While one tries to apply various fitness techniques, too much exercise can be damaging, says an expert. Even though the diet is almost always carefully planned out in accordance to a fitness routine, many fail to realize the impact excess training can have on the rest of their body, reports femalefirst.co.uk. Brisk walking for 30-45 minutes five days a week has been shown to boost immunity but more strenuous activities may have a negative impact on the body, says fitness expert Erin McCann. "When the body is exposed to physical stressors such as exercise it responds in a similar way to how it does when exposed to mental stress - the hormone cortisol is released. "Cortisol stimulates energy production and improves muscle endurance which supports fight or flight reaction. Cortisol however also acts as an immunosuppresant and following even just a moderate workout, immune function can take up to 72 hours to fully recover. This leaves individuals open to viral or bacterial infections," said McCann.McCann suggests top three ways to support immune function - * Incorporate adequate recovery time into your workout schedule. This will aid muscle recovery, reduce the risk of injury and improve immune health. * Increase consumption of immune supporting nutrients and antioxidants through food. Examples include Vitamin C containing foods, like berries and broccoli, as well as zinc rich foods like eggs and pumpkin seeds. * Supplement with immune boosting nutrients and herbs that are not commonly found in an 'every day' diet. Examples of these unique immune supporting agents are astaxanthin, reishi mushroom, bee propolis and olive leaf. Astaxanthin is a carotenoid with potent antioxidant and anti-inflammatory actions, and is often used by athletes to support muscle recovery and immunity.