Exercise Prescription Variables for Resistance Training

Introduction

Understanding the foundational variables of exercise prescription is essential for designing safe, effective, and individualized resistance training programs. This chapter reviews the resistance-training variables professionals use to build, monitor, and adjust the training dose.

Section 1: Resistance Training Variables

Resistance training is a cornerstone of any comprehensive exercise program, contributing to improvements in strength, local muscle endurance, power, and overall musculoskeletal health. The variables essential for designing effective resistance training programs, such as frequency, intensity, exercise selection, and progression, serve as the framework for creating individualized resistance training regimens that meet individual needs, goals, and capabilities.

By understanding and applying these variables, fitness professionals can optimize adaptations while minimizing the risk of injury and burnout. Whether the focus is on increasing strength, building muscle mass, or enhancing stamina, this section provides the tools and strategies necessary to guide program design. Moreover, this content complements aerobic training principles, forming a holistic approach to fitness programming.

1. 1.Frequency of training
2. 2.Intensity of training (objective and subjective)
3. 3.The number of sets per muscle group
4. 4.The number of repetitions per set
5. 5.Determining the appropriate weight/load to use for each exercise
6. 6.Order of exercises
7. 7.Choice of exercises (exercise selection)
8. 8.Tempo of exercise
9. 9.Rest periods between sets
10. 10.Rest and recuperation between training sessions
11. 11.Active rest or deload periods
12. 12.Breathing considerations

1. Frequency of Training

Leading health and fitness organizations recommend strengthening each major muscle group in the body two to three times per week. This recommendation is based on the amount of time required for the body to recover.

Recovery from training sessions typically takes 24 to 72 hours. The amount of time varies based upon the individual's fitness level, genetics, sleep, diet, stress levels, and the volume and intensity of the training session. Recovery means restoring a normal state of health, mind, or strength. When this occurs, it is safe to train again.

As discussed previously in the aerobic training variables section, the frequency of training for much of the general population is determined by their time and desire.

2. Intensity of Training

Intensity falls under two categories: objective and subjective.

Objective Intensity

When describing objective intensity, feelings, emotions, and perceived effort are removed from the equation. Objective intensity only considers the load that is being lifted. Table 5.3 reviews the objective intensity continuum that can be used to determine if a particular load will predominantly improve power, strength, or strength-endurance.

When training within these repetition maximum (RM) loading zones, it is important to recognize that RM represents the maximum load a person can lift for the specified number of repetitions while maintaining proper form. This refers to performing working sets to at or within one repetition of muscle failure.

Within this context:

Why is This Important?

For most people, strength development does not occur unless the load is at least 65% of an individual's 1RM. This equates to the 1 to 15 repetition range (Behm 1995; Jenkins 2027; Schoenfeld 2017). To increase strength, Type II muscle fibers must be both activated and trained. This requires adequate frequency, volume, and intensity, explained in more detail later.

Strength muscle fibers are optimally activated and trained at sets and loading zones corresponding to an 8RM, 80% of 1RM, or heavier that are taken to at or near muscle failure. It is important to understand that Type I and Type II muscle fibers can both be activated with much lighter loads, 30 to 40RM, when they are taken to at or near muscle failure.

However, as Henneman's Size Principle dictates, the Type II muscle fibers are not activated/recruited until the last few repetitions of the set in higher repetition ranges and thus do not have a sufficiently high load to induce significant gains in strength.

While research indicates that lean muscle tissue can significantly increase by training with very light loads, as light as 30% of 1RM or approximately 30 to 40 repetitions per set, the further away from an individual's 1RM the more important it becomes to train to at or very near muscle failure (Sundstrup 2012). This is hard to achieve, i.e., impractical, both mentally and physically for most people because of the accumulation of metabolites during the set and the corresponding discomfort and burning sensation that occurs (Ribeiro 2019).

Additionally, the fitness professional should understand that there are four primary physiological adaptations to resistance training and these adaptations should be the goal of all programs for all individuals across the lifespan:

• Strength
• Conditioning
• Power
• Increased lean muscle tissue (muscle hypertrophy)

Other goals, such as improvements in metabolic and cognitive health, performance, activities of daily living, and prevention or management of joint pain are directly or indirectly dependent upon these four adaptations. Training across the 4 to 15 repetition range optimally increases strength, conditioning, power, and lean muscle tissue. Therefore, fitness professionals should recognize the need to train across this repetition spectrum and, armed with the information provided throughout this book, will understand why it is important to train across this repetition domain whenever possible.

Subjective Intensity

Unlike objective intensity, subjective intensity focuses specifically on individual feelings and their rate of perceived exertion, i.e., perceived effort. Optimizing strength, strength-endurance, and lean muscle can occur without the need to train to complete muscle failure (Lacerda 2019; Santos 2019). Training to muscle failure can increase the risk of joint pain, can cause central nervous system burnout/fatigue, and should occur sporadically, if at all.

However, it is crucial to train near, or in close proximity to, muscle failure during working sets (Schoenfeld B 2017). When a set is taken to muscle failure, the individual has put in maximal effort. Whereas any set that is not taken to muscle failure is considered by definition sub-maximal. Since most working sets are sub-maximal in effort, i.e., not taken to true muscle failure, a distinction needs to be made between warm-up and working set.

Warm-up vs True Working Set

The merging of four important concepts will give clarity as to when a set is a warm-up set and when it is a true working set. The four concepts are:

1. 1.Rate of Perceived Effort Scales - RPE: This is also known as the effort the individual perceives they have exerted in the set (Tiggeman 2010). Specifically, it is the effort the individual perceives they have put forth at the end of the set, i.e., the last repetition or the last few seconds of a timed set such as a plank.
2. 2.Repetitions in Reserve (RIR): This term describes intentionally ending a set before reaching complete muscle failure, leaving a certain number of repetitions in reserve at the end of the set. For example, an individual might conclude a set feeling as though they could have performed three additional repetitions. This concept allows for controlled training intensity and progressive overload (Zourdos 2016).
3. 3.Face of Strain (or Effort): This refers to the look of strain on an individual's face when they are in close proximity to muscle failure or have reached muscle failure (Uchida 2018).
4. 4.Slowing of Movement Velocity: This phenomenon occurs as a lifter approaches muscle failure during a set. Neuromuscular fatigue becomes pronounced, resulting in noticeable reduction in the speed of movement even when maximal effort is applied (Moran-Navarro 2019).

FYI: These four concepts are married to each other and are referred to as The RPE Method throughout this book. Since most working sets are not taken to muscle failure, i.e., are sub-maximal, the fitness professional or individual must be able to accurately judge between warm-up and working set. Since the effort an individual puts into a set is one of the most important factors in reaching any goal, these concepts are among the most important a fitness professional or individual should understand.

Differentiating Between a Warm-up and a True Working Set

As noted in the figure below (Figure 5.2), on an RPE scale of 1 to 10, with 10 being defined as muscle failure, no more repetitions could have been performed with proper form because of the accumulation of extreme fatigue, 1 to 6 on the scale is considered a warm-up set and 7 to 10 is considered a working set. When the set is sub-maximal in effort, the merging of the concepts discussed previously determines the difference between warm-up and true working set.

Sets fall under one of two categories:

1. 1.Warm-up
2. 2.Working set

Assuming the set is within the 6 to 15 repetition range, the velocity of movement during the first several repetitions occurs at approximately the same speed. As the lifter begins to approach repetition maximum or muscle failure, the velocity of movement begins to slow. Typically, there is a corresponding look of strain on the lifter's face.

This combination of slowing movement velocity and face of effort becomes highly predictive of how many repetitions the person has left in reserve. Prior to this point, it is hard to predict how close the person is to repetition maximum or muscle failure.

Frequently, lifters will terminate a set prior to the velocity of movement slowing, suggesting that they are incorrectly perceiving that they are near the end of their set with only a few repetitions left in reserve. The fitness professional should recognize this during the set and may encourage the lifter to continue to do more repetitions until the velocity of the movement slows. Explaining this concept to people can help them understand how hard they should push themselves and provide confidence that you are pushing them at an appropriate level.

Below is a table to help the fitness professional or lifter distinguish between set end points:

When the velocity of movement begins to slow, the lifter has reached an RPE of approximately 7 on a 1 to 10 scale. This would be considered a working set, the onset of the slowing of movement equals 7 RPE.

*RPE of 7 = onset of the slowing of movement = working set*

If the lifter proceeds with another repetition without terminating the set, neuromuscular fatigue increases, velocity slows even more, the look of strain increases, and the lifter moves closer to muscle failure. Continued repetitions without terminating the set lead to near maximal fatigue, a near maximal look of strain, and markedly slowed movement velocity.

• Warm-up Sets: difficult or impossible to predict proximity to repetition maximum or muscle failure.
• Working Sets: proximity to muscle failure or repetition maximum becomes highly predictable.
• Muscle Failure: lifting, or the concentric part of the movement, is not completed because of fatigue.
• Repetition Maximum: the last completed lifting part of movement where accumulation of fatigue would not allow for another completed repetition.
• Rate of Perceived Effort: perceived effort being put into a set.
• Rate of Perceived Fatigue: perceived fatigue as an outcome of effort.
• The slowing of velocity of movement is the most important variable to determine proximity to muscle failure, to differentiate between warm-up and true working set, and to allow for an accurate prediction of repetitions in reserve because when velocity of movement slows towards the end of a set, neuromuscular fatigue has truly set in.

The merging of the above concepts is most accurate in the 6 to 15 repetition range. Below 6 repetitions the weight is very heavy to heavy; the movement is slow from the start of the set and the look of strain on the face begins immediately. Above 15 repetitions per set the weight is very light, the fatigue that initially sets in is metabolic fatigue, i.e., the burning sensation, and it is difficult to continue the set to very near muscle failure.

In high repetition ranges with very light weight it is also difficult to distinguish between metabolic fatigue and neural fatigue. This is an additional reason why it can be ineffective to train above 15 repetitions per set with some exceptions, e.g., an elderly person who is early in their training program or an individual who wants to greatly improve stamina.

Conclusion

Inquiring about how the last repetition of a set felt can supply crucial information. Correlating a subjective RPE with movement velocity and the look of strain provides an accurate assessment of whether the set was truly a working set or should be considered a warm-up set. Slowing of movement velocity is the most reliable marker and should be the primary metric to determine proximity to failure.

If the lifter felt their RPE was 7 or higher but the velocity of movement did not slow and there was no look of strain on their face, this was not a true working set. It is the fitness professional or lifter's responsibility to understand these concepts and use them as an ongoing guide to determine loads for warm-up and working sets. If a set was supposed to be a warm-up and the movement velocity slowed at the end of the set, the load chosen was too heavy and should no longer be used for a warm-up set.

As mentioned in Chapter 6, these concepts, The RPE Method, may also be used in the place of initial strength and strength-endurance testing as a method of determining initial loading.

3. The Number of Sets per Muscle Group

The duration of the training session is likely the most significant factor in determining the number of sets performed for each muscle group. Early in a training program, such as the Familiarization Phase and the onset of a periodization program, the exerciser is establishing a baseline fitness level.

Sets per muscle group during this period are typically two to three per large muscle group, i.e., legs, back, chest, and shoulders, and one to two sets per smaller muscle group, i.e., upper back/trapezius, calves, adductors, and abductors. As fitness level increases, it becomes increasingly important to progress towards 8 to 20 sets per muscle group per week for the large muscle groups, i.e., legs, back, chest, and shoulders. While each individual situation is different, this set range begins to optimize general fitness (Phillips 2019). Each muscle group should be targeted with multiple exercises to achieve 8 to 20 sets per week. For example, a training session which includes three sets of multi-joint lower body exercises can include two sets of squats and one set of barbell hip thrust.

4. The Number of Repetitions per Set

Individuals should generally start at 10 repetitions per set during the Familiarization Phase. The length of this phase depends on the length of time it takes to understand proper form, names of exercises, the flow of a session, establish mind-body connections, determine initial loads, and determine that the body is responding well within its comfort zone, i.e., begin with an RPE of about 5 on a 1 to 10 scale, approximately moderate warm-up weight.

As the person exits the Familiarization Phase and enters Flexible Linear Periodization, repetitions should increase to 12 to 15 per set. The RPE Method should be used to determine the loading and guide progression within this repetition range. After a phase of approximately two to four weeks at 12 to 15 repetitions per set, repetitions will be reduced to 10 to 12 repetitions per set.

The individual will have gained strength in the previous phase and should continue to progress during the 10 to 12 repetitions phase. The goal is to be stronger at the end of the phase than when it began, i.e., lifting more weight in each exercise during the phase as compared with week one. Increasing loads within this phase will, along with an optimally designed aerobic training program, increase overall conditioning.

After a phase of approximately two to four weeks at 10 to 12 repetitions, repetitions will be reduced to 8 to 10 repetitions per set. The goal is to be lifting more weight for each exercise at the end of the phase than when it began.

Following two to four weeks at 8 to 10 repetitions per set, it should be determined if repetitions should be reduced to 6 to 8 repetitions or if the person should begin an active rest or deload phase before beginning at 12 to 15 repetitions again. It is a case-by-case situation, but most often in an RPE-driven program, which allows for adjustments in subjective intensity from set to set, it is safe to progress to a two to four-week phase at 6 to 8 repetitions per set.

Progressing the program to the 6 to 8 repetition range and below will increase strength and power. As strength-fitness increases over time, more conditioned people may need to spend most of their time in the 4 to 12 repetition range with occasional two to four-week phases at 15 or 20 repetitions per set (Loveless 2015). Although the principles are the same, it is ultimately the fitness professional's or individual's responsibility to determine how to manipulate the repetition ranges for each unique situation.

5. Determining the Weight / Load to Use

Experience provides the best guidance for selecting appropriate loads. A new fitness professional or exerciser should always err on the side of caution and choose weights that may be too light. The fitness professional or individual will be able to tell if the weight was inappropriately light within a few repetitions and can adjust accordingly.

Otherwise, The RPE Method always determines the weight/load to use for each exercise. Loads should be increased when the current load is no longer challenging, i.e., the velocity of movement no longer slowed significantly at the end of the set.

As a general guideline for larger muscle groups and multi-joint movements, e.g., squats, deadlifts, leg press, upper body pushing and pulling exercises, the fitness professional or individual can increase the weight by 5 to 10 lbs. Smaller muscle groups and single-joint movements, e.g., knee extension, knee curl, calf raise, hip abduction and adduction, should be increased by 2 to 5 lbs (Sands 2012).

Ultimately, The RPE Method should be used to determine appropriate loads for each repetition range because there will be occasions when increasing in 2 to 10 lb increments will not lead to the desired intensity. An increase or decrease in weight may be required. It is important to ensure that the lifter can maintain proper form regardless of the weight chosen. Increasing weights too quickly can result in poor form and injury during a working set.

6. Order of Exercises

• Most important to least important.
• General to specific.
• Complex to simple.
• Large muscle group to small muscle group.
• Multi-joint movement to single-joint movement.

This usually equates to performing explosive movements early in the session, following the warm-up. This is generally followed by multi-joint exercises for the four large muscle groups: legs, back, chest, and shoulders. Smaller muscle groups are normally placed last in the workout, such as hip abductor/adductor and calf exercises.

7. Choice of Exercises / Exercise Selection

All strength training exercises fall into one of two categories:

1. 1.Primary movements/exercises: cleans, squats, hip hinge, i.e., deadlifts, hip thrusts, multi-directional lunges, pulls, i.e., rowing movements, and presses, i.e., horizontal chest or vertical shoulders.
2. 2.All other exercises by definition are assistance exercises.

While there will be situations where the person cannot perform some of the primary exercises, revolving programs around assistance exercises should be avoided whenever possible. Goals are optimally achieved when a program focuses on primary exercises. An assistance-exercise dominant program is less efficient, less effective, and will not allow the exerciser to reach their true potential.

FYI: It is very important when determining the insertion of an exercise into the program to consider the following points and concepts. First, the following questions should be asked:

1. 1.Does the exercise fit within short-term or long-term goal? If not, why is it being used?
2. 2.Does the benefit outweigh the risk?
3. 3.Are there more efficient, effective, or safer alternatives that would yield a similar or better result?
4. 4.On a continuum of difficulty, is the exercise in question challenging enough to cause the desired adaptation, i.e., is the individual ready for a more technically challenging exercise that might yield superior results?
5. 5.Will the exercise assist in improving the performance of a primary exercise or functional movement in daily life?

Increased variety and entertaining the client are not valid reasons to insert an exercise into a program. If the exercise does not fit within a short-term or long-term goal, if the risk outweighs the benefit, or if there are better and more appropriate exercises, the exercise in question should be discarded.

A recent study concluded that too much variety may have a negative effect on desired physiological adaptations, e.g., strength and hypertrophy. By their nature, primary exercises will lead to maintaining or improving the four primary adaptations to resistance exercise: strength, conditioning, power, and muscle hypertrophy. Therefore, optimally designed resistance training programs should revolve around primary exercises.

8. Tempo of Exercise

During the Familiarization Phase, weights should be lifted and lowered with control. As self-efficacy, i.e., confidence, and fitness level begin to improve, full effort should be put into the lifting, concentric, portion of each repetition of every set. This is accomplished by lifting the weight with velocity or lifting with the intent of velocity and lowering the weight with control.

The goal is to lift explosively through the concentric, muscle shortening, phase and lower the weight in a slower controlled motion through the eccentric, muscle lengthening, phase. A possible exception would be when training for strength-endurance, local muscular stamina, in the 12 to 20 repetition range whereby the lifter may choose to lift and lower the weight with control. This will increase time under tension and have a greater effect on strength-endurance.

As exercisers progress into the Flexible Linear Periodization model the following should be kept in mind regarding repetition tempo:

Conclusion

If the goal is strength-endurance, repetition duration, or repetition tempo, should be slower. When the goal is to increase lean muscle tissue, hypertrophy, it is beneficial to employ a range of tempos (Schoenfeld B 2015). If the goal is strength or power, it is beneficial to lift with velocity and lower with control. Slow tempos should be avoided, especially on the lifting portion of the exercise.

In most cases, lifting with velocity will mean that portion of the movement will be brief, usually less than two seconds. Lowering weights with control can vary between exercises but normally does not need to last longer than a few seconds.

Addressing Joint Stability

A view exists that to increase joint stability the lowering portion should last up to five or six seconds. This is inaccurate. Improving joint stability is multi-faceted. Controlling the lowering, eccentric, part of a movement is only one facet to improve joint stability. Other components include increasing overall strength, balancing strength around each joint, improving neuromuscular control through teaching and instilling proper form (Clare 2013), and including force absorption exercises, e.g., step-downs, hops, and jumps, among other things.

In most cases, a controlled lowering portion that lasts 2 to 3 seconds is adequate. Brief isometric contractions should be included when appropriate. This is usually to seek out maximum momentarily paused contraction in-between the lifting and lowering phase.

For example, when performing knee extension on a knee extension machine, the person should be instructed to fully extend the knee, known as terminal knee extension/lock-out, pause, and then lower the weight with control before repeating. This strategy is also used for various and appropriate exercises and muscle groups to help establish a mind-body connection.

9. Rest Periods Between Sets

For larger muscle groups and compound movements, rest between sets is usually longer as compared with smaller muscle groups and isolation movements (Sands 2012). The amount of recovery time needed generally correlates with the amount of muscle mass being worked, i.e., gluteal muscles will take longer to recover than calves. Table 5.6 shows typical rest periods for single-joint and compound exercises depending on the repetition range.

In the 1 to 6 repetition range, the exerciser usually performs little to no smaller, single-joint exercises because doing so may place too much stress on joints. These suggestions can vary based on goals and the level of intensity of the set. There is also individual variability that should be taken into consideration.

FYI: While the above suggestions correspond with the exercise science literature, there is a growing body of evidence showing that exercisers should be nearly recovered before beginning the next set. Unless the person is in a phase where they are seeking to improve strength-endurance and overall stamina, where rest periods should be monitored closely and kept short to moderate in length, the fitness professional or exerciser should wait until heart rate and breathing rate have returned to at or near resting level and, equally important, the exerciser is mentally ready to perform the next set.

Too often fitness professionals or exercisers will push too hard to perform another set when they are still trying to recover from the previous set and are not mentally ready. This unsafe situation should be avoided.

10. Rest and Recuperation Between Training Sessions

To allow for adequate growth and repair, lifters should normally avoid training muscle groups on consecutive days. Once the mind and muscle groups that were trained feel recovered, it is safe to commence the next training session. This is primarily determined by the cessation of any muscle soreness and the passing of 24 to 72 hours. However, higher volume and higher intensity sessions may require longer time to recover from. Joint pain should also be absent in the areas of interest to train (Kork 2015).

11. Active Rest and Deload Periods

It is important to allow the body to rest and recuperate between training cycles and occasionally between phases, i.e., prior to moving from one repetition range to the next (Sands 2012). Athletes typically refer to rest and recuperation as their postseason. For general fitness, many people train week after week, month after month, year after year. This can lead to accumulating fatigue and result in mental burnout and joint pain.

A core concept of Periodization is to schedule active rest or deload weeks where the exerciser either does not strength train at all, active rest, or significantly decreases volume and intensity, deload (Turner A 2011).

12. Breathing Considerations

During a set, the exerciser should exhale on the lifting, concentric, portion of the movement and inhale on the lowering, eccentric, portion of the movement. They should also avoid an extended, i.e., greater than two seconds, Valsalva maneuver. The Valsalva maneuver is defined by holding breath while the glottis is simultaneously closed. Doing this for too long may increase blood pressure to unsafe levels.

Research has shown that the Valsalva maneuver may not be able to be avoided in the 1 to 8 repetition range and the body may use it as a subconscious strategy to increase trunk stability (Hackett 2013). Research has also shown that the hold-breath maneuver where the exerciser briefly holds their breath without closing the glottis is safer than the Valsalva maneuver and may also be an appropriate strategy to increase trunk stability (Lepley 2010).

13. Progress as Tolerated: Adjusting Program Variables

In the context of program variables, progress as tolerated ensures that exercise progression respects the individual's capacity to adapt to increasing stress while mitigating the risk of exacerbations or injuries. This principle is critical when adjusting key variables such as intensity, volume, and frequency.

Application in Program Design

1. 1.Incremental Adjustments: Changes to volume, intensity, or exercise selection should follow the 10% rule to avoid overwhelming the individual's capacity.
2. 2.Readiness-to-Train: Tools like subjective feedback and readiness assessments should inform session-by-session modifications.
3. 3.Fitness Capacity and Flare-Ups: Strength and aerobic capacity play a pivotal role in reducing the frequency, intensity, and duration of flare-ups. Ensuring a gradual increase in these domains will enhance resilience and recovery.
4. 4.Lifestyle Medicine: Address systemic risk factors such as poor sleep, stress, and inadequate nutrition which compound flare-up risks and limit recovery.

By integrating these guidelines into the manipulation of program variables, fitness professionals can ensure progressive yet safe adaptations for their clients.

Practical Application of Resistance Training Variables

An effective resistance training program begins with assessing the individual's fitness level, goals, and readiness to exercise. Each variable, frequency, intensity, sets, repetitions, exercise selection, tempo, and rest periods, is then tailored to align with these goals, ensuring safety and effectiveness.

Programs should prioritize multi-joint compound movements early in the session to target larger muscle groups, followed by assistance exercises for smaller muscles. Initial sessions focus on 2 to 3 sets of 10 to 12 repetitions to build foundational strength and confidence.

Over time, progression includes increasing loads, training across a wider spectrum of repetitions, e.g., 6 to 15RM, and incorporating varied tempos to match goals such as strength, hypertrophy, or endurance. Rest periods are adjusted to support the session's objectives, with longer durations, 3 to 5 minutes, for strength and power and shorter ones, 45 to 90 seconds, for hypertrophy or endurance.

Regular adjustments to variables such as load, repetitions, and exercise selection ensure continued progress while preventing plateaus. This iterative process of assessment, application, monitoring, and progression allows individuals to achieve adaptations in strength, conditioning, and overall musculoskeletal health efficiently and sustainably.

The detailed examination of variables such as intensity, frequency, and progression underscores the adaptability of exercise programming. These principles are essential for aligning with the Universal Algorithm, ensuring continuous improvement and safety.

Recognizing that The Medical Fitness Bible is part of a larger ecosystem which includes instructional videos developed to bring the book to life, the reader is directed to www.MRFInstitute.org. It would be beneficial to view the videos, as they provide greater clarity to the information presented in this chapter.