Taking antihistamines prior to exercise can prevent the body from getting the full benefit of exercise.
That's the finding of a new study, which found antihistamines reduce normal increases in blood flow to the muscles by 35 per cent during exercise.
Conducted by Ghent University and the University of Copenhagen and published in the Science Advances journal
, the study also found that antihistamines decreased aerobic capacity, blocked the improvements that exercise has on circulation and the body's ability to tolerate glucose.
Antihistamines are a common drug used by hayfever sufferers – and many take some before exercising outdoors.
Senior author on the study, sport scientist Professor Dr Wim Derave, told HCM
: "Exercise training induces health-promoting adaptations to multiple organ systems, orchestrated by an interplay between various exercise factors and signaling events.
"In the present study, we show that histamine H1/H2 signaling is an essential transducer of the adaptive exercise training response, with broad clinical relevance: aerobic capacity, glycemic control, and vascular function.
"These detrimental effects of H1/H2 blockade on functional outcomes were caused by impaired adaptations in key regulatory proteins, illustrating the integrative role of H1/H2 receptors in mediating exercise responses.
"One potential functional cause of the blunted training adaptations with histamine receptor blockade is a substantially reduced post-exercise muscle perfusion."
To read the full research paper, titled Histamine H1 and H2 receptors are essential transducers of the integrative exercise training response in humans, click here