A dose of salbutamol – the active ingredient in medicines for asthma such as Ventolin – doesn’t increase the total amount of energy you use during a cardio training session by much, but it does change where you get the energy from. According to a study by sports scientists at the Université d’Orléans, athletes burn more fat if they cycle with a salbutamol capsule in their system.
More fat burnt in a cardio session with salbutamol
Salbutamol is a banned substance in the sports world. Cyclists go faster if they use salbutamol, but it’s not known where the extra energy comes from. The French decided to fill this knowledge gap by doing an experiment with eight reasonably trained amateur athletes. The subjects cycled for two hours at sixty percent of their VO2max – once with a placebo and once with salbutamol, containing 4 mg of active ingredient. The test subjects cycled a couple of hours after taking the pills.
The graph below shows how much energy the test subjects used. PLA = placebo; SAL = salbutamol.
The number of joules that the cyclists burned rose slightly as a result of the salbutamol, but not by a significant amount. However, when the researchers examined whether the cyclists derived their energy from fat or carbohydrates, they noticed that salbutamol promoted fat burning and reduced carbohydrate burning.
The researchers also measured the levels of insulin, growth hormone and ACTH (the messenger hormone that instructs the adrenal to make the stress hormone cortisol) in the subjects’ blood. Salbutamol reduced the production of ACTH. The salbutamol also resulted in a small, not statistically significant rise in the growth hormone level.
The researchers concluded that there was little ergogenic effect to be seen from their experiment: “Our data show that energy metabolism and regulation are not significantly affected by acute therapeutic salbutamol intake. Further studies will be necessary to study the effect of salbutamol on these parameters in other conditions, in particular in elite athletes under longer exercise durations.”
Well – we dare to disagree. Substances and methods that stimulate the burning of fat and save carbohydrates are always of interest to endurance athletes, even if the total amount of energy burned does not increase. And perhaps even more so when it comes to the reducing effect on ACTH of salbutamol.
Salbutamol intake and substrate oxidation during submaximal exercise.
In order to test the hypothesis that salbutamol would change substrate oxidation during submaximal exercise, eight recreationally trained men twice performed 1 h at 60% VO(2) peak after ingestion of placebo or 4 mg of salbutamol. Gas exchange was monitored and blood samples were collected during exercise for GH, ACTH, insulin, and blood glucose and lactate determination. With salbutamol versus placebo, there was no significant difference in total energy expenditure and substrate oxidation, but the substrate oxidation balance was significantly modified after 40 min of exercise. ACTH was significantly decreased with salbutamol during the last 10 min of exercise, whereas no difference was found between the two treatments in the other hormonal and metabolic parameters. The theory that the ergogenic effect of salbutamol results from a change in substrate oxidation has little support during relatively short term endurance exercise, but it is conceivable that longer exercise duration can generate positive findings.
PMID: 18925413 [PubMed – indexed for MEDLINE]