Originally posted by Dreampanther
Yes, but he didn't really exert himself. During the attacks on the safe houses he was walking the whole time, he never moved fast enough to push himself and I would assume he did the same thing when he swam - nobody was chasing him so he could take his time and conserve his energy. We never really see move Luke fast or with any sense of urgency that I can recall - he's always really careful to conserve his energy by walking and standing still, letting his opponents wear themselves out by attacking him until they get tired or run out of bullets.
Well, he did move with urgency when people were chasing him down with Judas bullets, as well as during his initial encounters with DB (including their first proper fight, when Luke had already taken a gut shot). Plus, I'd say the fact that he was still physically active for a significant amount after being shot by 2 Judas bullets shows some decent endurance.