That or just tape residue from a knee taped for weightlifting.

Just so much to see in this photo. '67 or '68 Mustang hard top. Super Beetle in front of it. I think a Maverick coupe a couple cars ahead of that. Bell bottom jeans. Gold's Gym from before it was franchised I think. Both bikes are lugged steel but I cannot make out the brands.

Arnold is in great shape, but not quite the musculature of his peak bodybuilding years, so I am guessing this may be a year or two after that, perhaps 1975 or 76, he did a film that came out in '76 and he supposedly lightened up some for that film. Arnold and Franco were both in the film, Franco uncredited, "Stay Hungry".

Either a great amateur photo, or one staged for a magazine photo op. Probably shot on Kodachrome slide film, good color durability from whenever this shot was digitized.