Becoming lightheaded or dizzy when working out is not an unusual response but is a sign that should be addressed for a more adequate and enjoyable work out.
– Low blood sugar
– Low blood pressure
– Valsalva (Holding your breath) with exercise common with high intensity exercises
– Shallow breathing, constant contraction of abdominals when running and not getting enough oxygen to the brain
– Overexertion (for example running 10 miles when your only used to being trained for 5)
– This could also be due to lack of proper warm up or running at a pace that your body is lacking fitness for
– Heat if occurred when running outside
– Food is energy.  Eat prior to working out (protein and high complex carbs)
– Hydrate
– Use controlled breathing
– Monitoring calorie intake, younger and more active individuals may be burning more calories than they are taking in. Proper food to fuel your body is essential.
If your feeling light headed during a work out its best to take a rest break, put your head between your legs with arms resting on knees or if tolerated arms on head to opening airway, and help proper blood flow to return. Nauseous and dizziness should subside with rest.  If it persist hours after your run or work out, you should seek additional medical advice. If you have tried prevention techniques and dizziness continues or occurs with light activity; a discussion with your doctor is needed to make sure no underlying health concerns are present.