[Breathing during bench press] Inhaling when exerting force can increase the amount of myoglobin for oxygen storage and muscle glycogen for energy supply, and expand the muscle capillaries, which is beneficial to exertion. If you exhale when exerting force, you will be hypoxic, the muscle glycogen supply will be insufficient, the muscle strength will be reduced, and the number of muscle fibers involved in exertion will also be reduced. In addition, insufficient "burning" of muscle glycogen will produce more lactic acid, causing muscle soreness and fatigue. So, inhale when pushing up and exhale when lowering.
