‘Exercise-in-a-pill’ boosts athletic endurance by 70 per cent
Every week, there seems to be another story about the health benefits of running. That is great — but what if you cannot run? For the elderly, obese or otherwise mobility-limited, the rewards of aerobic exercise have long been out of reach.
Salk Institute scientists, building on earlier work that identified a gene pathway triggered by running, have discovered how to fully activate that pathway in sedentary mice with a chemical compound, mimicking the beneficial effects of exercise, including increased fat burning and stamina.
The study, which appeared in Cell Metabolism on May 2, 2017, not only deepens our understanding of aerobic endurance, but also offers people with heart conditions, pulmonary disease, type 2 diabetes or other health limitations the hope of achieving those benefits pharmacologically.
“It’s well known that people can improve their aerobic endurance through training,” says senior author Ronald Evans, Howard Hughes Medical Institute investigator and holder of Salk’s March of Dimes Chair in Molecular and Developmental Biology. “The question for us was: how does endurance work? And if we really understand the science, can we replace training with a drug?”
Developing endurance means being able to sustain an aerobic activity for longer periods of time. As people become more fit, their muscles shift from burning carbohydrates (glucose) to burning fat. So researchers assumed that endurance is a function of the body’s increasing ability to burn fat, though details of the process have been murky. Previous work by the Evans lab into a gene called PPAR delta (PPARD) offered intriguing clues: mice genetically engineered to have permanently activated PPARD became long-distance runners who were resistant to weight gain and highly responsive to insulin — all qualities associated with physical fitness. The team found that a chemical compound called GW1516 (GW) similarly activated PPARD, replicating the weight control and insulin responsiveness in normal mice that had been seen in the engineered ones.
However, GW did not affect endurance (how long the mice could run) unless coupled with daily exercise, which defeated the purpose of using it to replace exercise.