For each conditioning bout, I’m wearing a chest-strap heart rate monitor. My intention here was use the treadmill for my moderate work, and the bike for vigorous LISS. The results have been confounding.
Because the treadmill work immediately follows my lifting sessions, I begin walking with a heart rate that is already a bit elevated. This allows me to quickly jump up to about 125 bpm, or 70% of heart rate max, which I sustain for the whole treadmill bout. I rate it 6 RPE. It feels great, like a nice fitness dessert after the heavy lifting.
The LISS on my off day, by contrast, feels like crap. I’m starting from “zero,” in a sense: no lifting precedes it. My heart rate slowly increases from <90bpm all the way up to about 125, which I hit only in the last few mins of the bout. RPE 7.
According to Polar app, I’m burning more calories on the treadmill than on the indoor bike … even though the treadmill feels much easier.
So I’m wondering two things.
Is this OK? Should I aim to increase output on LISS, even though I still rate it RPE 7?
Is the treadmill work “cheating,” since I’m getting a heart-rate “liftoff” beforehand?
Any other thoughts you have on this would be greatly appreciated!
Thanks for the question. Good to hear from you! Conditioning work after lifting will generally have a higher HR for the amount of work being done, which we think is a function of fatigue generated from the lifting session. Not really a big deal as far as needing to manage it specifically. The conditioning adaptations aren’t really different than doing it separately where you have to start from scratch. I wouldn’t worry about it!
I don’t think I would use Calorie expenditure to monitor conditioning. Rather, I would use heart rate, power output, blood lactate, breathing rate, and so on to make sure the conditioning is being done at the desired intensity. Calorie expenditure via a wearable doesn’t really do that.
Power output decreases through a zone 2 session or a high intensity interval.
So, if a lactate test shows for example, 135bpm is the threshold (or 170 bpm for VO2 max), as the session progresses over time do you keep it at that heart rate or at the power output.
If you keep at power output, heart rate will only go up over the session
Average power output shouldn’t decrease in a zone 2 session, as being able to maintain it for a relatively long period of time is a hallmark. Higher intensity efforts of the aerobic or anaerobic variety are different. Measuring power output to find threshold heart rates can be useful for developing training zones.
Generally speaking, I use a heart rate range to program conditioning efforts. I’ll sometimes put a power minimum in there as well, if known.
Thanks so much for weighing in here. Just to clarify, I’m not using the calorie reading only. I’m mostly using heart rate, along with the calorie reading, to calculate and track my weekly METS, as we discussed here:
As you can see, the post-lifting treadmill work allows me to shoot right up to the upper end of the 60-70% range and maintain it for the whole bout. For the LISS session, however, I have to spend almost half the bout working up to my target zone of 70+%, and even after I achieve that, it’s a struggle to maintain.
Part of this, I suspect, might result from the implement I’m using. The bike requires me to make the effort myself, whereas the treadmill sets the pace and requires me to just keep up.
Anyway, thanks again for your input here. Sounds like I’m on the right track. It’s just odd that I seem to be getting more out of walking than LISS!
Yea, it seems like you need a faster cadence/pace on the bike to get your HR up to speed and to maintain it. More resistance can be helpful provided it doesn’t make the cadence too slow.
