• Coach Jacob Puzey

Critical Velocity Intervals

Updated: Jun 13, 2019

One of the most essential, yet most challenging workouts for runners is the TEMPO RUN. Whether it be lack of long stretches of flat terrain without stoplights, high heat, or the inability of the athlete to run at or near their THRESHOLD without going over it, the TEMPO RUN is often a frustrating experience for athlete and coach alike.

Runners tend to run TEMPO RUNS either too fast or too slow, essentially losing the benefits of the workout – to build STAMINA and increase THRESHOLD by working in or just below the red line. While heart rate monitors can be helpful in learning what Tempo EFFORT feels like, not all athletes have access to such technology and most need to take a stepping stone approach to be able to handle a standard 20 minute TEMPO RUN.

Critical Velocity Intervals

One way to prepare for continuous THRESHOLD efforts while producing a similar stimulus is to break the THRESHOLD efforts down into shorter, more manageable segments known as CRITICAL VELOCITY (Tom Schwartz) or CRUISE INTERVALS (Jack Daniels).

Critical Velocity is often described as the pace or effort one could sustain for 30-40 minutes or 30-40 minute race pace/effort. For elites and sub-elites, this might mean 10K -12K pace on the road or the track. For others it might mean 5K or 8K pace or effort. The pace doesn't really matter as much as the effort and understanding where it sits along the Peak Run Performance Color Continuum.

Critical velocity intervals are color coded in reddish orange in our training plans to represent the blend between THRESHOLD and SPEED along the Peak Run Performance Color Continuum.

Critical Velocity Intervals allow the athlete to get in the needed volume of quality running, while providing regular feedback and adequate recovery to allow for sustained efforts. In fact, Critical Velocity Intervals often provide opportunities to cover more ground than the athlete otherwise could at the same pace if running continuously.


Georgetown 400s get their name from the former Georgetown University middle distance program notorious for transforming athletes with shorter distance speed into mid-distance superstars. When they started, many of the athletes struggled to sustain 20 minutes of continuous effort at THRESHOLD effort, so their coach, Frank Gagliano, had them start doing short cruise intervals to help build their STAMINA. They already had SPEED. They just needed to develop the STAMINA to extend it. Georgetown 400s helped them blend their SPEED with ENDURANCE and the results were astounding.

For more information on how to prioritize training to maximize performance gains, please read SPEED VS. STAMINA.

Coach Jacob Puzey running Georgetown 400s in the outside lane. Photo by Shara Giordano.

Nuts & Bolts of Georgetown 400s

Georgetown 400s are run in the outside lane of a track. Each interval begins at the outside lane stagger where you would start if you were starting the 400m dash in the outside lane. Run the entire 400m interval in the outside lane until you cross the finish line.

Track dimensions w/ 400m stagger. Modified image from track.isport.com

Warm Up: 15-20 minutes of EASY running + 3-4 x 20 second STRIDES, and DRILLS

Workout: 6-8 x 400m at CRITICAL VELOCITY PACE (30-40 minute race pace/effort) in outside lane starting at the 400m stagger

Recovery: Walk/jog from the finish line in the outside lane until you get to the start of the outside lane stagger (roughly 30-45 seconds). Then start again.