It is a common misconception that heart rate is equivalent to intensity. Heart rate can be a factor contributing to intensity; however the two are not analogous.
Intensity = Power = Work / Time = (Force x Distance) / Time
CrossFit emphasizes the use of functional movements because of their unique capacity to be preformed at relatively high intensities (more work in less time). During a WOD (Workout Of the Day) we move relatively large loads, long distances, very quickly! You can squat, dead-lift, and push-press more weight, longer distances, in much less time than you can performing a bicep curl, lateral raise, or a leg extension.
“Intensity is the independent variable most commonly associated with optimizing return.”
Increasing VO2 max, metabolizing fat, building muscle, getting stronger, and getting faster are all intensity dependent. Therefore, performing more work in less time will increase your strength, fitness, and overall health!
Relatively high intensities can only be reached through functional movements. CrossFit training demands relatively high intensities, hence our emphasis on functional exercise. How high is a relatively high intensity? The relative level of an individual’s power output is based solely upon that individual’s psychological and physical tolerance.
CrossFit forges elite fitness, but not exclusive fitness. This program is not designed to cater only to super athletes. Anyone can benefit from CrossFit training based on operating at the appropriate intensity.