The time taken between each set is referred to as the rest. As with all of the other variables, the rest taken will impact the physiological responses to the overall program. Rest can be as little as the five second transition from one exercise to another or the rest can be more than five minutes. There are a variety of factors that determine the adaptations resulting from particular rest periods, but the table below lists the general responses of each range.
During the rest period, different processes throughout your body are recovering from the stress of the previous set. Your muscles and cells have to replenish stores of ATP for energy production, while your nervous system has to replenish the various mechanisms responsible for the transmission of impulses from the brain to your muscles.
In general, the more intense and strenuous the exercise, the more rest you need between sets. For a program that is focused on general health and weight loss, 30 to 60 seconds is a good rest range for most exercises.
30 seconds or less
Hypertrophy, Relative Strength
Power, Absolute Strength, Relative Strength