A great number of studies have shown that moderate exercise improves immune function along with building endurance and strength. Yet while exercise is a good thing in general, it can be a double-edged sword.

Extreme exercise has been shown to significantly suppress immunity, especially cellular immunity. Post-race pulmonary infections are quite common in marathon runners and extreme athletes.

That’s because intense exercise dramatically increases metabolism, which in turn generates an outpouring of free radicals and lipid peroxidation products. Over time, this can cause considerable damage to cells, tissues, and organs.

That’s one reason it’s not uncommon to see extreme runners who look like POWs, with extensive atrophy of their muscles. Muscles should have bulk to them. Resistance exercises combined with moderate aerobic exercise is a good regimen for maintaining health as well as immune resilience. Swimming, brisk walking, bike riding, and weight lifting are all recommended.

Exercise has also been shown to protect the brain and reduce cancer risk. But again, extreme exercise can have the opposite effects. Increasing intake of antioxidants is important for protecting against the adverse effects of intense exercise.

Sources of such antioxidants include:

• Flavonoids

• B-complex vitamins

• Magnesium

• Selenomethionine

• Vitamin C

• Vitamin E

• N-acetyl-L-cysteine (NAC)

For older people, even leisurely walking will significantly improve cardiovascular health, and resistance exercises will strengthen bones, tendons, and ligaments.