The Research
Research shows that if you do high-intensity endurance exercise for more than 90 minutes, the athlete can be susceptible to illness for up to 72 hours after the exercise session.
After strenuous exercise the immune system is suppressed making athletes more susceptible to viral and bacterial infections, in particular Upper Respiratory Tract Infection’s.
Exercise in moderation however strengthens your immune system and decreases your chances of developing heart disease, keeps your bones healthy and strong, helps flush bacteria out of the lungs and airwaves reducing your chance of getting a cold, flu or other illnesses.