Over the course of this series, we have established that your skin's overnight repair programme depends on the timing and quality of your sleep, that systemic hydration affects the physical resilience of your skin barrier, and that what you eat provides or withholds the molecular raw materials your skin requires to function. All of those are inputs into the same biological system. Physical exercise is another one, and the mechanism by which it works on skin is more precise and better characterised than most people would expect.

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Did you know that skeletal muscle is a signalling organ?

For a long time, muscles were thought of primarily as the tissue that moves your body. What became increasingly clear over the last two decades is that contracting skeletal muscle also functions as an endocrine organ, releasing a family of proteins into the bloodstream called myokines during and after physical activity (Pedersen et al. 2023). These proteins travel to distant tissues, including the liver, the brain, adipose tissue, and the skin, where they alter the behaviour of cells in those tissues. This is how exercise produces benefits far beyond the muscles doing the work.

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How do myokines affect the skin?

One of the best-studied of these is interleukin-15, or IL-15. During aerobic exercise, muscles release IL-15 into the circulation. IL-15 travels to the skin, where it stimulates mitochondrial function in fibroblasts, which are the cells responsible for making collagen. When fibroblast mitochondria work better, collagen production improves, and the dermal layer maintains more of the structural integrity it tends to lose with age (Kubicka-Figiel et al. 2024).

A separate mechanism involves inflammation. Chronic low-grade inflammation is one of the primary drivers of skin aging. When inflammatory molecules circulate at persistently elevated levels, they suppress the proteins your skin needs to maintain its structure. Regular exercise, both aerobic and resistance-based, has been shown to reduce circulating levels of these inflammatory factors, which creates a better biological environment for the skin to maintain itself (Pedersen et al. 2023).

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The study that changed how we think about exercise and skin

The best evidence on this topic comes from a 16-week randomised study. Researchers enrolled 56 healthy, sedentary middle-aged women and divided them into an aerobic training group and a resistance training group. After 16 weeks, both aerobic and resistance training produced significant improvements in skin elasticity and upper dermal structure. The researchers also took blood plasma from participants before and after training and added it directly to human dermal fibroblast cells in the laboratory. The plasma collected after training caused a significant increase in the expression of collagen genes, hyaluronic acid synthase, and several other proteins involved in the extracellular matrix. In other words, the blood circulating after exercise contained signals that told fibroblast cells to build more collagen (Nishikori et al. 2023).

But here is the interesting part. Only the resistance training group showed an improvement in dermal thickness. The explanation the researchers identified involves a protein called biglycan, which is necessary for maintaining dermal thickness and regulating collagen architecture. Resistance training reduced circulating levels of three chemical signals, all of which were shown to suppress biglycan production in the dermis. By reducing those suppressors in turn, resistance training created conditions in which the dermis could rebuild structural depth (Nishikori et al. 2023).

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How much exercise is recommended for skin benefits?

The aerobic training in the randomised study was 65 to 70% of maximum heart rate for 30 minutes, twice a week. The resistance training was 75 to 80% of maximum capacity for 3 sets of 10 repetitions per exercise, twice a week. They match standard public health recommendations for physical activity, which means that if you are already meeting general exercise guidelines, you are likely already producing the skin-related benefits documented in the study. The take-home message is not to add more exercise. It is to appreciate that the exercise you are already doing is working on your skin in ways that no topical product replicates, and that the combination of aerobic work and resistance training produces a broader range of benefits than either alone.

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What is the take-home message?

Exercise works in concert with sleep, hydration, and nutrition, not in place of them. What the evidence from this series collectively says is that healthy skin is the output of a well-functioning body, and the most reliable way to support it topically is to first ensure the system it sits on is properly maintained.

References:

1. Kubicka-Figiel M, Martyka A, Taborska N. Fit body, fit skin – the multifaceted effects of physical activity on the skin. Medycyna Środowiskowa / Environmental Medicine. 2024;27(1):32–35. doi: 10.26444/ms/178481. Available here
2. Pedersen BK, Febbraio MA. From the discovery of myokines to exercise as medicine. Danish Medical Journal. 2023;70(8). Available here
3. Nishikori S, Yasuda J, Murata K, Takegaki J, Harada Y, Shirai Y, Fujita S. Resistance training rejuvenates aging skin by reducing circulating inflammatory factors and enhancing dermal extracellular matrices. Scientific Reports. 2023;13:10214. Available here

This post is for educational purposes only and does not constitute professional medical advice. Please consult a qualified healthcare provider for personalised guidance.