By Iris Saar, M.s. Applied Exercise Science candidate, ACSM CPT, RRCA
How one fuel-efficient supplement can enhance your strength
Creatine is produced endogenously, in the liver, kidney and pancreas and is classified as an amino acid. The overall amount produced by the cells equals to 1/gram/day (Cooper et al., 2012) and a significant amount is consumed exogenously from nutrition sources in a similar amount, with her concentrations of creatine in meats. Tissues store creatine mostly in the skeletal muscles and the rest is found in the brain, eye, kidney and testes (Smith-Ryan & Antonio, 2013). A fundamental metabolic fuel, creatine provides phosphates to replenish the synthesis of ATP and continue to fuel contracting muscles, mostly during anaerobic glycolysis. Creatine has been linked to improvement in short-term, high intensity strength exercise performance as well as to some endurance sports, in sparing muscular glucose and protein degradation following middle and long distance running (Tang et al., 2014). Metabolism of creatine is regulated by isoforms called CreaT1 and CreaT2, with the earlier mostly responsible for musculoskeletal tissue transfer (Smith-Ryan & Antonio, 2013). In its free form (unbound to plasma proteins), creatine is able to meet with its transporters, facilitating its contribution to ATP production. Muscle cells degrade creatine by forming creatinine through enzymatic activity of creatine Kinase (CK). CK has two roles in the synthesis of creatinine, the first contributing inorganic phosphate (Pi) to form energy (ADP > ATP) and to creatine itself, forming PCr which initiates anaerobic muscle contractions, mostly during high intensity or maximal effort (Kreider et al., 2017).
Positive effects of creatine on performance
The main physiological gain to supplement tissues with creatine is increasing the time in which high intensity effort can be sustained (Smith-Ryan & Antonio, 2013). This is achieved through increased saturation of creatine in the cytoplasm through both exogenous supplementation and endogenous synthesis. Creatine may be supplemented as both short and long term protocols, ranging between 5-7 days to a month long time span. Several positive effects have been shown on exercise performance following creatine supplementation:
Increased speed and agility in short, high-intensity bouts of exercise (cycling time trials) or sports (soccer). Cyclists who ingested creatine in large amounts (20 grams/day) shoed increased speed in short duration cycling, and young soccer players improved their agility during repeated tests (Mohebbi et al., 2012).
Hypertrophy: the relative contribution of creatine to hypertrophy is achieved through long term cell swelling when creatine is chronically supplemented; growth factors (IGF-1) concentrations increases with creatine levels in the cells, potentially encouraging muscle protein synthesis and eventually, hypertrophy. Creatine can also inhibit certain proteins which oppose growth factors, such as Growth and differentiation factor-associated serum protein-1 (GASP-1) (Smith-Ryan & Antonio, 2013).
Increased time under tension: creatine has the theoretical ability to buffer exercise-induced oxidative stress when hydrogen ions (H+) are generated, again mostly through glycolysis. This effect has been documented to be augmented when creatine was consumed together with ß-alanine acids. Pcr levels sometime serve as a marker for muscular damage, and were found to be lower after combined chronic supplementation of ß-alanine and creatine in supramaximal exercise bouts (Belviranli et al., 2016).
Reduced lactate accumulations in the muscles after short-term exercise: more precisely, reduced lactate threshold was reported in an incremented exercise testing following creatine loading; short term loading reduced both lactate accumulations and increased the threshold among cyclists. Interestingly, no similar effect was found among runners who performed a similar incremented testing.
Lean body mass increase: both acute and chronic creatine supplementation can increase lean body mass and potentially muscle fiber size (Antonio & Ciccone, 2013). The metabolic characteristics of creatine such as enhanced muscle protein synthesis and IGF-1, as well as activation of satellite cells contributes to muscle mass gains and reduction in fat mass.
Negative consequences of creatine supplementation
Although vast evidence supports the positive effects creatine has on performance, some negative considerations to its use are worth investigating. It seems as the increased presence of PCr following strenuous exercise leads to the notion that creatine can be negatively associated with performance; however as explained earlier creatine is a biomarker for muscular damage and not a physiological or metabolic direct cause. Two acids that are secreted in the urine when creatine is chronically supplemented in higher dosages (over 5 grams/day) are Methylamine and formaldehyde. Methylamine has been linked to renal (kidney) dysfunction and formaldehyde as potentially toxic when inhaled. Although kidney damage was not found following an increased creatine supplementation, individuals suffering from kidney disease are instructed to refrain from consuming higher amounts of creatine as a precaution (Cooper et al., 2012).
Although physiological damage or pathologies has not been studied to be affected by creatine supplementation, its efficacy seems to have a few limitations. First, there is a finite amount in which creatine seem to be influential on sports performance. Consuming creatine in excess of 20 grams/day has not shown further benefits on performance and the body exerts the excess through the urine. Second, creatine improves performance when combined with exercise and not as an independent compound. That is, exogenous supplementation alone does not induce physiological adaptations and may be perceived as less effective due to the requirement to incorporate exercise.
Weight gain is a potential detrimental result of creatine loading. As the body’s lean mass increases with the use of creatine, so does the overall body mass. While this can be desired for certain contact sports, other athletes such as body builders might find this detrimental. However, weight gain has been reported mostly during short-term creatine supplementation and can be reversed in the longer term (Hall & Trojian, 2013).
Creatine might not result in the same significant impact for all individuals. Genetic differences in response to creatine-limited effect of positive improvement may be experienced among individuals who possess a lesser amount of type II muscle fibers, making creatine a distinctive compound for certain athletes (Smith-Ryan & Antonio, 2013).
As creatine is mostly present in fish and meat (Herring, for example, has 3-4.5 grams per lb. and pork has 2.3 grams per lb), vegetarian or vegan diets might not be able to provide the individual with the same potent effect from nutritional sources. This may be a hardship for certain athletes seeking to refrain from omnivorous diets (Smith-Ryan & Antonio, 2013).
Recommended amounts and when it should be taken for maximal performance effect
Loading protocols of creatine differ and can be divided to acute (short term) or chronic (long term) supplementation. In short term creatine loading, a rapid increase in creatine levels is achieved in 5-7 days by ingesting 3 grams/day or 0.3 g/kg body weight. Longer term protocols span over 28 days, usually, and lead to a more gradual increase in creatine concentrations. Depending on the desired goal and phase of the training cycle, the duration of creatine supplementation should be considered as well as the lasting effect of creatine saturation; as even without further support, after long term loading creatine may last between 4-6 weeks in the tissues (Kreider et al., 2017). It is important to note that healthy, balanced diets already provide the muscles with a pool of 60%-80% creatine (Kreider et al., 2017), therefor supplementing in higher dosages might not always be required and is goal-dependent.
The timing of creatine intake does have an effect on performance. Close proximity of creatine consumption to exercise can increase the gains, with slight favorable gains to consuming creatine right after exercise termination. As creatine is transported into the tissues through its CreaT1, post-exercise intake might be beneficial due to higher levels of the transporter in the blood (Forbes et al., 2014). Some protocols suggest multiple creatine intakes during the day rather than before / after exercise. Rapid increases of creatine levels are apparent with multiple intakes of 5 grams a day for a week time, or a slightly reduced dose of 3-5 grams for a longer period of time (Smith-Ryan & Antonio, 2013). This, as stated earlier, is goal-dependent and should be planned ahead in the nutritional aspect of the athlete’s macro training cycle.
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Belviranli, M., Okudan, N., Revan, S., Balci, S., & Gokbel, H. (2016). Repeated Supramaximal Exercise-Induced Oxidative Stress: Effect of β-Alanine Plus Creatine Supplementation. Asian Journal of Sports Medicine, 7(1), 1–7.
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Mohebbi, H., Rahnama, N., Moghadassi, M., & Ranjbar, K. (2012). Effect of creatine supplementation on sprint and skill performance in Young Soccer Players. Middle-East Journal of Scientific Research, 12(3), 397-401.
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Tang, F.-C., Chan, C.-C., & Kuo, P.-L. (2014). Contribution of creatine to protein homeostasis in athletes after endurance and sprint running. European Journal of Nutrition, 53(1), 61–71.