let’s say you cycle a moderate amount (for an amateur)…call it ~10+ hours a week
assuming a perfect world where you had easy access to different sports (skiing, swimming, rowing)…
would it be better to take say 1 day a week and do a 1-2hour Zone 2 / Endurance session (say using heart rate) in a completely different sport?
not talking about doing serious intervals or perfecting technique
just to hit muscles / ligaments / tendons at different angles and minimize repetitive stress while still working your aeorbic base? (and taking 1 hour away from cycling out of 10+ isn’t going to make a big difference in your cycling technique I don’t think)
Not physiologist but I expect it does not – while cross-training might help to develop cardiovascular system, it does not help as much with cycling specific muscles i.e. you miss out specificity.
Nevertheless, it probably helps to strengthen supporting muscles: core, triceps, lower back, etc. I plan split time ~ 30:70 between SkiErg and bike (not only Z2 but also VO2max intervals), just for overall improvements.
To maximise cross-training benefits, maybe it is better to do high-volume Z2 on bike and lower volume VO2max on different sport
I am not sure I would say 10+ hours is a moderate volume for an amateur! That aside, I have recently started running in conjunction with my cycling, mainly for bone density and better all-around fitness and strength as well as trying some strength training; I noticed when I was only cycling, while I was getting fast on the bike, my body was good for literally nothing else… being over 40 this is a concern.
While I was not in prime cycling shape when I started running my experience is I was a lot slower at running than I anticipated given I have a good aerobic engine from cycling over a number of years. While other types of cross training may overlap more with cycling in terms of muscles e.g. cross country skiing, I would say if you are cross training it is purely to benefit your all-around health and fitness, rather than your cycling.
If you purely want to be a faster cyclist then cycle more, but if all around health and fitness is the goal then I would highly recommend cross training. Even mentally, doing one day on the bike then another day running feels less stressful and breaks up the monotony in my view.