Antihistamines could reduce the body’s ability to recover after vigorous exercise by nearly a third scientists have found.
About 3,000 genes have been found to be responsible for aiding recovery, by boosting muscles and blood vessels, but in the presence of high doses of antihistamines almost 27 percent of the gene response is blunted, scientists from University of Oregon have found. However quite how these 795 affected genes could affect competitive athletes, however, is not known, said co-author John R. Halliwill, professor of human physiology.
Histamine is a substance in the body that responds to pollens, moulds, animal dander, insect bites and other allergens, however some people’s body goes in overdrive and fuels uncomfortable allergic reactions, prompting the use of antihistamines.
In the research, 10 men and six women, all 23-25 years old, physically fit and active, performed an hour of knee-extension exercise at 60 percent of their peak power, about 45 kicks per minute. Biopsies were done before and three hours after exercise to obtain samples of the quadriceps.
Eight participants took 540 milligrams of fexofenadine and 300 milligrams of ranitidine — levels nearly three times the recommended dosages of the over-the-counter antihistamines. Each target one of the two known histamine receptors involved in recovery responses. During exercise, blood flow, blood pressure and heart rate were monitored.
The antihistamines had no effect prior to exercise and little influence on gene expression at the conclusion of the workout. Three hours after exercise 88 percent of the 795 genes affected by the antihistamines mostly responded with lower levels of expression.
“Histamine, a substance that we typically think of negatively and is most often associated with seasonal allergies, is an important substance contributing to the normal day-to-day response to exercise in humans,” said Romero, In their conclusion, the authors noted that the research highlighted only a small fraction of genes likely involved in signalling pathways influenced by histamine receptors activation during recovery.
However it is to early in the research to suggest people should avoid taking antihistamines when they exercise, Halliwill said.
“We’ve got more work that we have to do,” he said. “We need to do a training study in which we put people on histamine blockers and see if their adaptations to exercise training are as robust or diminished. There are a lot of redundancies in physiological systems. I wouldn’t be surprised if blocking histamine receptors ends up being overcome by something else, but I also wouldn’t be surprised if we can demonstrate that some responses to exercise training do become blunted if you take high doses of histamine blockers.”