Creatine is a hydrophilic polar molecule that consists of a negatively charged carboxyl group and a positively charged functional group [64]. The hydrophilic nature of creatine limits its bioavailability [65]. In an attempt to increase creatines bioavailability creatine has been esterified to reduce the hydrophilicity; this product is known as creatine ethyl ester. Manufacturers of creatine ethyl ester promote their product as being able to by-pass the creatine transporter due to improved sarcolemmal permeability toward creatine [65]. Spillane et al [65] analyzed the effects of a 5 days loading protocol (0.30 g/kg lean mass) followed by a 42 days maintenance phase (0.075 g/kg lean mass) of CM or ethyl ester both combined with a resistance training program in 30 novice males with no previous resistance training experience. The results of this study [65] showed that ethyl ester was not as effective as CM to enhance serum and muscle creatine stores. Furthermore creatine ethyl ester offered no additional benefit for improving body composition, muscle mass, strength, and power. This research did not support the claims of the creatine ethyl ester manufacturers.
Women who train hard and reach low body fat levels, say under 10 percent, may be at risk of losing their periods as a result of hormonal disruption to estrogen production. Exercise-induced estrogen declines can result in bone loss in a way similar to that which occurs at the menopause. Loss of periods from athletic training is not uncommon but does require that you see a doctor, or better still, a sports physician and sports nutritionist to assess what is required to address the problem. Calcium supplements may be a part of the solution if bone health is likely to be affected. 
In a sample of people with colorectal cancer given creatine supplementation for 8 weeks to assess its interactions with chemotherapy, creatine failed to benefit muscle function or quality of life. Benefits were observed in body cell mass and phase angle (indicative of cellular viability), but only in the subsample with less aggressive chemotherapy.[111]
Cyclocreatine (1-carboxymethyl-2-iminoimidazolidine) is a synthetic analogue of creatine in a cyclic form. It serves as a substrate for the creatine kinase enzyme system, acting as a creatine mimetic. Cyclocreatine may compete with creatine in the CK enzyme system to transfer phosphate groups to ADP, as coincubation of both can reduce cyclocreatine’s anti-motility effects on some cancer cells.[96]
Creatine supplementation appears to attenuate decreases in GLUT4 expression seen with immobility and may increase GLUT4 expression during exercise. While it seems capable of increasing GLUT4 during resting conditions, it has failed to reach significance, suggesting that creatine supplementation works best with some stimuli associated with exercise.
If you’re not lifting super-heavy weights, doing high-intensity workouts, or eating a mainly vegan or vegetarian diet, your body probably makes as much creatine as it needs. “Creatine is naturally found in animal-based products,” says Bates, “so your body can make plenty of creatine as long as you have a balanced diet that includes animal-based products.” Protein sources like beef, chicken, pork, and fish help your body produce the creatine it needs — it varies depending on the source, but, in general, a 3-ounce serving of meat will have about 0.4 grams (g) of creatine, Bates says. (6)
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.
If you’re the kind of person who shops for popular dietary supplements like protein or collagen powder, you’ve probably seen another popular bottle on the shelves: creatine. This supplement, which can be taken as a powder or liquid (and usually in some kind of healthy shake), is a staple in the bodybuilding community thanks to its ability to help you pack on muscle and work out longer and harder. (1) While creatine is generally considered safe — and is one of the most researched supplements out there (according to a review published in July 2012 in the Journal of the International Society of Sports Nutrition) — it is still a supplement, which means it’s not regulated by the Food and Drug Administration (FDA) and product claims don’t necessarily need to be substantiated (though the FDA can pull products that are found to be unsafe). (2,3)
Creatine is known to occur in highly concetrated levels in chicken photoreceptors, relative to other parts of the eye (10-15mM[466]) alongside high levels of creatine kinase.[466] The creatine transporter in human eyes also seems to be concentrated in the photoreceptors,[468] which are known to be susceptible to hypoxic cellular death[471][472] which, for humans, usually means retinal detachment.[473]
Need the motivation to push past your comfort zone and squeeze out one more push-up or bicep curl? Sure, it helps to remember that you’ll get stronger, rock more toned muscles and rev your metabolism, thanks to all that added muscle mass. But if that wasn’t enough, now comes news that all that pump-itude (yes, that’s an SNL reference) has psychological benefits, too.

For beginners, your own body weight might be enough to get you started. However, it can be hard to challenge your body without any additional resistance, so to progress, you'll need some equipment. If you decide to strength train at home, you'll want to invest in some basics, such as resistance bands, weights, and an exercise ball. Try to have a range of weights: a light set (3 to 5 pounds for women, 5 to 8 pounds for men), a medium set (5 to 10 pounds for women, 10 to 15 pounds for men), and a heavy set (10 to 20 pounds for women, 15 to 30 pounds for men).

You’d have to look hard to find a fitness expert who doesn’t recommend taking supplemental protein powder for building muscle. It’s one of the best supplements for building muscle on the market! In addition to serving as a muscle building supplement, protein powder can be the perfect complement to a successful weight loss plan. Studies show that the supplement can prevent loss of muscle mass, helping you lose fat exclusively instead.

Creatine is known to be present in the retina due to the expression of creatine kinase (CK)[466][39] and the GAMT enzyme of creatine synthesis, which is also present in the mammalian retina.[467] Creatine in the blood can be transported into the retina via the creatine transporter (confirmed in humans[468]), and inhibiting transporter activity (by depleting the medium of chloride and sodium) reduces uptake by 80%.[469] The fact that not all uptake was inhibited suggests that another transporter, such as the monocarboxylate transporter MCT12 (or SLC16A12),[470] plays a role, perhaps moreso in the lens, where its levels were comparable to that of the major creatine transporter SLC6A8.[470] 
Beast Creature could be another good option for female athletes. It’s tasty, it contains five types of creatine, and it contains ingredients that could improve fat loss by increasing insulin sensitivity. One potential bonus is that it also has 70 percent of your daily biotin, a nutrient often included in women’s multivitamins due its purported benefits for hair and nails.

The United States Army is about to undertake a dramatic and unprecedented overhaul to the way it tests, and promotes, military fitness. The man who headed the research into the new standards talks with us about how and why, as well as the future of Army nutrition and how the Army plans to circulate 80,000 kettlebells to bases around the globe. January 22, 2019 • 43 min read

These effects were noted before in a preliminary study of depressed adolescents (with no placebo group) showing a 55% reduction in depressive symptoms at 4g daily when brain phosphocreatine levels increased.[231] Other prelimnary human studies suggest creatine might lessen unipolar depression[256] and one study on Post-Traumatic Stress Disorder (PTSD) noted improved mood as assessed by the Hamilton Depression Rating Scale.[232]
Before getting into the nitty-gritty details about supplements, it’s important to have a good understanding of how muscle growth works. When you take a muscle growth supplement, the role it plays in helping you reach your goals should be very clear. With the supplements available on the market, you can be sure that while some serve an important purpose, others are gimmicks. It’s easier to identify the money wasters if you know how muscle building works.
If you'’re looking to add muscle mass to your frame, hitting the weights hard is a given. Quality time in the gym begins a cascade of changes that will stimulate your muscles to grow bigger in response to the challenges you throw their way. It'’s tempting to think that'’s all it takes to add muscle to your body. After all, you can actually feel your biceps growing after an intense set of curls.
High extracellular creatine concentrations induce the expression of a factor that inhibits the creatine transporter (CrT). To date, neither the identity of nor mechanism for this putative CrT-suppressing factor has come to light. Future studies that are able to identify this creatine transport-suppressing factor and how it works may provide valuable insight into possible supplementation strategies that might be used to increase creatine uptake into muscle cells.
Even if you have a schedule that allows for a 5-day workout split, many people (I’d even call it the majority) simply don’t have the recovery capacity needed to make that work. This could be due to genetics, age, injury history, various lifestyle factors (sleep, stress, etc.) and more. In these cases, better results would be seen with 3-4 workouts per week instead.
Stash away your scale for several weeks — and set a strength training goal instead. That’s the advice of Lisette Cifaldi, director of behavioral health at Hilton Head Health weight loss resort who counsels patients. “I think strength training shifts your perspective,” she says. “The happiness doesn’t come from achieving a certain number [on the scale]. It comes from the process of getting stronger and feeling empowered that you’re navigating your own success.”
Men appear to have higher active creatine-kinase systems, and racial differences favor black people over hispanic people over white people in terms of the activity of the creatine-kinase system. This system is more variable in men, independent of supplementation. Exercise may increase the activity of the creatine-kinase system independent of supplementation.