If you should hold your breath during a particular heavy lift, you run the risk of shutting down blood flow to the brain. That can cause anoxia, which is a shortage of oxygen in the brain. So, simple rule of thumbs while exercising is don't hold your breath for long periods.

Most experts agree that you should inhale while lowering the weight or at the top of the left and exhale while lifting the weight. But this is often too difficult to do because the heavy weight causes pressure to build up in the lungs and it's difficult to control your breathing pattern. Besides, the pressure in your lungs helps to stabilize your chest and shoulder muscles so they can exert maximum force more easily.

So, it is often advisable to hold your breath for a short period during the phase of the lift when you are just beginning to contract the muscle. The added stability afforded by thoracic pressure will make the left a bit easier. On the way up, however, begins exhale to release the pressure.

During the light sets in which ten or more repetitions are being performed simply breathe normally, do what comes naturally. Thoracic pressure rarely becomes a problem with lighter weights.

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