Intensity

"Intensity, as we define it, is exactly equal to average power (force x distance / time). In other words, how much real work did you do and in what time period? The greater the average power, the greater the intensity. This makes it a measurable fact, not a debatable opinion.

Intensity and average power are the variables most commonly associated with optimizing favorable results. Whatever you want from exercise comes faster with intensity. It’s not volume or duration or heart rate or even discomfort. Do more work in less time (without overdoing it), and you’ll get fitter faster." -Crossfit Journal

It has been proven that short, intense bouts of exercise are far superior to long, slow periods of exercise for improving overall fitness. Just compare the two physiques shown above. If we define fitness as having increased speed, strength, power and flexibility, as well as aerobic capacity, which physique meets this definition? How did they get that way?

Typical gym workouts include long slow runs on a treadmill or hours spent doing isolation exercises like leg extensions and dumbbell curls with lots of rest in between sets. How productive is that time? How much has fitness been improved?

Crossfit workouts are meant to be short and INTENSE. This involves pushing yourself in how much weight you can (safely) lift during strength training (using compund movements), or how much more work you can do (faster, more rounds) during metabolic conditioning training. The more intensity you give to your workout, the more you will gain from it.