Lighting is key for enhancing the look of muscles. My preference is to take my models outdoors, as I can change lighting situations fairly quickly. If I don't like a particular location and the outcome, all it takes is to move to another spot, and voila, you've got a totally different shoot! Studio is limited in this case... You have the setup the lights and work with one particular lighting scenario. Both have their merits, but I prefer outdoors when I can get out...

I've taken guys to the beach, only you've got to be careful of direct sunlight. Too much light will make the guys look washed out, there won't be enough shadows to make their muscles looked more defined and they'll just look unflattering at best...

Good times to shot at the beach:
- early in the morning (before noon; the earlier, the better), or
- in the evening, before sunset.

Hope this helps :-)

BrianDN