Hard set

A hard set is a work set taken close to muscular failure, ending between 5 and 0 reps in reserve (RIR) in Israetel and colleagues’ definition.^{1Israetel et al., Scientific Principles of Hypertrophy Training, p. 60.} Norton and Baxter use the same threshold: low-effort sets probably don’t stress muscle enough to cause adaptation, so a set must end within about 5 reps of failure to count.^{2Norton and Baxter, The Complete Reverse Dieting Guide, p. 110.}

In roughly the 6 to 20 rep range, the number of sets taken close to failure strongly predicts muscle growth and provides a useful measure of training volume.^{3Helms et al., The Muscle & Strength Pyramid: Training, 2nd ed., p. 49.} For example, 3 sets of 6 to 8 would probably build about as much muscle as 3 sets of 15 to 20.^{3Helms et al., The Muscle & Strength Pyramid: Training, 2nd ed., p. 49.} Israetel and colleagues limit hard sets to loads between about 30% and 85% of one-rep max (1RM).^{1Israetel et al., Scientific Principles of Hypertrophy Training, p. 60.}

In practice

• Count hard sets when adding up weekly volume, rather than including every set.^{2Norton and Baxter, The Complete Reverse Dieting Guide, p. 110.}
• Keep most hard sets at 1 to 3 RIR, with only occasional training to failure; routinely reaching failure adds fatigue and makes overreaching more likely.^{4Norton and Baxter, The Complete Reverse Dieting Guide, p. 111.}
• Light loads require more effort: most of a muscle’s motor units can be recruited at loads as low as 30% of 1RM, but only when sets are pushed hard.^{5Schoenfeld, Science and Development of Muscle Hypertrophy, 2nd ed., p. 138.}
• Set counts work as a volume measure from about 6RM to 20RM or more.^{6Schoenfeld and Snarr (eds.), NSCA’s Essentials of Personal Training, 3rd ed., p. 425.} Very heavy sets under 5RM require more sets for the same muscle growth, though not for strength.^{6Schoenfeld and Snarr (eds.), NSCA’s Essentials of Personal Training, 3rd ed., p. 425.}