Critical Speed
By Rich Strauss

The first alternative method of determining training intensity is Critical Speed. This method is especially applicable in swimming and running, and to cycling on a trainer.

Velocity is a measure of the work produced by a runner, swimmer, or cyclist. In order for a runner to move the mass of his body over a distance of 400 meters in 82 seconds, he must produce a very specific amount of work. The same is true of a swimmer that swims 100 yards in 75 seconds. However this use of velocity to measure work produced is only applicable if the effects of wind, grade, and current are minimized or eliminated. This means that Critical Speed workouts are best performed on a track, treadmill, bike trainer, or in the pool.

Critical Speed is defined as your maximum average velocity maintained for a specific period of time. For example, a swimmer performs a 1 minute time trial and swims 75 yards. Dividing 75 yards by 60 seconds gives us an average velocity of 1.25 yds/sec. Our swimmer next does a 6 minute time trial, and swims 425 yards. 425/360 = 1.18 yards per second. This process is repeated for time trials of 12 and 30 minutes in length.We put this data into a table and determine his Critical Speed for each time trial length, and from it determine his Critical Speed per 100 yard pace: