Strengthening the upper body's muscles means decreasing the work of the heart and lungs, and putting less strain on these vital organs makes them healthier in the long run. In simpler terms, your risk of a heart attack diminishes as you tone your body. That's why the American Heart Association recommends strength training for maintenance of overall heart health [source: Centers For Disease Control and Prevention: Growing Stronger].
While strength training has always played a vital role in cardiovascular rehabilitation after heart attacks or heart surgery, today we also use it in preventative cardio health. As muscle mass and strength improve, less demand is put on our most important muscle of all, the heart, which can then pump more oxygen in fewer beats. According to the American Heart Association, as your body's general strength increases, so does your functional capacity, your ability to move through the day's simple tasks. Activities like walking up the stairs or lifting heavy boxes become less taxing on your heart [source: Cybex Institute].
Strength training increases your heart rate just as cardio and circuit training does, depending on resistance, repetitions and rest between sets. As your heart rate increases, so too does your ability to burn calories and lose weight. Lung health improves, as well. While increasing muscular strength doesn't directly improve your lung health, strengthening weak arm and leg muscles increases your body's endurance. This, in turn, reduces your body's exhaustion and breathlessness, which means your lungs don't have to work as hard.
This is especially evident with lung diseases such as emphysema and bronchitis. A report in the medical journal CHEST shows increasing strength in the arms and legs helps chronic obstructive pulmonary disease (COPD) patients move through life with more ease. Household tasks that formerly caused fatigue, such as rising from a chair, become easier with simple strength training.
Read on to learn how the body actually builds muscles, and it's not during your workout.