Gymmaxxing: where the trend tracks real strength science, and where it doesn't

Gymmaxxing is the fitness wing of the optimisation trend: maximising muscle and strength through hard resistance training, a heavy supplement stack, precise protein timing and — at its more extreme edge — performance-enhancing drugs marketed as shortcuts. It is the rare "-maxxing" trend built on a genuinely strong evidence base, because the two things at its core, lifting weights and taking creatine, are among the best-supported interventions in the whole field. The problem is that the trend surrounds that solid core with a periphery of unproven products and genuinely dangerous ones, and treats all of it as equally validated.

The core that is real

Resistance training earns the confidence the trend places in it. A 2025 meta-regression pooling 67 studies modelled weekly set volume against muscle growth and found the probability that more volume produces more hypertrophy was effectively certain, with a clearer dose-response curve than earlier category-based analyses could draw — while showing that the variables driving size and strength are not identical [s2]. Our hypertrophy evidence that moved piece works through what that means for how people actually train.

The benefits are not confined to appearance. A pooled analysis of 147,374 adults followed for up to 30 years found that 90 to 119 minutes of resistance training a week, independent of aerobic exercise, was associated with 13% lower all-cause mortality, 19% lower cardiovascular mortality and 27% lower neurological-disease mortality [s3]. Our resistance training and mortality review covers the full dose-response, including where the returns flatten. This is the strongest thing gymmaxxing has going for it, and it is available for the cost of a couple of hours a week.

The same volume analysis also carries a lesson the trend tends to miss: the variables that build size and the variables that build strength are not identical, and both curves show diminishing returns rather than rewarding ever-more training without limit [s2]. More is better up to a point, and then it is not — which is the opposite of the "maximise everything" reflex the name encodes. The practical implication is that the marginal hour spent grinding extra volume returns less than the first hours did, and at some point returns fatigue and injury instead of muscle.

Creatine monohydrate is the one supplement that belongs in that first tier. A dose-response meta-analysis found it increased fat-free mass by 1.39 kg when combined with resistance training, with a benign safety profile [s1]. Our creatine 2026 evidence update and the piece on creatine's effect on mood, kidneys and strength lay out both the benefits and the recent safety questions honestly.

The periphery that mostly is not

Around that core, the returns fall off fast. The most durable myth the trend enforces is the "anabolic window" — the belief that protein must be consumed within a narrow post-workout period — which the evidence does not support once total daily protein is adequate; our protein timing and the anabolic window piece sets out why total intake, not timing, is what matters, and our protein targets review covers how much is actually enough. Most of the rest of the stack — testosterone-adjacent "boosters", exotic pre-workouts, recovery powders — carries far weaker evidence than its placement beside creatine implies. The error is the same one that runs through every optimisation trend: treating a validated intervention and a marketed one as members of the same category because they sit on the same shelf.

The dangerous edge: SARMs

At the trend's sharp end are selective androgen receptor modulators (SARMs), sold online as muscle- building compounds with fewer side effects than anabolic steroids. This piece gives no guidance on using them, because the evidence is that they are unapproved drugs with unestablished safety — and because, remarkably, they are frequently not even the drug on the label. When researchers chemically analysed 44 products sold as SARMs, only 23 (52%) actually contained a SARM, and a further 17 (39%) contained a different unapproved drug entirely [s4]. A user cannot know what they are taking, at what dose, or what undeclared substance came with it. That is a poisoning risk layered on top of a drug risk, and no amount of training discipline controls for it.

What to watch

Gymmaxxing is worth separating from the trends it travels with, because its foundation is sound in a way theirs are not. The reasonable version is almost boring: train with progressive resistance, take creatine if you like, eat enough protein, and ignore the rest. The trend's failure is one of proportion — spending on the periphery, chasing timing minutiae, and for a minority reaching for contaminated drugs — in pursuit of gains the boring version already delivers. The single highest- yield action in the whole stack is also its cheapest and best-evidenced: the training itself.

Sources

• [s1] Creatine supplementation and resistance training: a comparison between novice and experienced lifters — Journal of the International Society of Sports Nutrition, September 2025. https://pmc.ncbi.nlm.nih.gov/articles/PMC12777911/
• [s2] The Resistance Training Dose Response: Meta-Regressions Exploring the Effects of Weekly Volume and Frequency on Muscle Hypertrophy and Strength Gains — Sports Medicine, 4 December 2025. https://doi.org/10.1007/s40279-025-02344-w
• [s3] Long-term resistance training with all-cause and cause-specific mortality — British Journal of Sports Medicine, 2 June 2026. https://doi.org/10.1136/bjsports-2025-110503
• [s4] Chemical Composition and Labeling of Substances Marketed as Selective Androgen Receptor Modulators and Sold via the Internet — JAMA, 28 November 2017. https://doi.org/10.1001/jama.2017.17069