Can COVID-19 vaccines affect athletic performance in the short term?

Getting the 2019 coronavirus disease (COVID-19) vaccine – especially the second vaccine – can produce minor side effects such as pain and fever that tend to go away after a day or two.

Adding to the list, a small study from the University of Arizona, US, found that people may find it slightly difficult to exercise after receiving a two-dose vaccine against the coronavirus. In this study, the research team found that vaccinated people without a history of COVID-19 infection had slight increases in physiological demands on graduated exercise.

The researchers write:

While this indicates that the physiological demands on defined-intensity exercise are greater after COVID-19 vaccination, we must emphasize that these changes were small in magnitude and other key measures of metabolic load and exercise capacity (for example, blood lactate, plasma adrenaline, plasma cortisol, predicted VO_2max and ventilatory threshold) were not affected by vaccination.

Vaccination is recommended to protect athletes against COVID-19 during training or at matches abroad. But the results of the current study could help athletes decide whether to take the COVID-19 vaccine and subsequent boosters before or after a major sporting event. The researchers also found that the COVID-19 vaccination helped boost the metabolic response to exercise in people who had previously been infected with SARS-CoV-2. The increased metabolic response may help reduce the exercise capacity seen in people with long-term COVID.

Study “Recent COVID-19 Vaccination Associated with Modest Increases in Physiological Requirements for Graduated Exercise” is published in the prepublication medRxiv* server.

How they did

The team recruited 18 healthy participants aged 24 to 43 to perform a 20-minute graduated cycling exercise before and 21 days after receiving a two-dose Pfizer-BioNTech vaccine or a single-dose Johnson & Johnson vaccine. . About 12 people received their injections during the study period.

Participants had their oxygen measured and blood samples were taken to determine serological activity against Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) – the virus that causes COVID-19.

Vaccinated people have an increased physiological demand during exercise

COVID-19 vaccination has been associated with increases in several physiological responses during graduated cycling exercise. For example, researchers observed an increase in metabolic demand corresponding to an increase in oxygen supply, carbon dioxide production, respiratory exchange ratio, ventilation, heart rate, levels serum adrenaline and norepinephrine.

However, there was no difference in the ventilatory equivalents of oxygen uptake, carbon dioxide production, stroke volume, cardiac output, ventilatory threshold, serum lactate and serum cortisol before and. after vaccination.

People with no history of infection experienced higher heart rates and response to norepinephrine at 80% VO₂ max after receiving their Pfizer-BioNTech two-dose vaccine. In addition, these participants showed an increase in the volume of carbon dioxide relative to the amount of oxygen consumed after vaccination.

Enhanced metabolic response in vaccinated individuals who have previously been infected with SARS-CoV-2

The COVID-19 vaccine appeared to increase the metabolic response during exercise in people who have previously recovered from SARS-CoV-2. In four participants with natural immunity who received the Pfizer-BioNTech or Johnson & Johnson vaccine, there were lower adrenaline levels and a ratio of carbon dioxide production to oxygen consumption. Serum lactate levels appeared to be lower, but this result was not significant.

Despite the small sample size in individuals with natural immunity, the researchers suggest that vaccination could help people with long-standing COVID who have persistent physiological symptoms after infection. The fact that the vaccine increases the elevated metabolic response may support the ability of long-haul travelers to exercise.

Overall, the results indicate that vaccinated individuals without a history of SARS-CoV-2 may experience increased physiological demands for at least 2-3 weeks after receiving their second dose of the mRNA vaccine. However, future studies are needed to assess whether these modest increases in physiological demands could influence the performance of professional athletes. Conversely, vaccinated people with natural immunity to a previous infection do not find any problems with exercise.

*Important Notice

medRxiv publishes preliminary scientific reports which are not peer reviewed and, therefore, should not be considered conclusive, guide clinical practice / health-related behavior, or treated as established information.