"There is no danger in returning to regular activities after the flu vaccine, including exercise," Carolyn Kaloostian, MD, MPH, a clinical assistant professor of family medicine at the University of Southern California Keck School of Medicine, told POPSUGAR. "In fact, small studies have shown increased antibody development (and thus protection) from the flu vaccine after participating in exercise."
This should come as no surprise, as exercise is known to bolster the immune system. That said, it's probably best to avoid strenuous strength workouts while your arm heals.
"Aggressive activity of the vaccinated area may increase the pain after the vaccine," said Michael Ison, MD, professor of infectious diseases at Northwestern University Feinberg School of Medicine and a practicing physician at Northwestern Medicine. "Aerobic activity won't hurt, but arm weights might be best avoided for the first one or two days after getting the vaccine."