Stronger Calves and Achilles for Trail Running
Trail Notes | Strength, Injury & Recovery
build the lower leg that carries you further
Stronger Calves
and Achilles
Your calves and Achilles do not need to be protected from every hill. They need enough capacity for the hills you are asking them to carry.
Every climb, descent and hour on your feet asks something of the calf and Achilles complex. The muscles produce force, the tendon transfers it and the whole lower leg helps store and release energy with each step.
Problems often appear when the demand changes faster than the system can adapt. More vertical gain, faster running, a sudden increase in distance, different footwear or a return after time away can all alter the load.
This guide explains how to build lower-leg strength, manage training changes and respond when the Achilles begins to feel more reactive.
Tendons respond to appropriate load.
The important word is appropriate. The right load depends on the tendon, the person and what else the training week contains.
Trail Note · 01
Rest and rehabilitation are not opposites
Complete rest can settle symptoms temporarily, but it does not rebuild the capacity needed for running. At the same time, continuing unchanged through increasing pain can keep the tendon irritated.
Rehabilitation usually combines load modification with progressive calf exercise. You reduce or temporarily replace the part of training that is exceeding capacity while continuing tolerable movement and gradually strengthening the system.
Research supports tendon-loading exercise for midportion Achilles tendinopathy, but there is no single exercise protocol that is best for everyone. Heavy slow resistance, eccentric exercise and other progressive loading approaches can all be useful when appropriately prescribed.
The goal is not to avoid loading the tendon. It is to find the dose it can adapt to.
Trail Note · 02
Train both straight-knee and bent-knee strength
The calf complex includes the gastrocnemius and soleus. Both contribute to running, but changing the knee position changes how the work is shared.
Straight-knee calf raise
Raise and lower the heel with the knee straight. Begin with both legs or body weight if needed, then progress towards single-leg work and additional resistance as capacity improves.
Bent-knee calf raise
Perform the raise with the knee bent, either seated or standing. Progress the resistance gradually while maintaining a controlled range and tempo.
The correct number of repetitions, amount of weight, range and frequency depend on your current strength and whether the tendon is symptomatic.
If pain is near the heel attachment rather than through the middle of the tendon, exercise range may need to be modified to reduce compression. This is one reason an accurate assessment matters.
Trail Note · 03
Vertical gain is its own training load
Distance does not tell the whole story of a trail week. A run with sustained climbing can ask much more of the calves and Achilles than a flatter run of the same length.
When adding climbing, avoid simultaneously making the long run much longer, introducing faster work and changing footwear. Altering several demands together makes it difficult to know what the lower leg is responding to.
Her Trails coaching cue
Do not track only kilometres. Track climbing, harder running and the longest single session. Your lower leg experiences all of them.
Trail Note · 04
Let the terrain guide your technique
There is no single foot strike or posture that is correct for every runner and every gradient. Technique should help you remain balanced, controlled and responsive to the ground.
On climbs
Shorten your stride as the gradient increases.
Walk before your effort becomes unsustainable.
Use a steady rhythm rather than repeatedly surging.
On descents
Use shorter steps when the terrain becomes steep or technical.
Avoid reaching the foot far ahead and repeatedly braking.
Slow down or walk when fatigue reduces your control.
Trail Note · 05
Footwear can change the demand
Changes in heel-to-toe drop, stiffness, cushioning and fit can alter how a shoe feels and how load is distributed. A sudden move to a lower-drop or minimalist shoe can increase demand on the calf and Achilles for some runners.
A temporary heel lift or higher-drop shoe may reduce symptoms for some people, but neither addresses the whole rehabilitation picture. These options are best treated as short-term load-management tools and discussed with a physiotherapist when symptoms are present.
Any footwear change should be tested gradually in training. Race day is not the time to discover how your lower leg responds to a different setup.
Trail Note · 06
Fuel the whole training response
Tendon adaptation happens inside a body that also needs energy for training, recovery, hormones, immune function and daily life.
Adequate total energy, carbohydrate and protein support the broader recovery process. Under-fuelling can compromise health and adaptation, but an irritated Achilles should not automatically be assumed to be a nutrition problem.
Collagen or gelatin with vitamin C has shown promising effects on markers of collagen synthesis in small studies. Evidence that supplementation meaningfully improves Achilles pain, function or return to running remains limited.
Treat supplements as optional rather than the foundation. Progressive rehabilitation, appropriate training load and adequate everyday nutrition matter more.
Trail Note · 07
What we know about women and tendon health
Hormones may influence tendon structure and adaptation, but research has not established a reliable cycle-based Achilles training prescription.
Perimenopause, menopause, menstrual changes and low energy availability can form part of a woman’s broader health and training picture. They should be considered alongside age, strength, medication, previous injury, metabolic health and recent changes in load.
Track your own patterns if they are meaningful, but do not assume every tendon flare is hormonal or redesign an entire program around a theoretical vulnerable phase.
Hormones can be part of the context without becoming the explanation for everything.
Trail Note · 08
Use the next morning as feedback
Achilles symptoms often include pain or stiffness during the first steps after rest. The way the tendon responds later that day and the following morning can help guide the next training decision.
The response looks stable
Symptoms remain mild, movement is unchanged and morning pain or stiffness returns to its usual baseline.
The dose may have been too high
Pain increases through the session, changes how you move or morning symptoms are meaningfully worse than your recent baseline.
Seek urgent assessment
You feel a sudden pop or snap, develop marked swelling or bruising, cannot push off the foot, or cannot perform a calf raise after an acute event.
A pain score can be one useful measure, but it should not be the only decision rule. Trend, function and the following-day response matter too.
Trail Note · 09
Know when to get it assessed
Midportion Achilles pain and pain where the tendon meets the heel can require different rehabilitation choices. Calf strains, nerve-related pain and other conditions can also create symptoms in the same area.
Book an assessment if
Symptoms are worsening or appearing earlier in each run.
Pain changes your walking or running pattern.
Morning stiffness is increasing rather than settling.
You are unsure whether pain is through the tendon, at the heel or in the calf.
You have adjusted training but the overall trend is not improving.
Strong tendons are built across months, not repaired through one perfect exercise.
Build calf strength. Progress hills thoughtfully. Fuel the training. Watch the response. Ask for help before guessing becomes the plan.
build the lower leg that carries you further
Written by the Her Trails coaching team
Trail Notes are evidence-informed coaching journals written for women who train, race and run on trails.
General education only. This article does not diagnose Achilles or calf pain or replace assessment by a physiotherapist or doctor.
Key references
Chimenti et al. Midportion Achilles Tendinopathy Clinical Practice Guideline Revision, 2024.
de Vos et al. Dutch multidisciplinary guideline on Achilles tendinopathy, 2021.
This article focuses on general capacity building and midportion Achilles principles. Insertional Achilles pain may require different exercise ranges and load choices.
Keep moving with us
