Polyethylene glycol is a non-toxic, water-soluble polymer that is capable of enhancing the absorption of creatine and various other substances [66]. Polyethylene glycol can be bound with CM to form polyethylene glycosylated creatine. One study [67] found that 5 g/d for 28 days of polyethylene glycosylated creatine was capable of increasing 1RM bench press in 22 untrained young men but not for lower body strength or muscular power. Body weight also did not significantly change in the creatine group which may be of particular interest to athletes in weight categories that require upper body strength. Herda et al [68] analyzed the effects of 5 g of CM and two smaller doses of polyethylene glycosylated creatine (containing 1.25 g and 2.5 g of creatine) administered over 30 days on muscular strength, endurance, and power output in fifty-eight healthy men. CM produced a significantly greater improvement in mean power and body weight meanwhile both CM and polyethylene glycosylated form showed a significantly (p < 0.05) greater improvement for strength when compared with control group. These strength increases were similar even though the dose of creatine in the polyethylene glycosylated creatine groups was up to 75% less than that of CM. These results seem to indicate that the addition of polyethylene glycol could increase the absorption efficiency of creatine but further research is needed before a definitive recommendation can be reached.
^ Jump up to: a b c d Luckose F, Pandey MC, Radhakrishna K (2015). "Effects of amino acid derivatives on physical, mental, and physiological activities". Crit. Rev. Food Sci. Nutr. 55 (13): 1793–1807. doi:10.1080/10408398.2012.708368. PMID 24279396. HMB, a derivative of leucine, prevents muscle damage and increases muscle strength by reducing exercise-induced proteolysis in muscles and also helps in increasing lean body mass. ... The meta analysis studies and the individual studies conducted support the use of HMB as an effective aid to increase body strength, body composition, and to prevent muscle damage during resistance training.
Creatine, the amino acid, naturally helps your body produce more adenosine triphosphate, or ATP, a small molecule that’s actually your body's primary energy source. But research shows that your body is only capable of storing enough ATP for 8 to 10 seconds of high-intensity exercise — and after that, it needs to produce new ATP for you to continue. (9)

In a pilot study on youth with cystic fibrosis, supplementation of creatine at 12g for a week and 6g for eleven weeks afterward was associated with a time-dependent increase in maximal isometric strength reaching 14.3%, which was maintained after 12-24 weeks of supplement cessation (18.2% higher than baseline).[485] This study noted that more patients reported an increase in wellbeing (9 subjects, 50%) rather than a decrease (3, 17%) or nothing (6, 33%) and that there was no influence on chest or lung symptoms.[485]
Translation: your muscles are going to have more energy. The process of accessing that energy is so complicated, you almost need an organic chemistry degree to totally understand it. Yes, it’s complicated, but completely necessary for biochemical reactions like muscle contractions. And the more your muscle works, the more ATP is depleted and needs to be replaced for you to make progress toward your goals. With creatine supplementation, you can enhance your ATP regeneration and thus delay onset of muscle fatigue and work more intensely for a longer period of time. Little goes a long way in the pursuit of muscle gains.
Anti-cancer effects have been observed with the creatine analogue cyclocreatine[456][104][457] and have been replicated with creatine itself. These effects tend to be a reduction in which the rate of implanted tumors progresses.[458][459] It is suspected that these observed effects (inhibition of growth or attenuation of the rate of growth) are not due to the bioenergetic effect of creatine, secondary to creatine kinase. These anti-cancer effects do not have a known reliability, as the expression of creatine kinase varies widely based on the type of tumor.[460] However, some studies suggest an inverse relationship between tumor progression in mice and concentrations of creatine in cells, with creatine depletion coinciding with tumor development.[460]

^ Haykowsky MJ, Liang Y, Pechter D, Jones LW, McAlister FA, Clark AM (June 2007). "A meta-analysis of the effect of exercise training on left ventricular remodeling in heart failure patients: the benefit depends on the type of training performed". Journal of the American College of Cardiology. 49 (24): 2329–36. doi:10.1016/j.jacc.2007.02.055. PMID 17572248.

Creatine kinase enzymes (of which there are numerous isozymes) exist in both the mitochondria and the cytosol of the cell.[45][40] The four isozymes of creatine kinase include the Muscle Creatine Kinase (MCK), present in contractile muscle and cardiac muscle, and the Brain Creatine Kinase (BCK), expressed in neuron and glial cells and several other non-muscle cells. These two creatine kinases are met with Sarcolemmic Mitochondrial Creatine Kinase (sMitCK), expressed alongside MCK, and the ubiquitous Mitochondrial Creatine Kinase (uMitCK), which is expressed alongside BCK everywhere else.[25][39]
Spero Karas, MD, assistant professor of orthopaedics in the division of sports medicine at Emory University, says that testosterone, the male hormone responsible for muscle growth, maxes out between the ages of 16 and 18. It reaches a plateau during the 20s and then begins to decline. As a result, muscle building after the adolescent years can be challenging, he says. 

You can't scroll through Instagram without clocking a mammoth cheat day feast, but are real-life bodybuilders consuming such a crazy amount of calories every couple of weeks? Not quite. When he’s dieting for a competition, Terry incorporates ‘re-feed days’ into his schedule. This means he eats the exact same food, but essentially doubles the portion sizes.
Different exercises will require different weights, but there are some markers that can help guide you towards the right resistance, whether you're using dumbbells, kettlebells, or a barbell. Go for a weight that feel heavy enough to challenge you, but not so heavy that you sacrifice your form. For example, if you're doing 15 reps, you should feel pretty fatigued by the time you hit rep 15. If you can breeze through all your reps, though, that's a sign you should up the weight.
It is known that intracellular energy depletion (assessed by a depletion of ATP) stimulates AMPK activity in order to normalize the AMP:ATP ratio,[333][334] and when activated AMPK (active in states of low cellular energy[335] and colocalizes with creatine kinase in muscle tissue[336]) appears to inhibit creatine kinase via phosphorylation (preserving phosphocreatine stores but attenuating the rate that creatine buffers ATP). While phosphocreatine technically inhibits AMPK, this does not occur in the presence of creatine at a 2:1 ratio.[334] It seems that if the ratio of phosphocreatine:creatine increases (indicative of excess cellular energy status) that AMPK activity is then attenuated, since when a cell is in a high energy status, there is less AMP to directly activate AMPK.[334][336][337]