Because you breathe rapidly and heavily when you work out, you might think regular exercise would increase the maximum amount of air you could breathe in and out of your lungs, or vital capacity. However, with the exception of aquatic workouts, exercise training does not increase vital capacity.
Vital capacity, also termed forced vital capacity, is a measure of the maximum amount of air you can breathe out after a complete inhalation. It is not the same as your total lung capacity, because some air always remains in your lungs, even after a full exhalation. Vital capacity for a young man is typically between 4 and 5 liters, while for a young woman, it generally ranges between 3 and 4 liters.
Studies of exercise training on land, such as running, cycling and wrestling, have generally shown no increase in vital capacity with training. In addition, athletes typically have no greater vital capacity than couch potatoes of the same age and gender. In general, there are very few changes to your breathing with exercise training. The primary exception is that the amount of air you breathe during a normal resting breath, or your tidal volume, increases, while your resting breathing rate declines.
The reason exercise training doesn't increase your vital capacity is that, for a healthy person, even the most strenuous exercise does not require the maximum amount of air you can breathe. You have a breathing reserve, even during all-out exercise. That is why breathing generally does not limit athletic performance. Your cardiovascular system will reach the limit of its ability to provide your muscles with oxygen before your respiratory system maxes out its capacity.
Swim training, however, has been shown to increase vital capacity. Swimmers and divers have larger vital capacities than both land-based athletes and sedentary individuals. Swimmers breathe against the resistance of the water, expanding the lungs rapidly and fully between strokes. This additional work strengthens the respiratory muscles, which may account for swimmers' greater vital capacity. The fact that swimmers exercise in a horizontal position, which maximizes lung efficiency, may also play a role.
- Exercise Physiology for Health, Fitness and Performance; Sharon A. Plowman and Denise L. Smith
- Exercise Physiology: Energy, Nutrition and Human Performance; William D. McArdle et al.
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