A quantitative, comprehensive scientific summary and view of knowledge up to 2007 on the effects of creatine supplementation in athletes and active people was published in a 100 citation review position paper by the International Society of Sports Nutrition. More recent literature has provided greater insight into the anabolic/performance enhancing mechanisms of creatine supplementation [15,25] suggesting that these effects may be due to satellite cell proliferation, myogenic transcription factors and insulin-like growth factor-1 signalling . Saremi et al  reported a change in myogenic transcription factors when creatine supplementation and resistance training are combined in young healthy males. It was found that serum levels of myostatin, a muscle growth inhibitor, were decreased in the creatine group.
When it comes to building lean muscle, size bodybuilders are king. That’s their ultimate goal. Sure, Crossfit, powerlifting and all the other modalities will build muscle, but that’s not their focus. They want performance and any muscle they build is a side effect. Not so with bodybuilding where muscle size and shape are the priorities. Learning how to build muscle for the sake of building muscle has some benefits to the performance athlete. It allows for ais less injury prone. Its also a fact that bigger muscle contract harder regardless of technique or form, so it’s a good strategy to throw in some bodybuilder muscle building sessions here and there to give yourself stronger muscles to then train for performance. Build the muscle bigger, then train it to perform better.
Most typical bodybuilding programs have way too many sets and reps and use the wrong exercises. However, if you lower the total volume, go heavier, and use compound movements as I’ve outlined above, there is nothing wrong with a body-part split for advanced lifters. In fact, it’s often less stressful to the joints than your average upper/lower split.
Three additional studies suggest that creatine supplementation may not be beneficial for running velocity, sprint swimming performance, or a maximal cycling effort . Short bouts of repeated anaerobic activity have shown some potential benefits with creatine supplementation use in a laboratory setting. However, creatine supplementation has not been shown to enhance single-event performance such as stationary cycling [16-19]. Taken together, these studies do not support creatine supplementation to enhance aerobic activities such as distance running.
Despite the fact that BCAAs may offer some benefits, you should keep in mind that these three amino acids are also present in any quality whey protein that you purchase. You can also get these essential amino acids from food sources. Basically, as long as you’re meeting your daily protein intake goals, you’re probably getting enough of these essential amino acids. Research supports this approach. So, why spend more on another supplement?
The bulking and cutting strategy is effective because there is a well-established link between muscle hypertrophy and being in a state of positive energy balance. A sustained period of caloric surplus will allow the athlete to gain more fat-free mass than they could otherwise gain under eucaloric conditions. Some gain in fat mass is expected, which athletes seek to oxidize in a cutting period while maintaining as much lean mass as possible.
After your standard whey protein powder, creatine may be the most popular sports supplement on Earth, and with good reason. A lot of supplements out there have a few promising studies suggesting they may improve some aspect of performance. Creatine has hundreds of them, and study after study has shown that among most people (a small percentage of are non-responders) it can have a significant effect on several areas of performance.
Taking creatine supplements may increase the amount of creatine in the muscles. Muscles may be able to generate more energy or generate energy at a faster rate. Some people think that taking creatine supplements along with training will improve performance by providing quick bursts of intense energy for activities such as sprinting and weightlifting.
In regard to the blood brain barrier (BBB), which is a tightly woven mesh of non-fenestrated microcapillary endothelial cells (MCECs) that prevents passive diffusion of many water-soluble or large compounds into the brain, creatine can be taken into the brain via the SLC6A8 transporter. In contrast, the creatine precursor (guanidinoacetate, or GAA) only appears to enter this transporter during creatine deficiency. More creatine is taken up than effluxed, and more GAA is effluxed rather than taken up, suggesting that creatine utilization in the brain from blood-borne sources is the major source of neural creatine. However, “capable of passage” differs from “unregulated passage” and creatine appears to have tightly regulated entry into the brain in vivo. After injecting rats with a large dose of creatine, creatine levels increased and plateaued at 70uM above baseline levels. These baseline levels are about 10mM, so this equates to an 0.7% increase when superloaded. These kinetics may be a reason for the relative lack of neural effects of creatine supplementation in creatine sufficient populations.