Building Muscle but Neglecting Tendons? Why Wall Sits and Eccentrics Could Be the Missing Link for Performance and Injury Prevention

Many athletes and fitness enthusiasts know how to build muscle—but strengthening tendons? That’s a whole different story.

In a recent video by strength coach Matt from The Movement System, he dives deep into the science behind tendon development and lays out a practical roadmap to improve tendon and ligament resilience.

By understanding how tendons respond to stress and which exercises promote collagen synthesis, you can future-proof your joints and increase your performance.

Whether you’re recovering from a nagging injury or looking to boost long-term joint durability, this guide breaks down the research-backed strategies for building bulletproof tendons.

Why Tendon Strength Matters

Tendons are the connective tissues that anchor muscle to bone. Unlike muscle, they adapt more slowly to training stress but are just as critical.

Strong tendons enhance force transfer, reduce injury risk, and allow joints to handle more explosive movements. According to a study on college soccer players, a full season of competition actually increases ACL volume—a sign of adaptive strengthening through repetitive stress.

“Repetitive subacute trauma… leads to microscopic tears in ligaments, inducing an inflammatory response and subsequent remodeling.” — Study authors on ACL growth from seasonal play

This kind of remodeling isn’t exclusive to elite athletes. With the right stimuli, anyone can promote collagen synthesis and tendon growth—even during regular workouts.

Collagen Synthesis vs. Muscle Protein Synthesis

Building tendons involves a different biological pathway than muscle hypertrophy. While training triggers muscle protein synthesis to grow muscle fibers, tendon strengthening relies primarily on collagen synthesis.

Tendons are composed mostly of Type I collagen. When exposed to mechanical loading, they respond by laying down new collagen fibers—especially in regions experiencing strain. This means you can optimize your workout to target not just muscle growth but connective tissue enhancement as well.

Isometric vs. Eccentric Exercises: What the Research Says

A systematic review on patellar tendinopathy provides clarity on the most effective exercise modalities:

• Isometric exercises: Grade A evidence for short-term pain relief and tendon loading during competitive seasons
• Eccentric & heavy slow resistance: Grade B evidence, better suited for long-term tendon health and functional improvement

So, what does this mean practically?

In-season athletes or those dealing with pain can benefit from heavy isometric holds like wall sits, as they stimulate collagen without adding excessive load.

Off-season or rehab phases are ideal for incorporating heavy slow resistance (HSR) and eccentric work, which encourage hypertrophy of connective tissue and gradual tissue remodeling.

Best Isometric Exercises for Tendons

Isometrics help engage the tendon under load while minimizing joint motion. Some effective examples include:

• Wall sit: Targets knees and quadriceps tendons
• Spanish squat: Allows more vertical torso, maximizing quad tension
• Bent-arm hold: For elbow tendons and biceps

For optimal results, holds should be maintained for 30–45 seconds at high intensity (70%+ maximal effort).

Eccentric and Heavy Slow Resistance (HSR) Training

Eccentric loading is powerful because it stimulates both muscle and tendon adaptation. The classic example is the Nordic hamstring curl. During the descent phase, the hamstrings are lengthened under tension, enhancing fascicle length and tendon thickness.

Recent research in elite rugby players shows that consistent Nordic training improves eccentric strength and may lower hamstring injury rates significantly.

Top Exercises for Eccentric Loading

• Nordic Hamstring Curls: Excellent for posterior chain and hamstring tendon resilience
• Reverse Nordics: Targets quadriceps and patellar tendons
• Heel Drops (Alfredson Protocol): A go-to for Achilles tendinopathy

Incorporate 2-3 sessions weekly of eccentric or HSR exercises during off-season or training blocks focused on injury prevention.

Heavy Load vs. Low Load: Understanding Adaptation

One critical insight from Matt’s breakdown is that heavy loads strengthen tendons better than frequent, low-load activity.

This means sports like swimming, cycling, or even running—while great for cardiovascular fitness—may not sufficiently stimulate tendon remodeling on their own. In fact, excessive low-load stress without counterbalancing strength work may diminish tendon quality over time.

To combat this, pair endurance activities with targeted isometrics or heavy resistance training. For example:

• Runner’s prep: Add 2 sets of 45-second wall sits post-run
• Cyclist routine: Include eccentric squats twice weekly to prevent patellar issues

Why Tendons Get Stronger and Stiffer (And That’s a Good Thing)

As tendons grow thicker and stiffer, they become more resistant to deformation. This stiffness increases elastic storage, helping return energy more efficiently during explosive movements like sprinting or jumping.

Stiffer tendons are also less prone to excessive elongation under strain, reducing injury risk from overload or high-velocity motion.

Training that improves tendon stiffness includes:

• Heavy load resistance training (1–3 reps near-maximal effort)
• Vertical jump drills with short ground contact times
• High-tension isometrics integrated into compound lifts

Designing a Complete Tendon Health Program

For optimal tendon health, structure your weekly training to include:

Daily or Weekly

• Low-load endurance work or sport-specific activity
• Mobility and soft-tissue work

2–3 Times Weekly

• Isometric holds at high intensity tailored to specific tendons
• Eccentric-focused exercises or HSR depending on training cycle

Once Weekly or Biweekly

• High-load compound lifts (e.g., deadlift, squat, overhead press)
• Reactive or plyometric drills

Takeaway: Think Long-Term Tendon Health

Building tendon strength isn’t just about preventing injury—it’s about optimizing performance from the inside out. Understanding the roles of isometric and eccentric loading, and how collagen synthesis differs from muscle growth, enables smarter programming.

Balance your approach by tailoring your training phase: use isometrics during high-stress seasons and eccentric work in buildup phases. Combine endurance with targeted strength work to maintain healthy connective tissue for the long haul.

Let your muscles grow—but don’t ignore the foundation that supports them.

Want to Learn More?

Check out The Movement System Podcast on Spotify or Apple Podcasts for a deeper dive into tendon science and smart training strategies.