Like cardio, strength training increases the body's need for oxygen and automatically results in a faster breathing rate. However, many people have a tendency to hold their breath during strenuous activity like weight lifting. Known as the valsalva maneuver, this can limit oxygen delivery to the brain and cause dizziness, fainting, a spike in blood pressure and other complications. During strength training, the most important thing to remember about breathing is to just do it! Never hold your breath; be aware of how you are breathing at all times, whether through the nose or mouth.
Beyond that, fitness experts recommend that you exhale on the exertion phase of the exercise and inhale on the easier phase. The exertion phase is typically the hardest phase of the exercise—lifting, curling, or pushing the weight. The easier phase brings you back to the starting position by lowering or returning the weight. To help, all of SparkPeople's exercise demos explain when to inhale and exhale based on these recommendations. By focusing on breathing in on the return and breathing out on the exertion phase of each exercise, you'll also prevent yourself from holding your breath. However, don’t get too caught up about when to inhale and exhale. Breathing in reverse is much better than not breathing at all.
Properly breathing while you stretch after your workouts helps your body relax so that you can return to a resting state, in addition to aiding in the mechanical removal of waste byproducts of exercise. It may also allow you to increase your flexibility because proper breathing during stretches will help you to relax more fully and therefore stretch more deeply. Many people tend to hold their breath during stretching or to take short and shallow breaths, but ideally, we should take deep, relaxed diaphragmatic breaths. Most experts recommend inhaling through the nose and exhaling through the mouth when stretching. On every exhale, try to relax more fully or give into the stretch a little further, but make sure that you never stretch past a seven on a scale of 1-10.
Joseph Pilates used to say, “Even if you follow no other instructions, learn to breathe correctly," which is why breathing takes center stage during his mind-body exercises. Pilates typically involves lateral or ribcage breathing, which differs considerably from the diaphragmatic breathing explained previously. With your abdominals engaged (naval pulled toward your spine), inhale deeply through the nose without allowing your belly to rise; instead, think about the air filling your lungs and expanding them laterally and into your back while your belly remains tight and flat as if you are wearing a corset. On your exhale, open your lips slightly and push all of that air out of your mouth both forcefully and slowly, making your exhale audible (like a “whoooooo” or “seeeeeeee” sound). This style of breath keeps the abdominals engaged and helps you to perform Pilates exercises with greater ease and better control.