|Can creatine beneficially influence your neurotransmitter so that you can run longer?|
All clear: Creatine probably won't make you depressed
Contrary to BCAAs which exert their effect irrespective of whether you do or don't exercise. The current evidence suggests that creatine does the same only in the context exhaustive aerobic exercise (I would bet it does the same with high volume training, though). In their recently published paper, Moghadasi et al. describe the dopamine, serotonin and prolactin response of 20 healthy, but sedentary male volunteers (BMI 23.5; body fat %: 20.5%) who received 4x5g creatine (standard loading protocol) for 7 days before they underwent an exhaustive aerobic exercise test, the so-called Bruce protocol, in the course of which participants are made to run on a treadmill to exhaustion, while incline and speed are increased every three minutes.
|Figure 1: Dopamine and serotonin levels of the healthy, but sedentary volunteers before, immediately, 10 min and 20 min after the Bruce protocol (Moghadasi. 2012)|
|Figure 2: Effect of creatine supplementation on BMI and intra- and extracellular water (Moghadasi. 2012)|
The same is unfortunately true for the actual effects of the modified neurotransmitter response, while the authors are right to point out that 5-HT has been imlicated as a factor that induces mental and subsequently central fatigue, whereas dopamine is known as the "motivational neurotransmitter", previous studies by Wantanabe et al. suggested that respective cognitive benefits from creatine supplementation were facilitated by an increased oxygen utilization in the brain - not via changes in the neurotransmitter levels. And though these changes may not have reached statistical significance in the study at hand, there is actually better evidence for potential pro-dopaminergic effects of creatine, which has been shown to increase DA synthesis in the substantia nigra of mice by protecting against striata DA depletion (Klivenyi. 2003) and / or by enhancing the tyrosine hydroxylase activity and thus increasing the production of dopamine from its precursoe tyrosine (Matthews. 1999).
Much ado about nothing?
Is there a connection between creatine and prolactin: While the prolactin levels were not measured in the study at hand. The results of a 1996 study, in which Prysor-Jones et al. were able to show that the "creatine analogue" beta-guanidinopropionic acid (GPA) which is in fact a competitive inhibitor of creatine, increased the TRH induced release of prolactin. By implication this could mean that creatine will do the exact opposite. This hypothesis would also be supported by the increased dopamine levels after the workout - after all, dopamine is a natural prolactin antagonist (and vice versa).There is however one study, by Hadjicharalambous et al. that appears to support the hypothesis that the modified 5HT-to-DA ratio may in fact figure large. The authors found that 7 days of creatine supplementation effectively reduced the central fatigue index of subjects who had to exercise in the heat. In that, they observed that the additional creatine blunted the increase in the free tryptophan-to-tyrosine ratio, which suggests that the brain 5-HT and DA levels were modulated by the supplementation protocol, as well. According to Hadjicharalambous et al. this effect was yet single-sided and related to an overall reduction in serotonin levels, while there were no significant difference between two groups as far as their dopamine levels were concerned.
Bottom line: As it is the case in so many of the complex processes underlying human performance and the effects of proven and purported ergogenics, these insights into the effects of creatine as a potential mediator of the exercise induced neurotransmitter-response are still very preliminary. That may be surprising if you take into accaunt that millions of consumers are currently using creatine monohydrate or supplements that contain it, but in the end it's not much different from the way the same people use to train: Things that work will prevail - irrespective of whether or not the mechanisms have already been fully understood.
- Machado M, Sampaio-Jorge F, Dias, N, Knifis FW. Effect of oral creatine supplementation in soccer players metabolism. Revista Internacional de Ciencias del Deporte. 2008; 4:44-58.
- Moghadasi M, Rahimi E, Mahani MS, Molaee, AA. Effect Of Creatine Supplementation On Brain Neurotransmitters After An Exhaustive Aerobic Exercise. Brazilian Journal of Biomotricity. 2012; 6(3):213-221.
- Sevy S, Hassoun Y, Bechara A, Yechiam E, Napolitano B, Burdick K, Delman H, Malhotra A. Emotion-based decision-making in healthy subjects: short-term effects of reducing dopamine levels. Psychopharmacology (Berl). 2006 Oct;188(2):228-35.