I was on my trainer today going at a heartrate of about 145bpm. I had to take something off the stove so I jumped off and went to the kitchen. I started to feel dizzy and like my heart must be racing but my heart rate was down to about 120 then it just dove down to 80. I was feeling pretty dizzy at the moment. Then I got myself together and went back to my bike and kept going feeling fine once I got back on the bike. Any idea what the deal is here? I looked for other posts on this but did not find anything.
By the way The Great Escape is a great movie to watch on the trainer.
Low blood pressure due to loss in fluids. Are you in a nice aero position on your bike? Standing up makes a pretty big difference, especially after you’ve been going hard. Plus while your cycling, your moving legs help in circulating the blood around your body… stopping that suddenly, coupled with standing up could result in that dizziness.
Sounds like you’ve been running on empty… it has happened to me once when I headed out one morning without breakfast or anything to drink. Do you have low blood pressure? Hydrate with electrolytes… it’ll help keep the water in you.
The easy answer would be dehydration. I remember IMCDA racing with a target rate or 135-145. Mid bike I couldn’t get it up to 130 in 100 degree heat, DNF Med tent and 2 bags later I was fine )and I hadn’t pissed in 7 hours in spite of at least 2 gallons of water. Thats a place to start. Especially since indoor training doesn’t offer the cooling benifits pf outdoor riding.
Basically, your heart rate is dropping due to low blood volume in the heart. Most likely due to dehydration and the sudden shift in body position. Whether you’re on your elbows or up on your hands, you are leaning forward, then you suddenly go into a complete upright position. That can cause dizziness just by itself.
If it’s happening when you run, might be a good idea to have it checked out. Definitely I’d start monitoring my BP, most grocery stores have a BP machine anymore.
Didn’t you post about something like this after a long run while you were icing your legs a couple months ago? These are probably vasovagal episodes, but since they’re recurring it might be a good idea to see a cardiologist. You could be popping in and out of some kind of atrial rhythm disturbance.
I did have this problem once after a 5 hour run but I figured that was from being dehydrated I’ve gotten when running after I have gone about a mile or so and then have to stop at a stop light. I’m only 30 but I will be calling a cardiologist today. Thanks to you all.
Most likely a normal reflex to change in blood inflow to the heart. As you cycle, you keep a steady volume of blood returning to the heart, the veins and arteries in your legs are dilated, due to the need for blood flow in the muscle. Suddenly jumping off the bike causes ‘pooling’ of the blood in those dilated vessels in your legs, and therefore less inflow of blood into the heart. Normally receptors in the heart would sense this, and cause constriction of your vessels in the legs, to force the blood in the legs into the heart. In your case, jumping off the bike and suddenly ceasing activity did not allow enough time for this reflex loop to occur, perhaps being a little dehydrated or tired made it less efficient. The consequence is not enough blood coming into the heart (thus not enough leaving), and the dizziness you describe. As you got back on the bike, pedaling allows the ‘pooled’ blood in your legs to return to the heart, and you felt better. Same mechanism occurs when you suddenly stop at a stop light.