At this point in science, most athletes probably wouldn't because uncontrolled creatine (Cr) supplementation generally leads to a weight gain of both muscle tissue and water, which is something most endurance athletes want to avoid. But because of creatine's many benefits (beside increasing size, anaerobic power/strength) such as buffering lactate, increasing ATP levels, cell volumizing effects, etc., supplementation has and continues to be studied by sports scientists regarding these potential benefits for endurance athletes. All these later benefits could certainly be of benefit to endurance athletes as long as weight gain is controlled or offset by a performance increase due to the supplementation but it's too early to make recommendations for this group. A recent study determined that short-term Cr supplementation has no detectable negative effect on cardiac structure or function. Additionally, Cr ingestion improves submaximal cycling efficiency. These results suggest that the increase in efficiency may be related to peripheral factors such an increase in muscle phosphocreatine (PCr), rather than central changes. Role of Creatine in muscle:
Creatine plays a pivotal role in muscle ergogenics by acting as part of an energy-buffering system and helping replenish adenosine triphosphate (ATP) and thus supporting muscle contractions. During periods of muscle contraction when ATP breakdown exceeds synthesis, PCr rapidly replenishes ATP. PCr supplies the required energy to fuel 10 to 15 high-intensity contractions such as in weight lifting. The availability of PCr in skeletal muscle has often been cited as limiting to the continuation of maximal physical effort. To be sure, the depletion of muscle PCr stores during intense exercise is associated with the onset of muscle fatigue. Utilization of PCr will also contribute to buffering of lactic acid, assisting in continuation of maximal exercise. Since creatine supplementation has been shown to increase intracellular levels of PCr, intracellular levels of ATP may be maintained at higher levels for a longer period of time. Creatine ingestion has shown a reduction in plasma concentrations of hypoxanthine and lactate following exercise, suggesting lower levels of anaerobic glycolysis and another possible contribution to delaying muscular fatigue by maintaining a normal pH.