When I was 12 bodybuilding gyms were really rare. I never saw anyone lift weights. I only had a bunch of Weider magazines. I didn't know what they meant by 5 x 10. I looked at the pictures of the champs exercising and didn't know they were moving the weight. I thought they stayed in a isometric hold and maybe 5 x 10 meant five times of 10 seconds. I would stand there blue in the face holding a barbell in the curl position. My older brother saw me and said, "What the hell are you doing?" Now after almost 50 years later I know what I'm doing. LOL.