My son has been hounding me about getting in the gym 15yr old 5'11" 156lb .. Baseball only kid (pitcher).. Right now he runs everyday before school , bleachers 2 days a week mixed with wind sprints , and lower body explosive movements .. Box jumps etc. other days long toss and cage work .. He's highly motivated and pushes hard .. Doesn't need me lol .. Question is should we do a upper body / lower body type of workout ... I don't think my gym routine would be wise