Ben will have to focus on his upper body strength, he will have to do push-ups, bench pressing, shoulder presses, etc... His duration of practice and upper body will need more work since average humans use their legs more than their own hands, so Ben would need to completely give in his time for this. Ben and Janine will both have different diets as well because of the different body parts trained. Janine on the other hand, will need to focus on lower body strength and flexibility, because rollerblading depends on perfect balance and flow, she would need to do squats, leg stretches, kicks, jumping jacks, etc... Her duration during practice and lower body building would be less than Ben depending on her determination but generally it would be less since lower body building comes with ease because as I said the average humans use their lower bodies more than upper. Thats pretty much it. I hope it helps and I tried my best!
