Anti-histamines and the Impact on Exercise

It's that time of year when golf courses are open and home owners are tending to their yards and gardens. And nothing could be worse for the allergy sufferers that have to deal with congested airways, itchy throats, watery eyes and constant sneezing.

Fortunately there are over-the-counter products that help deal with the histamines that cause many of these symptoms. But as with many medications there can be side effects beyond the relief of symptoms.

A recent study looked at how anti-histamines blunt the benefits of exercise. Histamine function is vital to the short and long term benefits of exercise. However when the body has a reaction to dust or pollen the immune system stimulates the release of anti-histamines to deal with this.

But when it comes to exercise histamines play an important role in circulation, capacity and glycemic control. The researchers wanted to know what impact anti-histamines would have on these areas of our health.

For the study healthy male participants were assigned to a control group that would receive a placebo or anti-histamines. The subjects then followed a six week exercise program to assess the impact of anti-histamines on circulation, exercise capacity and glycemic control. These areas are directly related to overall health, performance and disease i.e. diabetes.

The researchers noticed the following results:

• the group taking the anti-histamines had 35% lower muscle perfusion post-workout i.e. less circulation
• time to exhaustion increased 81% for the placebo group versus 31% for those taking anti-histamines
• peak power increased 12% for the placebo group versus 7% for the anti-histamine group
• fasting blood glucose levels decreased only with the placebo group
• insulin sensitivity increased 26% for the placebo group but only 1% for those taking the anti-histamines

The take home points:

• The study involved only healthy males and and results may not be replicated for other groups i.e. females or unhealthy subjects.
• The dose of anti-histamines was quite high at 880 mg of H1/H2 histamine blockers. Common over-the-counter products may have 10% this dose at 80-100 mg.
• The study involved healthy subjects and investigated the impact on glycemic control. How would the results have differed had those with diabetes been involved in the study?
• The study is quite small, i.e. 20 subjects, and short, i.e. six weeks. What the results look like with a larger sample size with an experiment that continued for a longer period of time?
• Understand that anti-histamines do impact circulation, performance and glycemic control. Consider these when taking medicines with these ingredients and how they may impact blood flow, exercise capacity and the body's ability to metabolize carbohydrates.

Van der Stede, T., Blancquaert, L., Stassen, F., Everaert, I., Van Thienen, R., Vervaet, C., & Derave, W. (2021). Histamine H1 and H2 receptors are essential transducers of the integrative exercise training response in humans. Science Advances, 7(16), eabf2856.