So it’s been a while since I’ve blogged and even longer since I’ve had a guest blogger on The Sports Physio. However, I am really pleased to introduce you all to Marcus Blumensaat who has done an awesome post on that tricky and elusive question of… how much exercise is enough?
Why do we even care to know?
Many people do not like to exercise. At all. They do not want to perform exercises even if they have been told by a health care professional that it will help them to recover, heal or rehabilitate an ‘injury’. In my opinion, getting people to perform their prescribed exercises is one of, if not the most, challenging things we face as musculoskeletal (MSK) health care practitioners.
Many people don’t even meet public health exercise recommendations that have been shown to decrease all-cause mortality by 40%.1 40%!!! I suppose they are on the ‘we are here for a good time, not a long time’ train. Fair enough, I have been on and off that train many times. I usually buy a ticket when a freshly baked chocolate chip cookie is in front of me.
Back to the clinical setting… if a person is seeking our help and we have employed our critical thinking in a biopsychosocial (BPS) framework and have determined that the performance of exercise would be beneficial to the case at hand, the answer to this question, ‘what is the minimal effective dose?’, is very important indeed.
If we knew the minimum effective dosage of exercise, one would assume that we would increase the odds of the people we are working with actually performing the prescribed exercise(s). With the end result being better clinical outcomes, i.e., happier, healthier people!
Thus, it would be to everyone’s advantage if we could figure out what the minimal effective dose of exercise is for different pathologies and pain. Simple.
Like most questions in the MSK world regarding pathologies, pain, and rehabilitation, this one of ‘what is the minimal effective dose of exercise?’ is shrouded in uncertainty.
If one exercises (pun intended) their critical thinking skills when contemplating this question, it should become obvious that there are a few details that need to be clarified before trying to come up with an answer.
Most importantly, what is the desired ‘outcome’ or ‘effect’ that you are trying to stimulate in the person by having them perform the prescribed exercise? In other words, what are you hoping to accomplish by having the person perform the exercise?
Are you hoping to change their ‘capacity’ in some way to better handle the loads* that they face in life? Perhaps the goal is an increase in strength or range of motion.
* Load is the burden (single or multiple mechanical, psychological, or social stressors) that is applied to a human biological system (including subcellular elements, a single cell, tissues, one or more multiple organ systems, or the individual).2
Are you trying to decrease someone’s fear of movement (kinesiophobia) or increase someone’s confidence in using their body?
Are you trying to help them improve their mental health? Perhaps attempting to help decrease their stress levels or symptoms of anxiety or depression?
Are you trying to alter their pain experience? Help to decrease their self-reported level of pain?
Or are you trying to stimulate mechanotransduction in tissues thought to be in need of morphological or structural change?
Reflecting on and having a clear understanding of what you are trying to accomplish by having someone perform a certain exercise, will drastically affect not only your choice of exercise but also the variables (frequency, intensity, volume, rest) of your exercise prescription.
The ‘minimal effective dose’ will look very different for each of the above-mentioned ‘goals’ or desired ’outcomes’.
When it comes to strength and other physiological ‘capacities’, I would like to say that there is some certainty around the prescription variables to stimulate adaptations; but, even in this realm, there is new research coming to light that questions our old beliefs.
Strength & Conditioning
There are many components of physical fitness we could talk about, strength, power, aerobic capacity, aerobic power, anaerobic power, range of motion, etc. I would like to keep this blog focused more on pathology and pain so we will only briefly discuss the strength and conditioning (S&C) realm.
Many of these components of physical ‘capacity’ have generally accepted ‘minimal effective doses’ to stimulate desired adaptations at a population level. However, even some of these long-held beliefs are being challenged by studies and systematic reviews that have recently been published.
For instance, there was a great review3 that looked at the traditional ‘repetition continuum’ (Figure 1) which postulates that heavy load training optimizes/increases maximal strength, moderate load training optimizes/increases muscle hypertrophy, and low-load training optimizes/increases local muscular endurance.
Based on emerging evidence, the authors proposed a new paradigm whereby muscular adaptations can be obtained, and in some cases optimized, across a wide spectrum of loading zones (Figure 2). So, in some instances, it is not necessary to expose someone to as heavy loads as once thought to stimulate change.
This is especially true for stimulating muscle hypertrophy where the literature indicates that similar whole muscle growth (i.e., muscle thickness, cross-sectional area) can be achieved across a wide spectrum of loading ranges ≥ ~30% 1 Repetition Maximum (RM).
More recently, a randomized controlled trial was performed that compared moderate load (70% 1RM) with low load (30% 1RM) and measured lean body mass (LBM), 1RM strength and Fat Mass Loss after twelve weeks. Their study showed that twelve weeks of high-intensity functional training with either low or moderate loads resulted in an equal increase in LBM and 1-RM strength (Figure 3).4
So it seems the minimal effective dose may be lower than what we thought in the past.
These new findings have major implications for clinical practice as it is much easier to implement lower load exercises with people than heavier loads. Oftentimes people don’t have access to the equipment necessary to perform the heavier loads. Some people are scared that they are going to hurt themselves with the heavier loads. Some clinicians are scared that they are going to hurt people with such heavy loads.
From a practicality standpoint, anytime I see a randomized controlled trial (RCT) or systematic review (SR) that shows we can be effective with lower ‘loads’ than previously thought, I am stoked, do some fist pumps, and eat another chocolate chip cookie.
Ingesting cookies is one way to get a mental lift, exercise is another.
Exercise has long been shown to have positive effects on mental health.5 In an MSK clinical setting, decreasing someone’s anxiety or depression will not usually be one of your primary goals; however, decreasing someone’s fear around movement and their associated fear-avoidant behaviours is a common goal you may prioritize.
Graded exposure to feared movements is a fantastic approach to decrease fear around them. The exercise prescription for graded exposure to reduce fear will look vastly different than for S&C purposes as you are trying to create psychological changes versus physical changes.
One thing that you would want to be mindful of is not creating a pain flare as this could further exacerbate the fear-avoidant behaviour and unhelpful beliefs around movement that the person already possesses. In these cases, it would be incredibly important to start at a very minimal dose that is easily tolerated. Let the person experience that they can perform a version of the feared movement with no repercussions. This helps reduce their negative expectations and can start to create new, positive expectations around the feared movements.
“Reassurance is a bloody good pain killer”Louis Gifford
I believe that experienced physical reassurance is more powerful than verbal reassurance. In other words, a person is far more likely to have less fear and more confidence around feared movements if they experience they are safe when performing them versus being told that they are safe to perform them.
Simply begin at a tolerable dose for the individual and gradually progress. This initial, tolerable dose will usually be much less than the dose required to stimulate the physical changes that you would be looking for in an S&C setting or even in a clinical setting when trying to stimulate mechanotransduction of some sort.
When it comes to pathologies we see in the clinic, there are some accepted minimal effective doses for exercise prescription, but they too continue to evolve and change. Let us look at a couple of the most common conditions that we see in a clinical setting – tendinopathy and OA.
It is widely accepted that progressive tendon loading programs are the most effective conservative approach in the treatment of tendinopathy.6 Traditionally it was thought that to effect change in tendons you had to use heavy loads (70% 1RM). A recent study showed that in fact, you may not have to.
In a recent RCT it was found that there was no superior effect of exercising with a high load (90% 1RM) magnitude compared with a moderate load (55% 1RM) magnitude for the clinical outcome, tendon structure, or tendon function in the treatment of patellar tendinopathy.7
Regarding OA, a recent study looked at high-intensity strength training versus low-intensity strength training versus an attention control group (received 60 min educational workshops biweekly for 6 months and monthly thereafter). There was not a significant difference in self-reported pain between the three groups of subjects. In other words, low-intensity training was just as effective at decreasing self-reported pain in individuals with knee OA as high-intensity training.8
What is fascinating from this study is the group who did not perform strength training and only participated in regular educational workshops did equally as well as the two exercise groups!
Perhaps we are seeing the power of high-quality patient ‘education’ at play here?! In my opinion, we can often have a more powerful effect on clinical outcomes with the ‘education’ that we deliver versus any exercise prescription or passive therapy that we perform.
Often, ruling out red flags, reassuring the person (when indicated), encouraging the resumption of meaningful/valued activities at a tolerable level, and letting natural history do its thing is all we need to do to see successful clinical outcomes!
Just so that my movement optimism bias isn’t getting worried, I think it is worth clarifying that there is a copious amount of research showing that exercise of all types, including strength training, benefits those with OA and is a primary recommendation in clinical practice guidelines.9-13
It should be noted that there is not a significant difference in effect between the different types of land-based exercise interventions.14 The most beneficial exercise is probably just the one that the person is actually going to perform!
First off, let’s get on the same page regarding pain. I will assume that those of you reading this blog understand that pain is multifactorial (Figure 4) and rarely mediated by only one ‘thing’.
Even when we are talking about someone who has had a trauma, such as falling off a ladder, their resultant self-reported pain levels are affected by numerous factors. Things such as previous experiences, beliefs, emotional factors (stress, fear, anxiety, etc.), and quality of sleep, to name but a few.
Though we know that exercise helps reduce self-reported pain16, we do not know how it does this.
Pain is so multifactorial, and the concurrent effects of exercise are so numerous, that the potential combinations of ways that exercise could decrease pain are nearly infinite. I believe that it is a little presumptuous for us to think that we can explain the physiological and psychological mechanisms simultaneously occurring during exercise and exactly how those mechanisms are decreasing pain in an individual.
On any given day, exercise probably decreases pain in different ways in each individual case due to ever-changing contextual factors. Exercise also probably decreases pain in different ways from individual to individual due to the heterogeneity of the biopsychosocial factors in each person’s life.
In relation to this, there are many unknowns when it comes to the minimal effective dose of exercise to reduce pain.
In my opinion, there is not, and there may never be, an exact ‘recipe’ that exists for the minimal effective dose of exercise.
Although there is a significant amount of evidence in the literature suggesting exercise as an efficacious modality for the treatment of chronic pain, there is virtually no knowledge of the appropriate dose of exercise for a given disease or patient type.16
At the centre of this uncertainty, is the uniqueness of each human being.
N = 1 → Person-Centred Care
The minimal effective dose of exercise depends not only on what you are trying to accomplish but also on who the person in front of you is. Randomized Controlled Trials (RCTs) and Systematic Reviews (SRs) show us population-level data, but we are attempting to use that data to help guide our care of individuals that we see in a clinical setting.
In the clinical setting n=1.
A dose that is effective for one person may not be effective for another person.
What may be enough of a dose to change someone’s fear around a movement, may not be enough to change another person’s fear around the same movement.
A dose that is effective for reducing someone’s knee pain related to OA may not be effective for someone else who is suffering from knee pain related to OA.
For that matter, a dose that is effective for a person on Tuesday may not be effective for the same person on Friday!!!
Simplifying with a Person-Centred, Macro Persepective Approach in a Biopsychosocial Framework
Yes, the irony of the above heading was intended.
I believe we often overcomplicate things by trying to figure out specific recipes of sets, reps, intensity, duration, and frequency when prescribing exercise to simulate a change in physical ‘capacities’ or stimulate mechanotransduction. If we simply revisit the most basic principles of human physiology, it may allow us to simplify our approach.
The Overload Principle states that cells, tissues, organs, and systems adapt to loads that exceed what they are normally required to do. While the Specificity Principle states that overload results in adaptations specific to those cells, tissues, organs, or systems that have been overloaded.
You simply need to prescribe exercise at a level that is more than the person is currently adapted to and you will be stimulating adaptations.
This is an n=1 approach that accounts for individual heterogeneity in the population. The person who is performing the exercise simply needs to feel like it is difficult, challenging and is harder than other things that they are currently doing in their life.
This last point is very important. Though I have cited a couple of studies that have shown you can often be effective with a smaller dose than was once thought necessary, I feel that we often are under-loading people with our exercise prescription dosages.
By considering all the demands in a person’s life, you may realize that the exercise dosage you have prescribed is not harder than many other tasks that they must perform in life with the same tissues. Thus, you probably are not stimulating the adaptations that you are hoping to.
If you and the people you are working with are not seeing the changes that were hoped for, increasing the dosage would be one of the first things that you should consider doing.
I believe a person-centred approach is even more important when the primary goal of the exercise prescription is to help improve someone’s mental health, or to reduce their pain or kinesiophobia.
There is so much more uncertainty with these outcomes due to the increased involvement of psychological factors relative to cases where a physical change is the main outcome being measured.
Knowing the person in front of you will help you to better tailor your exercise prescription. Are they timid, fearful, anxious, depressed? Are they confident, happy, or resilient?
Do they have past experiences with pain, with pain in this region of their body? Has someone close to them experienced similar pain? Do they persist through pain? Or do they avoid feeling pain?
Do they have support? Do they want to change? Is pain a major part of their identity?
The reason that finding a minimal effective dose of exercise is so difficult is that we are all so different. The answers to the above questions, as well as to numerous other relevant questions, will be vastly different for each person we see in our clinics.
Let’s just have a little fun and say that we figure out the minimal effective dose for the person in front of us. Now the real challenge is having them perform the frickin exercises!!!
To me, this is the biggest challenge in prescribing exercise and/or movement in the health care setting. Earlier this year, I wrote a blog in which I touched on some strategies to help increase adherence to prescribed exercises. You can prescribe the perfect exercise at the perfect dose, but it doesn’t matter if the person does not perform it.
I digress…this blog may not have provided any concrete answers to ‘what is the minimal effective dose of exercise?’, but I hope that it got your cogs rotating (your upstairs cogs that is) on some of the pertinent topics surrounding exercise dosage in MSK health care.
It also stroked my movement optimism bias, touching on some of the different ways that exercise can stimulate positive changes in people’s lives.
Delving deeper into this topic reinforced to me the importance of n=1 in the clinical setting. In my opinion, it is so vitally important to work in a person-centred manner.
Who is the person in front of you? Where are they? And where do they want to be? The answers to these questions can help the two of you collaborate and determine a starting point of what to do, and how much, how often, and how intensely to do it. From there, it is a process of trial and error, re-evaluating and modifying according to the person’s reaction to the initial prescription.
Though we may not know with certainty what the minimal effective dose is, I hope that we continue to encourage people to move more and challenge themselves physically because there are so many primary and secondary benefits associated with movement. As I like to say, “Every move counts.” And as a wise man once said…
“You can’t go wrong, getting strong.”Adam Meakins
- Zhao, M., Veeranki, S., Magnussen, C., Xi, B. (2020). Recommended physical activity and all cause and cause specific mortality in US adults: Prospective cohort study. BMJ, 370:m2031. https://doi.org/10.1136/bmj.m2031
- Soligard, T., Schwellnus, M., Alonso, J., et al. (2016). How much is too much? (Part 1) International Olympic Committee consensus statement on load in sport and risk of injury. British Journal of Sports Medicine, 50(17), 1030-1041. Doi: http://dx.doi.org/10.1136/bjsports-2016-096581
- Schoenfeld, B. J., Grgic, J., Van Every, D. W., & Plotkin, D. L. (2021). Loading Recommendations for Muscle Strength, Hypertrophy, and Local Endurance: A Re-Examination of the Repetition Continuum. Sports (Basel, Switzerland), 9(2), 32. https://doi.org/10.3390/sports9020032
- Kapsis, D. P., Tsoukos, A., Psarraki, M. P., Douda, H. T., Smilios, I., & Bogdanis, G. C. (2022). Changes in Body Composition and Strength after 12 Weeks of High-Intensity Functional Training with Two Different Loads in Physically Active Men and Women: A Randomized Controlled Study. Sports (Basel, Switzerland), 10(1), 7. https://doi.org/10.3390/sports10010007
- Sharma, A., Madaan, V., & Petty, F. D. (2006). Exercise for mental health. Primary care companion to the Journal of clinical psychiatry, 8(2), 106. https://doi.org/10.4088/pcc.v08n0208a
- Millar, N. L., Silbernagel, K. G., Thorborg, K., Kirwan, P. D., Galatz, L. M., Abrams, G. D., Murrell, G., McInnes, I. B., & Rodeo, S. A. (2021). Tendinopathy. Nature reviews. Disease primers, 7(1), 1. https://doi.org/10.1038/s41572-020-00234-1
- Agergaard, A., Svensson, R., Malmgaard-Clausen, N., Couppé, C., Hjortshoej, M., Doessing, S., Kjaer, M., Magnusson, S. (2021) Clinical outcomes, structure, and function improve with both heavy and moderate loads in the treatment of patellar tendinopathy: A randomized clinical trial. Am J Sports Med;49(4):982-993. doi: 10.1177/0363546520988741.
- Messier, S. P., Mihalko, S. L., Beavers, D. P., Nicklas, B. J., DeVita, P., Carr, J. J., Hunter, D. J., Lyles, M., Guermazi, A., Bennell, K. L., & Loeser, R. F. (2021). Effect of High-Intensity Strength Training on Knee Pain and Knee Joint Compressive Forces Among Adults With Knee Osteoarthritis: The START Randomized Clinical Trial. JAMA, 325(7), 646–657. https://doi.org/10.1001/jama.2021.0411
- Uthman, O., van der Windt, D., Jordan, J., Dziedzic, K., Healey, E., Peat, G., et al. (2013) Exercise for lower limb osteoarthritis: systematic review incorporating trial sequential analysis and network meta-analysis. BMJ; 347. doi:10.1136/bmj.f5555
- Fransen, M., McConnell, S., Harmer, A. R., Van der Esch, M., Simic, M., & Bennell, K. L. (2015). Exercise for osteoarthritis of the knee. The Cochrane database of systematic reviews, 1, CD004376. https://doi.org/10.1002/14651858.CD004376.pub3
- McAlindon TE, Bannuru RR, Sullivan MC, et al. (2014) OARSI guidelines for the non-surgical management of knee osteoarthritis. Osteoarthritis Cartilage, 22, 363–88.
- Luan, L., Bousie, J., Pranata, A., Adams, R., Han, J. (2020). Stationary cycling exercise for knee osteoarthritis: A systematic review and meta-analysis. Clinical Rehabilitation Nov 10;269215520971795. doi: 10.1177/0269215520971795
- Kolasinski, S. L., Neogi, T., Hochberg, M. C., Oatis, C., Guyatt, G., Block, J., Callahan, L., Copenhaver, C., Dodge, C., Felson, D., Gellar, K., Harvey, W. F., Hawker, G., Herzig, E., Kwoh, C. K., Nelson, A. E., Samuels, J., Scanzello, C., White, D., Wise, B., … Reston, J. (2020). 2019 American College of Rheumatology/Arthritis Foundation Guideline for the Management of Osteoarthritis of the Hand, Hip, and Knee. Arthritis care & research, 72(2), 149–162. https://doi.org/10.1002/acr.24131
- Skou, S., Pedersen, B., Abbott, J., Patterson, B., Barton, C. (2018). Physical activity and exercise therapy benefit more than just symptoms and impairments in people with hip and knee osteoarthritis. J Orthop Sports Phys Ther.;48 (6):439-447. doi: 10.2519/jospt.2018.7877.
- Cholewicki, J., Breen, A., Popovich, J. M., Jr, Reeves, N. P., Sahrmann, S. A., van Dillen, L. R., Vleeming, A., & Hodges, P. W. (2019). Can Biomechanics Research Lead to More Effective Treatment of Low Back Pain? A Point-Counterpoint Debate. The Journal of orthopaedic and sports physical therapy, 49(6), 425–436. https://doi.org/10.2519/jospt.2019.8825
- Polaski, A. M., Phelps, A. L., Kostek, M. C., Szucs, K. A., & Kolber, B. J. (2019). Exercise-induced hypoalgesia: A meta-analysis of exercise dosing for the treatment of chronic pain. PloS one, 14(1), e0210418. https://doi.org/10.1371/journal.pone.0210418