What are the pro's and cons of pre work out supplements? How does it enhance performance while working out? Is there any side effects?Most of them are simply stimulants. Sometimes they're full of sugar, a bit of protein, and often creatine, and possibly nitric oxide (ala NO Explode).
Recently the stimulant is caffeine or B vitamins, in the past it could have been ephedrine, pseudoephedrine or some other pre-amphetamine or worse.
Looking at NO Explode, it has a bunch of stuff in it, Creatine, B-Vitamins (the preworkout might have caffeine also, based on the matrix on this page: BSN N.O.-Xplode at Bodybuilding.com), and nitric oxide.
Nitric oxide works as a vasodilator -- it opens up your blood vessels and allows more blood to flow. (It's also one of the active ingredients in viagra)
Usually you'll have more energy while on nitric oxide.
- Blurred vision.
- dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position.
- unusual tiredness or weakness.
Caffeine stimulates the Central nervous system allowing you to focus better. It also can raise your heart rate and blood pressure.
- Caffeine is addictive and can have withdrawal symptoms including headaches and low energy
- Caffeine is a diuretic, make sure to stay hydrated when using caffeine
- Could keep you up all night.
- Dehydration -- it draws water away from your body to your muscles, you'll gain weight, but it's water weight.
- Is an allergen and can trigger asthma
- There is some concern that it could harm the kidney, liver, or heart function. However, a connection between high doses and these negative effects has not been proven. Creatine can also cause stomach pain, nausea, diarrhea, and muscle cramping.
- There is concern that combining Creatine with caffeine could lead to conditions causing a stroke
Caffeine vs Nitric Oxide - Which to rely on? This article indicates you can use both at the same time, but I don't think that's such a good idea since caffeine is a vasoconstrictor and NO is a vasodilator.
Each of these is safe enough on their own. When you mix it up in some unregulated pre-workout mix all bets are off. I'd recommend trying one of the three in isolation from a trusted brand -- though I'd lean strongly to just getting a cup of coffee before hitting the gym in the morning -- rather than taking a crazy mix of stuff that you aren't sure what's in it.