Creatine gets talked about like it's a muscle-building supplement. That's true, sort of. But it's also a pretty poor explanation of what creatine actually does.
Creatine doesn't walk into a muscle cell and tell it to grow. It doesn't switch on some magical anabolic pathway. And taking five grams before training isn't going to suddenly make you stronger twenty minutes later. The interesting part happens much earlier in the chain: creatine changes your capacity to rapidly regenerate ATP. Once you understand that, a lot of the things associated with creatine, more reps, better repeated-effort performance, strength gains and eventually more muscle, start making considerably more sense.
So rather than starting with the supplement bottle, let's start with the thing your muscles are actually trying to do.
Every rep has a price
Every muscle contraction requires energy. Squatting 180kg. Accelerating off the start line. Doing your eighth clean at 120kg. Or simply getting out of a chair. At the cellular level, the immediate currency paying for that work is adenosine triphosphate (ATP). When ATP loses a phosphate group, ATP becomes ADP plus a phosphate group plus energy, and that released energy helps drive muscular contraction. Simple enough.
The problem is that your muscles don't store very much ATP. If you had to rely solely on the ATP already sitting inside the muscle, maximal exercise wouldn't last very long at all. So the important question during hard exercise isn't really "how much ATP do I have?" It's "how quickly can I remake it?" That's where creatine becomes interesting.
Creatine is really an ATP recycling story
Most of the body's creatine is stored in skeletal muscle, either as free creatine or as phosphocreatine (PCr). Supplementation can meaningfully increase that intramuscular pool. Phosphocreatine essentially acts as a rapidly accessible phosphate reserve. When ATP is broken down to ADP during muscular work, the enzyme creatine kinase helps transfer a phosphate from phosphocreatine back onto ADP, and ATP is available again. That's the phosphagen system.
It doesn't require oxygen delivery. It doesn't require a long sequence of reactions. It is exceptionally fast, which is exactly what you need when energy demand goes from relatively low to enormous almost instantly. Think about a heavy clean. The moment you start pulling, ATP demand doesn't politely increase while your aerobic system catches up, it explodes. Your mitochondria will contribute to restoring energy supply, and glycolysis will become increasingly important, but neither can instantaneously match the rate of ATP turnover required at the onset of maximal work. Phosphocreatine helps bridge that gap. That's why creatine matters.
But the phosphagen system isn't an eight-second stopwatch
You've probably heard something like "the ATP-PC system lasts about 10 seconds, then glycolysis takes over." It's a useful teaching model. Physiology isn't actually that tidy. Your energy systems don't operate like three runners passing a baton. The phosphagen, glycolytic and oxidative systems are contributing simultaneously. What changes is their relative contribution.
During extremely high power output, phosphocreatine turnover is enormous. As phosphocreatine availability falls, maintaining the same ATP turnover becomes increasingly difficult and glycolytic and oxidative contributions become proportionally more important. That's an important distinction, because phosphocreatine isn't only relevant to a five-second sprint or a 1RM. It also matters when you need to produce high power repeatedly. And that's where things get particularly relevant for CrossFit, HYROX, field sports and hybrid athletes.
Think about your second effort, not just your first
Imagine this: five rounds of 10 heavy calories on an Assault Bike, 10 power cleans, 60 seconds rest. The first round feels fantastic. The second is manageable. By rounds three and four, you're staring at the bar wondering why 80kg suddenly feels considerably heavier than it did three minutes ago.
There are obviously multiple fatigue mechanisms involved, but one of them is phosphocreatine availability. During the hard effort, PCr is being depleted. During recovery, it has to be restored. And importantly, phosphocreatine resynthesis is largely supported by oxidative metabolism, which gives us an interesting connection people often miss: your "anaerobic" repeatability is partly dependent on your aerobic system.
The phosphagen system allows you to produce very high power. The oxidative system helps recharge it between efforts. That's one reason two athletes with similar strength can have completely different abilities to repeat high-output work. The stronger athlete doesn't necessarily win. Sometimes the athlete who can restore the machinery required to express that strength wins. That's conditioning.
So what does taking creatine actually change?
Supplementing creatine increases the total creatine pool available within skeletal muscle. That gives the muscle a larger reservoir from which phosphocreatine can be maintained and regenerated. The practical effect isn't usually dramatic, you don't suddenly become 10% stronger overnight. Instead, creatine tends to improve your ability to maintain performance when ATP turnover is high, particularly during short-duration and repeated high-intensity work. The broader literature consistently finds benefits for strength and repeated-effort performance, while the effects become less compelling as exercise shifts toward steady-state endurance.
Think: one more rep. Or slightly less power drop-off. Or maintaining bar speed for another set. That sounds almost underwhelming, until you zoom out.
The real benefit compounds
This is where I think creatine is often explained poorly. People want to know "how much stronger will creatine make me?" But that's probably not the most useful question. Imagine Athlete A and Athlete B follow exactly the same training program for six months. Athlete A isn't taking creatine, Athlete B is. If Athlete B can occasionally perform one additional high-quality rep, maintain slightly higher power across repeated efforts, or preserve training quality deeper into a session, then their training stimulus is subtly different. One workout, almost irrelevant. Two hundred workouts, now we're talking.
This is why the longer-term strength and lean-mass effects of creatine probably shouldn't be thought of as creatine leading directly to muscle, but more like creatine leading to greater energetic capacity, leading to slightly more high-quality training, leading to greater accumulated stimulus, leading to greater adaptation. There may also be direct cellular mechanisms involved in hypertrophy and adaptation, including changes in cell hydration and signalling pathways, so training volume isn't the whole story. But from a coaching perspective, this is the part that matters: creatine helps you train. Training creates the adaptation.
Newer evidence continues to support that relationship. A 2025 systematic review and meta-analysis found significantly greater strength gains with creatine supplementation than placebo when both groups were exposed to comparable training. That's much more interesting than calling it a "muscle-building supplement."
Creatine doesn't create energy
This distinction matters. Creatine isn't an energy source in the same way carbohydrate or fat is. It doesn't magically manufacture additional energy. Think of it more like a buffer and shuttle within cellular energy metabolism. The creatine-phosphocreatine system helps move high-energy phosphate between the places ATP is produced and the places ATP is being consumed, and this relationship extends beyond the initial few seconds of exercise.
The mitochondrial creatine kinase system is part of a broader mechanism sometimes described as the creatine shuttle, linking mitochondrial ATP production with cellular sites of ATP utilisation. The physiology is more interconnected than the simple "ATP-PC system" diagram most of us learned in a textbook. Worth remembering: energy systems are models. The body doesn't know what chapter of an exercise physiology textbook you're currently reading.
Why creatine doesn't keep working forever
If five grams works, why not twenty? And if twenty works, why not fifty? Because muscle creatine storage has a ceiling. Once your intramuscular creatine stores are essentially saturated, adding more creatine doesn't continue increasing storage indefinitely. You're filling a tank. Once the tank is full, pouring another bucket over it doesn't make the tank bigger.
This also helps explain why individuals respond differently to supplementation. Someone beginning with relatively low intramuscular creatine stores has more room to increase them. Someone starting with relatively high stores has less. Diet appears to be part of this: people consuming relatively little dietary creatine, vegetarians are the obvious example, often begin with lower muscle creatine concentrations and therefore potentially have more headroom for supplementation. So-called "non-responders" aren't necessarily immune to creatine. Some may simply have less room to respond.
Do you need to load it?
No. Loading is about speed, not whether creatine ultimately works. The classic loading protocol is roughly 20 to 25 grams per day for 5 to 7 days, generally split across several doses, followed by 3 to 5 grams per day. Alternatively, take roughly 3 to 5 grams per day from the beginning. You'll eventually reach similar muscle saturation, it just takes longer. That's it. There isn't a special metabolic doorway that closes if you forget to load. If you have a competition in ten days and haven't been taking creatine, loading might make sense. If you're simply training year-round, take your daily dose and move on with your life.
Does timing matter?
Far less than consistency. Creatine isn't caffeine. You're not taking it because you need a spike in blood creatine at 5:27pm before your 5:30pm session. You're trying to maintain elevated intramuscular creatine stores. That is a chronic process. Taking creatine around training or with a meal may offer small theoretical or practical advantages for uptake, but the big rock is boring: take it consistently. Morning, after training, with lunch, whenever you will actually remember. The difference between taking creatine consistently and inconsistently is considerably more meaningful than the difference between taking it at 8am and 4pm.
What about carbohydrates and insulin?
This is where another half-truth became supplementary folklore. Carbohydrate ingestion, and the resulting insulin response, can increase creatine retention under certain conditions. Studies have also found enhanced retention when creatine is combined with carbohydrate and protein. Mechanistically, that's interesting. Practically, you probably don't need to drink a massive sugar shake with your creatine. If you're eating normally, training and consuming creatine consistently, you'll still saturate muscle creatine stores.
This distinction matters: something can improve a mechanism without meaningfully improving the outcome you care about. That's a useful filter for supplement research in general.
What about sodium?
Creatine doesn't simply wander through the muscle membrane. Its uptake is mediated primarily by the creatine transporter, SLC6A8/CrT1, which is sodium- and chloride-dependent. That's fascinating physiology. But it doesn't automatically mean "more sodium equals more creatine uptake equals more performance." That's where the mechanism gets turned into marketing. The transporter depends on electrochemical gradients, but in a normally fed and hydrated athlete, sodium availability isn't generally considered the bottleneck preventing creatine supplementation from working.
There is, however, a broader connection between sodium, hydration and performance, particularly in athletes accumulating large sweat losses. That's a different conversation, and one we'll come back to.
Does creatine make you hold water?
Yes, and that's not necessarily a bad thing. Increasing intramuscular creatine increases the osmotic pull of water into the muscle cell. That's why people can gain roughly 1 to 2kg during aggressive loading protocols. But notice the important word: intramuscular. We're not necessarily talking about walking around looking like you've retained three litres of water under your skin.
Cell hydration is part of the physiology. For most strength, CrossFit and hybrid athletes, that's not a problem. For an athlete competing in a weight-class sport or where running economy is critically important, the cost-benefit calculation becomes more interesting. A 60kg distance runner and a 100kg CrossFit athlete shouldn't automatically make identical supplementation decisions. Context matters.
Creatine isn't just a strength supplement either
Here's where the story has expanded considerably. Creatine metabolism isn't exclusive to skeletal muscle. The brain also has substantial energetic demands, and creatine participates in cellular energy buffering there as well. Research has investigated creatine in relation to cognition, ageing, sleep deprivation and neurological function, although the strength of evidence varies considerably depending on the outcome and population.
There is also research exploring creatine's relationship with oxidative stress and cellular protection. A review of the literature describes potential direct and indirect mechanisms, including maintenance of cellular energy status, mitochondrial integrity and modulation of antioxidant systems. This is interesting. It is not a reason to market creatine as some sort of anti-ageing brain antioxidant, that's exactly the kind of leap Bedrock shouldn't make. Mechanistic plausibility is not the same thing as a meaningful real-world outcome. But it does reinforce something important: creatine is involved in fundamental cellular energetics, not simply bodybuilding.
And what about endurance athletes?
This gets nuanced. If you're asking "does creatine meaningfully increase steady-state aerobic capacity," probably not in the way it improves repeated high-intensity performance. But endurance sport isn't always steady state. Cyclists attack. Runners surge and kick. Rowers start hard. HYROX athletes repeatedly transition between running and high-force stations. CrossFit athletes move constantly between oxidative work and extremely high rates of ATP demand.
Creatine becomes potentially useful wherever repeated high-intensity efforts are embedded within predominantly aerobic work. There's also the interaction we discussed earlier: oxidative metabolism helps restore phosphocreatine. So rather than thinking aerobic versus anaerobic, it's more useful to think about how these systems are interacting to meet ATP demand. That question gets us much closer to how athletes actually perform.
The supplement doesn't rescue bad training
This might be the most important part. Creatine works, but the size of the effect needs perspective. If your training program is poor, creatine won't fix it. If you're sleeping five hours per night, creatine isn't the bottleneck. If you're eating insufficient protein and calories to support adaptation, another supplement isn't the answer. If every conditioning session turns into you redlining yourself into the floor, five grams of white powder isn't going to magically create intelligent programming.
The broader principle from conditioning nutrition is simple: supplementation sits on top of the fundamentals rather than replacing them. And this is where the supplement industry often gets things backwards. We obsess over the final 2%. Meanwhile the first 98% is sitting there waiting to be addressed.
So should you take creatine?
For most healthy strength, power, CrossFit and hybrid athletes, there's a pretty strong argument for it. Creatine monohydrate is inexpensive, extensively researched, effective and generally well tolerated in healthy people. The evidence supporting fancy alternative forms is considerably weaker than the evidence supporting plain creatine monohydrate. You probably don't need a proprietary blend, a "rapid absorption matrix," or creatine infused with twelve other ingredients. You need creatine monohydrate, and consistency.
Three to five grams per day is a perfectly sensible starting point for most people. Loading is optional. Cycling isn't necessary. Timing isn't particularly important. And if you have kidney disease or another medical condition affecting creatine use or clearance, that's a conversation to have with your doctor rather than a fitness blog.
The bigger lesson
Creatine is interesting because it's one of the rare supplements where the mechanism and the outcome line up remarkably well. We understand the system. We understand what phosphocreatine does. We understand why increasing the intramuscular creatine pool should matter. And when we test it experimentally, performance and training outcomes generally move in the direction the physiology predicts.
But there's an even bigger lesson here. Your body doesn't care about supplements. It cares about energy demand. Every time you sprint, squat, row, clean or perform a burpee, ATP is being consumed and regenerated at enormous rates. Creatine simply gives one of those regenerative systems a little more capacity. And "a little more" doesn't sound particularly exciting, until you multiply it across hundreds of sets, thousands of reps and years of training. That's where small physiological advantages stop being small. That's why creatine works.