Longevity Drug May Harm Exercise Benefits

A new study indicates that rapamycin, a drug used to prevent organ transplant rejection and favored by some for longevity, may diminish the positive effects of exercise.

Researchers observed that sedentary older individuals who took a low weekly dose of rapamycin gained less strength and physical function from an exercise program than their counterparts taking a placebo. This effect is concerning because exercise is a primary method for improving health and longevity during aging.

The study, published in the Journal of Cachexia, Sarcopenia and Muscle, explored the interaction between rapamycin and exercise. Scientists hypothesized rapamycin would enhance exercise benefits, but instead, found it may blunt them. Participants on rapamycin also reported more aches and fatigue.

Rapamycin works by inhibiting the mTOR enzyme, which plays a role in cell growth and muscle building. While inhibiting mTOR can promote cellular cleanup (autophagy), excessive inhibition can hinder muscle growth and repair, potentially negating exercise gains. This effect was noted in the study despite a dosing schedule intended to minimize interference.

Lead researcher Brad Stanfield, who funded the study himself, noted that while the effects were not large, the results pointed in an unexpected direction. He advises against taking rapamycin off-label until more is understood about its benefit-cost ratio, preferring personal lifestyle choices like hiking for longevity.

Limitations of the 13-week study include its small sample size, unsupervised home exercise, and lack of direct muscle analysis. Further research is needed to fully understand rapamycin's complex effects on exercise and aging.