Yeah a lot going on there so prepare for a more complicated answer than it needs.
I’ll start by saying that I’m not training for rowing events so there isn’t as much utility in specific distances as much as there would be say for a runner training for a race. Years ago when I was training for triathlons and bike racing at a fairly high level, we would often break up runs into 5k sessions just so you could put a full 5k type effort into each session.
What I’m really trying to do is manage cardiac drift while still focusing on applying force through the workout. By breaking it into 5k segments, I still get the volume/distance/time I’m after while also maintaining more of a muscular focus.
When I just row say 10-20k, it’s easy to soft pedal it which means less muscle engagement and really, if you are trying to say roughly in a HR zone, you have to back off due to cardiac drift as the workout goes on.
In sticking to 5k segments, it really becomes sort of an ME workout, I can push/pull hard, focus on perfect form while keeping my HR where I want it. If I rowed like that for 15k straight, there’s no chance I’d keep that HR in the upper 130s.
Additionally, research shows there is no drawbacks to doing it from a cardiovascular standpoint. The final point behind it is that it helps break up the monotony of indoor training. Living in AK, I have to do quite a bit of indoor work for one reason or another, short days in the winter, bad conditions in the spring, bugs during parts of the summer. By breaking it up into shorter sessions it’s easier to keep my head in it rather than staring at a wall for 80-100 minutes.
When I was bike racing, the coaches I used insisted that indoor bike workouts were ONLY for quality work, not to mimic road riding, meaning that if I had a 6 hour ride planned but it snowed, I’d train indoors but be much better off with a 60-90 minute session of intervals than I would be for a 6 hour ride watching videos in my garage on my 13” tv. Even lance Armstrong trained that way in that if he was training indoors, it wasn’t just a smooth ride, it was quick and dirty. I’m just sort of applying that logic here.
I don’t always break it up like that but I have been for the past few months as recently managing HR and cardiac drift has been a major focus for me.
