If you want to be a strong/lean surfer you want to stay with a circuit type workout. It is the best way to build muscle and use your fat stores as energy to burn. The workout I put my athletes through usually last between 30-45 min of high intensity training. That is usually enough. Everyone's body is different and will adapt to training stimuli differently so adjust accordingly. You want to keep your heart pumping. Hope this helps. www.functionalsportsperformance.com
Eric, Great information! I completely support your approach and it is a pleasure to see more people using the assessments you described from your website as a means to a starting point for better and safer fitness.