Understanding Runner's Knee
Patellar tendon strain, often called 'runner's knee' or 'jumper's knee', is an overuse injury affecting the tendon that connects your kneecap (patella) to your shinbone (tibia). This tendon works with your thigh muscles to straighten the knee, playing
a crucial role in running, kicking, and jumping. When you repeatedly stress this tendon through the high-impact nature of road running, you can cause tiny tears in the tissue. Over time, if the stress outpaces your body's ability to repair, this can lead to pain, stiffness, and weakness, particularly when you run, squat, or even climb stairs. It's not necessarily a sign of a single bad step, but rather the result of cumulative load that has overwhelmed the tendon's capacity.
The Contraction You're Forgetting
When we think of strengthening muscles, we usually picture the 'concentric' phase of an exercise — the part where the muscle shortens to lift a weight, like curling a dumbbell up. However, every movement also has an 'eccentric' phase, where the muscle lengthens under tension to control a load. Think about the motion of slowly lowering yourself into a chair; your quadriceps are active and lengthening to control your descent. This is an eccentric contraction. For runners, this braking and shock absorption happens with every single foot strike. Most non-contact injuries actually occur during these eccentric phases, when muscles and tendons are working their hardest to absorb force and decelerate the body. If your eccentric strength is lacking, your patellar tendon may take on excessive strain, leading to injury.
Why Eccentric Loading Is a Game-Changer
Eccentric loading specifically targets this lengthening phase of muscle contraction. Research shows this type of training is uniquely effective for tendon health. When you apply a slow, controlled load as the muscle-tendon unit lengthens, you stimulate a process called mechanotransduction. This fancy term simply means that the tendon cells respond to the mechanical stress by producing more Type I collagen, the strong, resilient protein that gives tendons their structure. This process not only helps heal existing damage but also encourages the new collagen fibres to align in a neat, parallel structure. This organised structure makes the tendon stiffer and stronger, increasing its capacity to absorb and release energy without getting damaged. In essence, you are 'bulletproofing' your tendon against the repetitive demands of running.
Essential Eccentric Exercises for Runners
Incorporating eccentric exercises into your routine doesn't have to be complicated. The focus is always on the slow, controlled lowering phase. One of the most recommended exercises is the single-leg decline squat. You can use a dedicated decline board or simply place a weight plate or thick book under your heel. Stand on one leg on the decline, then slowly bend your knee to lower yourself down over 3-4 seconds. Use your other leg to push yourself back up to the starting position, ensuring the injured or target leg is only doing the lowering work. Another simple yet effective exercise is the slow lowering phase of a standard squat. Stand with your feet shoulder-width apart and take 3-5 seconds to lower your hips down and back, as if sitting in a chair. Push back up to the start at a normal pace. The key is the controlled, slow descent that puts the right kind of stress on the patellar tendon.
How to Add Eccentric Work to Your Plan
The goal of these exercises is tendon adaptation, not total exhaustion. Start by adding them to your routine 2-3 times per week on non-running days or after an easy run. A common protocol for patellar tendinopathy involves performing 3 sets of 15 repetitions. However, it's crucial to listen to your body. You may feel some discomfort in the tendon while performing the exercise, but it should not be sharp or severe, and it shouldn't be worse the following day. Consistency is more important than intensity, especially at the beginning. As you get stronger, you can progress the exercises by adding weight, such as holding a dumbbell or wearing a weighted vest, to continue challenging the tendon to adapt and grow stronger.
