Exercise Improves Dermal Collagen and Elastic Fibers: In Vivo Evidence From Female Volunteers and an Animal Model
Qi Luo, Minghao Wang, Zhu ShenABSTRACT
Background
With increasing interest in aesthetic appearance and skin health, direct, objective, in vivo evidence remains limited regarding whether exercise improves the structural status of dermal collagen and elastic fibers.
Objective
To investigate the effects of exercise on dermal collagen and elastic fiber status.
Methods
This study combined an animal experiment with a human observational study. In the animal experiment, healthy female C57BL/6J mice were divided into a middle‐aged exercise group (ME, n = 10, 43 weeks old), a middle‐aged sedentary group (MS, n = 5, 43 weeks old), and a young sedentary group (YS, n = 5, 6–8 weeks old). The ME group underwent 4 weeks of voluntary wheel running, whereas the MS and YS groups served as sedentary controls representing different age stages. After 4 weeks, in vivo two‐photon imaging of dorsal skin was performed in all three groups. Two‐photon images were quantitatively analyzed to obtain autofluorescence (AF), second harmonic generation (SHG), the SHG‐to‐AF aging index of dermis (SAAID), and the elastin‐to‐collagen ratio (ELCOR). Immunofluorescence staining for Collagen I and Elastin was performed on skin tissue from the imaging site. In the human study, a total of 156 female volunteers completed an exercise questionnaire and underwent two‐photon imaging of the right zygomatic region of the face. SHG, AF, SAAID, and ELCOR were obtained using an image analysis approach consistent with that used in the animal experiment. Weekly total exercise duration (WeeklyMinutes) was calculated from the questionnaire. Participants were analyzed using both a 150 min/week grouping strategy and a median‐based grouping strategy. Propensity score matching was first performed using age as the covariate, followed by multivariable regression adjustment in the matched samples.
Results
In the animal experiment, SAAID, SHG, and AF were increased and ELCOR was decreased in the ME group compared with the MS group, with several indicators shifting toward YS levels. Immunofluorescence showed stronger Collagen I‐ and Elastin‐related signals in the ME group than in the MS group, consistent with the two‐photon results. In the human study, 48 and 69 matched pairs were obtained after propensity score matching under the 150 min/week and median‐based grouping strategies, respectively. The results were consistent across both grouping strategies. Higher exercise levels were associated with higher SAAID and SHG, lower ELCOR, and no significant difference in AF. After further adjustment for BMI, smoking, alcohol use, and average daily sleep duration, the overall pattern of the results remained unchanged.
Conclusion
Using two‐photon microscopy, this study provides direct, objective, in vivo evidence that exercise may favorably affect dermal collagen and elastic fibers. These findings provide experimental and population‐based evidence supporting exercise as a strategy for maintaining skin health.
Trial Registration
This study was registered in the Chinese Clinical Trial Registry (registration number: ChiCTR2600123115)