Should You Exercise When Your Knee Hurts?

knee pain exercises

Story at-a-glance -

  • Osteoarthritis, one of the most common forms of arthritis, may cause knee pain; however, while you may be tempted to rest, staying active has been shown to reduce your pain and reduce your potential need for knee replacement surgery
  • It is important to evaluate your level of pain after exercise and the following morning, as well as the type of pain you experience, to determine if you are suffering from expected discomfort or something more serious
  • A sedentary lifestyle increases your risk of suffering from osteoarthritis, but it’s never too late to start exercising when you pay attention to your pain levels
  • Increasing muscle or connective tissue pain may indicate your lower extremity and hip biomechanics are unbalanced, creating greater stress on your knee joint

By Dr. Mercola

Arthritis is a general term encompassing over 100 different conditions affecting your joints and surrounding tissues.1 Any joint may be affected, but the most common are the knees, hips, hands and wrists.2 One of the most common forms of arthritis, osteoarthritis (OA), contributes to the ever-rising prevalence of knee pain across the world. In one study of elderly people living in Korea, researchers found knee pain in 32 percent of men and 58 percent of women.3

Another study,4 using a representative sample of the U.S. population from the Framingham study, found the prevalence of knee pain had increased substantially over a 20-year period, but obesity accounted for only a small portion of this increase. This study found frequent knee pain affected approximately 25 percent of all men and women, limiting function and mobility and impairing quality of life. Among those suffering knee pain from OA, the pain was a major reason cited for undergoing knee replacements.5

Risk factors for knee pain are not limited to arthritis, but also include sprains and strains, patellofemoral syndrome, overuse, misuse and referred pain from the hip, femur or spine.6 Determining whether or not you should continue exercising when you experience knee pain will depend upon your symptoms and the reason for the pain.

The Rule of Pain

Sometimes pain is your body’s way of telling you it’s time to take it easy. At other times, pain may be the result of becoming active after a period of inactivity. How do you know the difference?

Although you may have heard “no pain, no gain” is a necessary evil when starting an exercise program, the reality is there are two different kinds of pain or discomfort associated with activity. In some instances it's important to continue to stay active through the pain, while in others it's important to rest. Understanding the differences can help reduce your knee pain in the long run.

There are two simple rules of pain7 to use as you evaluate whether remaining active is the best choice or not. To track changes in the pain you experience it is helpful to keep a calendar or diary in which you’ll record a rank immediately after you exercise and again the next morning. These two pain rankings will help you determine if the pain you experience can be safely worked through and will in fact help reduce your overall day-to-day pain, or is just making the situation worse.

Using a zero-to-10 scale where zero to 2 is considered safe, 2 to 5 is acceptable and 5 to 10 is pain to be avoided, you'll rank your pain immediately and the next morning. For instance, if your usual pain level is 2 and after exercising it rises to 4, a 2-point bump may be considered safe. If however, it rises to 7, you've likely done too much and should cut back.

Using the same scale, if your normal morning pain is 2 and it remains at 2 the following morning, then you likely didn't do too much exercise. However, if the pain rises the next morning more than two points over your normal then you should back off and lower the level of intensity. You also want to evaluate the type of pain you're having.

Delayed onset muscle soreness (DOMS) is a common occurrence when you start a new exercise program. Often referred to as post-exercise muscle soreness, this stiffness is not usually a cause for concern and may be treated at home. However, if you experience sharp shooting pains or a dull, deep-seated pain not relieved by changing position, you may be experiencing bone pain or neurological pain requiring further evaluation.

A Sedentary Lifestyle Damages Joints and Increases Pain

A visit to orthopedic specialist Dr. Bridget Quinn from Beth Israel Deaconess Medical Center in Boston gave NPR journalist Richard Knox hope his knee pain had not permanently sidelined him from his exercise of choice, running. Instead Quinn pointed out:8

"One thing about your history that's very telling is this all started after a period of inactivity. Your tissues, when you're not active, get tight and weak. And this can predispose you to this condition, called chondromalacia of the patella."

Instead of rest, Quinn prescribed months of physical therapy to focus on the journalist’s knee, hip, back, abdomen and quadriceps muscles, all important in helping the kneecap track properly. The physical therapist treating Knox finds the mechanics of the entire lower extremities, from the core to the feet, are needed to correct the problem in the knee.9 A program of stretching and strengthening is often prescribed to reduce increasing pain caused by biomechanical problems.

This type of pain is different from minor aches and pains often experienced after beginning an exercise program following months of sedentary activity. A sedentary lifestyle may increase your risk for slight injuries to your knee. It can also influence pain caused by arthritis.

In a study10 analyzing over 1,500 people who died between 1905 and 1940, and another 819 who died between 1976 and 2015, researchers found OA in the knee was 2.5 times greater when you were born in the post-industrial age as when you were born in the late 1800s.

Senior study author Daniel Lieberman, Ph.D., paleoanthropologist at Harvard University, believes the study demonstrated the rising number of people suffering from OA is a result of an increase in sedentary lifestyle habits. Lieberman believes this might be triggered by weaker cartilage and leg muscles, causing the joint to break down more quickly than expected.11

Thus, research data has demonstrated the rising incidence in knee pain may be related to declining strength in muscles supporting your knee and the answer to your knee pain is likely not more rest but, instead, more exercise.

Exercise May Change Your Mind About Joint Replacement

How much pain relief you experience may depend upon how much exercise you do and the quality of your biomechanics. In a study of nearly 10,000 people suffering from knee and hip OA,12 researchers found those who exercised at least twice a week for six weeks experienced a 25 percent pain relief on average. This has an impact on reducing the intake of painkillers and improving productivity in the workplace.

In another study,13 researchers enrolled individuals with severe arthritis who fulfilled the criteria to have a knee replacement surgery. The participants took part in supervised exercise twice a week for eight weeks, saw a dietitian if they were overweight and maintained their pain during exercising using the parameters discussed above. Half of the participants were randomized to continue with their knee replacement surgery.

Only 25 percent of those who were not immediately scheduled for a joint replacement went on to have the knee replaced within a year, stating their pain relief was significant enough from exercise to delay their surgery for at least a year. Although physical activity is often prescribed to treat a range of diseases, many don't follow the advice as they fear exercise may harm joints that already hurt.

While global studies14 have demonstrated exercise is the treatment of choice for painful joints in middle-aged and older individuals, encouraging patients to put this recommendation into practice is sometimes challenging. Initially, some experience a 10 percent increase in pain15 when they begin an exercise program. This is not a warning sign of a medical problem but rather a signal you're doing something you're not used to.

Research continues to provide high-quality evidence16 indicating therapeutic exercise provides benefits of reducing knee pain sustained up to six months after stopping formal treatment. The magnitude of the effect is comparable with estimates reported for nonsteroidal anti-inflammatory drugs, and thus demonstrates safer and healthier treatment is available to those who suffer from OA.

The benefits of remaining active with arthritis also include17 controlling pain and swelling, slowing deterioration of the joint, reducing anxiety and improving mood and sleep. Rest should be considered when the pain you experience is not from muscles having had a healthy workout, but acute pain resulting from hurting an arthritic joint.

However, once you're feeling better you should return to your activities and consider modifying your exercise to accommodate a painful joint.18 For example, try water aerobics for a few weeks to reduce stress on the knee.

Lower Body Mechanics Focused on the Knee

In this short video, podiatrist Dr. Ian Sadler describes some of the biomechanical triggers of knee pain. These changes contribute to cartilage damage in the knee, and ultimately OA. As the knee sits between the hip and foot, there's often a relationship between your knee pain and the biomechanics of your foot and hip.

For every 1 degree of pronation in the foot, your tibia internally rotates 1 degree, which in turn affects the knee joint as it takes stress generated by the rotation.19 Internal or external rotation of the tibia can cause displacement of the path your kneecap takes as you bend and straighten your knee. As well, internal or external rotation of your hip will be compensated at the knee.

This means, if you continue to have muscle-related, increasing knee pain with exercise, you may want to have your lower extremity biomechanics evaluated to determine if you have tight muscles negatively impacting the way in which you walk. These tight muscles and tendons are contributing factors to strain on ligament structures wrapping around the knee and lower leg, and thus increase the potential for pain.

Although some of this biomechanical challenge may be addressed using orthotics, these devices do not encourage strengthening of your muscles supporting your foot, knee and hip. Instead, orthotics work much like a cast or splint, actually weakening some of your muscle while the device changes the way in which your foot works.

A strong physical therapy program or knowledgeable personal fitness trainer may help you improve your biomechanics through flexibility and strength training.20 Sometimes simple walking exercises can help to retrain weak muscles, therefore reducing knee pain and increasing your functional ability.

Psychological and Physical Benefits of Exercising in Groups

One study suggested you experience significant improvements in your physical, mental and emotional health when you work out in a group setting. In contrast, those who work out alone tended to put in more effort in the study but experienced little to no change in their stress level, or perceived level of fitness.21 Those who worked out in a group setting lowered their stress by 26 percent on average.

While this study did not demonstrate whether physical improvements were stronger working out as a group or solo, it does suggest reduced stress and improved emotional well-being may be tremendously motivating.

Increasing your motivation may also lead to improvements in physical strength and ability. While these are positive benefits, it's important not to push yourself to the point you experience greater knee pain from overexertion. Rob McGillivray, personal trainer and founder of RETROFIT, commented on the growing trend of group classes:22

“Group activity may not be a new concept but it has certainly seen massive international up-trends over the last 20 years with rapidly rising numbers in spin cycling, aerobic and dance-based classes and the emergence of CrossFit and its tribe mentality. I believe it to be a key indicator that working out in a motivational pack or using it as a tool to enhance internal or external competitive performance is fast becoming the preferred form of exercise.”

Other benefits of group exercise include working in a social and fun environment reducing the potential you'll quit because of boredom.23 Groups are designed to be safe and effective, using a consistent exercise schedule, increasing your accountability for participating in the class and often having specific classes for those who have no prior exercise knowledge or experience.

Whether working out in a group or solo, exercise improves your release of endorphins and creates feelings of happiness and euphoria.24 Exercise helps improve your self-confidence, prevents cognitive decline,25 alleviates anxiety, boosts overall brain performance and sharpens your memory.26

Pain Management at Home

Exercise should not trigger significant pain or discomfort above your normal pain level. In fact, research has demonstrated exercise may reduce your normal pain level by building strength and flexibility in muscles supporting your joints, thus reducing stress to the cartilage, tendons and bone. However, occasionally you may experience DOMS. To reduce the potential muscle discomfort may sideline your activity, consider using these “13 Mind-Body Techniques That Can Help Ease Pain and Depression.”

If you also suffer from OA, the addition of methylsulfonylmethane (MSM) may help reduce inflammation and provide your body with sulfur, the third most abundant mineral in your body based on percentage of total body weight.27 MSM has been used as a supplement to help treat pain, especially associated with arthritic conditions. Studies28,29 of patients with OA of the knee demonstrate significant physical improvement in physical function, compared to those taking a placebo.

However, while MSM offers relief from pain related to OA, a single dose may also reduce oxidative stress following exercise and thus improve pain related to DOMS.30 Results from studies31 of MSM suggest oral supplementation will reduce oxidative stress, muscle damage and pain.

Since oxidative stress contributes to muscle pain this reduction following MSM administration may help reduce recovery time and markers of muscle damage.32 For more information about supplementation with MSM, see my previous article, “The Benefits of Sulfur — Why You Need Epsom Salt, Broccoli and MSM.”