Cardiac drift whilst base training

simonahfrost

1.5 to 2 hrs base training on a turbo is mind numbing, I think we all agree!

I have a large fan to provide cooling, MHR is 177, my age 56, base training level I take to be 132(+/- 5) = 75% MHR, a tad high perhaps?

I can sustain around 190 - 220 watts (not brilliant, I accept this, but this is the reason for training!) during this depending on cadence and resistance, but get cardiac drift into 135 - 145 toward the end of the session.

Do I reduce resistance / cadence appropriately to keep in the lower HR zone, I'm not aware of working harder, breathing still controlled and able to speak though not at length!, or do I keep going as perceived work rate is the same?

Alex_Simmons/RST

power & PE
drift is pretty normal.

moorjohn

does this happen because, as the ride progresses, the glycogen store in the muscles/liver/blood is getting run down => muscular respiration is more weighted to aerobic than anaerobic => more blood circulates to supply oxygen => heart beats faster?

mclarent

CV drift appears to be caused by a progressive decrease in stroke volume (the amount of blood leaving the heart with each contraction), thus an increase in HR is required to maintain cardiac output during endurance events.

A number of studies have shown that CV drift is caused by dehydration and reduced fluid/ electrolyte replacement. One other factor related to CV drift is blood glucose levels (carbohydrate, once broken down), therefore the evidence is clear that optimal re-fuelling and energy replacement are vital in reducing the effects of the drift.

http://optimahealth.co.uk/documents/Cardiac%20Drift01.doc

simonahfrost

Thanks one and all for the answers and references. Back to the I-pod and Tacx Flow I guess, it is always dark wet and cold by the time I get home after 6 every weekday evening. I'll have to think of something else now that I know these answers, or succumb to the mind numbing process!
I'm grateful for the replies.
Simon

bahzob

Not too sure too many people will be doing 1-2 hours base training on a turbo. Typically turbos will be used at training intensities above base.

So you could try upping the intensity which would mean reducing time on the turbo. This may also lead to better results.

moorjohn

interesting article mclarent. Like a lot of these things, looks like no-one knows for sure, but it can't be wrong to keep well-hydrated!

I would think that training at higher intensities would be the best move. But if you are looking to do events lasting > 4-6 hours, there is an element of performance linked to maintaining glycogen levels which is trainable, and which can only be trained by really long sessions.

They always say on the tour commentaries (Phil and Paul) that the day after someone's dropped off the pack with hunger knock, they'll come back really strong. I think this must be the same sort of thing

Ken Night

Very interesting....

I used to worry about the 15% HR rise when doing a base session on the turbo. I find keeping going, the hr stabilises

Like Bahzob, I don't do base effort on the turbo if I can possibly help it, reserving that time for above and below threshold intervals.

If I do "steady" sessions these are around around 85% HR Max for an hour, to get max value from that dead time-I like to listen to radio plays on the earphones, but it's still a bore