You are here: Home / HPRC Blog

Filed under: Exercise

Preparation for the PFT/PRT part 1: aerobic conditioning

The PFT/PRT is designed to test your cardiovascular endurance and muscular strength. In this three-part series, we’ll take a closer look at each component, offer tips on optimizing your training, and show you how to prevent common injuries associated with different types of training.


In a recent study investigating risk factors for discharge from Army Basic Combat Training (BCT), researchers concluded that increased risk for both men and women was associated with failure on the initial two-mile run test. The current Physical Fitness Tests (PFT) or Physical Readiness Test (PRT) use a one and a half to two-mile run test to assess cardiovascular, or aerobic, fitness.

When mapping out a fitness program, learn the components of the FITT principle and apply them for each type of training. FITT stands for “frequency,” or how often; “intensity,” or how hard; “type,” or the kind of activity; and “time,” or how long. Progression (see below) is also an important part of an exercise plan. Using the FITT Principle, here are some guidelines to help optimize your cardiovascular fitness.

Frequency. The U.S. Surgeon General and other U.S. government agencies recommend physical activity on three or more days a week.

Intensity. According to updated guidelines The American College of Sports Medicine (ACSM) recommends adults engage in moderate-intensity exercise (i.e., at 40-60% Heart Rate Reserve (HRR)) five days a week or vigorous-intensity exercise training (i.e., at ≥ 60% HRR) three or more days a week. They also recommend a combination of moderate- and vigorous-intensity exercise. You can use this calculator from Kirtland AFB to determine your HRR.

Type. ACSM defines aerobic activities as being continuous, rhythmic, and using large muscle groups, such as your lower and upper body muscles. Examples of these kinds of activities are running, biking, swimming, rowing, and jump roping.

Time. The Surgeon General, ACSM, and American Heart Association recommend expending at least 1,000 calories per week through exercise (i.e., in addition to calories burned through normal everyday activities). This can be achieved through moderate-intensity exercise, as described above, and should last about ≥ 30 minutes per day for a total of  ≥ 150 minutes per week; or with vigorous-intensity exercise for ≥20 minutes per day for a total of ≥75 minutes per week. The maximum safe duration is unknown, but exercise lasting more than an hour and a half increases risk of overtraining and/or overuse injuries such as stress fractures.

Progression. During the initial phase of an exercise program, ACSM recommends increasing duration (minutes per session) gradually. Increasing 5-10 minutes every one or two weeks over the first four to six weeks of an exercise program is reasonable for healthy adults. After an exercise routine has been maintained for one month or longer, it is reasonable to gradually increase frequency, intensity, and/or time over the next four to eight months. As a general rule of thumb, though not scientifically backed, increasing your workloads or volume by 10% will also help you gradually progress your exercise program.

Due to the repetitive and rhythmic nature of aerobic exercise, overuse injuries can occur as a result of your training. Cross training—training with a variety of aerobic exercises—is recommended. Examples of this would be alternating running, swimming, and rowing exercise sessions.

Part two of this series (upcoming) will address the muscular strength component of PFT/PRT.

Stress Fracture Prevention: Strengthening the Lower Extremity Muscles

Maintaining strength and flexibility in the lower extremities is one of the many important steps toward decreasing the likelihood of developing the small cracks in a bone commonly known as stress fractures.

There are several risk factors for stress fracture development, but a 2011 article in Medicine and Science in Sports and Exercise found that maintaining adequate muscle strength and flexibility in the hips, legs, knees, ankles, and feet is of great importance, especially for women. Here are some exercises from the American Council on Exercise that can help you build strength and flexibility:

Ankle Flexion

Single Leg Push-off

Forward Hurdle Run

Seated Calf Stretch

Standing Dorsi-Flexion (Calf Stretch)

Supine Hamstrings Stretch

Barbell Calf Raises

Jump and Reach

Agility Ladder: Lateral Shuffle

Alternate Leg Push-off

Barbell Jammers

Before beginning any exercise program, however, make sure to consult with a medical professional, especially if you are more than 45 years old.

Back in motion: Can swinging a kettlebell improve back and shoulder pain?

Exercises with strength-training equipment known as kettlebells may provide relief from back, shoulder, and neck pain.

Kettlebells have been used in Europe for years in strength training, and now they’ve become a popular workout tool here in the United States too. The benefit of kettlebells is that they provide the user a wider range of motion than dumbbells do. Kettlebell workouts engage multiple muscle groups at once, making them a great option for getting a whole-body workout in a short time.

Interestingly, the January 26 edition of the New York Times Health Section reported on a Danish study that suggests kettlebell exercises are a promising musculoskeletal therapy for low-grade back and neck pain.

The study involved middle-aged women with low-grade back, shoulder, and neck pain who were randomly assigned to either a regular kettlebell workout or a general-exercise control group. The study did not include those with chronic pain.

According to the Times article, at the end of the study, the group that did the kettlebell exercises reported less pain, as well as improved strength in the trunk and core muscles, compared with the control group. Overall, the study showed exercising with kettlebells reduced lower-back pain by 57% and neck and shoulder pain by 46%.

For those with core-muscle instability or weak core muscles, kettlebells can be a great way to strengthen those muscles (back, abdominal, glutes, quads, hamstrings) and improve posture. However, along with exercise it is imperative to stretch the hamstrings, since this tends to be a major contributor to lower back pain or discomfort.

It’s important to start slow when using kettlebells and seek professional guidance. Like any other exercise equipment, if used improperly, kettlebells can cause serious injury, and their swinging motion can be difficult to control.

Working out with babies

An Army base in Germany includes babies in their workouts!

At the U.S. Army Garrison in Kaiserslautern (Germany), the base is trying to find more ways to include families in physical fitness. They are providing classes— called “Binkies and Babes” —that spouses can do with their babies. These classes are great ways for spouses to workout with their young children, socialize with other military families, and get a great individual workout!

Overseas military families can sometimes find it difficult to both exercise and manage child care. This is one way overseas bases are moving towards Total Family Fitness. Renee Champagne, the Fitness Coordinator for the Army bases in Germany (and a military spouse herself), sees how “working out and staying physically fit may help a spouse cope during a deployment… which in turn could provide peace of mind to the military member downrange.”

For more information, see the article and video on Stars and Stripes.

Runners’ trots


There’s a phenomenon runners sometimes experience that’s commonly called “runners’ trots” – otherwise known as diarrhea – that has risk factors and that can possibly be avoided. Although the “trots” usually don’t last long and are generally nothing to worry about, they certainly can be a major annoyance, causing lost time in training or competition and even embarrassment if there is literally “nowhere to go.”

The most common risk factors cited are for those who are young, female, susceptible to irritable bowel syndrome, or lactose intolerant, as well as those who have had a previous abdominal surgery. The things we do to our bodies that reportedly increase risk are high-intensity exercise, dehydration, vertical-impact sports (e.g., running vs. biking), poor conditioning, medication, and diet. Although these are stated in the medical literature as risk factors, a recent study published in the International Sportmed Journal examined the evidence behind each of these risks to see if they hold up under scrutiny – and there’s surprisingly little evidence to support many of the statements about risk factors for developing “runners’ trots.” Most of the evidence was limited and relied on either single studies or multiple studies with varying results but a tendency toward supporting the conclusion.

Here are the conclusions of this evidence-based study:

The only strongly supported evidence was for dehydration to increase the risk of diarrhea. Female gender, younger age, high-intensity training, vertical impact, and medication had limited support and could go either way. Finally irritable bowel, lactose intolerance, previous abdominal surgery, poor conditioning, and dietary factors had very weak support. Keep in mind that little or no evidence does not make something true or false; it just means we have insufficient scientific evidence for any assumption.

So, based on the studies, how can you avoid “runners’ trots?”

  1. The evidence certainly supports staying well hydrated so that the bowel gets an adequate blood supply.

Even though the evidence for doing some things is not strong, they make sense and are not harmful. These include:

  1. Avoid a large meal 3-6 hours prior to running.
  2. Avoid food or drinks that have non-absorbable sweeteners (such as sorbital or sucralose), caffeine, and/or a high fat content.
  3. Don’t ingest concentrated carbohydrates (high glycemic index) before running.
  4. Be aware that energy bars and gels may contribute to the “trots” for some people.
  5. Avoid taking anti-diarrheal medications such as loperamide (e.g., Imodium) or Lomotil, since they can affect the ability of the body to tolerate heat.
  6. Wear loose-fitting clothing to reduce irritation.
  7. If symptoms persist for more than a few days, seek medical attention to be sure there is not an underlying cause.

    Enjoy your run!

    Announcing Family Physical Fitness on HPRC

    HPRC's Family & Relationships section has a new area on family physical fitness. See what it has for you and your family!

    Warfighters have specific physical activity requirements, but their spouses, children, parents, and other loved ones also have physical fitness requirements for their own individual and family missions. HPRC's family section has a new area that summarizes recent guidelines for physical activity for U.S. adults, and children, and identifies military resources, interactive tools, and exercise workouts and videos. Check it out here!

    Running to exercise

    Running is one of the easiest forms of aerobic exercise, which strengthens your heart and improves your overall health.

    Running is a great exercise to help reduce your risk of heart disease and stroke. Running improves your cardiovascular system by strengthening your heart muscle and improving your circulation. As your heart muscle becomes stronger, your heart can pump more blood more easily. This helps deliver more oxygen to fuel your working muscles and remove byproducts such as carbon dioxide.

    Workouts you can do at home during the holidays

    You can fit in these workouts at your home through the holiday season to keep you on track.

    With the holiday season upon us, finding time for our usual workouts can sometimes be difficult. Two great physical fitness resources are the American College of Sports Medicine (ACSM) and the American Council on Exercise (ACE). Each has online workouts that you can try for free.

    For a total body workout that you can do at home with free weights, try this total body workout from ACE that includes videos of the warm-up, the workout, and the cool-down. For a total body workout without additional equipment, try this at-home workout.

    If you have less time, try this Basic Bodyweight Strength Training Program from ACSM.

    Fit in these workouts in at home through the holiday season to keep you on track.

    Brazilian Jiu-Jitsu

    This martial art relies on technique and balance to overcome an opponent, but it will also tone and build muscle without the use of weights.

    Brazilian Jiu-Jitsu—or BJJ—focuses on ground fighting techniques, also known as grappling. You can start your training at a level appropriate to your physical fitness, but ultimately you will find that your endurance increases as your opponent also learns the techniques designed to dominate. Although BJJ requires little to no physical strength—mainly technique and balance—you will find that your muscle tone and mass increase gradually without requiring weight training.

    Swim to stay healthy

    Swimming is not only one of the best total-body exercise forms, it can also help you avoid getting sick. Take the plunge!

    Swimming is an excellent way to reduce the risk of disease. It works your entire body and activates all the major muscle groups; contributes to muscle strength, flexibility, posture, and endurance; promotes weight loss and stress reduction; and improves cardiovascular conditioning by lowering your resting heart and respiratory rates and making blood flow to the heart and lungs more efficient. Swimming is also very low risk for injury because it places stress on your bones, joints, and connective tissues, thanks to the buoyancy of the water. Swimming 15 to 30 minutes each day can have a very positive effect on your overall health.

    RSS Feed