I very highly recommend a HIIT program - High Intensity Interval Training. Just search for HIIT to get more info.
It is considered THE most effective aerobic conditioning program - alternating high intensity heart beats with normal heart beats...and the heart is THE most important muscle in the body.
A good heart monitor is needed and I use this Fitcent model with re-chargeable battery - accurate to 1 beat per minute.
https://www.amazon.com/dp/B0995HMQ17?ref=ppx_yo2ov_dt_b_fed_asin_title
Ummm, I’m in my 80s so I’m just need something that is relatively easy but gets me moving.
I don’t doubt the study’s conclusions. However, on the other hand, good studies show an increased risk of Afib in life-long endurance athletes. This puzzles researchers, but it may be that athletes grow thicker and tougher heart muscles that cause an interruption in the electrical signals.
The true cause remains speculative, but the correlation is slight but undeniable. I am an example. 60 years of track, soccer, triathlons and competitive cycling. I had an ablation 7 years ago and am now symptom free. Ran 400 miles and cycled 2000 miles this year. Not huge numbers, but steady. I’m 74.