Safety. Iron overload may cause a disease called hemochromatosis in some susceptible people. Iron supplements should only be prescribed by a doctor, and for athletes or those who train heavily, a sports physician combined with a sports dietitian may be preferable. Be sure to take care with this because iron supplements should not be taken casually. Iron supplements may cause constipation and gastric upset in some people.
Co-ingesting creatine with caffeine partially negated the benefits of creatine supplementation (at 5mg/kg bodyweight) during the loading phase in one study.[590] The exact mechanism responsible for this effect is not known, but might be related to opposing actions on muscle contraction time.[591] However, another study in trained men found that co-ingestion of 300mg caffeine per day during creatine loading at 20g per day (split into 4 doses) had no effect on bench press 1RM, time to fatigue, or sprinting ability.[592] However, this study also found that creatine alone or when combined with caffeine had no effect on any of these parameters over placebo, either. Thus, the study may have been underpowered or done in too short a time frame (the test was done after only 5 days of loading) to observe any possible effects.[592]
Previous investigations have shown that a single dose of CM (8 grams) increased the number of repetitions performed during an upper-body resistance training protocol and reduced soreness at 24 and 48 hours post-exercise (compared to a placebo).7 Recently, researchers from Mississippi State University found that a single dose of CM (8 grams) significantly increased the number of lower-body repetitions compared to a placebo group.[8]

Beach muscles and Olympic lifts draw more attention. But the many little stabilizer muscles around your shoulders, hips, and midsection — collectively the core — provide a strong foundation. Challenging the stability and mobility of these key muscles with medicine balls, physioballs, mini-bands, and rotational movements (lifting, chopping) pays huge dividends.
Extracellular creatine (creatine outside of a cell) appears to influence creatine uptake into a cell. It seems that prolonged and excessive levels of creatine actually suppress uptake (a form of negative regulation to prevent excessive influx).[180] In vitro studies in rat muscle cells have shown that including 1mM creatine into cell culture medium substantially reduces creatine uptake into cells. The inhibitory effect was partially negated by protein synthesis inhibitors, suggesting that high levels of creatine induce the expression of a protein that suppresses creatine transporter activity.[180] Similar findings were reported in a later study in cultured mouse myoblasts, which noted a 2.4-fold increase in intracellular creatine levels in the presence of the protein synthesis inhibitor cyclohexamide.[174]
Using too much weight, too soon; always start lower than your expected ability and work your way up that first workout. If your form suffers, you are swinging the weight, or using momentum, this indicates you may be using too much weight. Greater momentum increases the potential for injury and reduces the effectiveness to the muscle group being targeted.