|Bodybuilding and creatine ain't mentioned in one breath without a reason - Crea simply works! Dozens of studies have shown that... not one, however, tested the effects on the CNS.|
Not every study? Oh, yes, obviously, study #103 showing that creatine yields strength and size increases on your average hypertrophy workout would indeed no longer be news-worthy. Much in contrast, however, to a study that claims that creatine may blunt the beneficial effects of resistance training on heart health? Ok, I see that's getting you excited. So let's take a closer look at how the authors come up with claim...
As the Turkish authors of the corresponding peer-reviewed paper that's about to be published in Pacing and Clinical Electrophysiology (Mert 2017) point out, 'bodybuilding' is not just an increasingly "popular sport among adolescents", it is also a sport that involves exercises capable of "increas[ing] stroke volume and cardiac output to a greater degree than [selected other sports]" (Mert 2017 base this statement on Ahlgrim 2009). As a gymrat, you will not be surprised to hear that bodybuilding type workouts have also been found to affect heart rate variability (HRV | learn what it's got to do with overtraining), of which you, as a SuppVersity Reader, know that it can be used (comparing intra-individual values, not as in the study at hand for intra-individual comparisons) to decently predict/measure overtraining - or, more precisely, the way in which your training impacts your autonomic nervous system (ANS). Now that, in turn, will affect your heart health, because...
- sympathetic stimulation increases the heart rate, contractility, and conduction velocity, whereas parasympathetic stimulation has the opposite effects;
- there's a significant relationship between ANS imbalance and cardiovascular mortality, including sudden cardiac death;
- the effects of exercise on cardiovascular mortality and sudden cardiac death may be mediated by its effects on ANS or, more specifically, the way it modifies the autonomic balance.
Hey, bros: Let me measure your HRV!
For their observational study, the Turkish scientists recruited 32 male "competitive" bodybuilders - 16 of these sportsmen, who were no pro-bodybuilders, but had at least 5 years of training experience (10–12h/week), had been taking creatine for at least 4 weeks (7.5 mg/day | range 3.5-15.0mg) the other 16 sportsmen didn't.
Please note: This is an observational, not an experimental study! As previously highlighted (underlined), the study at hand is not a randomized controlled trial. It is an observational study. An observational study that didn't reliably test the subjects for current or prior steroid use and took for granted that all "bodybuilders" consumed protein supplements - if the subjects were actually clean, how much protein they consumed and, more importantly, how that differed from one group to the other, however, is not clear... with obvious consequences for the practical significance and reliability of the results.
|Table 1: Overview of selected subject characteristics in the control, and the subjects in the two training groups of Mert et al.'s observational study.|
The scientists found no significant inter-group difference in the trained study subjects; even though there were fewer smokers in the creatine compared to the 'no creatine' group. As you can see in Table 1 that's different for the comparison of the two training groups to the untrained control subjects.
To be precise, a significant difference was observed for the resting heart rate between the 'no creatine' and the control, yet not the creatine and the control group - a significant difference between the two training groups, however, didn't exist. Additionally, the subjects in the creatine group had significantly higher BUN and - quite obviously - creatinine levels.
|My criticism of the scientists use of HRV in the study at hand does not contradict the previously discussed usefulness of HRV as a marker of overtraining | more|
Accurate analysis, that's at least what a recent from Italy suggests, this may require more than a simple heart-rate monitor and a software that analyzes the frequency. Ideally, an ECG should be recorded at respiratory rates above 10 breath/min to get 100% reliable data (Lucini 2007).
- SDNN - estimate of overall HRV; A decrease in SDNN has been associated with sudden cardiac death
- SDANN - reflects circadian rhythmicity of autonomic function
- pNN50 - is virtually independent of circadian rhythms; reflects alterations in autonomic function that are primarily vagally mediated
- RMSDD - estimate of the short-term components of HRV, provides Vagal Index.
- Ahlgrim, Christoph, and Maya Guglin. "Anabolics and cardiomyopathy in a bodybuilder: case report and literature review." Journal of cardiac failure 15.6 (2009): 496-500.
- Akselrod, Solange, et al. "Power spectrum analysis of heart rate fluctuation: a quantitative probe of beat-to-beat cardiovascular control." science 213.4504 (1981): 220-222.
- Appel, Marvin L., et al. "Beat to beat variability in cardiovascular variables: noise or music?." Journal of the American College of Cardiology 14.5 (1989): 1139-1148.
- Billman, George E. "The LF/HF ratio does not accurately measure cardiac sympathovagal balance." Heart Rate Variability: Clinical Applications and Interaction between HRV and Heart Rate (2007): 54.
- Bizzarini, E., and L. De Angelis. "Is the use of oral creatine supplementation safe?." Journal of Sports Medicine and Physical Fitness 44.4 (2004): 411.
- Buford, Thomas W., et al. "International Society of Sports Nutrition position stand: creatine supplementation and exercise." Journal of the International Society of Sports Nutrition 4.1 (2007): 6.
- Houle, Melanie S., and George E. Billman. "Low-frequency component of the heart rate variability spectrum: a poor marker of sympathetic activity." American Journal of Physiology-Heart and Circulatory Physiology 276.1 (1999): H215-H223.
- Jäger, Ralf, et al. "Analysis of the efficacy, safety, and regulatory status of novel forms of creatine." Amino acids 40.5 (2011): 1369-1383.
- Juhn, Mark S., and Mark Tarnopolsky. "Potential side effects of oral creatine supplementation: a critical review." Clinical Journal of Sport Medicine 8.4 (1998): 298-304.
- Kim, Hyo Jeong, et al. "Studies on the safety of creatine supplementation." Amino acids 40.5 (2011): 1409-1418.
- Kreider, Richard B. "Creatine supplementation: analysis of ergogenic value, medical safety, and concerns." J Exerc Physiol Online 1.1 (1998).
- Lucini, Daniela, et al. "Heart rate variability to monitor performance in elite athletes: Criticalities and avoidable pitfalls." International Journal of Cardiology (2017).
- Mert, Kadir Uğur, et al. "Effects of creatine supplementation on cardiac autonomic functions in bodybuilders." Pacing and Clinical Electrophysiology (2017).
- Schilling, Brian K., et al. "Creatine supplementation and health variables: a retrospective study." Medicine and science in sports and exercise 33.2 (2001): 183-188.