The FITT Principle for Muscular Strength (A Tool for Dietitians) - image of various sized dumb bells.

The FITT Principle for Muscular Strength (A Tool for Dietitians)

Using the FITT Principle for muscular strength is a great way to help patients better understand how to include strength training to achieve their health goals.

As dietitians, we regularly talk to our patients about various areas of health, including physical activity. Strength training is a key part of physical activity, and it can significantly improve the quality of your patient’s life.

According to the Exercise is Medicine Toolkit, “Providing [Physical Activity] PA guidance to apparently healthy individuals represents an opportunity for RDNs to expand their ability to leverage their full scope of practice,”(1).

Dietitians are encouraged to use credible resources (like the 2018 Physical Activity Guidelines for Americans) to provide general PA recommendations. 

Image of a dietitian leaning on her desk.

What are the Recommendations for Strength Training?

The U.S. Department of Health and Human Services last shared the recommendations for physical activity in 2018. According to their report, strength training is a key element in a physical activity program.

More specifically, they recommend the following:

  • Incorporate moderate or high intensity strength training exercises that involve all major muscle groups on 2 or more days per week.
  • Progressively strengthen muscles over time by increasing the amount of weight used during the exercises or by increasing the number of days per week spent strength training.
  • Include at least one set of 8 to 12 repetitions for each exercise.
    • Of note, completing 2 to 3 sets (vs. one) has been shown to be more beneficial for muscular strength gains.
  • Strength training exercises can be completed using household items, resistance bands, body weight, free weights, or machine weights (2).
Benefits of strength training - image of a woman lifting weights

Benefits of Strength Training

The benefits of strength training are many.

The summary below includes the moderate (+) or high (++) beneficial effects of strength training found in research.

Body Composition

  • Increased lean weight (++)
  • Increased resting energy expenditure (++)
  • Decreased fat weight (+)

Physical Discomfort

  • Reduced low back pain (+)
  • Reduced arthritic pain (+)

Diabetes

  • Increased insulin sensitivity (+)
  • Improved glucose control (+)

Cardiovascular Health

  • Reduced resting blood pressure (++)
  • Improved blood lipid profiles (+)

Musculoskeletal Health

  • Increased bone mineral density (++)
  • Reversed aging factors in skeletal muscle (+)

Mental Health

  • Improved cognitive ability (+)
  • Enhanced self-esteem (++)

Activities of Daily Living

  • Increased functional independence (++)
  • Enhanced movement control (+) (3).
What is the FITT Principle?

What is the FITT Principle?

The FITT Principle is a method used to prescribe physical activity. It is an easy way keep things fun and interesting by changing one or multiple parts of a training program.

The FITT Principle acronym stands for:

  • Frequency
  • Intensity
  • Time
  • Type

F = Frequency

Frequency means how often you carry out an activity. For example, this could be the number of times per week you strength train.

I = Intensity

Intensity names how hard you work during an activity. Muscular strength training could be easy, moderate, or hard (high) intensity.

Ultimately, with strength training, the goal is to progressively overload the muscle, so it gets stronger over time.

T =Time

T stands for Time, or how long it takes to complete an activity.

For strength training, this can be measured by the number of sets and repetitions (reps) completed of the specific exercise.

T = Type

Big picture, the Type of physical activity you complete could be:

  • Activities of daily living
  • Aerobic activity
  • Recreational activity
  • Leisure activity
  • Strength training
  • Flexibility training
  • Or Sedentary time.

For this article, we are focusing on strength training. The type of strength training could be further broken down to the specific exercises being completed, for example bench press, squat, or bent over rows.

How to Use the FITT Principle for Strength Training

How Dietitians Can Use the FITT Principle for Muscular Strength

Below is a quick overview of how the strength training recommendations can be placed in the FITT Principle.

  • Frequency – 2-3 days per week
  • Intensity – varies (goal muscle overload)
  • Time – 2-3 sets of 8-12 reps
  • Type – (example: bench press)

Frequency: How Often?

Strength training is recommended 2-3 days per week. For simplicity, this could be scheduled for Tuesday and Thursday (2 days/week) or Monday, Wednesday, Friday (3 day/week). 

Allow your patient to decide what frequency would work best for their schedule.

Encourage at least 48 hours between strength training sessions to allow enough muscle recovery time.

Intensity: What Amount of Weight Should be Lifted?

This will take some time to figure out because the correct weight is based on your patient’s individual abilities.

Proper technique is more important than the amount of weight being lifted. If your patient begins lifting too much weight, injury is more likely to occur.

  • If your patient cannot lift 8 repetitions
    • The weight is TOO HEAVY – decrease weight
  • If your patient can easily lift 12 repetitions
    • The weight is TOO LIGHT – increase weight

Time: Number of Sets and Reps

Patients can start with one set of 8-12 repetitions (reps). However, 2-3 sets of 8-12 reps have been shown to be more beneficial for strength gains.

What is a Rep?

One rep, or repetition, is completing the full range of motion of an exercise.

For example, if your patient is completing the flat bench chest press, one rep would be lowering the bar to their chest and then pushing it back up to the starting position.

What is a Set?

One set includes 8-12 repetitions of that exercise.

Type: The Strength Training Exercises

The guidelines encourage 8-10 exercises that work all major muscle groups of the body. For example, these 10 exercises could be used in a full body circuit 2-3 days per week:

  1. Chest: Machine chest press
  2. Back: Lat pulldown
  3. Shoulders: Machine shoulder press
  4. Biceps: Dumb bell curls
  5. Triceps: Cable triceps press
  6. Lower body: Machine leg press
  7. Quads: Knee extensions
  8. Hamstrings: Leg curl
  9. Calves: Seated calve raises
  10. Abs: Twisting crunch
FITT - Frequency, Intensity, Time, Type

Safety Tips for Patients When Strength Training

  • Breathe throughout the entire exercise. Do not hold your breath.
    • Exhale upon exertion.
    • Inhale when returning weights to the starting position.
  • Avoid locking joints or jerking the weight into position.
  • Strength training exercises should not cause pain or injury.
  • Muscle soreness lasting a few days with slight fatigue is normal after strength exercises.

A Sample Program Using the FITT Principle for Muscular Strength

The following sample training program will use the FITT Principle for strength training:

  • Frequency – 2-3 days per week
  • Intensity – varies based on weight used
  • Time – 2-3 sets of 8-12 reps
  • Type – Exercise
ExerciseSetsReps
Machine Chest Press2-38-12
Lat Pulldown2-38-12
Machine Shoulder Press2-38-12
Dumb bell curls2-38-12
Cable triceps press2-38-12
Machine leg Press2-38-12
Knee Extensions2-38-12
Leg Curl2-38-12
Seated Calve Raises2-38-12
Twisting Crunch2-38-12

Final Thoughts on the FITT Principle for Muscular Strength

Because a dietitian’s scope of practice is fluid and based on personal competencies, it is important that dietitians continue to practice at the peak of their license. 

By incorporating physical activity discussions within your practice, while using evidenced-based resources, your patients will have the best opportunity to achieve their health related goals.

And remember, if your patient needs more guidance beyond basic exercise recommendations, you can always refer them to a personal trainer or exercise physiologist. 

For more information about The Dietitian Resource, visit our site or check out the blog.  Thanks for visiting!

References

  1. Kruskall, L., Schwartz, J., Stuhr, R. & Manore, M. M., n.d. A Physical Activity Toolkit for Registered Dietitians: Exercise is Medicine. [Online]
    Available at: https://www.exerciseismedicine.org/wp-content/uploads/2021/08/ExerciseIsMedicine_v8.pdf
    [Accessed 5 October 2022].

2. Services, U. D. o. H. a. H., 2018. Physical Activity Guidelines for Americans (2nd edition). [Online]
Available at: https://health.gov/our-work/nutrition-physical-activity/physical-activity-guidelines
[Accessed 5 October 2022].

3. Westcott, W. L. & La Rosa Loud, R., 2013 Vol 17 (2). Enhancing Resistance Training Results With Protein/Carbohydrate Supplementation.. ACSM’s Health & Fitness Journal, pp. 10-15.

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More About Rochelle

Rochelle Inwood MS, RDN, ACSM EP-C

Hello there! I’m Rochelle Inwood, a Registered Dietitian Nutritionist (RDN) and Exercise Physiologist (ACSM EP-C). With over 14 years of experience, I have sharpened my expertise through diverse roles, including weight management program co-coordinator, patient/employee gym supervisor, outpatient dietitian, program manager, dietetic internship preceptor, and more. I am passionate about learning, creating, teaching, and supporting personal growth and development.