New research from Iowa State University has found a long bout of moderately intense exercise following COVID-19 or influenza vaccination can amplify the body’s immune response. The study showed 90 minutes of exercise immediately after vaccination increased antibody responses four weeks later.
The relationship between exercise and general health is so obvious that it is barely worth mentioning. But, investigations into exactly how exercise improves our health have yielded some fascinating studies over the past few years, from the way exercise helps the body kill cancer cells to the anti-inflammatory proteins released during physical activity that can prevent cognitive decline.
More specifically, the association between physical activity and the immune system has been of particular interest to researchers in recent times. A massive meta-analysis last year looked at data from several studies encompassing more than half a million people and found regular exercise significantly reduced a person’s risk of contracting an infectious disease.
This new study set out to very specifically home in on whether single bouts of exercise can influence the efficacy of vaccination. To investigate this question the researchers recruited a number of healthy subjects who were about to be immunized with one of three different vaccines (2009 pandemic influenza H1N1, seasonal influenza, or COVID-19).
Each subject was randomly assigned to one of three groups: a no exercise control, or either 45 minutes or 90 minutes of moderate exercise commenced within a half hour of receiving the vaccine. All participants had blood samples taken before the vaccine, then two and four weeks later, to track the effects of exercise on antibody levels.
The subjects that performed 90 minutes of exercise following vaccination showed statistically significant increases in antibody levels several weeks later compared to the no exercise group. Interestingly, the researchers did not detect differences in antibody levels between the control and 45-minute exercise groups.
An experiment in mice showed similar differences in post-vaccine antibody boosts between 45-minute and 90-minute exercise sessions. The researchers hypothesize the differences in immune responses between 45- and 90-minute exercise sessions offers clues to how physical activity could be boosting vaccine-induced antibody responses.
Prior studies have shown longer durations of exercise generate different kinds of immune effects. In particular the researchers point to specific immune proteins called interferon alpha (IFN-α), which have previously been found to increase relative to the duration of exercise.
Exercise-induced increases in IFN-α are hypothesized as one of the possible mechanisms that could explain how antibody responses can be boosted by physical activity. However, Marian Kohut, lead author on the new study, says it is likely a number of different mechanisms are playing a role in the new findings.
“… a lot more research is needed to answer the why and how,” said Kohut. “There are so many changes that take place when we exercise – metabolic, biochemical, neuroendocrine, circulatory. So, there’s probably a combination of factors that contribute to the antibody response we found in our study.”
The researchers note further work will be needed to ascertain the optimal type of exercise and duration necessary to enhance vaccine response. So, while 45 minutes of activity may not have been enough here, maybe 60 minutes could be effective.
A number of different exercise interventions were used the participants in the study, from vigorous walking to riding an exercise bike. The main focus was on intensity of exercise, with all participants required to maintain a heart rate of around 120 to 140 bpm. This rate of exertion is feasible at a variety of different fitness levels, the researchers say, and there is no evidence post-vaccination exercise increases adverse side effects from the vaccine.
“The exercise intervention is feasible for people who exercise regularly at light intensities such as walking, and persons with a range of health characteristics were able to complete the exercise,” the team wrote in the study. “For example, nearly half of the participants in the COVID-19 vaccination trial had a BMI in the overweight or obese category, and the distance covered in 90 min ranged from approximately four miles (6.4 km) to over 10 miles (16 km), representing a variety of fitness levels as heart rate and relative perceived exertion level were maintained within a constant range.”
The new study was published in the journal Brain, Behavior and Immunity.
Source: Iowa State University