Different forms of physical activity affect the body differently. Various effects of training on hormones such as adrenalin are long known, but strength training and cardio exercises affecting FGF hormones differently is a relatively new understanding according to the researchers.
10 healthy young men were put into 2 groups to either cardio or weight training training once a week for 60 minutes. Strength training subject group exercises consisted of 5 exercises repeated 5×10 times involving the main muscle groups of the body; and cardio group subject exercises consisted of cycling at a level of 70% maximum oxygen intake for an hour. Blood samples were taken from the subjects 8 times over a period of 4 hours after exercising to measure for development of blood sugar, lactic acid, various hormones, and bile acid. According to the researchers their measurements revealed significant increases in production of FGF21 in connection with cardio exercises with strength training showing no significant change in this hormone.
FGF19 hormone level was also measured which is linked to muscle growth in animal studies. Expecting strength training to have an effect on this hormone, researchers were surprised to see production of FGF19 drop slightly after strength training in direct conflict with their hypothesis, indicating not enough knowledge of something about the effects of strength training and may give rise to more research.
Additional investigations will be conducted to more closely examine other links between hormones involved in metabolism and exercise. This was a randomised crossover study which will hold more weight evidence wise than animal and cell culture studies, but less than a larger cohort. Researchers suggest that their findings on FGF21 were significant enough to provide solid foundation for study whether similar effects can be produced in other groups of test subjects.
The study was limited to the blood samples not being taken more than 4 hours after training, and nothing can be said about effects of a full training programme on the hormones.
