By: Mike Caviston, Director of Fitness, Naval Special Warfare Center
Posted: March 4, 2020

Running performance is the best predictor of Hell Week success, but there is more to success than simply running a certain distance in a specific time (such as a competitive 1.5-mile run time for the Physical Screening Test (PST), or being able to meet the 4-mile run standards throughout the phases of BUD/S).

It's important to be able to recover quickly and completely between several high-intensity evolutions. Those who are faster on timed runs tend to have a more developed capacity to recover. Research from various military selection/training programs shows that performance on timed runs is also the best predictor of injury (slower runners get injured more frequently during the program).

For three years the Naval Special Warfare's (NSW) Director of Fitness studied Basic Underwater Demolition/SEAL (BUD/S) classes 300 - 318 at the NSW Preparatory School (NSW Prep) to find out if successful SEAL candidates, who complete Hell Week, show different physical abilities than SEAL candidates who drop from training.

The study found that running is the biggest predictor of BUD/S success. Running as a predictor of BUD/S success was greater than for any other fitness variable measured (including: swimming, calisthenics such as push-ups, sit-ups, and pull- ups, and measures of strength including bench press and dead lift).

The study was comprised of the NSW Prep PST and Exit Test.

Total SEAL candidates

  1. PST: 1,291
  2. Exit Test: 2,208


SEAL candidates who completed Hell Week

  1. Best run time: 15:33 minutes
  2. Worst run time: 22:37 minutes

SEAL candidates who didn't make it

  1. Best run time: 17:18 minutes
  2. Worst run time: 25:07 minutes

As run times get faster, the odds of completing Hell Week improve and the risk of being medically rolled back/dropped from training gets smaller, though benefits seem to plateau when runners are faster than 19 minutes for the PST 3-mile run.





In the athletic arena, for sports like soccer, there is a correlation between aerobic fitness and injury. It makes sense - when people get fatigued, technique tends to break down and they are more likely to make mistakes that result in injury. People with more endurance are more resistant to fatigue and less likely to make injury-prone technical mistakes, no matter the sport or standardized military training program.

Running ability correlates strongly with success in BUD/S. It has the largest impact. Running quantifies aerobic fitness, which impacts your ability to sustain work output and recover quickly after physically demanding evolutions. As run times get faster, the odds of completing Hell Week improve, though benefits seem to plateau when runners are faster than 19 minutes for the PST 3-mile run.

Shoot for this goal

  1. 3-Mile run: 18:00 - 19:00 minutes

The take-home message is to improve your running to the best of your ability, because it is the single most important factor for completing BUD/S. Use good judgment when training to reduce the risk of getting injured while running.






Since there is a competitive element to BUD/S ("It pays to be a winner"), you have to be faster than the majority of your classmates to have a reasonable chance of succeeding. In some cases, what was fast in one class (310) would be slow in another (314). This is out of your control so don't worry about it. The best strategy in preparing for BUD/S is to reach the best performance you can without overtraining or causing injury. Yes, that is a tough course to follow and a hard line to balance.

Preparation for the SEAL PST and BUD/S must include a sound running program. Performance on times runs of varying distances (1.5 miles, 3 miles, 4 miles) correlates well with probability of completing Hell Week in a fairly linear fashion ( faster means higher probability of completion). Students in BUD/S must complete 4-mile runs in progressively faster times throughout First, Second, and Third Phases. BUD/S students in Third Phase must complete a 14-mile run. BUD/S students must run dozens of miles per week moving to and from different locations at the BUD/S compound just to do other training evolutions like swimming or carrying boats or even to get chow at the galley. The running program detailed in the Physical Training Guide (PTG) is designed to develop the endurance and speed to excel on the PST and the necessary abilities to complete BUD/S. The NSW Prep conditioning program which candidates complete following boot camp in Great Lakes, Illinois prior to shipping to Coronado, CA provides the opportunity to further develop running fitness.

Students who begin BUD/S have demonstrated that they're solid runners. Yet some BUD/S students struggle, at least initially, with the running evolutions at BUD/S. How can this happen? Most likely they are affected by the demands of performing in a new environment under novel circumstances. For example, after months of training in running shoes, BUD/S students run in boots at all times. Despite what you may have read elsewhere, and the apparent logic behind preparing early, the various medical and conditioning experts at the Naval Special Warfare Center recommend that candidates limit training in boots prior to beginning BUD/S. Wear appropriate running shoes for the majority of training, and restrict running in boots to short, occasional sessions. BUD/S students wear boots while at Great Lakes except for running and physical fitness (PT), so they get a chance to break them in and condition their feet, and will begin to wear them during running and PT during NSW Orientation. The transition will go smooth for students who arrive with a solid conditioning base and a natural, efficient running style.

A major adjustment to running at BUD/S is the soft sand that forms the terrain of many conditioning runs and training evolutions. Many students arrive having put in plenty of miles on roads or tracks but never having run on a beach or other yielding surfaces. BUD/S candidates who have access to beaches or other spongy terrain may take advantage of the opportunity to incorporate these surfaces into their running program. Be aware that running on sand is more stressful than many people would expect. We tend to equate soft with cushion and low impact, but the flip side to the coin is soft sand offers little support and too much give during propulsion. In short, running in sand is quite stressful and (as with all aspects of training), SEAL candidates should add sand running to their overall mileage gradually and progressively, beginning with a modest tolerable amount such as half a mile or less. The percentage of total miles on soft sand should initially be limited to no more than 10-15%. Eventually, as conditioning improves, sand mileage can be increased to a larger percentage of total mileage, but as a general rule of thumb, limited to no more than 50% of total miles, with one third of total miles probably a good proportion. It is important to keep a balance between getting familiar with soft sand and running on firm surfaces to allow appropriate speed development.

Running on sand requires stabilizing work from the lateral muscles of the hip such as the gluteus medius, and the peroneus muscles of the lower leg. When these muscles are weak or become fatigued, performing on unstable surfaces causes misalignment of the lower extremity that may result in pain and injury. BUD/S candidates should have a proactive strategy for increasing the strength and endurance of these muscles before entering the official NSW training pipeline. There are a wide variety of exercises and activities that can be incorporated into a general conditioning program, as detailed in the NSW PTG.



  1. Do monster walks using an elastic band for resistance
  2. Do standing hip abduction using a cable machine, elastic bands or rubber tubing
  3. While lying on one side, perform hip abduction against manual resistance from a partner, or using ankle weights
  4. Do the calisthenics exercise known as the "dirty dog" or "fire hydrant": begin in a stable position on all fours (hands and knees), and externally rotate one hip out to the side, keeping the hip and knee bent to 90 degrees, until the thigh is parallel to the ground. Perform the desired number of repetitions and switch to the other hip
  5. Perform side lunges using body weight or while holding dumbbells
  6. Use a slide board, or do lateral skater's hops back and forth to points a couple feet to either side of your starting position
  7. Do short sprints that require zigzag or cutting movements, or do carioca maneuvers
  8. Use equipment that requires balance and stability, such as wobble boards or both sides utilized "BOSU" trainers
  9. Do in-line skating, ice skating, or cross-country skiing

As with all aspects of fitness, start at a manageable level and be progressive over time. Vary your routines to emphasize both strength and endurance. Be aware of the effects of adding new exercises or routines to your overall program (including running and swimming). Work hard, but also be creative and have fun.