Why does my knee hurt when I bend and straighten it?

Bad news – knee injuries among runners and triathletes are very common and there are myriad diagnoses that exist for knee pain. But experiencing pain when bending and straightening the knee is a particularly common complaint, and is the one we’re going to focus on here.

So read on to find out what could be causing your knee pain and, most importantly, how to fix and prevent it.

What are the possible causes of pain when bending and straightening your knees?

If an athlete experiences pain at, around, or behind the kneecap on bending and straightening of the knee the pain is likely to be patellofemoral (kneecap) in origin.

If the pain, however, is more posterior (in the knee crease behind the leg), medial or lateral, the pain may be emanating from the medial or lateral joint lines, which may be due to cartilaginous or meniscal tissue pathology.

Most common causes of knee pain

The most common causes of knee pain that triathletes experience are:

Patellofemoral (kneecap) pain

Patellofemoral pain will produce pain at, around, or behind the kneecap when performing single-leg squats, walking up or down stairs, and sometimes with prolonged sitting.

IT band pain

IT band pain (commonly referred to as IT friction syndrome) tends to be the most common cause of lateral knee pain in triathletes and runners. IT band pain will be experienced at the level of the lateral femoral condyle.

It can feel very sharp and intense, and is made worse by the repetitive, weight-bearing loading cycles experienced when running.

Meniscus injuries

Meniscal injuries have been reported to occur in 5% of runners, although running has not been implicated as a cause of acute meniscal tears. Meniscal tears can be acute or chronic in nature and can occur at either the medial or lateral meniscus.

Symptoms may include pain along the medial or lateral joint lines, locking of the knee, and giving way of the knee.

Osteoarthritis or arthropathy

Osteoarthritis or arthropathy of the knee is commonly experienced by masters runners. Osteoarthritis can occur at either of the three compartments of the knee: patellofemoral, or medial/lateral tibiofemoral.

Symptoms of knee arthropathy can include pain and stiffness, with the pain going from sitting to standing or on commencement of activity.

Other less common causes

Other less common causes of knee pain among runners can include: bone stress injuries, prepatellar bursitis, quadriceps tendinopathy, pes anserine syndrome, and baker’s cyst pain.

How do you fix a knee that hurts when you bend and straighten it?

Reducing soreness in a knee that is experiencing pain during extension and flexion is reliant on an accurate diagnosis of the presenting knee condition. Assuming an accurate diagnosis has been made, you’ll be encouraged to modify the load bearing in your run and bike sessions in order to ease the symptoms and reduce the pain.

For example, by reducing the overall run workload – in particular speed work – knee pain and symptoms should be reduced. Alongside a reduction in run workload, efforts can be made to strengthen key muscle groups around the knee.

This may include targeted strength exercises for the quadriceps, calf, hamstring, hip abductor and hip adductors.

How do you prevent knee pain when bending and straightening?

Preventing knee pain is not possible, unfortunately, and knee pain is prevalent in both athletic and sedentary populations. However, having ‘resilient’ muscles around our knees may reduce the risk of injury.

Once again the key muscle groups include: the plantar flexors (calf), quadriceps, hamstring, and hip muscles (adductors and abductors).

Another area to consider is your gait, as running with an overstriding gait and ‘hip dip’ have been shown to correlate with numerous running-related injuries, including knee pain.

So it reasons that we may reduce some risk of developing running-related knee pain by avoiding overstriding, and also by minimising hip dip when running, which seems to be a function of good pelvic muscle control.

How do I know if my knee pain is serious?

While a runner’s knee may be ‘sore’ it may be still ‘safe’ to continue running. For conditions such as patellofemoral pain, for example, complete cessation of running is rarely required.

However, there are some knee injuries such as IT band pain that can produce very high levels of pain that make running impossible.

While the degree of symptoms or pain experienced may determine if a runner can or can’t run, the pain severity does not necessarily always correlate with injury severity or prognosis.

The pain experienced is a reflection of tissue sensitisation as opposed to structural ‘damage’ to the tissues. The exception to this being bone stress injuries where ongoing pain correlates with a worsening of the tissue quality.

Should I squat with knee pain?

Squatting is permissible and in most instances favourable for knee pain. However, if knee-pain levels are high and the knee feels quite ‘flared up’ then avoiding squatting positions and squats as a conditioning exercise may be an effective strategy in reducing aggravation of the knee and associated symptoms.

The benefits of squatting include conditioning the muscles around the knee, which improves joint function. A further benefit is conditioning the tissues of the knee joints themselves, such as the fibrocartilage, which lines the joints and responds well to repetitive and cyclical loading (such as squatting or running).

Exposing the tissues of the knee joints to exercises beyond running can expose the knee to superincumbent loads, which can improve the tissue tolerance of the knee, and therefore the knee’s tolerance, to the loads associated with triathlon and general daily-life activities.

Is squatting bad for knees?

No, squatting is not bad for knees. If you think about it, we perform many squat-based movements throughout the day such as getting in and out of a car, going to the toilet, getting up and down from sitting.

So squatting is considered a favourable or ‘good’ thing to do for knee health as the squat movement involves multiple joints (hip, knee, and ankle) and large muscle groups.

Which is why a strength-and-conditioning programme that incorporates squats can be hugely beneficial for triathletes.

Top image credit: Getty Images