Knee Pain in Trail Runners: Why It Occurs and How to Prevent It

The knees are among the most heavily loaded parts of the body during trail running. Long ascents, technical descents, constantly changing terrain, and the need for continuous adjustments with every step create conditions in which the knee functions as the primary shock absorber and stabilizer. It is therefore no surprise that knee pain is one of the most common issues among mountain and trail runners.

In this article, we explain why knee pain occurs in trail running, which structures are most commonly affected, how forces act on the knee in this environment, and how strength training reduces the risk of injury.

What Happens in the Knee During Uphill and Downhill Running?

The knee acts as a hinge between the ankle and the hip. During trail running, each step activates a series of mechanisms that control movement and absorb forces. On descents, the knee decelerates the body through the quadriceps, meaning the muscles work eccentrically—they lengthen while generating tension. This form of muscle action is the most demanding and fatiguing over time. As a result, pressure on the patella, menisci, and anterior ligaments increases. From a biomechanical standpoint, the forces acting on the knee during trail running are significantly greater than during flat running. Studies show that compressive forces on the knee can increase by more than 50% during prolonged descents, particularly when the runner is fatigued.

Common Knee Injuries in Trail Runners

• Runner’s Knee (Iliotibial Band Syndrome) This condition results from friction of the iliotibial band against the outer side of the femur. Pain appears on the lateral side of the knee, often after just a few kilometers of descending. A hallmark sign is localized tenderness and a sensation of tightness.

• Patellar Tendinopathy (Jumper’s Knee) This injury affects the tendon below the kneecap. Pain occurs during hopping, downhill running, or squatting. It is a classic overuse condition caused by repetitive eccentric loading of the quadriceps.

• Meniscus Injuries These often occur due to twisting of the knee, landing on uneven terrain, or overload in deep squat-like positions. Symptoms include pain on the inner or outer side of the knee, a catching or locking sensation, and swelling.

• ACL Injuries Less common but more severe. They occur during sudden changes of direction, slips, or improper landings. Symptoms include a popping sensation in the knee, instability, and frequent swelling.

The Role of Muscles in Protecting the Knee

The knee does not function independently. It is supported by the muscles of the thigh, hip, and calf. The most important groups include:

• Quadriceps: primary decelerators during descents
• Hamstrings: stabilize the knee and control tibial movement
• Gluteal muscles: stabilize the hip and prevent excessive knee rotation
• Calf muscles: absorb landing forces and influence overall stability

Weakness in any of these groups increases the load on the knee joint and, over time, manifests as pain or injury.

Strength Training as Prevention and Rehabilitation

Strength training is not merely a useful addition—it is a fundamental requirement for trail runners. It enables more stable movement, better force absorption, greater tissue resilience, and improved motor control in the unpredictable conditions of mountain terrain.

On uneven descents, the body functions as a system of shock absorbers in which the muscles must control movement in the eccentric phase—lengthening under load. Without adequate strength and control, stress on the knee structures increases, potentially leading to tendinopathies, patellar irritation, or even ligament injuries.

Research clearly shows that targeted strength training:

• reduces the risk of IT band syndrome and patellar tendinopathy,
• improves shock absorption during descents (Ferber et al., 2010),
• increases activation and control of the gluteal muscles, which significantly influence knee alignment during running (Esculier et al., 2017),
• lowers the risk of sudden ligament injuries such as ACL tears (Andersen et al., 2008).

Strength training also enhances neuromuscular coordination, meaning runners react more quickly and effectively to changes in terrain, slips, or rotational forces. This is especially important for the hip and core muscles, which control knee position in all three planes of motion.

Essential Strength Exercises for Trail Runners

To protect the knee and improve preparedness for technical terrain, we recommend the following exercises:

Reverse Lunges With Trunk Rotation Rotate toward the front leg on each step. This activates the glutes and improves knee control.

Nordic Hamstring Curls (Modified Version) From a kneeling position, lean forward while controlling the descent and return with assistance from your hands. Anchor your heels under a bar or couch. This strengthens the hamstrings.

Single-Leg Calf Raises

Rise onto your toes on one leg and lower slowly. This strengthens the calves and improves balance.

Glute Activation With Resistance Band

With a band around your knees, perform slow lateral steps or clamshell variations. This strengthens hip and knee stabilizers.

Approach at Kinvital

Their assessment begins with a detailed movement analysis—particularly running analysis. Based on the findings, they design a targeted program that includes functional exercises, motor control training, and manual therapy when needed.

In practice, they observe significant improvements within just a few weeks: reduced pain, better stability, and increased confidence on technical terrain.

Who are they? Kinvital is a specialist physiotherapy and kinesiology center focused on sports rehabilitation, running analysis, and preparing the body for physical challenges. Their goal is to help runners move pain-free—safely and sustainably.

If you are experiencing knee pain, you can book an initial assessment.