Today's Comfort, Tomorrow's Discomfort
Our bodies are remarkably good at giving us exactly what we ask of them. Physiologists call this the SAID principle: Specific Adaptation to Imposed Demands. Lift heavy things and the body builds the capacity to lift heavy things. Climb hills, breathe hard, and the heart and lungs answer the call. The other half of that bargain receives less attention. When we stop asking, the body stops offering. Muscle, bone density, aerobic capacity, balance, even the quickness of our reflexes are all metabolically expensive to maintain, and the body is a frugal accountant. What we don't use, it quietly lets go. You've probably heard the old saying: "You don't stop playing because you get old; you get old because you stop playing." Swap in running, dancing, lifting, or climbing stairs two at a time, and it holds up. Having just turned 60, I've thought about this more than usual. Part of the decline we blame on aging is real. A surprising amount of it, though, is just detrain...