Question: how many calories do you burn doing 20 minutes of strength training?
Answer: According to this exercise list from Harvard Medical School, a general 30-minute strength training session burns an average of 90 calories (180 calories per hour) for a 125-pound person, 112 calories (224 calories per hour) for a 155-pound person and 133 calories (266 calories per hour) for a 185-pound person.