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. 

References:

1.   Weight loss: the treatment of choice for knee osteoarthritis? A randomized trial. Christensen R, Astrup A, Bliddal H. Osteoarthritis Carti

lage. 2005 Jan;13(1):20-7.

2.   Exercise and dietary weight loss in overweight and obese older adults with knee osteoarthritis: the Arthritis, Diet, and Activity Promotion Trial.  Messier SP, Loeser RF, Miller GD, Morgan TM, Rejeski WJ, Sevick MA, Ettinger WH Jr, Pahor M, Williamson JD.  Arthritis Rheum. 2004 May;50(5):1501-10.

3.   Body weight changes and corresponding changes in pain and function in persons with symptomatic knee osteoarthritis: a cohort study.  Riddle DL, Stratford PW.  Arthritis Care Res (Hoboken). 2013 Jan;65(1):15-22.

4.   Manual therapy, exercise therapy, or both, in addition to usual care, for osteoarthritis of the hip or knee: a randomized controlled trial. 1: clinical effectiveness. Abbott JH, Robertson MC, Chapple C, Pinto D, Wright AA, Leon de la Barra S, Baxter GD, Theis JC, Campbell AJ; MOA Trial team. Osteoarthritis Cartilage. 2013 Apr;21(4):525-34.

5.   Impact of exercise on the functional capacity and pain of patients with knee osteoarthritis: a randomized clinical trial. Oliveira AM, Peccin MS, Silva KN, Teixeira LE, Trevisani VF. Rev Bras Reumatol. 2012 Dec;52(6):876-82.

6.   Effect of high-speed power training on muscle performance, function, and pain in older adults with knee osteoarthritis: a pilot investigation.  Sayers SP, Gibson K, Cook CR. Arthritis Care Res (Hoboken). 2012 Jan;64(1):46-53.

7.   The biomechanical effects of focused muscle training on medial knee loads in OA of the knee: a pilot, proof of concept study.  Thorp LE, Wimmer MA, Foucher KC, Sumner DR, Shakoor N, Block JA. J Musculoskelet Neuronal Interact. 2010 Jun;10(2):166-73.

8.   After patients are diagnosed with knee osteoarthritis, what do they do? Grindrod KA, Marra CA, Colley L, Cibere J, Tsuyuki RT, Esdaile JM, Gastonguay L, Kopec J.  Arthritis Care Res (Hoboken). 2010 Apr;62(4):510-5.

9.   Change of quality of life due to exercise training in knee osteoarthritis: SF-36 and WOMAC.  Aglamiş B, Toraman NF, Yaman H.  J Back Musculoskelet Rehabil. 2009;22(1):43-5, 47-8, 46.

10.        The effects of a non-operative multimodal programme on osteoarthritis of the knee.  Patel S, Hossain FS, Paton B, Haddad FS.  Ann R Coll Surg Engl. 2010 Sep;92(6):467-71.

11.        Factors influencing health-related quality of life after TKA in patients who are obese. Nuñez M, Lozano L, Nuñez E, Segur JM, Sastre S. Clin Orthop Relat Res. 2011 Apr;469(4):1148-53.

12.        Knee extensor torque of men with early degrees of osteoarthritis is associated with pain, stiffness and function. Serrão PR, Gramani-Say K, Lessi GC, Mattiello SM.  Rev Bras Fisioter. 2012 Jul-Aug;16(4):289-94.

13.        Knee extensor strength does not protect against incident knee symptoms at 30 months in the multicenter knee osteoarthritis (MOST) cohort. Segal NA, Torner JC, Felson DT, Niu J, Sharma L, Lewis CE, Nevitt M.  PM R. 2009 May;1(5):459-65.

14.        Quadriceps weakness and its relationship to tibiofemoral and patellofemoral knee osteoarthritis in Chinese: the Beijing osteoarthritis study.  Baker KR, Xu L, Zhang Y, Nevitt M, Niu J, Aliabadi P, Yu W, Felson D. Arthritis Rheum. 2004 Jun;50(6):1815-21.

15.        A comparison of various therapeutic exercises on the functional status of patients with knee osteoarthritis. Huang MH, Lin YS, Yang RC, Lee CL. Semin Arthritis Rheum. 2003 Jun;32(6):398-406.

16.        Osteoarthritis of the knee: isokinetic quadriceps exercise versus an educational intervention. Maurer BT, Stern AG, Kinossian B, Cook KD, Schumacher HR Jr. Arch Phys Med Rehabil. 1999 Oct;80(10):1293-9.

17.        Effects of kinesthesia and balance exercises in knee osteoarthritis. Diracoglu D, Aydin R, Baskent A, Celik A. J Clin Rheumatol. 2005 Dec;11(6):303-10.

18.        Effects of strengthening and aerobic exercises on pain severity and function in patients with knee rheumatoid arthritis. Rahnama N, Mazloum V. Int J Prev Med. 2012 Jul;3(7):493-8.

19.        Management of knee osteoarthritis: an evidence-based review of treatment options. Merashly M, Uthman I. J Med Liban. 2012 Oct-Dec;60(4):237-42. Review.

20.        OARSI recommendations for the management of hip and knee osteoarthritis, Part II: OARSI evidence-based, expert consensus guidelines. Zhang W, Moskowitz RW, Nuki G, Abramson S, Altman RD, Arden N, Bierma-Zeinstra S, Brandt KD, Croft P, Doherty M, Dougados M, Hochberg M, Hunter DJ, Kwoh K, Lohmander LS, Tugwell P.  Osteoarthritis Cartilage. 2008 Feb;16(2):137-62.

21.        OARSI recommendations for the management of hip and knee osteoarthritis: part III: Changes in evidence following systematic cumulative update of research published through January 2009. Zhang W, Nuki G, Moskowitz RW, Abramson S, Altman RD, Arden NK, Bierma-Zeinstra S, Brandt KD, Croft P, Doherty M, Dougados M, Hochberg M, Hunter DJ, Kwoh K, Lohmander LS, Tugwell P. Osteoarthritis Cartilage. 2010 Apr;18(4):476-99.

22.        Quadriceps weakness and osteoarthritis of the knee. Slemenda C, Brandt KD, Heilman DK, Mazzuca S, Braunstein EM, Katz BP, Wolinsky FD. Ann Intern Med. 1997 Jul 15;127(2):97-104.

23.        Quadriceps strength in women with radiographically progressive osteoarthritis of the knee and those with stable radiographic changes. Brandt KD, Heilman DK, Slemenda C, Katz BP, Mazzuca SA, Braunstein EM, Byrd D. J Rheumatol. 1999 Nov;26(11):2431-7.

24.        Quadriceps weakness in knee osteoarthritis: the effect on pain and disability. O'Reilly SC, Jones A, Muir KR, Doherty M. Ann Rheum Dis. 1998 Oct;57(10):588-94.

25.        Effectiveness of home exercise on pain and disability from osteoarthritis of the knee: a randomised controlled trial. O'Reilly SC, Muir KR, Doherty M. Ann Rheum Dis. 1999 Jan;58(1):15-9.

26.        Home based exercise programme for knee pain and knee osteoarthritis: randomised controlled trial. Thomas KS, Muir KR, Doherty M, Jones AC, O'Reilly SC, Bassey EJ. BMJ. 2002 Oct 5;325(7367):752.

27.        A systematic review of randomized controlled trials on exercise parameters in the treatment of patellofemoral pain: what works? Harvie D, O'Leary T, Kumar S. J Multidiscip Healthc. 2011;4:383-92.

28.        Focusing osteoarthritis management on modifiable risk factors and future therapeutic prospects.  Hunter DJ.  Ther Adv Musculoskelet Dis. 2009 Feb;1(1):35-47.

29.        Effectiveness of exercise for osteoarthritis of the knee: A review of the literature. Iwamoto J, Sato Y, Takeda T, Matsumoto H. World J Orthop. 2011 May 18;2(5):37-42.

30.        Osteoarthritis 2012 year in review: rehabilitation and outcomes. Roos EM, Juhl CB. Osteoarthritis Cartilage. 2012 Dec;20(12):1477-83.