It seems like 'frequency', 'volume', and 'intensity' correspond to
- lifting sessions per week or
- sets per session or
- reps per set or
- total reps or
- weight per rep
but I'm not sure which term goes with what. Or do some have more general meanings?
Frequency
Can be used to describe how often a particular movement is performed. If Lifter A squats once per week and Lifter B squats twice per week, then Lifter B squats more frequently than Lifter A.
Intensity
Used to compare sub-maximal efforts to a person's max effort for a particular exercise. In terms of lifting this tends to be given as a percent of their 1 rep max. The closer they are to their 1 rep max, the more intense the effort will be. Conversely, the further from their 1 rep max, the less intense it will be.
Volume
Volume is a broad concept as it can be used to analyze a program from multiple levels. At the workout level it will comprise of sets * reps for each exercise (and sometimes multiplied by weight lifted to find the tonnage that was lifted). This allows for a per-workout way to balance antagonistic movements. It can also be used with a larger scope (on a weekly, monthly, or larger scale) to show how a lifter is progressing when the intensity (amount of weight) is not changing. For instance, if a lifter can only bench press 135 lbs for 3x8 one week and then the following week they can bench press 135 lbs for 4x8, then they have progressed through volume rather than intensity.
I would say generally frequency is referred to how often you workout. For example you working at 3 times a week would be how frequently you workout.
Volume would refer to the amount you do while working out. For example reps and sets would be labeled as the volume.
Intensity can mean many things, but generally I use it do distinguish how difficult my workout will be.
Hope that helps.
