PFT/PRT training series—Part 3: Flexibility and mobility

Flexibility and mobility are important because they affect your joints and the surrounding muscles, tendons, and ligaments—and the way you move. You need give-and-take between joint flexibility, mobility, and stability for coordinated and efficient movements as well as injury prevention. It’s important to keep your body fit for movement, especially as you train for your Physical Fitness (PFT) and Physical Readiness Tests (PRT).

You can perform stretching and mobility exercises to promote long-term changes and improvements too. To boost and maintain your flexibility and mobility, you need to incorporate dynamic warm-ups, as well as a stretching or mobility cool-down into your regular training regimen. 


Joint flexibility—also known as range of motion (ROM)—is the amount a joint can move before the surrounding ligaments, muscles, and tendons restrict its movement. That is, it depends partly on the flexibility or “give” of these surrounding tissues. The same FITT framework provided in parts 1 and 2 of this series (on cardiovascular fitness and muscular-strength training) also applies to mobility training: frequency, intensity, type, and time, combined with progression.

There still isn’t agreement among experts as to exactly how much mobility training you need. The following is a summary of flexibility-exercise recommendations.


Flexibility exercises (stretching) should be done at least 2–3 days per week, but daily exercise is most effective too. You might see short-term improvements in flexibility after each session of stretching, but long-term changes usually take 3–4 weeks of regular stretching exercises.


Your flexibility exercises should involve major muscle groups (neck, shoulders, upper and lower body, etc.). Static stretching is great for making long-term improvements in your flexibility. Stretch only to the point of slight discomfort within your range of motion, but no further. Read HPRC’s suggestions for ways to improve your flexibility.


There are several different types of stretches:

  • Static stretching slowly elongates a muscle when you hold the stretched position for a period of time.
  • Dynamic stretching is often sport-specific and involves a joint being stretched by controlled movement through its full range of motion to lengthen and increase your muscle’s temperature. This is ideal for warm-up, and it helps improve your mobility.
  • Ballistic stretching is a type of dynamic stretch where the muscle is forcefully elongated through a bouncing motion. There’s no evidence that ballistic stretching results in injury more than other types of stretching, but whether this technique affects muscular performance is still being investigated.
  • Proprioceptive Neuromuscular Facilitation (PNF) stretching often can produce greater gains in ROM, but you need an experienced partner to perform this type of exercise.


Probably the most important aspect of “time” is when to stretch: Dynamic stretching should be part of your pre-activity/exercise warm-up, for at least 5–10 minutes in duration. Static stretches aren’t useful as a warm-up to exercise and might actually hurt your performance. A reasonable target for stretches, including ballistic and PNF, involves a 3–6 second contraction followed by 10–30 seconds of assisted stretch—about 40 seconds of total stretching time for 2–4 sets.


The methods for optimal progression are unknown, but if you have very limited mobility and flexibility, start slowly and gradually increase the length and depth of your stretches, as you feel more comfortable.


Try the Navy Operational Fitness and Fueling System (NOFFS) training videos to help build your workouts. Its Endurance and Strength series allow you to choose the type and length of your workout. Each workout begins with a warm-up, includes some type of cardio exercise, and ends with a cool-down or stretching.

Use caution when performing mobility exercises. Done properly, they shouldn’t cause pain in your joints or muscles. Never push through your threshold, be patient, and treat your joints with care.

The goal is to prevent injury (not cause it) and contribute to your overall fitness for PFT/PRT and more. If you keep up your exercise routine after the tests and continue to set goals and challenge yourself, you’ll stay warrior-athlete fit. And if you haven’t seen them yet, be sure to read parts 1 and 2 about cardiovascular fitness and muscular-strength training.

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Garber, C. E., Blissmer, B., Deschenes, M. R., Franklin, B. A., Lamonte, M. J., Lee, I.-M., . . . Swain, D. P. (2011). Quantity and quality of exercise for developing and maintaining cardiorespiratory, musculoskeletal, and neuromotor fitness in apparently healthy adults. Medicine & Science in Sports & Exercise, 43(7), 1334–1359. doi:10.1249/mss.0b013e318213fefb

Sharman, M. J., Cresswell, A. G., & Riek, S. (2006). Proprioceptive neuromuscular facilitation stretching. Sports Medicine, 36(11), 929–939. doi:10.2165/00007256-200636110-00002

U. S. Army. (2009a). Building the Soldier Athlete: Injury Prevention and Performance Optimization. Falls Church, VA: Rehabilitation & Reintegration Division, Department of the Army.

U. S. Army. (2009b). Building the Soldier Athlete: Reconditioning (Profile) PhysicalTraining Supplement. Falls Church, VA: Rehabilitation & Reintegration Division, Department of the Army.