Runner’s knee: snap, crackle, and pop                 

Pain usually arouses injury concerns, but with knees, it’s often the cringe-worthy sounds they make that send an athlete to see a physiotherapist. The sounds may be worse when going up and down stairs or squatting. These sounds lead the athlete to believe their knee is worn out or damaged(1). Their concern alone often leads them down the rabbit hole of negative thinking and activity avoidance.

In one study, noise, or crepitus, presented in the knees of nearly 40% of women and 20% of men over the age of 40-years-old(2). However, the incidence of crepitus in the general population isn’t known. No research to date indicates that noise in the knees indicates damage or injury, and  most of the physiological causes are benign, including:

  • Small bubbles within the synovial fluid bursting upon joint movement
  • Ligaments snapping, usually over a bony protuberance
  • Little bits of synovium or plica catching between the bones
  • Movement of the meniscus

Complaints of pain with knee noise usually centers on the patella, especially with stair climbing. In this case, the athlete may suffer from patellofemoral pain syndrome. Common in runners, the incidence is more than two times higher in women than men(3). While most rehab programs focus on the VMO to improve patellar tracking, physiotherapist Pat Gillham describes how strengthening and lengthening the soleus may relieve the stress on a runner’s patella (see figures 1 and 2). Like an unwelcome party guest, the knee can produce some disturbing sounds. While some may accompany pathology, most of the time, reassurance is all that’s needed.

Figure 1: Balance training to promote soleus activity with flexed knee single limb squats

Figure 2: Weight training to promote soleus slow-twitch muscle fiber and eccentric development


  1. Musculoskelet Sci Pract. 2017 Apr;28:59-64
  2. Clin Orthop Surg. 2018 Mar;10(1):1-8
  3. Phys Ther Sport.2018 Sep;33:7-11


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