I’ve been noticing some moderately significant increases in heart rate when sitting up on the bike vs staying down on the hoods/bars during my recovery intervals.
I’m hoping this is an expected result of postural changes but thought I’d throw it out there in case anyone has any deeper insight into it.
In theory it does make sense that extra overall ‘energy’ and strength is required to hold body upright and unsupported and that would lead to an increased heart rate.
In the example from my workout this morning (screenshot below), I was in my third recovery interval and I sat up on the bike for about 30 seconds.
My heartrate was trending down from about 185 bpm at the end of the work interval to about 134 bpm about 2.5min into the recovery.
When I sat up, my heartrate rose steadily to about 153 bpm in 30 seconds after which I went back down onto the hoods.
I’ve seen this happen very regularly in my workouts when I sit up - usually just to move around a bit for comfort, read an email on my phone or have some food/drink.
Anyone else notice this and is it anything to be concerned about?
I’m trying to minimise sitting up as I (quite obviously) feel that keeping HR low during recovery intervals maximises my recovery before kicking into the next working set.
Your body position can influence the number of times your heart beats per minute. When you are in a declined position your heart beats fewer times per minute than when you are sitting or standing. When you are in a a declined position, the effect of gravity on your body is reduced, allowing more blood to flow back to your heart through your veins. Because more blood returns to the heart, the body is able to pump more blood per beat, which means that less beats per minute are required to satisfy your body’s demand for blood, oxygen and nutrients.
As noted above, yes lower HR when lower on bike. In fact, when I’m on TT bike (maybe 50% of workouts), my HR will typically be about 5 BPM lower at same power. I test on the TT bike and get higher power results likely due to the lower HR. But, I do make it a point to alternate bikes to be able to adapt the physiology. My $.02.
I think it’s also different demands on the muscles responsible for posture and breathing. I listened to a podcast about the science of breathing and apparently the demands on tehse muscles just from breathing are surprising.
