Intensity

Intensity is determined by the amount of weight (resistance) used (Fleck & Kraemer, 1997). It is also affected by exercise speed, the number of reps and sets, the rest interval, and the duration of the workout.

Intensity of training is determined primarily by the amount of resistance (load), and is additionally affected by the number of sets and reps, the rest interval, exercise speed, and the duration of the workout.

In strength-training circles (training athletes), intensity can be differentiated by labeling loads as light, medium, or heavy. The following guidelines, based on 1 RM, are used:

• Heavy: 90 – 100% effort
• Medium: 80 – 89% effort
• Light: 70 – 79% effort

For example, if a trainee has a personal best (1 RM) of 400 lb and the workout demands an exercise intensity level of 80% for a predetermined number of repetitions, the trainee uses 320 lb (80% of 400 lb = 320 lb). Note that athletes do not always train to failure. Increasing intensity by increasing the velocity of movement is important when a major goal is to increase the power output of the muscle, not just the ability to lift maximal loads.

The development of a particular feature of muscular performance (e.g. absolute strength) is directly related to the load used; this program variable must be addressed when prescribing exercises.

• Intensity = the amount of weight (resistance).
• Affected by: exercise speed, number of reps and sets, rest interval, workout duration.
• Load labels (based on 1 RM): Heavy 90-100%, Medium 80-89%, Light 70-79%.
• Worked example: 80% of a 400 lb 1 RM = 320 lb.
• Increasing movement velocity increases intensity for power development.

• volume — inverse relationship with volume.
• repetition-maximum — RM expresses intensity at an individual load.
• rm-continuum — rep ranges map to intensity percentages.
• periodization — intensity is cycled against volume.