Training volume refers to the total amount of work carried out in a single training session, which can be summed over weeks or months of training. Evidence indicates that volume is a major driver of muscle gain,[1] and thus, tracking training volume can be important to ensure the dose of training is sufficient to facilitate positive adaptations, without reaching a point of diminishing returns and overtraining.
There are many different ways to track volume. Volume load (i.e., sets multiplied by repetitions multiplied by weight load) is a popular and adequate method. However, it falls short in protocols that utilize sets of very high repetitions (e.g., 25–30 repetitions per set). In these protocols, volume load can be especially high, but muscle gain is no greater than that achieved with the same number of sets performed using a higher load and a lower number of repetitions.[2] Another shortcoming of volume load becomes apparent when comparing different exercises. For example, using the same number of sets and repetitions, volume load will virtually always be higher for a leg press than a leg extension, but a leg press will not necessarily produce greater quadriceps hypertrophy.
A reliable method to quantify training volume implies similar muscle gain at matched training volumes, independent of other training variables. Evidence suggests that counting the total number of hard sets (i.e., sets performed within four repetitions of muscular failure) when the repetition range lies between about 6 and 30 repetitions fulfills this criterion.[3] As discussed in the FAQ below, “Are heavy or light weights better for muscle gain?”, beyond 20 repetitions or so, a set should probably only be counted as a “hard set” if it is performed to muscular failure.
However, when trying to quantify training volume between a program that consists of low-repetition sets (i.e., <5 repetitions per set) and a program that consists of moderate-repetition sets (i.e., 8–12 repetitions per set), it seems best to use volume load.[3] Some evidence indicates that, when equated for total number of sets, moderate loads (8–12 repetition maximum) are superior to very heavy loads (2–4 repetition maximum) for muscle gain.[4] In contrast, when moderate loads and very heavy loads are equated for volume load, no differences in muscle gain have been observed between groups.[5][6][7]