|Yes, this study suggests that my previous statement that 3g of creatine per day are probably enough.... still direct comparisons of diff. doses are warranted.|
In a new study from the Baylor University, Andre, et al. did just that: They tested the effects of five weeks of resistance training in conjunction with a typical relative Cr dosing protocol followed by four weeks of resistance training after ceasing Cr supplementation on: 1) body composition and muscle strength, 2) whole-body Cr metabolism.
The scientists recruited nineteen apparently healthy, resistance-trained [regular, consistent resistance training (i.e., thrice weekly) for at least one year prior to the study], males between the ages of 18-23 completed the study. Participants were required to perform a leg press 1-RM of at least 2.5 times their body weight followed by at least 10 repetitions at 70% of their 1-RM during a familiarization session to be considered trained to participate (Coburn and Malek, 2012). Afterwards, the subjects were randomly assigned to groups using a random number generator. Supplementation involved orally ingesting packets containing
- powdered dextrose placebo [PL (AST Sports Science; Golden, CO, USA)] or
- Cr monohydrate [CR (AST Sports Science; Golden, CO, USA)].
Participants followed a periodized 4-day/week resistance-training program split into two upper-body and two lower body workouts/week, for nine weeks (Table 1). As the authors further point out, the subjects performed "three sets of 10 repetitions with as much weight as they could lift per set (~70 – 80% of 1RM). If they could lift fewer than 10 repetitions, they were instructed to reduce the weight, and if they could lift more than 10 repetitions at a given weight, they were instructed to increase the weight" (Andre. 2016). The subjects were also instructed to rest "no longer than three minutes between exercises and no longer than two minutes between sets" (Andre. 2016); verbal confirmation of how to properly perform each exercise was given only during the familiarization session, though - still, resistance training compliance for CR and PL were 95.23 ±9.36 % and 93.74 ±8.82 %.
"Participants performed four one-repetition maximum (1-RM) tests on the angled leg press sled (Nebula, Columbus, OH, USA) at Day 0, 8, 36, 64. Participants warmed-up by completing two sets of 8-10 repetitions at approximately 50% of the estimated 1-RM, with two minutes rest in between all sets. Participants completed three to five repetitions at approximately 75% of the estimated 1-RM. The weight was increased conservatively, and the participant attempted to lift the weight for one repetition. If successful, the participant rested for two minutes before attempting the next weight increment. This was continued until the participant failed to complete the lift (Schwarz. 2015). For the 70% 1-RM evaluation during the familiarization session, participants were allowed to rest five minutes following the determination of their 1-RM" (Andre. 2016).
Table 1: Overview of the training program the subjects followed (Andre. 2016).
|Figure 1: Relative changes (difference to day 1) in lean mass and leg press strength (Andre. 2016)|
- a group x time interaction for increases in total body mass Day 1 and 64 (p = 0.03) and exclusive lean mass at Day 1 and 64 (p = 0.01) favoring, as expected, the creatine group,
- significant leg strength increases in both groups without inter-group differences, even though the absolute strength gains on the leg press were almost 6kg higher (31.16 ± 26.90 vs. 25.68 ± 17.77 kg) for the creatine group,
- no significant effects on body water (in neither of the groups, by the way)
- no significant differences in food intake and / or the macronutrient composition of the diet, of which you will probably be intrigued to hear that it was between 1.1 and 1.3 g/kg, only
|Figure 2: Levels of muscle and serum creatine in the subjects over the course of the study (Andre. 2016).|
"[t]hese findings are consistent with previous studies showing increases in urinary Cr but not in urinary Crn (Powers et al., 2003; Syrotuik and Bell, 2004). This suggests the supplementation dose of Cr was higher than the functional capacity to be metabolized, and was wasted via urinary excretion. Despite the supplementation dose based on lean mass measures to attempt to reduce this occurrence, considerable amounts of Cr were still essentially wasted" (Andre. 2016).The increases in serum Cr concentrations, which were significant after three and seven days of Cr supplementation, and at the end of the maintenance phase, are likewise no and the lack of increase of serum creatinine good news. As the scientists point out, the increases in serum and urinary creatine in combination with the intramuscular total Cr data allow us to postulate that "the exogenous Cr supplementation apparently saturated intramuscular Cr stores given the high levels of serum and urinary Cr" (Andre. 2016).
- Andre, Thomas L., et al. "Effects of Five Weeks of Resistance Training and Relatively-Dosed Creatine Monohydrate Supplementation on Body Composition and Muscle Strength, and Whole-Body Creatine Metabolism in Resistance-Trained Males." International Journal of Kinesiology and Sports Science 4.2 (2016): 27-35.
- Lemon, Peter WR. "Dietary creatine supplementation and exercise performance: why inconsistent results?." Canadian journal of applied physiology 27.6 (2002): 663-680.
- Powers, Michael E., et al. "Creatine supplementation increases total body water without altering fluid distribution." Journal of athletic training 38.1 (2003): 44.
- Schwarz, Neil A., et al. "Acute Myosin Heavy Chain Isoform mRNA Expression in Response to Two Resistance Exercise Intensities With Equal Volume Load in Resistance-Trained Men." The Journal of Strength & Conditioning Research 29.8 (2015): 2326-2332.
- Syrotuik, Daniel G., and Gordon J. Bell. "Acute Creatine Monohydrate Supplementation: Adescriptive Physiological Profile of Responders Vs. Nonresponders." The Journal of Strength & Conditioning Research 18.3 (2004): 610-617.