When we discuss weight training, one of the key things we talk about is the volume of work done. Volume can mean different things to different people.
To Mike Mentzer and the HIT gang, volume was the number of sets done. Most bodybuilders still think in these terms; the number of sets per body part.
To athletes and strength coaches, volume takes on a different meaning. In this circle, volume is generally measured as the number of barbell lifts done (NL), or as the tonnage of a workout (sets * reps * weight used).
Volume is also manipulated by the frequency of workouts. If you lift once a week, you’ll have less volume than someone lifting three times a week, all things equal (note that this isn’t always the case; you can take the workload of a single workout and spread it across multiple sessions).