Nov 28, 2023

Why You Have Knee Pain After Working Out (And What to do About it)

You never know how much you rely on your knee for working out until it hurts with every movement you produce. Jogging, sprinting, squatting, jumping, lunging, deadlifting, and so many other strength training exercises require a happy set of knees. But it can be even more frustrating when your knee only hurts after working out.

Sure, lots of people have knee pain after working out, but just because something is common doesn’t mean it's normal. A lot of things can go wrong with the knee, and thankfully, there are a lot of ways to resolve these issues. In other words, you don’t have to live with knee pain.

In this article, you’ll gain critical insight into basic knee anatomy and function, common causes of knee pain that can arise after working out, prevention and management strategies, and how to get the most out of your knee rehabilitation when working with healthcare professionals.

Having a rudimentary understanding on these topics is like having the cheat codes to a video game; you’ll be at a significant advantage for avoiding the worsening of any knee pain you’ve been experiencing, you’ll optimize your recovery, you’ll miss fewer training sessions, and have a greater sense of confidence throughout the entire process.

So, if you want to know how to stop your knees from hurting after exercise, let’s dive into answering your questions and getting you back to pain-free training.

Knee anatomy and function

Gaining a basic understanding of knee anatomy and function is necessary to win the war on knee pain. While you don’t need to know the hardcore details, being aware of the basics will go a long way in understanding the following topics within this article and the concepts that comprise successful care and treatment of your knee.

Introduction to the knee joint

The knee consists of two distinct articulations (interactions of one bone with another). These articulations are:

The tibiofemoral joint (where the bottom of the femur [thigh bone] meets the top of the tibia [shin bone])
The patellofemoral joint (where the patella [knee cap] meets with the femur [thigh bone]).

The knee acts as a hinge joint, meaning it’s designed to bend and straighten (flex and extend, respectively), though it does have the capacity to produce a small amount of internal and external rotation of the tibia (a bit of twisting of the shin bone). The average knee can undergo about 135 degrees of flexion and can achieve 180 degrees of extension (i.e., it can straighten out until the shin bone and thigh bone are one continual line).

The knee is a relatively stable joint thanks partly to its natural design and its reinforcement through its joint capsule, various ligaments, and tendons that surround and cross the joint.

Role of muscles, tendons, and cartilage in knee movement

The ability of the knee to produce movement is the result of various structures and tissues working together in a coordinated manner, collectively allowing for its function. Each of these tissues and structures contributes in a unique way, similar to individual musicians in an orchestra contributing to the song with their unique instruments.

Acquiring a basic understanding of these tissues can be profoundly helpful when dealing with knee pain by cutting down on confusion when searching for answers to your pain and making the recovery process much more intuitive. Below, you’ll find a very brief description of each of the commonly involved tissues when dealing with knee pain after squatting.

Muscles

Muscles are what provides the force to produce movement (flexion or extension) of the knee. Additionally, muscles involved with producing knee movement also play a critical role in helping to achieve the knee’s stability. This is especially true for the hamstring muscles, which are three distinct muscles that run down the back of the thigh and cross the knee joint on either side of the knee. These muscles act as the body’s natural knee brace for preventing unwanted twisting, excessive straightening, and additional unwanted movement that could be detrimental to knee health.

Tendons

Tendons are the fibrous tissue that attach the end of a muscle to a bone. Their role is to transmit the force of a muscle’s contraction onto the respective bone to which it attaches, allowing the bone to move.

There are numerous tendons within the knee, and they can have a notorious reputation for producing knee pain — especially knee pain that arises after a workout. The following section of this article will unpack this all-too-common phenomenon in much greater detail, so be sure to keep reading.

Ligaments

Ligaments are tough, fibrous tissue that connects one bone to another bone. There are numerous ligaments within the knee, all of which act to reinforce its integrity by providing further stability to the joint.

The main ligaments to be aware of within the knee are the two cruciate ligaments and the two collateral ligaments. These ligaments are:

The anterior cruciate ligament (ACL)
The posterior cruciate ligament (PCL)
The medial collateral ligament (MCL)
The lateral collateral ligament (LCL)

These ligaments are only compromised and produce pain with traumatic injury. If you have a history of traumatic knee injury, these ligaments could be contributing to your pain, in which case it is advisable to seek medical consultation.

In the absence of any history of knee trauma, there is no reason to suspect they’re contributing to knee pain. As such, they won’t be further discussed in this article.

Cartilage

Cartilage is a specialized type of connective tissue that, in the knee, helps ensure smooth, pain-free movement and absorption from forces that compress the joint (running, jumping, squatting, etc.)

There are two specialized types of cartilage within the knee:

The articular cartilage that covers the ends of the femur, tibia, and the underside of the patella.
The menisci — two fibrocartilage rings that sit between the tibia and femur and act as shock absorbers for the joint.

Each of these types of knee cartilage are prone to being damaged, either through traumatic injury or through degenerative processes that occur with aging, leading to conditions such as osteoarthritis of the knee, which will be discussed in the following section.

Bursas

Bursas are lesser-known structures to the average individual, yet they play a critical role in maintaining knee health. They are little fluid-filled sacs or discs that serve to decrease friction that would otherwise arise as tendons slide across the knee joint.

There are four primary bursas of the knee:

The suprapatellar bursa
The infrapatellar bursa
The prepatellar bursa
The semimembranosus bursa

When these bursas become irritated (not uncommon), they can become inflamed and painful, resulting in a condition known as bursitis. Activity modification can help resolve the issue, though sometimes a corticosteroid injection may be required. Both of these solutions are covered further in this article.

Causes of knee pain after working out

There are hundreds of potential causes for knee pain, all of which certainly can’t be covered in a single article. However, experiencing knee pain that arises after working out reveals a few key pieces of information that can help dial in on some of the more likely culprits. (Pro tip: when assessing musculoskeletal dysfunction, pain patterns are often more important than pain locations.)

Knee injuries and their impact on pain

Knee injuries, whether recently incurred or from a long time ago, can cause pain and dysfunction that becomes prominent during or after a workout. Below are some of the more common conditions that can cause knee pain after working out.

Patellofemoral pain syndrome

Patellofemoral pain syndrome (often known as PFPS or Runner’s knee) is a blanket term for pain that arises within the region of the kneecap (the patella). It can be caused by multiple factors. The most common factors are:

Overuse or overloading of the patellofemoral joint
Muscular weakness of the hip and thigh muscles
Muscular imbalance of the quadriceps muscles
Biomechanical abnormalities that affect lower extremity position

With PFPS, the pain is generally felt within the knee; however, it’s critical to understand that the underlying cause can arise from elsewhere in the body, such as the foot, ankle, or hip.

Patellar and quadriceps tendinopathy

Tendinopathy is an umbrella term for lack of adequate health within a tendon. It includes the well-known (but not as common as once thought) condition of tendinitis. Tendons are susceptible to becoming unhealthy and painful for different reasons, though they’re most often affected either by repeated overuse or by lack of use (under-stimulation).

When this occurs, the tendon becomes sensitive and painful to mechanical forces, which occur whenever the knee is moved, particularly against resistance. Keep on reading to discover how to overcome this all-too-common situation.

Muscle imbalances and their effect on knee pain

Muscle imbalance within the quadriceps refers to excessive strength or tension present within one or more of the muscles with notable weakness in others. All four quadriceps muscles converge to attach to the common quadriceps tendon (just above the kneecap), and when tension differences are present within the muscles, it can lead to poor tracking of the kneecap, cause pain to arise within or around the knee.

The most common presentation of muscular imbalance within the thigh is:

An excessively hypertonic (tight) vastus lateralis (the quadriceps muscle on the outer portion of the thigh)
A weak or underdeveloped vastus medialis (closest to the midline of the body), notably in a portion of the muscle fibers just above the knee, known as the vastus medialis obliquus (VMO).

Arthritis and its contribution to knee pain

Arthritis of the knee is a common cause of knee pain and often presents with soreness or pain during or after a workout. There are two main categories of arthritis to be aware of that can affect the knee.

Osteoarthritis

Osteoarthritis of the knee refers to the degeneration or wearing down of knee cartilage. This breakdown of the tissues becomes more common as we age due to the years of “wear and tear” we place on the knee through our physical activity, and it can lead to high levels of pain and dysfunction when in advanced stages.

Systemic arthritis

Distinctly different from osteoarthritis, systemic arthritis refers to different types of autoimmune diseases that can affect joints throughout the entire body (including the knee). Examples of these types of systemic diseases include:

Rheumatoid arthritis
Psoriatic arthritis

If you suspect (or know) you have a systemic disease that is affecting your knee and making it painful after working out, you will need to consult with your rheumatologist or family doctor for medical interventions, including (but not limited to) activity changes and pharmacological intervention.

Prevention and management of knee pain after working out

Warm-up and stretching exercises to loosen tight muscles

Don’t neglect the importance of a proper warmup. Yes, basically every lifter is aware that warming up before a workout or physical activity session is a good idea; the problem is that not everyone warms up in a manner that optimizes the readiness for their knees (or the rest of their body) to deal with the demands of their workout. If the knees aren’t fully warmed up and prepared for exercise, they can be predisposed to excessive stress and strain, which can lead to pain and injury.

While the specifics of a warmup can vary from one lifter to the next, the principles that comprise an effective warmup should largely be the same. These principles include:

Five or more minutes of continual, low-intensity movement (that doesn’t cause pain or discomfort in your knee) to break a light sweat.
Dynamic movements (not static stretches) that take your joints through large (but tolerable) ranges of motion in a controlled manner.
Specific movements and working warmup sets that further prepare the knee for the upcoming workout or physical activity session.

Strengthening exercises to address muscle imbalances

Muscle imbalances within the leg are relatively common and can wreak havoc on the knee. Thankfully, these issues can often be rectified with a combination of strengthening exercises for the weaker muscles and mobility exercises for the excessively tense or tight ones. The most commonly prescribed exercises to treat muscle imbalances causing knee pain are:

Quadriceps strengthening exercises
Hamstring strengthening exercises
Hip strengthening exercises

Finding the best exercises to suit your needs is a critical step and is best done with the help of a knowledgeable professional who has evaluated your situation. See the physical therapy section below for more insight!

Proper technique and form during exercise

Using proper form and technique with all of your exercises is essential for pain-free knees after working out. Even if every other aspect of your training were to be perfect, poor technique can sabotage your hard work.

Taking the time and deliberate effort to learn proper technique with each of your exercises will drastically decrease your chances of experiencing knee pain during or after your workouts.

General parameters for proper exercise technique include:

Maintaining control of your movement at all times.
Keeping your knees in strong and stacked positions (not letting them cave inwards or twist)
Using ranges of motion that you are comfortable and confident with.

Low-impact and modified exercises for individuals with knee problems

Knee pain can arise or be worsened due to impact forces that the joint experiences when working out. If you find that pain in your knee after working out is often worse after performing impact-based exercises or activities, finding ways to modify exercises and reduce impact force through the knee can be a highly effective strategy.

Examples of modifications can include:

Performing non-impact cardio sessions, such as using a bike, elliptical machine, or swimming rather than jogging or sprinting.
Avoiding or limiting explosive movements, such as lower-body plyometrics and performing upper-body plyometrics instead.

Use of knee sleeves for added proprioception & warmth

Wearing knee sleeves during your workouts can be an easily incorporated strategy that can have benefits in reducing knee soreness during and after physical activity. This is a strategy I have often used throughout my years of lifting, with notable benefit.

Knee sleeves can help retain extra warmth around the knee, and the mild compression they provide can help improve proprioception. (Proprioception refers to the awareness of a joint or limb’s position without the need for visual input.)

This makes wearing them a solid strategy for those who have sore knee tendons or lack positional awareness of their knee when exercising (which can result in poor exercise technique and subsequent knee pain).

Treatment options for knee pain after working out

If the knee pain you’re experiencing after working out is persistent, getting worse, or excessively painful, considering various treatment options and pain-relief measures might be warranted. A brief rundown of these options and interventions is discussed below.

Physical therapy

Physical therapy often plays a critical role in knee rehabilitation. An assessment and subsequent intervention from a physical therapist can provide invaluable insight into what is causing your pain and the optimal path forward for returning to working out.

While physical therapists have numerous techniques for treating knee pain, therapeutic exercise with optimal loading is often the backbone of improving knee health.

For knee pain that is primarily the result of muscle imbalance, tendinopathy, and poor movement control of the knee or hip, targeted exercises are often given to correct these issues. Commonly prescribed exercises that often prove very therapeutic for these specific knee issues include:

Peterson step-ups
Poloquin step-ups
Patrick step-ups

Each of these exercises might seem quite similar but, in fact, are executed in slightly different manners to achieve slightly different results.

Pain relief measures

When dealing with acute (brand new) knee pain of relatively high intensity, it’s best to stick with the acronym POLICE, which stands for:

Protection
Optimal Loading
Ice
Compression
Elevation

This is an updated approach to the more traditional RICE (Rest, Ice, Compression, Elevation) approach that is being now being favored by many healthcare providers. The premise behind this model is that higher levels of pain that are not chronic can be controlled by balancing rest with appropriate movement. The specifics are beyond the scope of this article, but reading up on this new approach to treating acute pain could be quite helpful.

Additionally, anti-inflammatory medications such as NSAIDs (non-steroidal anti-inflammatory drugs) are often used for acute knee pain, which characteristically produces high levels of inflammation. If you opt for using an anti-inflammatory drugs, you will need to ensure it is appropriate for you to do so.

Medical interventions in severe cases

While far outside the scope of this article, it’s worth briefly mentioning higher-level interventions for dealing with knee pain when conservative treatment fails. Keep in mind: a brief rundown of these topics is merely for raising awareness of these interventions; if you feel you need higher-level intervention, you will need to discuss this with a qualified healthcare practitioner.

Injection therapies

Recalcitrant (pain that is stubborn and doesn’t go away) knee pain often requires a higher-level intervention known as injection therapy. Different types of injections can be administered for a painful knee, depending on the type of pain or its underlying cause. Below are the three most commonly administered injection therapies for the knee.

Corticosteroid injection

The most common intervention for pain-based injection is a corticosteroid injection (typically cortisone or another similar medication) into the area of the knee that is persistently painful. This type of injection is used for conditions when pain arises from high levels of inflammation and can be administered in different areas around the knee into the involved tissue. The steroid acts as a powerful anti-inflammatory medicine to help reduce or eliminate pain.

These types of injections are typically not meant to be an outright cure but rather as an adjunct to reduce pain in a manner that creates a window of opportunity for conservative measures (physical therapy exercises, etc.) to be tolerated, allowing for lasting improvement in one’s knee pain.

Hylauronic acid (HA) injection

Hyaluronic acid injections are a type of injection used primarily for the treatment of osteoarthritis of the knee (a condition where the cartilage within the knee degenerates and breaks down). The hyaluronic acid is injected directly into the knee joint and acts as a joint lubricant, similar to the natural joint lubricant within the knee (known as synovial fluid). This procedure often requires more than one injection, though this will vary based on an individual’s circumstances.

Platelet-rich plasma (PRP) injection

Platelet-rich plasma injections are a relatively new type of injection. This procedure involves drawing a sample of the patient’s blood and thereafter centrifuging it (quickly spinning it around in a specialized machine) to separate its platelets (a special type of cell) from the other components within the blood.

These platelets are collected and injected into the injured area at a concentration much higher concentration than would otherwise be found in the body.

Surgical interventions

Surgical interventions for fixing knee pain are reserved as a last resort, either when conservative interventions have failed or when reconstruction or removal of damaged tissue is necessary, which often occurs after traumatic injury (torn ACL, severely torn meniscus, etc).

For the majority of lifters experiencing knee pain after a workout, especially those without a history of trauma to their knee, surgical territory isn’t anything to worry about. And, if on the off-chance that surgery could be a possibility, conservative rehabilitative measures should first be implemented.

When to seek medical help for your knee pain

While knee pain or discomfort that arises after a workout can often be managed by oneself, there are times and circumstances when it is within one’s best interests to seek medical help from a licensed healthcare provider. The following are signs that indicate the need for a professional evaluation regarding knee pain.

Signs that indicate the need for a professional evaluation

Chronic knee pain

Chronic pain, by definition, refers to pain that persists beyond three months. You can also think of it as pain that persists longer than it should. Not all chronic knee pain signifies that something is seriously wrong; however, persistent pain is usually a good indication that a professional evaluation would be in your best interest.

The longer a knee issue persists, the longer it can take to resolve the issue. Additionally, allowing the worsening of a condition or your knee pain symptoms can lead to further complications, dysfunction, and, ultimately, a loss of training time. So, if your knee pain has persisted longer than three months or continually worsens, get a professional to look at the issue.

Limited range of motion

Limited range of motion in the knee can arise for various reasons, such as swelling, mechanical blockage (a piece of loose cartilage becoming stuck within the joint), spastic (tight) muscles, or even pain. Sometimes, a limited range of motion will be painful, while other times, it might not be.

The main issue with limited range of motion in the knee is the impact it can have on causing dysfunction elsewhere in the lower body. This arises due to movement compensation (either consciously or unconsciously) and can cause muscles around the knee, ankle, thigh, or hip to become overworked, tight, sore, or even painful.

It can also create abnormal mechanics within joints of the lower body, predisposing one to further pain, either in the knee, or elsewhere.

As such, if you are experiencing a notable and chronic limited range of motion within your knee, an evaluation and treatment from a qualifed professional, such as a physical therapist, can help avoid further worsening of symptoms and can often help improve and restore full range of motion within the knee.

Swelling or redness around the knee

Notable swelling or redness around the knee — especially in the absence of trauma — can signify the need for medical evaluation. While some forms of spontaneous swelling can be benign (not harmful), swelling that is painful and persistent should be assessed for further evaluation.

Spontaneous redness or notable warmth that is observable around the knee after a workout should be assessed to rule out further complications that can either be related to the workout (such as pseudo gout) or unrelated to the workout (such as a local infection).

The importance of healthcare professionals in diagnosing and treating knee pain

When dealing with knee pain (or any other persistent pain), it’s important to know the golden rule: When in doubt, seek medical insight. Persistent pain isn’t worth trying to figure out on your own.

By seeking expert evaluation, you are setting yourself up for multiple favorable circumstances, including:

Learning the optimal exercises and strategies needed to make progress in reducing your knee pain.
Ensuring the true underlying cause of your knee pain is treated rather than the mere symptoms.
An improved understanding of how to prevent the issue from arising again.
A quicker return to pain-free workouts and no pain after workouts

Start by finding a professional who is qualified to assess and diagnose the cause of your knee pain, hopefully, someone who understands the nature of the exercises and workouts you like to perform. As you begin to work with them, they will be able to help come up with an effective treatment plan to deal with your knee pain.

Conclusion

Experiencing knee pain after working out is a common orthopedic issue, but that doesn’t mean it’s normal. Pain arising in the knee after a bout of physical activity is often the result of dysfunction in tendons and muscles that are involved with producing knee movement, though at times, it can also be due to other tissues such as cartilage and bursas.

It’s prudent to get your knee pain under control as quickly as possible since chronic or persistent knee pain can get out of hand and lead to more serious issues. The right guidance and intervention (exercises, activity modifications, etc.) from a qualified professional can help resolve many common causes of knee pain, allowing you to get back to pain-free workouts and preserve your knee's future health and well-being.