Eur J Appl Physiol DOI 10.1007/s00421-014-2903-0
Creatine supplementation prevents acute strength loss induced by concurrent exercise Vítor de Salles Painelli · Victor Tavares Alves · Carlos Ugrinowitsch · Fabiana Braga Benatti · Guilherme Giannini Artioli · Antonio Herbert Lancha Jr · Bruno Gualano · Hamilton Roschel
Received: 23 January 2014 / Accepted: 28 April 2014 © Springer-Verlag Berlin Heidelberg 2014
Abstract Purpose To investigate the effect of creatine (CR) supplementation on the acute interference induced by aerobic exercise on subsequent maximum dynamic strength (1RM) and strength endurance (SE, total number of repetitions) performance. Methods Thirty-two recreationally strength-trained men were submitted to a graded exercise test to determine maximal oxygen consumption (VO2max: 41.56 ± 5.24 ml kg−1 min−1), anaerobic threshold velocity (ATv: 8.3 ± 1.18 km h−1), and baseline performance (control) on the 1RM and SE (4 × 80 % 1RM to failure) tests. After the control tests, participants were randomly assigned to either a CR (20 g day−1 for 7 days followed by 5 g day−1 throughout the study) or a placebo (PL-dextrose) group, and then completed 4 experimental sessions, consisting of a 5-km run on a treadmill either continuously (90 % ATv) or intermittently (1:1 min at vVO2max) followed by either a leg- or bench-press SE/1RM test. Results CR was able to maintain the leg-press SE performance after the intermittent aerobic exercise when compared with C (p > 0.05). On the other hand, the PL group showed a significant decrease in leg-press SE (p ≤ 0.05). CR supplementation significantly increased bench-press SE after both aerobic exercise modes, while the bench-press SE was not affected by either mode Communicated by Michael Lindinger. V. de Salles Painelli and V. T. Alves contributed equally. V. de Salles Painelli · V. T. Alves · C. Ugrinowitsch · F. B. Benatti · G. G. Artioli · A. H. Lancha Jr · B. Gualano · H. Roschel (*) School of Physical Education and Sport, University of Sao Paulo, Av Prof. Mello Moraes, 65‑Butantã, São Paulo, SP 05508‑030, Brazil e-mail: [email protected]
of aerobic exercise in the PL group. Although small increases in 1RM were observed after either continuous (bench press and leg press) or intermittent (bench press) aerobic exercise in the CR group, they were within the range of variability of the measurement. The PL group only maintained their 1RM. Conclusions In conclusion, the acute interference effect on strength performance observed in concurrent exercise may be counteracted by CR supplementation. Keywords Creatine supplementation · Interference · Resistance training · Fatigue Abbreviations 1RM Maximum dynamic strength ATv Anaerobic threshold velocity Ca++ Calcium CE Continuous aerobic exercise and strength endurance assessment condition CM Continuous aerobic exercise and maximum strength assessment condition CR Creatine HPLC High-performance liquid chromatography HRmax Maximum heart rate IE Intermittent aerobic exercise and strength endurance assessment condition IM Continuous aerobic exercise and maximum strength assessment condition PL Placebo SE Strength endurance VE/VCO2 Ventilatory equivalent for carbon dioxide VCO2 Carbon dioxide output VO2 Oxygen consumption VO2max Maximal oxygen consumption vVO2max Maximal oxygen consumption velocity
Introduction Many athletes and physically active individuals incorporate strength and endurance exercises into their training routines. However, this type of training, often called concurrent training, may impair strength gains (Hickson 1980; Nelson et al. 1990; Hennessy and Watson 1994; Docherty and Sporer 2000; Sporer and Wenger 2003). It has been suggested that an acute interference of aerobic training upon the subsequent strength training could be responsible for the decreased muscle force (Craig and Lucas 1991; Leveritt et al. 1999). According to this hypothesis, the peripheral fatigue induced by aerobic exercise could reduce the ability of the skeletal muscle to produce tension (Leveritt and Abernethy 1999; Bentley et al. 2000). In this scenario, it would be possible to speculate that optimizing energy provision could have a role in mitigating the negative effects of acute concurrent training on muscle strength performance. Creatine/phosphorylcreatine system exerts a crucial role in skeletal muscle energy metabolism. It has been showed that phosphorylcreatine acts as a “temporal energy buffer” at sites of high energy translocation which operates when the rate of ATP utilization outstrips the rate of production by mitochondrial respiration, thereby maintaining ATP/AMP homeostasis (Greenhalff 2001; Wallimann et al. 2011). A second role proposed for the creatine/phosphorylcreatine system is that of a cellular energy transport system (i.e., the “creatine/phosphorylcreatine shuttle”) from mitochondria to cytosol, especially in tissues in which energetic demand is high. This function is only possible due to different creatine kinase isoforms, which link the sites of ATP generation (i.e., mitochondria) to those of ATP consumption (e.g., myofibril, sarcoplasmic reticulum Ca2+-ATPase and Na+/K+-ATPase). This arrangement enables the creatine/phosphorylcreatine system to function as a “spatial energy buffer”. The seminal paper by Harris et al. (1992) showed for the first time that oral creatine loading (i.e., 20 g day−1 for 7 days) was capable of increasing creatine and phosphorylcreatine in human skeletal muscle. Subsequently, a number of studies demonstrated that increased skeletal muscle creatine via dietary supplementation could improve muscle strength, resistance to fatigue, and anaerobic capacity in a variety of laboratory and sports-specific tests (for a comprehensive review, see Gualano et al. 2012). The fact that creatine effects are amplified when multiple exercise bouts are performed (Casey et al. 1996; Greenhaff et al. 1993; Vandenberghe et al. 1997; Van Leemputte et al. 1999) suggests that this dietary supplement could be particularly ergogenic in those conditions where skeletal muscle energy status is prejudiced, with a decline in both phosphorylcreatine content and ATP/ADP ratio. Accordingly, it has been previously demonstrated that subsequent bouts of intermittent high-intensity aerobic
Eur J Appl Physiol
exercise (which could theoretically induce a significant imbalance in phosphorylcreatine content and ATP/AMP ratio), but not continuous moderate-intensity aerobic exercise, negatively affected muscle strength performance (De Souza et al. 2007). In this regard, the acute interference phenomenon induced by concurrent training is considered to be mainly present when both aerobic and strength exercises are dependent upon similar mechanisms (e.g., both the aerobic and the strength exercise performance are mainly dependent upon energy substrate availability) (Docherty and Sporer 2000) and when the same muscle group undergoes both aerobic and strength stimuli (De Souza et al. 2007; Sporer and Wenger 2003). Therefore, the aim of this study was to examine the possible influence of creatine supplementation on muscle strength performance (i.e., maximum strength and strength endurance) after two modes of aerobic exercise (highintensity intermittent exercise or continuous moderateintensity exercise). Considering that the detrimental effect of concurrent training has been associated with peripheral fatigue, which, in turn, could be due to a partial depletion in high-phosphate energy levels (i.e., phosphorylcreatine), it was hypothesized that creatine supplementation could prevent the acute interference effect of high-intensity intermittent aerobic training upon strength performance. Additionally, we hypothesized that creatine supplementation would increase muscle performance in the non-aerobically exercised muscle group (upper limb) after either aerobic exercise modes.
Methods Participants Thirty-two recreationally strength-trained (1–3 years of strength training experience) males took part in this study. One participant withdrew from the study due to personal reasons; therefore, thirty-one participants were included in the final data set. Participants’ characteristics are presented in Table 1. The exclusion criteria included: vegetarian diet, use of creatine supplements in the past 6 months prior to the study, use of nutritional supplements, and use of anabolic steroids. Participants were regularly involved in weight training (3–4 times per week) and were requested to maintain similar levels of physical activity and dietary intake throughout the study. Compliance with this request was verbally confirmed with the participants throughout the study. Participants were fully informed of any risks and discomforts associated with the study before providing written consent. All of the procedures were approved by the local Ethical Advisory Committee.
Eur J Appl Physiol Table 1 Participants’ characteristics
ATv anaerobic threshold velocity, Speedmax maximum speed, HRmax maximum heart rate, VO2max maximum oxygen consumption, 1RM maximum dynamic strength
Age (years) Body mass (kg) Height (m) ATv (km h−1) Speedmax (km h−1) VO2max (ml kg−1 min−1) HRmax (beats min−1) Time to exhaustion (min) Leg-press 1RM (kg) Bench-press 1RM (kg)
Creatine (N = 15)
Placebo (N = 16)
28 ± 5 78.9 ± 8.6 1.77 ± 0.07 8.33 ± 1.11 15.0 ± 1.5 40.80 ± 4.22 190 ± 8 14.1 ± 1.5 326.9 ± 62.5
24 ± 5 74.8 ± 8.6 1.76 ± 0.06 8.25 ± 1.29 15.5 ± 1.3 42.27 ± 6.09 194 ± 9 14.4 ± 1.5 329.1 ± 46.1
0.07 0.18 0.69 0.84 0.35 0.43 0.24 0.57 0.91
85.2 ± 14.6
79.2 ± 15.3
Fig. 1 Overview of the experimental sessions. A Warm-up. B Aerobic exercise (either continuous or intermittent) C Passive recovery. D Lower-body strength tests (either maximum dynamic strength or
strength endurance tests). E Passive recovery. F Upper-body strength tests (either maximum dynamic strength or strength endurance tests)
aerobic exercise and strength endurance assessment (CE), intermittent aerobic exercise and maximum strength assessment (IM), and intermittent aerobic exercise and strength endurance assessment (IE). Each experimental session was conducted at least 72 h apart (Fig. 1). The order of the experimental sessions followed a William’s square distribution to avoid carryover effects (Kuehl 2000). Participants were requested to abstain from alcohol and strenuous exercise in the 48-h period prior to the experimental sessions. Participants arrived at the laboratory at least 2 h following their last meal, and immediately began their warm-up followed by the exercise protocol. Ad libitum water consumption was allowed during the sessions. A systematic dietary intake analysis was performed by means of three 24-h food recalls undertaken on separate days (2 weekdays and 1 weekend day) using a visual aid photo album of real realsized foods and portions (Scagliusi et al. 2003). The participants verbally agreed to maintain similar dietary intake for the duration of the study.
To evaluate the effects of creatine supplementation on the acute concurrent exercise-induced impairment in muscle strength, the participants were first familiarized with the procedures before testing for their baseline (control condition) maximum dynamic strength (1RM) and strength endurance performance. Participants were also submitted to a maximal graded exercise test for maximal oxygen consumption (VO2max) determination and then, they were randomly assigned to receive either creatine (CR) or placebo (PL) in a double-blind fashion. One week after the supplementation started, participants performed four experimental sessions consisting of a 5-km run on a treadmill continuously (90 % of the anaerobic threshold velocity-ATv) or intermittently (1:1 min at the velocity correspondent to the VO2max). Ten minutes after the aerobic exercise either a 1RM or a strength endurance test was performed (leg-press and bench-press exercises). This protocol has been previously demonstrated to induce acute interference effect of the aerobic exercise on strength performance (De Souza et al. 2007). Thus, the four experimental sessions were: continuous aerobic exercise and maximum strength assessment (CM), continuous
Familiarization All of the participants were familiarized (3 sessions) with the strength tests in the inclined (45°) leg-press and in the
bench-press exercises, and estimates of the participants’ one repetition maximum (1RM) for both exercises were obtained. During the familiarization sessions, participants performed a general warm-up consisting of 5 min of running at 9 km h−1 on a treadmill (Movement Technology®, Brudden, São Paulo, Brazil) followed by 3 min of whole body light stretching exercises. After warming-up, the participants were familiarized with the leg-press and the bench-press exercise 1RM testing protocol. The individuals were considered acquainted to the 1RM test, as the relative difference between familiarization sessions two and three was 99.9 %, creatinine 0.05) (Fig. 3b).
Blinding efficacy and side effects
No significant differences were observed in the total number of repetitions either for the leg- (p = 0.59) or the benchpress exercises (p = 0.80) between CR and PL groups in the control condition (prior to supplementation). A significant decrease in the total number of repetitions for the leg-press exercise was observed in the PL group in the IE when compared with both the CE (−20.31 %; p = 0.02) and the control conditions (−21.69 %; p = 0.04). Importantly, CR supplementation was able to maintain the total number of leg-press repetitions as no significant differences were observed in this parameter in the CR group across the conditions (all p > 0.05) (Fig. 3a). Additionally, the CR group showed a significant increase in the total number of repetitions for the bench press in the CE and IE conditions following supplementation when compared with control (+13.35 %; p = 0.001, and +13.00 %; p = 0.001, respectively). No significant differences were observed in
Only six out of the 15 participants were able to correctly guess their supplement in the CR group, whereas only 8 out of 16 correctly guessed their supplement in the PL group. There were no significant differences in the correct guessing rate between the groups (Fisher exact test: p = 0.72). No side effects were reported from the ingestion of either creatine or dextrose.
Fig. 2 Maximum dynamic strength (1-RM kg) for the creatine and placebo groups during each experimental condition in the leg-press (a) and bench-press exercises (b). CM Continuous aerobic exercise + maximum dynamic strength test. IM Intermittent aerobic exercise + maximum dynamic strength test. Asterisk indicates p