Around age 35, human bone mass and total muscle strength peak, after which muscle decreases at a rate of 3% annually. Doctors say the best way for middle-aged and older adults to slow muscle and joint degeneration is through aerobic exercise, with each session lasting no less than 20 minutes.
During the first 20 minutes, energy is primarily drawn from muscle glycogen stores. Only after 20 minutes does the body begin utilizing fat as fuel—commonly referred to as fat burning. Thus, the exercise period beyond 20 minutes becomes crucial. Extending workouts by 10, 20, or more minutes significantly enhances fitness gains.
Another key indicator of exercise effectiveness is heart rate. Maximum heart rate is generally calculated as 220 minus your age. To achieve aerobic fitness benefits, heart rate should reach 65% to 85% of maximum heart rate. If the minimum threshold isn't met, exercise effects will be minimal. If heart rate exceeds 85%, the activity becomes anaerobic, reducing its effectiveness for lowering blood lipids and blood pressure.
Before age 35, health is in a reserve phase. After 35, no amount of exercise can surpass peak bone mass or muscle mass; these enter a maintenance and gradual decline phase. Therefore, it is recommended that before age 35, engage in any exercise that does not cause injury to muscles or joints.
Engage in any form of exercise to maximize peak bone density and muscle strength. This ensures that after age 35, when career and family demands require significant physical exertion, your body can supply greater energy reserves, promoting overall health.