Immune support is important because you don't want a viral infection putting your life on pause. From a nutritional perspective, it is key to prevent deficiencies and consume optimal amounts of nutrients that play an essential in maintaining a healthy immune system. Periods of heavy exercise are also associated with a depressed immune function and compromised immune function can be further aggravated by inadequate nutrition. The body's susceptibility to a respiratory infection can be elevated for 24 hours after a tough workout. So you will probably want to do something to boost your immune system when you work out.