Few supplements have the solid scientific foundation that creatine has. Studies show that it's effective for 80 percent of those who use it. Since creatine is found naturally in meat, the more meat you eat, the less likely you'll need creatine supplementation. Vegetarians or those who rarely eat meat, however, can get huge boosts from most creatine supplements.
Yes, you can pack on size while only doing bodyweight exercises – I did it while traveling the world – and gymnasts train mostly with bodyweight movements. However, this can feel like playing Halo on Legendary difficulty. It can be done, but damn it can be challenging – especially for lower body movements. If your sole goal is to get bigger as fast as possible, access to a barbell for squats and deadlift is almost a requirement.
Though weight training can stimulate the cardiovascular system, many exercise physiologists, based on their observation of maximal oxygen uptake, argue that aerobics training is a better cardiovascular stimulus. Central catheter monitoring during resistance training reveals increased cardiac output, suggesting that strength training shows potential for cardiovascular exercise. However, a 2007 meta-analysis found that, though aerobic training is an effective therapy for heart failure patients, combined aerobic and strength training is ineffective; "the favorable antiremodeling role of aerobic exercise was not confirmed when this mode of exercise was combined with strength training".
Crave instant gratification? Strength training is a good motivator because you see progress quickly. “If you put someone on a walking program, it will take time before they perceive their body is changing,” explains Katula. “But with strength training, you can feel a difference in your muscles even after one session.” And it only takes a couple workouts before you’ll notice some muscle definition in the mirror. (Go ahead and flex. We dare you.)
A meta-analysis of 16 studies conducted on creatine and its influence on power and strength, (with or without exercise in all age groups above 16, but placebo controlled and without crossover) compiled studies utilizing a 5-7 day loading period with continued maintenance thereafter and studies assessing 1-3 rep bench press strength in trained young men. Seven studies (four of which are online) totaling 70 people using creatine and 73 people in placebo showed a 6.85kg increase in strength relative to placebo, the benefits of which peaked at 8 weeks. This meta-analysis also quantified a significant increase in squat strength (9.76kg) yet failed to find a significant influence on peak bicep contraction power, which may have been influenced by the two null studies being in elderly people while the positive study was statistically outweighed, but noted an 1.8-fold increase in power associated with creatine over placebo. The other meta-analysis conducted the following year calculated effect sizes for creatine supplementation and noted no significant differences between genders or when comparing trained and untrained individuals. The mean effect size of exercises lasting below 30s (those that use the creatine-phosphate system) was 0.24+/-0.02 and performed significantly better than placebo, where exercise increased performance by 4.2+/-0.6% while the addition of creatine enhanced this effect to 7.5+/-0.7%.
The first thing you need is a weight training program that signals the muscle building process to begin. Research has shown that a well designed program will generate this “signal” via a combination of progressive tension overload (as in, getting stronger over time), metabolic stress (as in, fatiguing the muscle and getting “the pump”), and muscular damage (as in, actual damage to the muscle tissue itself).
Creatine supplementation may also be of benefit to injured athletes. Op’t Eijnde et al  noted that the expected decline in GLUT4 content after being observed during a immobilization period can be offset by a common loading creatine (20g/d) supplementation protocol. In addition, combining CM 15g/d for 3 weeks following 5 g/d for the following 7 weeks positively enhances GLUT4 content, glycogen, and total muscle creatine storage .
Collectively the above investigations indicate that creatine supplementation can be an effective strategy to maintain total creatine pool during a rehabilitation period after injury as well as to attenuate muscle damage induced by a prolonged endurance training session. In addition, it seems that creatine can act as an effective antioxidant agent after more intense resistance training sessions.