Cardio has many positive health effects, but hair growth isn't really one of them. Hair growth is a natural three-phase process; growth is never directly caused by exercise.
But, the hair growth process can be interrupted by mental and physical health problems, resulting in hair loss. Cardio can't make your hair grow, but regular cardio exercise can improve your health and mood — discouraging interruptions in the natural hair cycle. So while it can't reverse balding or make your locks long and lush, cardio may be able to reduce or eliminate some of the health problems that lead to hair loss.
How Hair Grows
Hair grows in a repeating cycle of three phases. A new hair shaft forms during the first phase — or anagen phase. It's nourished by blood and grows, which takes from two to eight years. The next phase, or catagen phase, lasts for two to four weeks. The hair is pushed away from the blood supply and stops growing. In the final resting — or telogen — phase, which lasts two to four months, the hair is no longer nourished but doesn't fall out.
After the final phase, the hair-growth cycle is complete, and the first phase starts over again, pushing out the old hair shaft and forming a new one. As a natural part of the process, 50 to 100 hairs are lost each day so new hair can grow.
Causes of Hair Loss
Hair is lost temporarily or permanently when the hair growth cycle ends, but a new hair shaft isn't formed. Stress, illness, hormonal changes, poor nutrition and medications are some of the things that can disrupt the growth cycle and cause hair loss.
Some people experience hair loss about three months after the start of a stressful period of their lives. If the stress continues, the hair loss continues for about three months more — and even longer for some people — after things calm down again. Some medications that treat heart problems, high blood pressure and depression can cause temporary hair loss. Both men and women can experience hair loss caused by hormonal changes related to aging.
Read more: Scalp Exercises to Reduce Hair Loss
Hair Health and Happiness
Lower your chances of experiencing hair loss caused by stress and physical health problems by keeping both your mind and body in the best possible health. During cardio, you release endorphins and other feel-good hormones, which can make you happier and reduce the effects of stress.
For good physical health, the American Heart Association recommends at least 150 minutes of moderate cardio exercise, or at least 75 minutes of vigorous cardio exercise, to maintain a healthy heart and veins. This optimizes circulation and reduces inflammation, which can have positive effects on your skin, hair and nails.
Food for Healthy Hair
Low iron and a low-protein diet can also cause hair loss. Cardio depletes iron supplies, and young female athletes and vegetarians are at the greatest risk of developing anemia.
Iron-rich foods — including red meat, fish, poultry, spinach and beans — can prevent low iron levels caused by exercise. Avoid hair loss from protein deficiency with a diet that includes a minimum of 46 grams of protein each day for women and 56 grams for men.
Read more: How to Care for Hair After a Workout