An experimental drug that is capable of helping mice to run on a treadmill for 70% longer before becoming exhausted might be used to develop a tablet that provides the same effects as exercise.
Although things that work for mice do not always work for humans, the researchers at the Salk Institute (USA), are so confident of the drug’s potential they are presently looking for a pharmaceutical company to help them do human tests and, hopefully, produce an exercise replacement tablet in the future.
All of the mice used in the study had a sedentary lifestyle and were only normally capable of running in a treadmill for 2 hours 40 minutes. However, when some of the mice were given the drug they managed to keep running for 4 hours 30 minutes.
The drug is called GW501516. It was developed during the 1990s, but was dropped by its creators when it was discovered it may cause dangerous side effects. However, its performance boosting abilities make it very attractive to some athletes and it is presently available to buy illegally, on the black market.
GW501516 activates a gene called PPARD that is associated with the ability to run long distances. It also appears to alter insulin sensitivity and prevent weight gain. These are all capabilities that are normally associated with exercise and physical fitness.
One of the researchers, Dr Weiwei Fan, said: “Exercise activates PPARD, but we’re showing that you can do the same thing without mechanical training. It means you can improve endurance to an equivalent level to someone in training without the physical effort.”
Dr Fan’s colleague, Professor Ronald Evans is equally enthusiastic about the idea of creating an exercise tablet. “It’s well known that people can improve their aerobic endurance through training,” Evans said. “The question for us was: how does endurance work? And if we learn to really understand the science, can we replace training with a drug?”
As people start to attain a greater level of physical fitness, their muscles start to burn more fat and less blood sugar. It is believed the PPARD gene is involved in the process.
However, although burning fat is a desirable benefit dieters will appreciate, the brain prefers the energy provided by sugar. This explains why long-distance runners “hit the wall” and become confused.
According to the researchers, as people become more used to exercise their body adapts by prioritizing the use of sugar to power mental function, while the muscles burn fat instead.
The study was published in the journal Cell Metabolism (02-05-2017) and was inspired by previous research into the relationship between exercise and endurance.
Although an exercise tablet could easily be misused by athletes hoping for an edge over their competitors, and could also be used by unscrupulous horse trainers, it could offer hope to people who are seriously overweight but cannot exercise due to health restrictions or old age.
If it is ever created, an exercise tablet may be of particular value to people who have heart conditions and need to lose weight, but have to be careful about overdoing things.
In a statement, the researchers said: “The team can envision a number of therapeutic applications for a prescription drug based on GW501516, from increasing fat burning in people suffering from obesity or type 2 diabetes to improving patients’ fitness before and after surgery.”
However, some medical experts are not convinced using GW501516 to create an exercise tablet is a good idea. Ali Tavassoli, professor of chemical biology at Southampton University, said, “Someone with obesity or diabetes could be taking a pill for 40 or 50 years. What happens when you take a drug like this for that long? I can’t see these things getting regulatory approval.”