That’s cool you use a Nordic Track. I used to have one many years ago, as part of off-season training for real nordic (skating mostly) racing. Those years taught me alot about conditioning. Way too much than I have time to write now, but I’ll try to contribute some basics that work for me.
I find training for muni to be very similar to training for xc skiing, because they’re both “total body” sports. You essentially have three “needs” you’re training for: endurance, strength, and power. You get all three just by riding the muni, but cross-training can be very beneficial to any sport. For example, I’ve found that strength training has REALLY helped me feel more “in charge” of the muni, especially when steering & correcting using the seat handle.
BTW, obviously you’re also training for TECHNIQUE, muscle memory, etc., things I lack in a big way right now as a beginner, but since your question is just about cross-training I’m just focusing on that. Also it’s important to note that beginners do not get the same aerobic effect in an hour of muni-ing that pros get, because we spend so much time on UPDs. So cross-training is a great way to keep in shape so that when we CAN hop through rock gardens like a gazelle, we have the endurance to keep going for many more miles.
Back to your question. I would recommend getting up to at least 25 min. sessions on the Nordic Track, preferably 30 if possible, at least 3x a week, preferably 4. The purpose of this is to raise your aerobic conditioning, endurance, and anaerobic threshold (that line you cross when you start breathing like a locomotive). Check your heart rate and try to hover at 70 percent max (max = 220 minus your age). So if you’re 50, your target rate would be 119. The formula varies depending on your conditioning, you can check the web for more on this.
And man, that Nordic Track (or any exercise machine) can get REAL boring, so think about mixing it up with some running, swimming or other aerobic activity.
One cool thing about the Nordic Track is you’re working arms & legs, mostly legs, so it’s probably a great choice for muni.
Then add in some strength exercises. Just a quick 20-min session doing 1-2 sets of dumbell curls, military press, pushups, situps, bar dips and pullups is good. You can do legs too, but I think you get enough of that on the muni rides. Try to do this 2x - 3x a week.
As for power, that explosive ability to stab the pedals hard and fast when you need to, probably the best training for that is the muni.
One more element is stretching. Especially for us older folks, I can’t stress the importance of stretching enough. It keeps up limber, flexible, less injury-prone (or able to recover from one faster) and much more. Do it while you watch TV.
This is a really basic program, old school. There have surely been many advances in physical conditioning that you can read about or discuss with a professional trainer. Interval training, plyometrics and other activities can be part of a well-rounded program. And of course, don’t overdo it, and consult with your doc if you’re going to start really pushing it beyond your normal regimen.
I’m sure there are countless pro riders who have really effective routines, and hopefully they’ll contribute here and give us all some good pointers. Hope this helps.