1. Exercise intensity
How to choose a fleece for intense exercise? During intense exercise, you sweat more. It's important to wear breathable fleece to keep yourself dry. Breathable fabric can wick away moisture and perspiration more efficiently.
Made of breathable material as well, polar fleece comes with zips so you can control the ventilation depending on your exercise’s intensity: half chest zip, full zip, side zips under armpits etc.
During a less intense workout, we warm up slower and sweat less. Breathability is therefore less important. We will rather choose a polar fleece with better heat retention.