If you are experiencing pain on the back and outer side of your knee when running, it could be the result of an overuse injury known as biceps femoris muscle strain – a common overuse running condition which may lead to chronic inflammation in the tendon sheath called tendinopathy.
The Biceps Femoris has two heads; the “long head” starts from your sit bone while its short head originates on your thigh bone (femur). As one of three hamstring muscles, this one flexes and extends your hip while also helping bend your knee.
Pain Under the Buttocks
Biceps femoris is one of the three hamstring muscles located on the back of each leg, and features two heads – its “long head” originates in your pelvis while its “short head” reaches down across your tibia and fibula bones. It works together with other hamstring muscles to bend your knee, with particular activity during running.
This muscle is susceptible to overuse injuries. Overstretch injuries often develop into tendonitis – inflammation of tendons that insert into your tibia and fibula bone structure- known as “biceps femoris tendinopathy.” Running with short strides and increasing training intensity too quickly may aggravate it further, while sitting or standing with hips hanging over to either side or performing leg extensions during yoga may exacerbate its condition further.
Symptoms may include pain in the area of the buttocks, pain beneath your knee, ankle, hip pain and snapping sensation during knee flexion – making this an injury frequently suffered by runners.
Pain Along the Outside of the Knee
The biceps femoris muscle is an extremely effective leg flexor that aids runners by slowing knee and foot movement during running. When sprinting at speed, this muscle receives significant force which could potentially cause it to tear or even rupture if the force exceeds what can be sustained by it.
Muscle fibres unite to form a tendon at the back of your knee that connects directly with both tibia (shin bone) and fibula. Just before inserting them, muscle fibres split apart and pass either side of fibular collateral ligament, where they insert.
Tendinopathy or hamstring injuries occur when there is inflammation and degeneration of one or more hamstring muscles or tendons, either through overuse, partial tear failure, or trauma to these structures. Pain in the area around the back of your knee often indicates this issue.
Stiffness
The biceps femoris muscle extends from your sit bone (ischial tuberosity) down your leg on its backside to insert at the backside of your knee, providing flexibility when flexing or extending either knee, and tilting pelvis posteriorly.
Hamstring group muscles include three distinct muscles that make up this group; it is most frequently injured through repetitive activity causing inflammation to the tendons & tendonopathy causing pain in the back of your thigh.
Physiotherapy plays a crucial role in treating this type of injury. We focus on reducing inflammation, increasing joint range of motion and strengthening biceps femoris. Ice application several times each day along with stretching are crucial, and our physiotherapists can assess your injury to develop a personalized rehabilitation program designed to speed your return to running.
Loss of Strength
An injury to this muscle may cause a snapping sensation that is both excruciatingly painful and severely affect your ability to walk or run. Therefore, it’s essential that you take things slowly and consult your physician about when strengthening exercises should begin.
Biceps femoris muscles form a fusiform muscle structure with its spindle-shaped fibers arranged into an undulating fiber bundle, and with its muscle belly wider than its origin and insertion points. The long head of biceps femoris runs down and laterally (on the outer side of leg) until reaching knee joint where it joins under short head of biceps; this portion often sustains injury from sprinting sports1-3.
At present, it remains unknown exactly how this type of injury happens, although it’s thought to occur at the musculotendinous junction similar to dancers’ semimembranosus muscle stretch injuries7. Biceps femoris muscles tend to be more vulnerable to fatigue-related injury due to exerting higher forces when lengthening (elongating) them than semimembranosus and semitendinosus muscles because their lengthening requires higher force levels when lengthening them (elongating them).
