Side stitches are a problem for runners if they eat or drink too much before running. This is true for me as well, but Runner's High made this to mix with a small 4 ounces of liquid. That's less than 3 shots worth. You can see the final 4 ounce mixed serving in the last picture. I take it about an hour before I run just to be safe. It's not a delicious concoction, but it's not bad and also not a lot to drink. Runner's High said the caffeine makes it bitter and they didn't want to put too much sugar in or make you have to drink too much. They don't use artificial sweeteners either, so it's a natural mix. It's definitely drinkable though and the glass is empty before you know it, but I recommend mixing it with some lemon-lime gatorade instead of water if you want to take away the slight bitterness. It becomes almost tasteless mixed with 8 ounces, but that's too much to drink before running for me. Side stitches are not an issue for me before cycling though so I can eat or drink as much as I want. Sometimes for long rides I would mix this in with my sports drink and sip it as I went.
This basically replaces the pre-race coffee, energy drink, gel, flat coke, or whatever you've been using before. The label says it increases aerobic energy, improves time to exhaustion, protects against high blood acidity, clears more ammonia, increases cardiac output, and stimulates the nitric oxide system. I can't specifically point out which of those things are happening, but I know that something is happening. This puts me in an awake and ready to run state and yet I am also relaxed. It's not something that made me hyper and jumping out of my skin only to burn out shortly after. I was a believer after my first use when I took it before a long run. I never felt like my leg muscles were really burning with effort even on the steepest hills. It felt like the only thing that was limiting me was how much air I could pull in. I beat my Broad Street Run 10 mile race time that night. For those that don't know, the Broad Street Run is flat as a pancake and the 10 miles I had just run on Race Primer had several significant hills. I even felt like I had more left in me after I finished, but decided I shouldn't overdo it. You still need to hydrate and get calories in during your run or your legs are going to run out of steam eventually, but this helped make the long run fly by.
Since then I have used Race Primer many more times and love it. It helped me to a half marathon PR and makes me feel the "runner's high" with every workout. One mistake I made was when I once used it for a long run in the evening and I couldn't fall asleep until about 3am. I now stick to using it in the morning only.
It's listed for sale at $29.95 which works out to about $1.25 per serving. That may be more expensive than a normal sports drink, but this isn't a sports drink. When people are paying $3 for a 5 Hour Energy shot, I don't think this pricing is that bad at all for what it brings to the table.
Overall I think it's a great product for it's purpose and I recommend giving it a try. If you can handle caffeine and aren't afraid of a few shots worth of bitterness, then I don't see any reason not to.
You can find more detailed information about Race Primer at the Runner's High website here: http://www.runnershighnutrition.com/race-primer/