Activate every muscle fiber to boost your fat burning. When you lift weights, your muscle fibers are not all recruited. According to Henneman's Size Principle, smaller, lower-threshold motor units are activated first in a set. Since the first few reps of sets don't recruit all muscle fibers, you are going to need to make sure you are close to failure on each set. But for heavy sets, think 1-8 reps max, all your muscle fibers are recruited from the beginning,
