David Guetta, 53, sent fans into meltdown with topless snap on Miami beach
Photograph, taken on Saturday, shows off his muscular physique and toned abs
Fitness expert Griffiths said doesn t have the traditional body builder physique that most guys get from the basic gym split routines of chest, legs and back days
Added strong, lean and light look comes from balance of strength and cardio
Anti-aging expert Dr Ross Perry suspects DJ may have seen dermatologist