Wow, thanks Oxy, I'm flattered 
....
Enrique: my trainer says that barefoot sprints are the best exercise for legs/gluteous, and recommended me to do at least 5 sets of them daily on the beach.... 
I don't know if I'll have the perserverance to follow his advice.
yes i can't really think of anything much more effective for overall development especially lower body (but really sprints are a full body body weight movement, as evidenced by the soreness you fell ALL OVER after a good intense run at them ).
i think 5 sets daily can be excessive in people that have not been building up to that level of volume, i.e. it can be done but seldom sustained and usually only by folks that have worked specifically at being able to handle that work load. also it owuld be hard to train anything else doing that. also it is somehwat pointless if sprint performance is not the primary goal, i.e. sprinters train like that somewhat but they are gearing for their sport, it is more practice than working out or physical recreation.
i would suggess you start with 1 session every 4-6 days for two weeks, then increase to 1 session every 3 days for two weeks. then rest for about a wekk, then start up again 1 ever 3 days, then 1x every other day, when you can hanlde that i would do that for three weeks, rest a week, then keep going your sprints every other day or so. the main thing is listen to your body, how you are recovering. your sleep (i.e. lots of it) and stress (i.e. keep it LOW) will have a big impact on your sustainability. it is one of the most intense stressful things you can put yourself through and done improperly you can really wreck yourself (i..e mess with stress homrones, stall fat loss, etc.).
however LOTS of barefoot walking on the beach is HIGHLY reccommended especially as a fat loss modality. i suggest if you can schedule it a minimum of say 75 minutes up to 5-6 days per week in addition to your other training.
Topic: Project Shapety Shape