The Soleus: The Most Important Muscle You’re Probably Not Training (But Should Be)
- Raquel Lines
- Apr 2
- 3 min read
When most people think about calf training, they think about the gastrocnemius: the big calf muscle you see. But the soleus, the deeper calf muscle, is actually the workhorse for walking, running, hiking, stairs, and especially downhill movement.
If the gastrocnemius helps push you forward, the soleus helps slow you down.
And in real life (and in sport) deceleration is where most injuries occur.
Why the Soleus Matters So Much
The soleus plays a major role in:
Walking and running
Downhill hiking
Descending stairs
Shock absorption
Controlling the tibia over the foot
Reducing load on the knee
Protecting the Achilles tendon
Endurance performance
Biomechanical research shows the soleus produces the majority of plantarflexion force during locomotion and can experience forces several times bodyweight during running, meaning it functions more like a brake than a power muscle in endurance and downhill activities.
If the soleus cannot absorb force effectively, that load gets transferred to:
The knee
The Achilles tendon
The plantar fascia
The anterior shin
This is why weak soleus strength is commonly associated with:
Achilles tendinopathy
Shin splints
Knee pain
Overuse injuries
Increased ACL stress (due to reduced tibial control)
The Soleus Is an Endurance Muscle
The soleus is composed primarily of Type I slow-twitch muscle fibers, which means:
It needs endurance strength, not just power.
This is why high-repetition calf work is important (especially for runners, hikers, and field athletes).
Clinical Strength Benchmarks
Seated Calf Raise Strength (Soleus Bias)
A commonly used performance guideline:
Level | Strength Goal |
General population | ~0.5 × bodyweight |
Recreational athlete | ~1.0 × bodyweight |
Well-trained athlete | ~1.25–1.5 × bodyweight |
High-performance athlete | ~1.75–2.0 × bodyweight |
A long-term goal for many active individuals is building toward ~1–1.5× bodyweight on a seated calf raise for adequate load capacity.
Single-Leg Calf Raise Endurance (Gastrocnemius bias)
This is one of the most useful clinical tests because it requires no equipment and correlates well with lower leg capacity.
Level | Repetitions |
General population | ~20 reps |
Recreational athlete | ~25–30 reps |
High-level athlete | ~35–40 reps |
Full range of motion matters: heel drops fully down, then rises fully up.
If someone cannot reach at least 20 quality single-leg calf raises, they likely do not have enough calf capacity for running, hiking, or downhill loading.
Why This Matters for Downhill and Deceleration
When you walk or run downhill, your body is not pushing — it is braking.
The soleus helps:
Control forward movement of the tibia
Absorb shock
Reduce stress on the knee
Protect the Achilles
Improve endurance and efficiency
Downhill is a deceleration task. Deceleration requires the soleus muscle.
So if you are training for:
Hiking
Trail running
Skiing
Field sports
Court sports
Longevity and joint protection
…you should be training the soleus directly.
Best Exercises to Strengthen the Soleus
To target the soleus, the knee must be bent.
Best options:
Seated calf raises
Standing bent-knee calf raises
Single-leg calf raises
Heel-elevated wall sits
Slow lowering calf raises (great for downhill training)
How To start implementing this into your routine
Test your single-leg calf raises full depth (goal: 20–30 reps)
Add seated calf raises 2× per week (gradually increase load as tolerated)
Add slow lowering calf raises for downhill control
If you hike or run downhill, train calves with bent knee
Build toward strong, fatigue-resistant calves — not just big calves
Key Takeaway
Most people train the muscle that pushes them forward (gastrocnemius).
Very few train the muscle that slows them down (soleus).
But in life and sport, the ability to decelerate is what protects your:
Knees Ankles, Achilles, Feet
And that job belongs largely to the soleus muscle.
So if you want stronger legs, healthier knees, and better downhill control:
Don’t just train the push. Train the brake.
Raquel Lines, PT, ILM, PYT
Raquel Lines Wellness
Mountains & Missions Journal
The Art of Sustainable Performance
Key Research Articles
1. Soleus is a Primary Force Producer in Running
Hamner & Delp, 2013 — Journal of Biomechanics
2. Soleus Weakness Linked to Achilles Tendinopathy
O’Neill et al., 2019 — Physical Therapy in Sport
3. Soleus Produces Large Forces During Running
Dorn et al., 2012 — Journal of Experimental Biology
4. Soleus Size & Performance (Marathon Study)
Kovács et al., 2020 — Scientific Reports
5. Plantarflexors Control Forward Movement During Walking
Francis et al., 2013 — Gait & Posture
6. Soleus Helps Reduce Knee Load / ACL Load
Maniar et al., 2020 — Scandinavian Journal of Medicine & Science in Sports
Disclaimer: This content is provided for educational purposes only and is not intended as medical advice or a substitute for physical therapy or healthcare treatment. Always consult with a qualified healthcare professional before beginning a new exercise program, especially if you are experiencing pain or recovering from an injury.
