Is All Stress Bad?

When we hear the word “stress”, we tend to think of it as being a negative thing. Chronic stress can certainly have physical, emotional, and behavioural symptoms and sequelae affecting your health. But stress is the body’s natural response to pressure or demands, and in the short term, it can be extremely motivating, such as finishing a project before a deadline or running away from a dangerous situation.

But “stress” is also used in the strength and conditioning, training, and rehab world with a negative connotation. We hear people say, “don’t do the knee extension machine because it stresses your knees” or “deadlifts put stress on your low back.” While said with good intentions, there is a lot of context missing in these statements. Rather than viewing stress as only bad, we need to look back at the SAID principle to see how stress can be a good thing.

The stress we’re usually referring to in the rehab world is the physical demands we place on our bodies through physical activity. In material science and physics, the mathematical formula for stress is: stress = force / surface area. This formula explains why it is dangerous to step on a single nail but safe to lay on a bed of nails. When stepping on a nail, you have your entire body weight (the force) coming down through your foot onto the pinpoint (surface area) of a nail. But when you lay on a bed of nails, your body weight is displaced over a larger surface area, despite still being sharp nails.

This is usually the context that people use when it comes to stress and exercise. In the above comment about knee extensions stressing the knee, the implied warning is that weight, positioning, and movement from the knee extension machine applied more force over the small knee cap. What is usually offered as a safer alternative is squats, as the movement allows for more muscles and joints to be used to lessen the stress on the knee via a larger surface area.

While mathematically this may be true, it is important to remember that the human body is not a machine and is capable of adaptation. Just like you shouldn’t start your first day of running by doing a marathon, you should be selecting an appropriate weight for the knee extension machine. With time and consistency, you should be able to progress your weight because your body adapts and gets stronger, even if it is more “stressful” than other leg exercises. As well, the human body is highly individualistic. While one person may find the knee extension machine irritating for their knees, someone else may find this perfectly fine and a great quadriceps-isolation exercise. Differences in anatomy, training history, previous injuries, and beliefs are some examples of why an exercise would vary between people.

We can also refer to stress in a more general sense when we think of our training program and physical activities as a whole, and our ability to recover from them. This is where semantics may muddle things, as sometimes stress, load, and volume are used interchangeably when referring to the total amount of physical activity someone is doing. But in reality, when we do physical activity, we are increasing the demands on our cardiovascular, respiratory, and musculoskeletal systems, thereby “stressing” them. But this stress is needed, as it is the main driving force for adaptation and improving these systems. If we don’t stress our bodies enough, we don’t see improvements in our function, and we may even regress. If we over-stress our bodies with excessive activity, we’re not allowing for the recovery needed to cause improvements, and we may even be setting ourselves up for injury and burnout.

When we talk about stress in rehab, there needs to be context behind it. Stress is just a number, or rather just the representation of force over surface area - it means nothing without context and is inherently neither good nor bad. Stress, both the colloquial and mathematical meaning, in rehab is necessary for a full recovery. An injured muscle, tendon, ligament, or bone must be loaded and stressed in order to induce physiological adaptations leading to the healing of the tissue with greater strength capabilities if one hopes to return to physical activity pain-free. The timing of this stress and the amount of stress are key though in a rehab program— stressing a tissue too early or too much can certainly cause setbacks, but we also want to make sure we’re not delaying or under-stressing the tissue as this will not set us up for success.

Stress is necessary, but whether it helps or harms depends on how much you can tolerate at the time. Rehab then isn’t about avoiding stress, but about applying the right amount at the right time, based on what the person can tolerate.

Understanding the S.A.I.D. Principle in Rehab

An important concept I apply to my rehab, borrowed from the strength and conditioning world, is the SAID principle, which stands for Specific Adaptations to Imposed Demands. What this means is that how and what we train determines how our body adapts. Or even simpler, we get better at what we do.

For example, if a runner mainly trains with short sprints and drills to build maximum speed, they’ll become a better sprinter, but that won’t prepare them to complete a marathon. On the flip side, a runner focused on long distance endurance will do well in a marathon but won’t be the fastest sprinter. Both may include some elements of each other’s training, but their bodies adapt specifically to the type of work they do. That is the SAID principle in action- our body adapts to the demands we place on it.

In rehab, applying the SAID principle helps the body prepare for the stresses and demands of sport or activity. This becomes especially important in the later stages of recovery as we bridge the gap between rehab and competition.

Using our runner example again, after a hamstring strain, we want to load the hamstring early, but appropriately. This might start with a simple exercise like digging the heel into the floor and sliding it toward the hips at a tolerable intensity. From there, we’d progress to a weighted hamstring curl and gradually increase load. Because they’re a runner, we’d also include other lower-body exercises like leg extensions, hip abductions, and calf raises.

As their strength improves, we can progress to multi-joint exercises like squats, deadlifts, or RDLs. Squats are great because they don’t heavily load the hamstrings but still strengthen the quads and glutes. Deadlifts and RDLs may also be well tolerated since they involve multiple muscles and place more emphasis at the hip — depending on the location of the strain.

Next, we’d add single-leg work, followed by plyometric or power exercises like hopping, skipping, and bounding. These more closely resemble the single-leg loading and push-off nature of running.

We’d also begin to reintroduce running itself — starting with slower speeds and shorter durations, then building from there. Returning to running is a graded exposure to the specific demands of running. It’s not about sport mimicry; it’s about directly applying the SAID principle by progressively exposing the hamstring to the real forces it will face.

Sometimes, though, the SAID principle is taken too far. We start believing every exercise must match or mimic the sport exactly — using single-limb movements, unstable surfaces, or weighted sport-specific motions. These have their place, but it’s important to recognize the different roles of strength training and sport practice.

• The goal of strength and conditioning is to build muscular strength and power — to help your body generate more force.

• The goal of sport and skills training is to improve coordination, timing, and technique within the sport itself.

Working out in the gym won’t automatically make you a better soccer player, just like playing soccer won’t make you jacked. Both are vital — but they need to be trained separately. If the goal is to build strength that transfers into sport, we need to maximize load on the muscles. Single-leg squats and lunges are useful, but they can’t be loaded as heavily as a barbell squat. Both can be included in a training week or within a periodized plan — but our gym sessions don’t need to look like our practice sessions.

Of course, the SAID principle can also be underused. Sometimes rehab consists only of a resistance band and a few easy exercises, with minimal load or challenge. In these cases, there’s not enough demand on the muscle to drive adaptation.

There’s always nuance and context to every rehab plan. But overall, we want to apply the SAID principle by ensuring our exercises appropriately load and challenge the injured area, progress in complexity and demand, and build capacity for return to sport. What we don’t need to do is make every exercise look like the sport itself — because we’ll reintroduce those sport movements separately, starting at low intensity and building from there.

In summary, the SAID principle reminds us that our body adapts to exactly what we demand of it. In rehab, that means loading the injured area appropriately and progressing toward the real demand of your sport, without trying to turn every exercise into a copy of the sport itself.

A Traffic Light Guide To Exercising With Pain

One of the harder parts of the rehab process from the practitioner side, and what makes rehab sometimes more of an art than science, is knowing when we accept pain during the rehab process. While we do have general guidelines, such as saving eccentrics for the later stages, or not progressing weights too quickly, we are working with human beings who are dealing with the experience of pain. The problem though is, pain is not always a reliable experience. The challenge then becomes when do we trust pain and when do we not? Or maybe a more relevant question is, when is it okay to work through pain? We’ve all experienced the “no pain, no gain” mentality in some form, but this may not always be the best approach depending on your injury.

The short answer is yes, it is okay to work through some pain, but with a bit of common sense. Of course context matters, so we’ll break it down a bit further, but knowing when to push and when to tweak or even hit pause can have a big impact on your recovery.

This is an important concept to address because pain is a complex, individual and multifactorial experience, meaning that everyone experiences it differently and there can be many factors influencing your pain. Pain is also contextual— we (patients and practitioners) seem to accept pain when we’re providing hands-on treatment. I lost track of the number of times someone would ask for more pressure during a massage despite them wincing in pain, or who thought that more would mean a faster recovery. But then when it comes to exercise, we tend to quickly abandon an exercise if the patient experiences any pain with it. So why do we accept pain in some cases, but not others (rhetorical question for the purpose of this blog).

Just know that pain doesn’t always mean damage during the rehab process. The tissue can still be sensitive to loading without resulting in further damage or reinjury.  When it comes to pain that develops through overuse or pain that lasts beyond the typical healing time, that’s when pain can be a bit more unreliable, and is still more about sensitivity than damage. Staying active and mobile can help with recovery, provided it is within reason. Being unsure of what is safe or not can certainly cause a dilemma with your recovery - if you back off you might be under-loading yourself, but if you keep going you might be overloading yourself. Neither of these are ideal. But there is a simple analogy you can use to help better gauge your pain and add some clarity to the decision to work through pain during your rehab— the traffic light.

Green Means Go!
In these cases, the pain is mild— I usually consider this to be a self-rated 4/10 or less on the pain scale. This pain generally settles down fairly soon after exercise, or at least within 24 hours, and during the exercise you’re still moving well and feeling confident. This is a good space to work in. The pain is there, but it is not modifying how you perform. You might feel a twinge or ache, but you’re not doing any harm, and your body can handle this. This doesn’t mean that we’re in the clear to go crazy, but it does give an indication that we’re in a good spot with the loading. You should still continue to monitor the pain though, because that leads into…

Yellow Means Caution (and Adjust)
This is when the pain increases to a 5/10 or 6/10 on the pain scale, and usually the pain lingers longer than 24 hours before subsiding. Movements might feel a little forced or you might feel guarded, hesitant, deliberate, or cautious during activity. We may not be causing physical damage yet, but we’re certainly starting to push the limits of what the injured tissue can tolerate, and we need to adjust accordingly. The good news is we can still continue some form of exercise, and there are many ways you can adjust to get back into a green light— changing the movement or reducing the weight are just a couple of examples.

Red Means Stop (For Now)
I don’t like having patients stop their exercises, and there are always some unrelated activities they can do to remain active, but sometimes stopping an aggravating exercise is needed. These are cases when the pain is a 7/10 or more; the pain sticks around at that level for longer, or even worsens, and you’re uncomfortable or hesitant to move. This is your cue to rest or scale back to simpler movements that calm the area down, rather than push through and hope for the best because we are at a higher risk of injury. It may seem like we’re losing progress, when really it is just being smart—short-term sacrifice for long-term gain.

It’s okay to feel some pain during the rehab process— tolerable pain doesn’t mean something is injured further. In fact, some studies show it leads to better outcomes than completely avoiding pain (maybe the point when you feel pain is the lower end of the stimulus threshold to cause adaptation, so by avoiding pain you’re not providing adequate stimulation). There’s no need to panic, but it is still worth paying attention to to see how it changes. Maybe it is just a one-off thing because you didn’t sleep very well the night before or maybe it’s a sign that you are not tolerating the exercise well and an adjustment is needed.

Staying active helps the healing process, as long as we are respecting that process and respecting where your body is at.

Ways to Reduce Pain Without Stopping an Activity

One of the most frustrating parts of dealing with an injury is when it takes us away from the things we enjoy- sports, training and daily movement. Sometimes the pain itself forces us to stop, but even when it’s manageable, many people still choose to stop. Hoping the pain goes away on its own, fear of making things worse, fear of more pain, uncertainty, or apprehension are all reasons we stop. This can be especially confusing when the pain only bothers during activity, and not with everyday life.

For the majority of injuries, maintaining some level of activity, even with some pain, is still okay, and in many cases encouraged. We still want to load the painful area so it can adapt, get stronger and become less sensitive. There are many ways to do this, but they mainly fall into three categories.

There are a couple of caveats to this though. Some injuries, such as high-risk bone stress fractures, do require rest. The pain also needs to be at a tolerable level. Pain over a self-reported 7/10 is usually a red light for me as it means the load is too much. It is always important to get a proper assessment so you know whether continuing is safe.

With that said, the three major ways to keep training while managing pain are: movement preparation, movement modification and load adjustment.

Movement Preparation
Sometimes a thorough warm-up or a few targeted exercises to the specific injured/painful area can make a big difference. Increased body temperature, increased blood flow, muscle activation/priming (even though muscles are technically always active unless there’s a nerve injury) and mental preparation all help modulate pain during your session.

Take a runner who feels calf tightness, especially at the start of a run. Exercises like calf stretching, calf raises, double leg hopping, skipping or bounding before the run can help. These exercises prepare the calf muscles for what’s coming and give you way more control over intensity and progression compared to jumping straight into the run.

Movement Modification
Small changes to how you perform an exercise can go a long way for some people when dealing with an injury. The goal here is to train the same muscle groups but in a way that you tolerate more. If someone has shoulder pain when doing lateral raises with their palms down, switching to a more thumbs-up position or bringing their arms forwards a bit can reduce sensitivity. Sometimes it is just specific movements that are irritated. Switching a squat to a leg press machine, or adjusting cadence (step frequency) when running can immediately make training more tolerable.

Load Adjustment
Often the issue isn’t the movement itself — it’s that the load exceeds what your body can currently handle, and usually the simplest step is to temporarily reduce the load. Yes, people dislike lowering weights, but it’s a straightforward and effective strategy. Reducing volume (sets × reps) or training frequency are other options. You’re still doing the activity — just at a level your body can manage right now. Think quality over quantity. For a runner who consistently notices pain getting worse around the 5 km mark, dropping to 4 km and building back up is a perfectly valid approach. Or changing from five runs per week to three, or removing the most stressful run from the schedule.

The key to any of these changes is trial and error. Everyone is different and everyone’s pain experience is different, which makes blanket recommendations tough. The good news is that we have lots of options available to us, which makes the chances of finding something that works very high. The other thing to remember is these changes are temporary. They are short term changes to help bring the pain down while still staying active. Once pain is more under control, then we start progressing back towards our previous levels.

What’s in your cup? The Load-Capacity Framework in Rehab

The load-capacity framework can also guide our treatment plan and what we work on in our rehab. As a reminder, injuries occur when a load on your body exceeds your body’s capacity to handle it. That leaves us with two main ways to help someone- decrease the load or increase their capacity.

A great analogy for this comes from Greg Lehman when he asks, “what’s in your cup?” Imagine yourself as a cup filled with water. The water represents all the loads you face — not just physical activity, but also work stress, family demands, past injuries, and changes in training or routine. Your cup represents your current capacity to handle these loads. Things like anxiety, lack of sleep, prior beliefs about injury, or self-confidence can all change your cup’s size. Sometimes factors, such as your health status, can both add water and limit your cup’s size.

In rehab, our goal is to either limit the water or build a bigger cup. Limiting water could include adjusting your training program (like decreasing running volume or intensity), managing stress, or changing certain habits. Building a bigger cup might involve strengthening tissues, improving nutrition and hydration, or addressing fears about a specific movement.

Ideally, we can do both at the same time — reduce water and expand the cup. But sometimes we can only tackle one at a time. And sometimes, we can’t change either — reducing work stress might not be realistic, for example. That’s okay. The cup analogy is a way to acknowledge the factors influencing how we feel, and to understand that they’re always changing. Some days it’s like water slowly dripping into a pint glass. Other days, it’s like the Torc Waterfall into a shot glass, and it’s overwhelming.

Recognizing this helps you make informed decisions in training and rehab. A small change — decreasing intensity, taking an extra rest day, or adding one isolation exercise to the painful area — can be enough to manage the load or grow your capacity.

Rehab can be simple but also complex. The simple part is knowing to reduce load temporarily and increase capacity. The complex part is figuring out how, because everyone is different. That complexity might feel intimidating, but it also gives us freedom to find what works best for you.

Reference: Lehman, G. Do our patients need fixing? Or do they need a bigger cup? Online source, 02/05/2018.