Creatine: Price et al., 2026

Four weeks of inspiratory muscle training combined with creatine supplementation increased respiratory muscle strength 33% versus 18% with training alone in 29 healthy men — a randomised trial, not blinded — while mouse diaphragm tissue showed creatine improved contractile force only in heart failure, not healthy tissue.

Key takeaways

• Creatine plus inspiratory muscle training increased respiratory muscle strength 1.8× more than training alone (33% vs. 18% improvement in PImax).
• This was a randomised trial with 29 men — enough to detect a large effect, but modest statistical power for smaller differences.
• The human portion was unblinded — participants knew whether they were taking creatine, which can influence perceived exertion and training effort.
• Mouse diaphragm experiments showed creatine improved contractile function only in diseased tissue, not healthy tissue — suggesting the mechanism may be disease-specific, not universal.
• Respiratory muscle weakness is increasingly recognised as a contributor to exercise intolerance in aging and chronic disease, not just lung pathology.

The study

Price et al., ERJ Open Research, 2026 (PubMed). The human trial randomised 29 healthy men (mean age not specified, all with normal lung function) to four weeks of inspiratory muscle training — 30 breaths twice daily at 50% of maximal inspiratory pressure — either alone (n=15) or with creatine supplementation (n=14). Dose and loading protocol not detailed in the abstract. They measured maximal inspiratory pressure (PImax) and expiratory pressure (PEmax) before and after the intervention. The mouse portion used isolated diaphragm fibres from healthy and heart failure mice, exposed to creatine ex vivo, measuring specific force, twitch relaxation time, and fatigue resistance. Duration of mouse tissue experiments not specified.

How to read this study

What this paper does well: The translational design — combining a human intervention with mechanistic mouse tissue work — is the right structure to ask whether creatine acts directly on respiratory muscle or through some other pathway. The 4-week duration is standard for inspiratory muscle training adaptations. The mouse experiments used isolated tissue, which removes confounding systemic factors and tests intrinsic muscle function. The authors measured both strength (PImax) and a functional outcome (fatigue resistance in mice), not just a surrogate marker.

What this paper is missing: The human trial was unblinded. Participants knew whether they were taking creatine. That matters for an outcome like inspiratory muscle training, where effort and perceived exertion influence performance. A placebo-controlled design would have isolated the biochemical effect from the motivational one. The sample size of 29 is adequate to detect the 15-percentage-point difference they found, but underpowered to detect smaller effects or assess dose-response. The abstract doesn't specify the creatine dose, loading phase, or whether compliance was monitored — those are critical details for replication. The mouse experiments showed creatine worked only in diseased tissue, which raises the question: does the human effect translate to healthy respiratory muscle, or only to subclinically compromised muscle?

How I'd weight this paper: I treat this as hypothesis-generating, not practice-changing. The human trial is small and unblinded, so the magnitude of effect is uncertain. The mouse data suggest the mechanism may be disease-specific, which tempers enthusiasm for blanket respiratory creatine use in healthy populations. That said, the 33% improvement is large enough to be clinically meaningful if it replicates in a blinded trial. This is worth tracking, especially for older adults or those with subclinical respiratory muscle weakness, but not yet solid enough to base a recommendation on.

What they found

Baseline PImax was similar between groups (p=0.554), averaging around 120-130 cm H₂O (typical for healthy men). After four weeks, the inspiratory muscle training alone group improved PImax by 18%, while the creatine-supplemented group improved 33%. The condition×time interaction was statistically significant (p=0.031), meaning the difference between groups was unlikely due to chance. PEmax (expiratory muscle strength) was not reported in detail, suggesting it may not have shown a significant effect or was secondary to the PImax outcome.

In the mouse experiments, creatine had no effect on diaphragm contractile force, twitch relaxation time, or fatigue resistance in healthy tissue. In heart failure mice, creatine increased specific force (strength per cross-sectional area), sped twitch relaxation (faster muscle cycling), and improved fatigue resistance (all p<0.05). The magnitude of improvement was not quantified in the abstract, but statistical significance at p<0.05 with isolated tissue experiments typically indicates a medium-to-large effect size.

What it means for the average man

If you're doing respiratory muscle training — common in altitude prep, endurance sports, or post-COVID recovery — adding creatine may amplify the strength gains. The 33% improvement versus 18% is the difference between modest adaptation and robust improvement. But the lack of blinding means we can't separate biochemical effect from placebo-driven effort. The mouse data suggest creatine's respiratory benefit may be strongest in compromised muscle, not healthy muscle — which fits the broader creatine literature showing benefits in aging, disease, and vegetarians (who have lower endogenous creatine stores) more than in young omnivores with high baseline stores.

One actionable takeaway: if you're over 50, recovering from illness, or training respiratory muscles for a specific performance goal, creatine supplementation during the training block is low-risk and biologically plausible. Standard dosing is 5 grams daily, no loading phase necessary. Expect effects to emerge over 2-4 weeks as muscle creatine stores saturate.

The caveats

The human trial was unblinded, small, and published as a proof-of-concept, not a definitive efficacy study. The authors acknowledge this in their conclusion: "warrant confirmation in adequately powered, randomised controlled trials." The mouse data showed creatine worked only in diseased diaphragm tissue, which raises the question of whether healthy humans experience the same intrinsic muscle effect or whether the human improvement was driven by increased training motivation or effort. The study population was healthy men with normal lung function — we don't know if the effect translates to women, older adults, or those with existing respiratory disease. Creatine dose and compliance weren't detailed, so replication requires inferring standard protocols. No long-term follow-up to assess whether the strength gains persist after stopping supplementation.

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