cross training can be complex. I remember when my arms got bigger it hurt my swimming a little. I had a little bit of heaven for a while bike commuting 26 miles round trip 3-4 days a week, swimming 1500 meters twice a week, running 3 miles 3 times a week & weight training 3 days a week. nutrition timing and protecting myself from injury was key. but man, I was in the best shape of my life at age 50!