Physical activity, however, may worsen the condition, result in impaired performance, or infect others. On the other hand, some contagious diseases are relatively benign, and some activities don't affect others. Therefore, clinicians need to understand both the sport and the illness to know what level of activity to recommend. For example, solo exercise at a reduced intensity is generally safe for patients whose symptoms are above the neck. A lthough regular exercise can help improve health, even well-trained athletes develop acute infectious diseases.
Most physicians advise patients to rest during an acute illness.
She develops infectious gastroenteritis. She does not want to miss a day of running and fall behind in her training schedule. Despite several episodes of diarrhea the night before, she decides to accompany her friends on their usual Saturday morning 20-mile run. The weather that day is unusually warm and humid. During the run she collapses and suffers heatstroke.