In my book Rejuvenation!, I reiterate that the exercise coefficient, which compares our capcoity to exercise maximally with what we should be  able to do at age 25. This coefficient, not only measures skeletal muscle tone, but implies the extent to which our interstitial space sanitation has been optimized. When the coefficient in close to one, interstitial space hygiene is optimal which means the capillaries are dancing with great rhythm,  chronic inflammation has been blocked, and disease venues such as cancer, autoimmune disease, infections, thrombosis and scarring have been eliminated.