First let me state that I'm sharing this event as a learning experience and hopefully sparing someone else the same experience.
I'll begin by defining Heat Syncope according to Wikipedia. http://en.wikipedia.org/wiki/Heat_syncope
Heat syncope is another stage in the same process as heat stroke, occurs under similar conditions as heat stroke and is not distinguished from the latter by some authorities. The basic symptom of heat syncope is a body temperature above 40°C (104°F) with fainting, with or without mental confusion, which does occur in heat stroke. Heat syncope is caused by mild overheating with inadequate water or salt.
Causes:
Heat syncope occurs when blood pressure is lowered as the body dilates (widens) arterioles (small blood vessels) in the skin to radiate heat. Also, water is evaporated from the blood, reducing the blood's volume and therefore lowering blood pressure further. The result is less blood to the brain, causing light-headedness and fainting.
Based on my experience this is exactly what occurred to me.
So what happened?
I went to the Silver Comet to ride with Vanessa and Kelley. I planned on riding 60 miles with some intervals thrown in. I actually scaled back my training as the Augusta schedule had me riding 5 hours + 1 hour brick. I ended riding about 3.5 hours and running about 32 minutes.
First 15 miles were at a comfortable pace averaging just under 17 mph and then I picked up the pace and threw in some intervals. My HR average at Zone 4 which is what I needed to be. Only during intervals, did I creep into Zone 5a. Overall, I felt great on the bike and finished averaging just under 18 mph.
I took off on the run and still felt pretty good. Because I'm doing PTC Tri next week, I wanted to see how I could push myself on the run. My legs felt great and I was running at a great pace (for me) right off the bike. I think this is where I over did it.
Because I screwed up my nutrition at Gulf Coast, I've been a stickler for writing down in a notebook exactly how many calories I'm consuming on the bike and how much water I'm consuming. This helps me compare week to week and see what I need to tweak (umm, there's going to be some major tweaking).
So for reference, here's what I had on today's ride.
Pre-ride: 8 oz of Cytomax
Ride: 1 bottle of Perpetuem = 810 calories for about 294 cal/hr. (I did not consume any Perpetuem during the first 15 miles)
5 bottles of water = 80 oz for about 22 oz/hr.
3 salt tablets (761 mg electrolytes)
Run: 8 oz of EFS (580 mg electrolytes)
Post Run: 1/2 PBJ sandwich & 4 oz of EFS
BTW: I peed before the ride and 15 miles into the ride. This should have clued me into possible dehydration.
Once I got done with the run, I grab a PBJ that I had prepared and my second fuel belt bottle with EFS. I went to stand in the shade just 15 feet from my truck. As I proceeded to eat, it felt difficult to chew. I drank about 4 oz of the 2nd bottle of EFS and then started seeing bright spots. I leaned up against a tree and closed my eyes for a few seconds. When I opened them back up, everything looked really bright and my vision was almost pure bright white. Next thing I know, I'm falling. Apparently head first. Luckily I was standing in a mulch area. I got up, picked up the remaining PBJ in the zip lock bag and the water bottle, both of which I dropped when I fell. A gentleman standing across the parking lot came over to help and asked if I was okay. I said yes, but I was kind of out of it. I was standing next to my truck and he proceeded to call 911. While he was on the phone, I fell again. I felt like I was closing my eyes and falling asleep (similar feeling to dozing off at the wheel on a long drive). As soon as I fell, I was getting myself right up. He helped me into the bike shop/depot and got me a chair. The AC helped. When the EMTs showed up, they checked my vitals and said everything looked good. I described to them my workout and what I had consumed. They realized that I was not the normal, under trained, enthusiastic bike newbie who is typically dehydrated. I never lost consciousness and was able to describe exactly how I felt and what happened. Since I was feeling much better, I declined to go to the hospital. I sat in the shop another 5 minutes taking advantage of the AC and then walked a bit to make sure I felt fine. I went back to the car, drank some more water (another 20 oz). I was by myself as Kelley rode 30 miles and Vanessa was still out. I decided I wouldn't drive home yet to make sure I actually felt fine. I also wanted to wait on Vanessa to make sure she got back safely. She was riding with a guy we met at the parking lot at the start of our ride. I continued drinking and sat in the shade at one of the picnic tables. When Vanessa got back it had been an hour since the EMTs left and I had no residual effects from Heat Syncope and drove home.
As I look over previous entries on my nutrition log book, nothing seemed out of the ordinary. I have been consuming about 20-23 oz of water on most of my rides. 2 weeks ago I did a similar ride. I rode 80 miles and then ran 4. The main difference was that I pushed the pace on the run. This time I ran an 8:05 pace versus the 8:35 pace from 2 weeks ago. Temperature was about the same. I think today it was drier (low humidity) and that made it feel a bit cooler. I never stopped sweating, got chills or cramped up, typical symptoms of dehydration.
When I got home I drank another 2 bottles of water before I had to pee again and I was still 2 pounds under from what I weighed first thing this morning (oh yeah, I weigh myself 1st thing in the morning and before I go to sleep).
Based on these last items, I must have been dehydrated, yet my fluid consumption hadn't changed from previous rides. I've been increasing my fluid intake over the last month as I was only taking about 16 oz/hr. It must have been a combination of things. I've probably been dehydrated in previous rides, but because I didn't push the run, I didn't experience the effects of Heat Syncope.
I was lucky to have been back at the parking lot and within sight of someone that could help.
Take my story as a word of warning and monitor your fluid levels and your effort level. A slight change can make a huge difference if you're not taking enough fluids. Be safe out there.
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