usage has been studied to determine its efficacy in treating congestive heart failure, gyrate atrophy, insulin insensitivity, cancer, and high cholesterol. In relation to the brain, creatine has been shown to have antioxidant properties, reduce mental fatigue, protect the brain from neurotoxicity, and improve facets/components of neurological disorders like depression and bipolar disorder. The combination of these benefits has made creatine a leading candidate in the fight against age-related diseases, such as Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, long-term memory impairments associated with the progression of Alzheimer's disease, and stroke. In this review, we explore the normal mechanisms by which creatine is produced and its necessary physiology, while paying special attention to the importance of creatine supplementation in improving diseases and disorders associated with brain aging and outlining the clinical trials involving creatine to treat these diseases.
Creatine supplementation is a widely used and heavily studied ergogenic aid. Athletes use creatine to increase muscle mass, strength, and muscle endurance. While the performance and muscle- building effects of creatine supplementation have been well documented, the mechanisms responsible for these muscular adaptations have been less studied. Objective: The purpose of this review is to examine studies of the mechanisms underlying muscular adaptations to creatine supplementation. Data sources: PubMed and SPORTDiscus databases were searched from 1992 to 2007 using the terms creatine, creatine supplementation, creatine monohydrate, and phosphocreatine. Study selection: Studies of creatine supplementation in healthy adults were included. Data extraction: Due to the small number of studies identified, a meta-analysis was not performed. Data synthesis: Several potential mechanisms underlying muscular adaptations to creatine supplementation were identified, including: metabolic adaptations, changes in protein turnover, hormonal alterations, stabilization of lipid membranes, molecular modifications, or as a general training aid. The mechanisms with the greatest amount of support (metabolic adaptations, molecular modifications, and general training aid) may work in concert rather than independently. Conclusions: Creatine supplementation may alter skeletal muscle directly, by increased muscle glycogen and phosphocreatine, faster phosphocreatine resynthesis, increased expression of endocrine and growth factor mRNA, or indirectly, through increased training volume. Keywords: dietary supplement, creatine monohydrate, phosphocreatine, muscle, sport nutrition
Purpose:
Long-term safety of creatine supplementation has been questioned. This retrospective study was performed to examine markers related to health, the incidence of reported side effects and the perceived training benefits in athletes supplementing with creatine monohydrate.
Methods:
Twenty-six athletes (18 M and 8 F, 24.7 +/- 9.2 y; 82.4 +/- 20.0 kg; 176.5 +/- 8.8 cm) from various sports were used as subjects. Blood was collected between 7:00 and 8:30 a.m. after a 12-h fast. Standard clinical examination was performed for CBC and 27 blood chemistries. Testosterone, cortisol, and growth hormone were analyzed using an ELISA. Subjects answered a questionnaire on dietary habits, creatine supplementation, medical history, training history, and perceived effects of supplementation. Body mass was measured using a medical scale, body composition was estimated using skinfolds, and resting heart rate and blood pressure were recorded. Subjects were grouped by supplementation length or no use: Gp1 (control) = no use (N = 7; 3 F, 4 M); Gp2 = 0.8-1.0 yr (N = 9; 2 F, 7 M); and Gp3 = 1(+) (N = 10; 3 F, 7 M).
Results:
Creatine supplementation ranged from 0.8--4 yr. Mean loading dose for Gp2 and Gp3 was 13.7 +/- 10.0 and the maintenance dose was 9.7 +/- 5.7 g.d(-)1. Group differences were analyzed using one-way ANOVA.
Conclusions:
Expected gender differences were observed. Of the comparisons made among supplementation groups, only two differences for creatinine and total protein (P < 0.05) were noted. All group means fell within normal clinical ranges. There were no differences in the reported incidence of muscle injury, cramps, or other side effects. These data suggest that long-term creatine supplementation does not result in adverse health effects.
This study examined the acute hormonal responses to a single high power resistance exercise training session. Four weight trained men (X ± SD; age [yrs] = 24.5 ± 2.9; hgt [m] = 1.82 ± 0.05; BW [kg] = 96.9 ± 10.6; 1 RM barbell squat [kg] = 129.3 ± 17.4) participated as subjects in two randomly ordered sessions. During the lifting session, serum samples were collected pre- and 5 min post-exercise, and later analyzed for testosterone (Tes), cortisol (Cort), their ratio (Tes/Cort), and lactate (HLa). The lifting protocol was 10 × 5 speed squats at 70% of system mass (1 RM + BW) with 2 min inter-set rest intervals. Mean power and velocity were determined for each repetition using an external dynamometer. On the control day, the procedures and times (1600-1900 h) were identical except the subjects did not lift. Tes and Cort were analyzed via EIA. Mean ± SD power and velocity was 1377.1 ± 9.6 W and 0.79 ± 0.01 m s-1 respectively for all repetitions, and did not decrease over the 10 sets (p < 0.05). Although not significant, post-exercise Tes exhibited a very large effect size (nmol L-1; pre = 12.5 ± 2.9, post = 20.0 ± 3.9; Cohen's D = 1.27). No changes were observed for either Cort or the Tes/Cort ratio. HLa significantly increased post-exercise (mmol L-1; pre = 1.00 ± 0.09, post = 4.85 ± 1.10). The exercise protocol resulted in no significant changes in Tes, Cort or the Tes/Cort ratio, although the Cohen's D value indicates a very large effect size for the Tes response. The acute increase for Tes is in agreement with previous reports that high power activities can elicit a Tes response. High power resistance exercise protocols such as the one used in the present study produce acute increases of Tes. These results indicate that high power resistance exercise can contribute to an anabolic hormonal response with this type of training, and may partially explain the muscle hypertrophy observed in athletes who routinely employ high power resistance exercise.
Dissertação (mestrado)—Universidade de Brasília, Faculdade de Ciências da Saúde, 2008. A creatina como suplementação nutricional tem se popularizado e sido indiscriminadamente utilizada por apresentar ganho de massa magra e melhora do desempenho de atividades que envolvam exercícios de curta duração e alta intensidade. Porém, as intercorrências advindas do seu uso não estão totalmente elucidadas. Os efeitos adversos, principalmente em relação à sobrecarga renal e/ou hepática, foram tratados neste estudo através de avaliações bioquímicas sobre uma amostra de 35 desportistas divididos em três grupos de consumo (PLA: placebo, CRE1: 0,03g de creatina por kg de massa corporal por dia e CRE2: 5g de creatina por dia) durante oito semanas de treinamento. Os voluntários foram avaliados, através de medidas antropométricas, quanto ao ganho de massa magra e composição corporal. Para avaliação da composição corporal utilizou-se o protocolo de sete dobras e os perímetros de braço e coxa. Os participantes foram submetidos a um programa de treinamentocom exercícios resistidos constituídos de três séries, variando entre 8 a 12 repetições em cada série, com intervalo de um minuto, quatro ou mais vezes por semana e não sofreram intervenção na composição de suas dietas, que foram registradas e analisadas. Houve ganho ponderal, de 2,1% (CRE1) e 3,5% (CRE2) e a massa corporal magra aumentou significativamente entre os grupos PLA–CRE1 e PLA–CRE2 (P<0,01). Entre o PRÉ e o PÓStreinamento foi registrado aumento das circunferências de braço tenso, coxa, circunferência muscular do braço e da perna e índice de massa magra do braço nos tratamentos CRE1 e CRE2 (P<0,01). Todos os resultados dos exames bioquímicos realizados permaneceram dentro das faixas de normalidade. Quanto à função renal a creatinina aumentou significativamente nos grupos suplementados com creatina, porém sem sair dos valores de normalidade. Os valores dos exames da função hepática diminuíram em quase todas as frações, em todos os tratamentos, entretanto sem significância estatística. Estes resultados contribuíram no esclarecimento dos efeitos advindos do uso de creatina, permitindo o uso mais seguro deste suplemento nutricional. Concluiu-se que ocorreu ganho de massa magra para os grupos suplementados com creatina, independentemente das dosagens oferecidas, e de forma segura, não encontrando efeitos adversos nas funções hepáticas e renais. _________________________________________________________________________________________ ABSTRACT The use of creatine as nutritional supplement has become popular and has been widely used because of its effect on mass gain and as a performance-enhancing supplement on short duration, high intensity exercises. The intercurrence of its usage has yet to be clarified. The adverse effects, especially in relation to kidney and liver overload, were treated on this study through biochemical analysis on 35 volunteers, divided in 3 study groups (PLA: Placebo, CRE1:daily ingestion 0,03g creatine/kg of bodyweight, CRE2: daily ingestion of 5g creatine/kg of bodyweight) during a 8 week period. The volunteers were submitted to anthropometric measurements in relation to muscle mass and body composition (skinfolds, arm and anterior thigh circumferences). The volunteers were in a resistance exercise program and did not have a dietary change (observed). The exercise program consisted in 3 sets, with 8 to 12 repetitions each, and a minute break between sets, 4 times a week. The overall gain was of 2.1% (CRE1) and 3.5% (CRE2) and the fat-free mass gain was significant among the supplemented groups compare to placebo (P<0.01). Between the pre and post treatments an increase in the arm and leg circumferences in both treatments CRE1 and CRE2 was found (P<0.01). All the biochemical tests made throughout the study were within the normality range. The kidney function had a significant increase with the creatine but without being abnormal. In relation to the liver function, it presented lower performance in all treatments without statistical significance. The results contributed to the enlightment on the usage of creatine supplementation allowing a safer use. In conclusion the fat-free mass increased in creatine supplemented groups, independent of the dosage used and in a safe manner without adverse affects on liver and kidney functions.
In this study, the effect of short-term creatine supplementation on the growth hormone, testosterone, and cortisol response to heavy resistance training was investigated.
According to a double-blind crossover study design, 11 healthy young male volunteers underwent a 1-h standardized heavy resistance training session (3 series of 10RM; 12 exercises), both before (pretest) and after (posttest) 5 d of either placebo (P, maltodextrine) or creatine (CR; 20 g.d-1, 5 d) supplementation. A 5-wk washout period separated the treatments. Thirty minutes before each training session, CR subjects ingested 10 g of creatine monohydrate (CR) while P subjects received placebo. Venous blood was sampled before, immediately after, and 30 and 60 min after the training session.
The exercise-induced increase (P < 0.05) of serum growth hormone was not altered by acute creatine intake and was similar in P and CR. The weight training session, either or not in conjunction with acute or chronic creatine intake, did not significantly impact on serum testosterone. However, serum cortisol during recovery tended to be higher in CR than in P.
It is concluded that short-term creatine supplementation does not alter the responses of growth hormone, testosterone, and cortisol to a single bout of heavy resistance training.
Creatine monohydrate (CrH2O) supplementation has been demonstrated to increase skeletal muscle power output in men. However, its effect upon women is not as clearly defined. This study investigated the effect of oral creatine supplementation upon muscle function, thigh circumference, and body weight in women. Twenty-two consenting college-age women were assigned to 1 of 2 groups matched for dietary and exercise habits, phase of menstrual cycle, and fat-free mass (FFM). After familiarization with testing procedures, pretrial measures of muscle function (5 repetitions 60 deg x s(-1) and 50 repetitions 180 deg x s(-1) were conducted during maximal voluntary concentric contraction of the preferred quadriceps muscle using an isokinetic dynamometer. Subjects then ingested 0.5 g x kg(-1) FFM of either CrH2O or placebo (one fourth dosage 4 times daily) in a double-blind design for 5 days. Resistance exercise was prohibited. After the ingestion phase was completed, all measures were repeated at the same time of day as during pretrials. Statistical analysis revealed time to peak torque in quadriceps extension decreased from pre-test values of 255 +/- 11 ms (mean +/- SEM) to post-test values of 223 +/- 3 ms; average power in extension increased from 103 +/- 7 W pre-test to 112 +/- 7 W post-test; and, during flexion, average power increased from 59 +/- 5 W pre-test to 65 +/- 5 W post-test in the creatine group as compared to controls (p .05). FFM, percent body fat, mid-quadriceps circumference, skinfold thickness of the measured thigh, and total body weight did not change for both groups between trials. We conclude that CrH2O improves muscle performance in women without significant gains in muscle volume or body weight.
OBJECTIVE: To compare the effects of low doses of creatine and creatine loading on strength, urinary creatinine concentration, and percentage of body fat. DESIGN AND SETTING: Division IA collegiate football players took creatine monohydrate for 10 weeks during a sport-specific, periodized, off-season strength and conditioning program. One-repetition maximum (1-RM) squat, urinary creatinine concentrations, and percentage of body fat were analyzed. SUBJECTS: Twenty-five highly trained, Division IA collegiate football players with at least 1 year of college playing experience. MEASUREMENTS: We tested strength with a 1-RM squat exercise before, during, and after creatine supplementation. Percentage of body fat was measured by hydrostatic weighing before and after supplementation. Urinary creatinine concentration was measured via light spectrophotometer at 0, 1, 3, 7, 14, 21, 28, 35, 42, 48, 56, and 63 days. An analysis of variance with repeated measures was computed to compare means for all variables. RESULTS: Creatine supplementation had no significant group, time, or interaction effects on strength, urinary creatinine concentration, or percentage of body fat. However, significant time effects were found for 1-RM squat and fat-free mass in all groups. CONCLUSIONS: Our data suggest that creatine monohydrate in any amount does not have any beneficial ergogenic effects in highly trained collegiate football players. However, a proper resistance training stimulus for 10 weeks can increase strength and fat-free mass in highly trained athletes.
To determine the effects of creatine supplementation during short-term resistance training overreaching on performance, body composition, and resting hormone concentrations, 17 men were randomly assigned to supplement with 0.3 g/kg per day of creatine monohydrate (CrM: n=9) or placebo (P: n=8) while performing resistance exercise (5 days/week for 4 weeks) followed by a 2-week taper phase. Maximal squat and bench press and explosive power in the bench press were reduced during the initial weeks of training in P but not CrM. Explosive power in the bench press, body mass, and lean body mass (LBM) in the legs were augmented to a greater extent in CrM ( P<or=0.05) by the end of the 6-week period. A tendency for greater 1-RM squat improvement ( P=0.09) was also observed in CrM. Total testosterone (TT) and the free androgen index (TT/SHBG) decreased in CrM and P, reaching a nadir at week 3, whereas sex hormone binding globulin (SHBG) responded in an opposite direction. Cortisol significantly increased after week 1 in CrM (+29%), and returned to baseline at week 2. Insulin was significantly depressed at week 1 (-24%) and drifted back toward baseline during weeks 2-4. Growth hormone and IGF-I levels were not affected. Therefore, some measures of muscular performance and body composition are enhanced to a greater extent following the rebound phase of short-term resistance training overreaching with creatine supplementation and these changes are not related to changes in circulating hormone concentrations obtained in the resting, postabsorptive state. In addition, creatine supplementation appears to be effective for maintaining muscular performance during the initial phase of high-volume resistance training overreaching that otherwise results in small performance decrements.
The objective of this study was to determine the effect of creatine supplementation on performance and body composition of swimmers. Eighteen swimmers were evaluated in terms of post-performance lactate accumulation, body composition, creatine and creatinine excretion, and serum creatinine concentrations before and after creatine or placebo supplementation. No significant differences were observed in the marks obtained in swimming tests after supplementation, although lactate concentrations were higher in placebo group during this period. In the creatine-supplemented group, urinary creatine, creatinine, and body mass, lean mass and body water were significantly increased, but no significant difference in muscle or bone mass was observed. These results suggest that creatine supplementation cannot be considered to be an ergogenic supplement ensuring improved performance and muscle mass gain in swimmers.
The preoptic area contains thermosensitive neurons, thought to be important in thermoregulation, and steroid-sensitive neurons, thought to be involved in reproduction. The preoptic area also contains osmosensitive neurons, considered important in water balance, and glucosensitive neurons, thought to function in the regulation of glucose. If these various neurons belong to separate populations, one might predict that most osmosensitive, glucosensitive, and steroid-sensitive neurons constitute the population of temperature-insensitive neurons rather than thermosensitive neurons. To test this hypothesis, single unit activity was recorded in preoptic tissue slices prepared from male rats. In addition to temperature changes, neuronal responses were examined with various perfusion media containing testosterone or estradiol (30 pg/mL), low glucose (1.0 mM), and increased osmotic pressure (309 mosmol/kg). It was found that the steroid-sensitive, osmosensitive, and glucosensitive neurons were not confined to the temperature-insensitive neurons; but that nearly half of the thermosensitive neurons responded to these nonthermal stimuli. This lack of specificity was also observed between osmosensitive and glucosensitive neurons; however, most of the steroid-sensitive neurons were highly specific for either estradiol or testosterone. Although these findings do not suggest a strong functional specificity for preoptic neurons, they do support studies emphasizing interactions between regulatory systems.