This 2023 human study of 144 men average age 68 investigated relationships among physical fitness measurements and three epigenetic clocks:

“We investigated relationships between physical fitness and age-adjusted values from residuals of the regression of DNAm aging clocks to chronological age (DNAmAgeAcceleration: DNAmAgeAccel) and attempted to determine the relative contribution of physical fitness variables to DNAmAgeAccel in the presence of other lifestyle factors.

• Volume of oxygen (VO₂/kg) at ventilatory threshold and at Peak, fat free mass, calf circumference, serum HDL-C, daily intake of carbohydrates, iron, copper, vitamin C, and β-carotene were negatively related with DNAmAgeAccel.
• Body fat, visceral fat area, and serum TG were positively related to DNAmAgeAccel.

Frequent alcohol consumption and past- and current-smoking status were associated with accelerated DNAmAgeAccel, while a morning lifestyle was associated with deceleration of it. Multiple regression analysis suggested that – rather than physical fitness – serum triglycerides, carbohydrate intake, and smoking status were significantly associated with DNAmAgeAccel.

In conclusion, the contribution of cardiorespiratory fitness to DNAmAgeAccel was relatively low compared to lifestyle factors such as smoking. However, this study reveals a negative relationship between cardiorespiratory fitness and DNAmAgeAccel in older men.”

https://www.medrxiv.org/content/10.1101/2023.04.12.23288187v1.full-text “Associations between cardiorespiratory fitness and lifestyle-related factors with DNA methylation-based aging clocks in older men: WASEDA’S Health Study”