When Exercising Hurts Your Knees, Exercise More

I’ve always suffered sporadically from knee pain, mostly when running and wearing the wrong shoes.  But now that I’m in my 40’s, my knees seem to hurt more consistently.  When going down stairs.  When going up stairs. When walking around early in the morning.  When running on the treadmill. I’ve noticed that my knee pain increases when I’m out of shape or haven’t worked out for a while.  But my knee pain has never been bad enough to sideline me. 

My husband, on the other hand, has suffered from aches and pains that have caused him to stop running or playing basketball for several days or longer. And he’s not alone.  His basketball and soccer buddies are a brace-wearing, Bengay-using Band of Brothers who all hobble off the court or field after playing, and spend the next day or two nursing their pain. We’ve often wondered whether or not he should have surgery or try other treatments.  We’ve considered everything: from corticosteroid injections to hyaluronic injections; from aspirin to acupuncture.  And yet we’ve leaned away from treatments requiring surgery or injections.  We wondered if there were non-surgical treatments he could use to ease his pain? Are there non-pharmacological treatments that are effective? What do the clinical studies show?

What the research says:

The medical term for knee pain is “patellofemoral pain syndrome (PFPS)” and it ”is one of the most common knee conditions, affecting one in four people of the total population” [27].  This pain is normally caused by osteoarthritis, and is aggravated by activities that load the patellofemoral joint, such as climbing stairs, squatting and running [27].   So imagine my surprise when I found studies purporting a link between increased exercise and decreased knee pain?  Actually, I wasn’t surprised, because my experience has been that my knee pain peaks when I don’t consistently work out, and decreases when I do.  But I had no idea how many studies had been done to clarify the link between exercise and decreased knee pain. And almost all have found that exercising painful knees eases the pain and improves your ability to function. Here’s a summary of those results. 

  • People suffering from knee pain usually have lower quadriceps strength [12,14, 24].  Clinical studies have found that quadriceps strength is significantly lower in those with knee pain compared with controls [24].   Why? Researchers aren’t sure but they propose the following mechanism: The quadriceps muscle is an important structure in the absorption of impacts experienced by the knee joint. Strength deficits in this muscle can compromise its role in absorbing loads. Considering that individuals with knee OA usually present weakness of the quadriceps muscle, perhaps those patients experience increased joint loading, which contributes to increased pain and the progression of osteoarthritis [12].  Whatever the mechanism, people experiencing knee pain will generally have less muscle strength in the muscles around their knee.
  • Exercise reduces knee pain and improves knee function [4, 5,7, 9, 10, 15-17,25-30].  Several clinical studies have been done investigating the effect of exercise on knee pain.  These studies were generally limited to patients with mild or moderate knee pain (not severe osteoarthritis), and generally included aerobic, flexibility, strengthening and balance components.  The results demonstrated that the exercise regimens investigated were “effective in reducing pain and improving physical function in patients with mild to moderate OA of the knee” [29].   In fact, every type of exercise tested demonstrated an improvement over controls.
  • Aerobic, strengthening and flexibility exercises done daily work best.  You may be wondering which exercises worked best when decreasing knee pain?  Researchers reviewed the studies conducted and concluded that results were optimal when the exercise regimen was done daily; done progressively starting with a small number of sets of ten or more repetitions and increasing gradually to include more sets and reps; and included knee extension, squats, stationary cycling, static quadriceps, active straight leg raise, and step up and step down exercises combined with flexibility exercises [27].
  • Strengthening muscles around the hip, as well as the knee, is important [7,29]. Clinical studies have revealed that muscles in both the hip and knee are important when targeting knee pain. In fact, a study conducted by Thorp et al. found that knee pain decreased when “hip muscle exercises, targeting the hip abductor muscles” were added to a conventional knee OA exercise regimen [7].  The authors hypothesize that the muscles in and around the hip influence the biomechanical balancing of the knee [7], and consequently muscles in and around the hip must be considered when creating a knee-pain exercise program. 
  • Losing weight helps, but should be combined with exercise [2, 30]. Weight loss has also been shown to decrease knee pain [2, 30], conceivably by decreasing the mechanical load on the knee.  However, a study by Roos et al. found that “weight loss induced by a low-energy-diet led to reductions in both leg muscle tissue and absolute knee muscle strength” [30]. We now know that decreased knee muscle strength is correlated with increased knee pain, causing some concern regarding those results and causing the authors to highlight “the importance of implementing an exercise regime to restore, or better still, improve muscle mass in knee OA patients while they are undertaking a weight loss program” [30].   This may explain why Messier et al. (who conducted a study comparing diet alone, exercise alone, and diet combined with exercise) found that subjects realized the greatest and statistically significant benefit in function only when diet was combined with exercise [2]. 

What does this all mean?

The Osteoarthritis Research Society International is the “premier international organization for scientists and health care professionals focused on the prevention and treatment of osteoarthritis”.  I was a member of OARSI and I know of all the great work that they’ve done to combat osteoarthritis and the pain it causes.  In 2008, OARSI published a list of recommendations for the management of hip and knee pain [20], and that list was updated most recently in 2010 [21].   Their recommendations include exercise, with a strength-of-recommendation rating of 96%, one of the highest.  Their recommendation reads:

"Patients with hip and knee OA should be encouraged to undertake, and continue to undertake, regular aerobic, muscle strengthening and range of motion exercises" [20].

So if you suffer from mild or moderate knee pain, you should consider starting an exercise regimen that includes aerobics, strengthening the muscles around the knee and hip, flexibility, and balance. 


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