Does Red Light Therapy Boost Resistance Training Results?
Adding photobiomodulation (red light or near-infrared therapy) to a structured resistance training program does not appear to meaningfully increase maximal strength gains in older adults, based on the current body of randomized controlled trial evidence. A 2026 systematic review and meta-analysis found no statistically clear benefit on one-repetition maximum (1RM) outcomes, though a small effect could not be ruled out, and some recovery-related improvements were observed. If you are a serious lifter weighing whether to invest in PBM devices or protocols, the honest answer right now is: the strength evidence is not there yet.
Key Finding
The meta-analysis pooled data from 11 randomized controlled trials and found that PBM — delivered via low-level laser therapy (LLLT) or light-emitting diodes (LEDs) — did not produce a statistically clear improvement in maximal strength (1RM) when added to periodized resistance training in older adults. The effect size was small and the confidence intervals crossed zero, meaning the data is consistent with no meaningful difference. However, the narrative synthesis of included studies pointed toward possible benefits in recovery-related outcomes and training tolerance — a distinction worth understanding before you write off PBM entirely.
Study Details
What was studied: The researchers conducted a systematic review and meta-analysis of randomized controlled trials examining PBM as an adjunct to resistance training or strength-oriented loading tasks in older adults.
Search scope: Seven major databases — PubMed, Scopus, Embase, PEDro, Web of Science, the Cochrane Library, and CNKI — were searched from inception through January 2026.
Population: Older adults participating in structured resistance training programs.
Primary outcome: One-repetition maximum (1RM), the gold-standard measure of maximal strength.
Design: Only RCTs were eligible. The prespecified meta-analysis was restricted to trials combining PBM with periodized resistance training that reported 1RM outcomes. Other studies were included in a narrative synthesis.
This is a methodologically conservative approach — and that conservatism is appropriate. Restricting the primary analysis to 1RM outcomes in periodized programs means the headline result reflects the question most lifters actually care about: does adding PBM make you stronger?
Results
The core findings, plainly stated:
- No clear benefit on maximal strength (1RM): The pooled meta-analysis did not demonstrate a statistically significant improvement in 1RM from adding PBM to resistance training.
- Small effect cannot be excluded: The data is consistent with a small positive effect, but also consistent with no effect. The evidence base is not large enough to confidently detect a modest benefit if one exists.
- Possible recovery and tolerance benefits: The narrative synthesis suggested PBM may support recovery-related outcomes — such as reduced muscle soreness or faster return to training readiness — and may help vulnerable older adults maintain training consistency.
- 11 RCTs included: This is a relatively small evidence base, which directly limits the conclusions that can be drawn.
The distinction between strength adaptation and recovery support matters here. These are different biological targets. If PBM reduces delayed-onset muscle soreness or helps an older lifter train more sessions per week without excessive fatigue, that is a real — if indirect — contribution to long-term progression, even if it does not directly accelerate the strength adaptation itself.
Limitations
The authors are transparent about the constraints on their conclusions, and you should be too when interpreting this research.
Small evidence base: Eleven RCTs is a limited sample. Meta-analyses built on small numbers of trials are sensitive to the characteristics of individual studies, and a few well-designed trials in either direction could shift the pooled estimate substantially.
Heterogeneity in PBM protocols: Photobiomodulation is not a single, standardized intervention. Wavelength, irradiance, dose, timing relative to training, and application site varied across trials. Pooling studies with meaningfully different protocols introduces noise that can obscure real effects — or manufacture apparent ones.
Population specificity: These findings apply to older adults in periodized resistance training programs. Extrapolating to younger, recreationally trained, or advanced lifters requires caution. The biology of recovery and adaptation differs across age groups.
What This Means for Your Training
This is where the research earns its keep — not as a headline, but as a framework for decision-making.
If you are training for strength, PBM is not a substitute for progressive overload. The 2026 ACSM resistance training guidelines — the first major update in 17 years, drawing on over 130 systematic reviews and more than 30,000 participants — reinforce that the primary driver of strength adaptation is consistent, progressive training volume. No adjunct intervention changes that equation.
PBM is not a priority investment for most lifters. If you are deciding where to put your time, money, and attention, the evidence does not support prioritizing PBM devices over more fundamental variables: program structure, session consistency, sleep, and nutrition. The effect on maximal strength, if it exists at all, is small.
The recovery angle deserves more attention than the strength angle. For older lifters — particularly those managing soreness, joint sensitivity, or reduced recovery capacity — the narrative evidence around training tolerance is worth watching as the research matures. The question "does PBM make me stronger" may be less useful than "does PBM help me train more consistently without breaking down." Consistency, as the 2026 ACSM guidelines note explicitly, is the best predictor of long-term outcomes.
Track your actual training, not your biohacking stack. One of the clearest signals in resistance training research is that lifters who systematically track their sessions — volume, load, progression — outperform those who train by feel. Before adding any adjunct intervention, the higher-leverage question is whether your training data is telling you something actionable. Kenso's rule-based progression engine and session logging exist precisely for this: to give you a clear picture of whether your program is working, week over week, without noise.
If you are already tracking your training with Kenso and your progression is stalling, the answer is almost certainly in your program variables — not in a light therapy device. If you want to explore PBM for recovery support, that is a reasonable experiment, but treat it as one variable in a well-tracked program, not a solution.
FAQ
Does photobiomodulation (red light therapy) increase strength in older adults?
Based on the current best evidence — a 2026 systematic review and meta-analysis of 11 RCTs — PBM does not clearly improve maximal strength (1RM) when added to resistance training in older adults. A small effect cannot be ruled out, but the evidence is not strong enough to support PBM as a strength-enhancement tool.
What is the difference between photobiomodulation and red light therapy?
Photobiomodulation (PBM) is the clinical and research term for the use of low-level laser therapy (LLLT) or light-emitting diodes (LEDs) at specific wavelengths — typically red (630–700 nm) or near-infrared (700–1100 nm) — to influence cellular processes. "Red light therapy" is the popular consumer term for the same category of devices.
Can PBM help with muscle recovery after resistance training?
The narrative synthesis in this 2026 meta-analysis suggested PBM may have selective value in improving recovery-related outcomes and supporting training tolerance, particularly in older adults. This is a different claim from improving maximal strength, and the evidence here is preliminary. Larger, well-controlled trials are needed.
What actually drives strength gains in resistance training?
The primary driver of strength adaptation is consistent, progressive resistance training volume over time. The 2026 ACSM resistance training guidelines — based on over 130 systematic reviews — confirm that any well-structured resistance training program improves strength and muscle function, and that consistency is the most important variable. Adjunct interventions like PBM are secondary to getting the fundamentals right.
How should I track whether my resistance training program is working?
The most reliable method is systematic session logging — recording sets, reps, and load over time so you can identify real progression versus stagnation. Tracking your training in an app like Kenso gives you a data-driven view of your progression trends, which is more actionable than subjective feel alone.
Citation
Chen H, Eungpinichpong W, Asawaphureekorn S, Manimmanakorn N, Yang Y, et al. Photobiomodulation as an Adjunct to Resistance Training in Older Adults: A Systematic Review and Meta-Analysis. Photobiomodulation, Photomedicine, and Laser Surgery. 2026. DOI: 10.1177/25785478261469320. PubMed: https://pubmed.ncbi.nlm.nih.gov/42473844/
Track your training with intention. Download Kenso on iOS at kensoforge.com.