Scientifically-Proven Achilles and Knee Pain Relief Strategies Marathon Runners Need to Know
As a marathon runner, you’re used to pushing through discomfort — sore muscles, heavy legs, the occasional blister. So it might be easy to think that stubborn issues like Achilles or knee pain are just part of the marathon journey. But it doesn’t have to be the case!
With the right approach, you can reduce your risk and manage these pains safely and effectively. Understanding why these stubborn issues pop up and knowing what actually helps is the key to smarter training and your best marathons yet.
Let’s break down what’s really behind your Achilles and knee pain and explore practical, science-backed ways to keep your body pain-free.
Why do Marathon Runners Persistently Face Achilles and Knee Pain?
If you’ve struggled with persistent Achilles or knee pain, you’re not alone. These two types of tendon injuries are incredibly common in marathon runners, mainly because of the repetitive stress placed on your body during long-distance training.
Let’s break down each one separately to see exactly what’s going on:
Achilles Tendinopathy (Achilles Pain)
Pain in the Achilles tendon is one of the most frequently reported running injuries. It’s felt along your Achilles, the thick band connecting your calf muscles to your heel bone.
Research shows that about 3.5% to 8.3% of recreational runners deal with Achilles issues, and among marathoners specifically, that number climbs as high as 7.4%. In other words, nearly one in every twenty marathon runners will experience Achilles pain at some point.
When your Achilles tendon is repeatedly overloaded (like during long training runs) you’re likely to notice pain, stiffness, and swelling. Initially, this discomfort might come and go, but with continued stress, it often becomes chronic.
If the pain is chronic, the tendon itself can start to undergo structural changes. Specifically, the collagen fibers within the tendon begin to degenerate. This makes recovery time much longer and significantly harder.
Patella Tendinopathy (Knee Pain)
Persistent knee pain, particularly just below your kneecap (the patella tendon), is another persistent problem area for marathon runners. Recent research found that up to 27% of marathon runners experience this type of knee tendon pain (often called “runner’s knee”).
The patella tendon connects your kneecap to your shinbone and is critical for running, jumping, and explosive movements. Just like your Achilles tendon, it becomes painful when overloaded through repetitive, high-intensity stress. Over time, this repeated stress leads to similar degenerative changes within the tendon, causing prolonged pain and more difficult recoveries.
A Common Thread
Whether it’s your Achilles or your knee, persistent tendon pain usually stems from a combination of factors: prolonged repetitive stress, fatigue, and subtle abnormalities in your running mechanics. When your body becomes fatigued during long-distance training, maintaining optimal running form gets harder. These small biomechanical shifts can significantly increase stress on your tendons, turning minor irritations into chronic issues.
Basically, fatigue leads to abnormal mechanics, which then increases tendon stress. So once you know what’s causing your Achilles or knee pain, you’re much better equipped to address it effectively.
Why Stretching Alone Won’t Fix Your Achilles or Knee Pain
Many runners turn to stretching when tendon pain pops up. And it’s easy to see why — stretching feels good! But while it might help you feel better temporarily, research shows that it falls short of actually fixing stubborn Achilles or knee pain.
Instead, a targeted approach like eccentric strength training (where you slowly lengthen your muscles under tension) works much better. Let’s get into the science of why this type of training is more effective.
What the Research Says About Stretching vs. Eccentric Training
One key study compared stretching alone with eccentric strength training (slow, controlled movements that lengthen your muscles under load) for treating Achilles pain. Participants were split into two groups and performed their specific regimen twice a day for 12 weeks:
STRETCHING GROUP
The stretching group performed traditional calf muscle stretches twice a day for 12 weeks, holding each stretch for 30 seconds.
ECCENTRIC TRAINING GROUP
The eccentric training group performed slow, controlled calf-lowering exercises on a step, progressively increasing the load by adding weight as they improved.
After just three weeks, both groups experienced some relief, but the eccentric training group showed significantly greater improvements over time. This aligns with a wider body of research confirming eccentric exercises as the first-line recommendation for persistent Achilles issues.
1. Structural Changes to Tendons
Eccentric training places targeted stress on your tendons, stimulating collagen production and alignment. This structural adaptation helps your tendons better handle the repetitive loads of running.
2. Changes to Muscle-Tendon Lengths via Sarcomerogenesis
Eccentric exercises might help increase dorsiflexion range of motion (ROM) through altering the length of muscle fibers, which allows your muscles and tendons to absorb impact more efficiently and safely.
3. Improved Muscle-Tendon Unit (MTU) Stiffness
Evidence shows reduced tendon stiffness when comparing Achilles Tendinopathy patients with healthy controls. For example, a recent study found that eccentric training for 6 weeks significantly increased* Achilles tendon stiffness in long distance runners.
* We explain why improved tendon stiffness is desired in runners to boost running economy in this blog post!
4. Decreased Neuro-Vascular Ingrowth
Painful tendons often show tiny new blood vessels and nerves (neurovascular ingrowth) that heighten sensitivity. Studies have shown that eccentric training helps reduce this abnormal growth in blood vessels and nerves, effectively decreasing pain.
5. Neurochemical Adaptations
Chronic tendon pain makes your tenocytes (tendon cells) produce more pain-related neurotransmitters. Eccentric loading appears to down-regulate the activity of these neurotransmitters, making the tendon less sensitive to pain. It also rebalances the behavior of tenocytes, which decreases tendon swelling and makes the tendon more functional.
6. Improved Fluid Movement Within the Tendon
Eccentric exercises may improve fluid regulation within your tendon, potentially reducing swelling and improving tendon function.
7. Enhanced Neuromuscular Adaptations and Stretch Shortening Cycle (SSC)
Eccentric training strengthens your muscles’ ability to pre-activate and stiffen before loading. Better muscle activation helps your tendon absorb forces without excessive strain, lowering your injury risk.
Similar Principles Apply to Knee Pain
These eccentric training principles can also apply to knee pain. Research clearly shows that combining eccentric and heavy slow resistance training effectively rebuilds knee tendon strength, reduces pain, and improves tendon function long-term.
For persistent knee issues, experts recommend a progressive three-stage approach:
Stage 1
Isometric exercises (like holding a leg extension) to manage acute pain.
Stage 2
Eccentric and heavy slow resistance training to rebuild tendon strength.
Stage 3
Plyometric and sport-specific exercises to safely return to full running.
So while stretching alone can temporarily ease discomfort, it won’t rebuild tendon health or fully resolve the underlying issue. To actually move past stubborn Achilles and knee pain, your training must be structured and targeted to build up your tendon’s strength and resilience at every stage.
Why ‘Slow and Heavy’ Works better than ‘Fast and Light’ for Achilles and Knee Health
Contrary to what many people think, if you’re serious about helping your Achilles and knees heal, science says slowing things down and adding weight is far more effective than lighter, quicker movements. Here’s why heavy slow resistance training (HSR) works better.
What is HSR Training?
HSR (Heavy Slow Resistance Training) involves performing strength exercises at a slow, controlled pace (around three seconds down and three seconds up) using heavier weights. Common moves include barbell squats, leg presses, and Bulgarian split squats, designed to increase your muscles’ time under tension and strengthen your tendons.
Evidence says HSR is highly effective for treating knee pain. A recent study compared HSR with therapeutic ultrasound (a common treatment for knee pain) and found athletes who used HSR significantly improved their pain and function scores. Specifically, their knee pain and function scores improved by 17 points on a specialized questionnaire (VISA-P), compared to just a 6-point improvement in those receiving ultrasound alone. Even more impressively, athletes who combined both treatments saw a 21-point improvement. Crucially, these improvements remained stable four months later, clearly demonstrating the lasting impact of slow and heavy training.
Key Benefits of HSR for Tendon Pain
Research identifies several reasons why heavy slow resistance is especially effective for stubborn tendon pain:
Heavy slow movements stimulate collagen production and reinforce tendon structure, helping tendons handle more stress.
Increases in muscle mass around your knees and calves support your tendons, making them stronger and more resilient.
Slow and controlled reps increase muscle activation and improve motor control, reducing excessive tendon strain during running.
Similar to eccentric exercises, HSR helps manage abnormal blood vessels and swelling that contribute to chronic pain.
How HSR Compares to Other Common Treatments
In a comprehensive review of various rehab methods for knee tendon pain, researchers compared three popular treatments (which we’ve condensed here):
1. Isometric Exercises
(static holds like a leg-extension hold) provided rapid, short-term pain relief, beneficial during competition or acute flare-ups.
2. Heavy Slow Resistance (HSR) Training
(slow, heavy movements like leg presses) resulted in significant long-term pain reduction, improved tendon strength, and better overall function
3. Eccentric Exercises
(slow, controlled muscle-lengthening movements like eccentric squats) consistently demonstrated strong results and remain the established “gold standard” for long-term tendon pain relief.
Ultimately, the study found that isometric exercises are best suited for quick symptom management, while both eccentric and especially HSR exercises provide sustained improvements (which are important factors for successful tendon rehab over the long term).
This being said, it’s important to remember that tendon injuries exist along a continuum! Different stages require different treatment approaches. Matching the right exercises to the specific stage and condition of your injury is crucial for effective rehabilitation.
Does Your Achilles or Knee Pain Require Different Exercises?
Ultimately, every runner’s tendon injury is unique. Your Achilles or knee pain might need different exercises than someone else’s. Choosing the right type of exercise depends heavily on your injury stage and how your tendon responds to different loads.
Matching Your Training to Your Injury Stage
Effective rehab isn’t about randomly choosing exercises. Instead, it involves carefully adjusting specific training parameters, including:
Why Tempo Matters
Let’s look at one of these parameters — tempo.
Research emphasizes that slower lifting tempos (longer time under tension) are especially beneficial in tendon rehab. Slow and controlled movements reduce sudden force on your tendons, which helps safely remodel tendon tissue, decrease pain, and build long-term strength. Slower movements also improve muscle activation and neuromuscular control, both of which are crucial for safe recovery.
Trained individuals can handle about 10 reps at 85% of their maximum weight in exercises like the squat. Untrained individuals typically manage far fewer reps at the same weight. This highlights why individually tailored exercises (with appropriate tempo and intensity, of course) matter so much for effective rehab.
The Bottom Line
Achilles and knee pain are common for marathon runners, but they’re not inevitable.
Understanding the root causes (repetitive stress, fatigue, and biomechanical shifts) is the first step to effective recovery. Research consistently shows that targeted, controlled exercises like eccentric and heavy slow resistance training outperform basic stretching or lighter movements, especially when tailored to your specific injury stage.
However, know that your Achilles and knee pain are unique, and your rehab plan should reflect that. By carefully matching exercises to your injury stage and focusing on slow, controlled movements, you’ll recover faster, reduce injury risk, and come back stronger.
If you need help crafting the perfect plan for you, book a free consultation with SCIENCED Athletics. Our expert team uses personalized assessments and keeps up with the scientific evidence to ensure you get exactly what your body needs to run stronger and pain-free.
