What Is the Rathleff Protocol?

The Rathleff protocol is a high-load strength training program for plantar fasciitis (plantar fasciopathy) developed by researchers at Aalborg University in Denmark. It centers on performing slow, weighted heel raises with a towel placed under the toes to increase loading on the plantar fascia.

In a 2015 randomized controlled trial, Rathleff and colleagues found that this strength training approach produced better self-reported outcomes at 3 months compared to plantar-specific stretching combined with shoe inserts.

The protocol represents a shift in how plantar fasciitis is treated — from passive stretching toward progressive loading, reflecting the growing understanding that tendinopathies often respond better to controlled loading than to rest or stretching alone.

The Evidence Behind the Protocol

The Original Trial (2015)

The landmark study randomized 48 patients with ultrasound-confirmed plantar fasciitis into two groups:

  • Strength group: shoe inserts plus high-load strength training (heel raises with a towel under the toes) performed every second day
  • Stretch group: shoe inserts plus daily plantar-specific stretching

At the 3-month primary endpoint, the strength group showed a Foot Function Index score 29 points lower than the stretch group — a statistically and clinically meaningful difference. By 6 and 12 months, both groups had similar outcomes, suggesting that strength training may accelerate recovery without changing the long-term trajectory.

Follow-Up Research

Subsequent studies by the same research group and collaborators have expanded on the original findings:

  • A 2019 trial (Riel et al.) found that self-dosed and pre-determined progressive heavy-slow resistance training had similar effects in people with plantar fasciopathy, suggesting that patients can effectively self-manage their own loading progression.
  • The FIX-Heel trial (Riel et al., 2020/2023) investigated whether adding a corticosteroid injection to the exercise program provided additional benefit beyond exercise plus patient advice and a heel cup.

How to Perform the Rathleff Protocol

Equipment Needed

  • A step, stair, or thick book (approximately 10 cm high)
  • A hand towel or small towel rolled into a cylinder
  • A wall or railing for balance support
  • Weights for progression (a backpack with books, a dumbbell, or a weight vest)

The Exercise: Towel Heel Raise on a Step

Setup:

  • Place the rolled towel on the edge of the step
  • Stand on the step with the balls of your feet on the edge, heels hanging off
  • Position the toes of the affected foot on the rolled towel — this places the toes in dorsiflexion, which increases tension on the plantar fascia during the exercise
  • Hold a wall or railing for balance

Execution:

  • Raise up onto your toes slowly over 3 seconds (concentric phase)
  • Hold at the top for 2 seconds (isometric hold)
  • Lower slowly over 3 seconds until your heels drop below the step edge (eccentric phase)

The tempo matters. The slow speed ensures high load on the plantar fascia and calf muscles throughout the full range.

Progression Schedule

The protocol progresses over approximately 12 weeks by reducing repetitions, increasing sets, and adding external load:

Week 1–2:

  • 3 sets of 12 repetitions
  • Both legs (bilateral)
  • No added weight
  • Every second day

Week 3–4:

  • 4 sets of 10 repetitions
  • Transition from bilateral to unilateral (single leg) when able
  • Add weight if sets feel manageable
  • Every second day

Week 5 onward:

  • 5 sets of 8 repetitions
  • Single leg
  • Progressive weight addition as tolerated
  • Every second day

How to Add Weight

The original protocol used a backpack filled with books as an accessible way to add load. Other options include:

  • Holding a dumbbell or kettlebell
  • Wearing a weighted vest
  • Holding a gallon water jug

Add weight in small increments when you can complete all prescribed sets and reps with good form and without significant symptom increase the following morning.

Managing Pain During the Exercise

The Rathleff protocol acknowledges that some discomfort during the exercise is expected and acceptable. This is different from stretching protocols where pain is typically avoided.

Guidelines for pain management:

  • Mild to moderate discomfort during the exercise is acceptable
  • Pain should not be significantly worse the morning after exercise compared to a typical morning
  • If morning pain increases substantially the day after, reduce the load or repetitions
  • Pain that is still elevated 24 hours after exercise suggests the load was too high

Why Towel Under the Toes?

Placing a rolled towel under the toes serves a specific biomechanical purpose. By keeping the toes in a dorsiflexed position during the heel raise, the plantar fascia is pre-tensioned through the windlass mechanism. This means the exercise loads the plantar fascia more directly than a standard heel raise would.

This targeted loading is the key difference between the Rathleff protocol and a general calf strengthening program.

Who May Benefit from This Protocol

The Rathleff protocol may be appropriate for:

  • People with plantar fasciitis who have not responded to stretching alone
  • People with symptoms lasting more than 4–6 weeks
  • Active individuals who want to maintain a structured progression
  • Anyone looking for an evidence-based exercise approach beyond passive treatments

Who Should Be Cautious

Consider modifications or clinical guidance if you:

  • Have very acute, recent-onset heel pain (the protocol may be too aggressive initially — start with stretching and progress to loading)
  • Have difficulty with balance or standing on one leg
  • Have other foot conditions such as stress fractures, nerve entrapments, or rheumatological conditions
  • Experience sharp, worsening pain with every attempt at the exercise

In these cases, a physiotherapist can modify the starting load and progression rate.

Combining the Rathleff Protocol with Other Treatments

The protocol does not need to be performed in isolation. The research trials used the following as baseline treatments for all participants:

  • Shoe inserts or heel cups for daily wear
  • Patient education about load management and activity modification
  • General advice on footwear

Other treatments that can be combined with the protocol include:

  • Calf stretches (gastrocnemius and soleus) before or after the heel raises
  • Plantar fascia stretches, particularly in the morning before getting out of bed
  • Self-massage using a frozen water bottle or tennis ball roll
  • Activity modification to reduce aggravating loads during the initial weeks

Rathleff Protocol vs. Stretching Alone

The key differences:

  • Load: The Rathleff protocol uses progressive resistance; stretching uses body weight or passive positioning
  • Mechanism: Strength training promotes tendon adaptation and increased load tolerance; stretching primarily reduces muscle tension
  • Speed of improvement: The strength group improved faster at 3 months, though both groups converged by 12 months
  • Effort: The protocol requires more discipline and structure than a simple stretching routine

For people willing to commit to a structured program, the evidence suggests that heavy slow resistance training offers a faster path to improvement. For those who prefer a simpler approach, stretching combined with appropriate footwear and load management remains a reasonable option.

FAQ

How long does the Rathleff protocol take to work?

The original trial showed meaningful improvement at 3 months. Some people notice changes sooner, particularly in morning pain and pain with the first steps after rest. Consistent adherence every second day is important for results.

Do I need to do the exercise every day?

No. The protocol specifies every second day (approximately 3–4 times per week). This allows recovery time between sessions, which is important for tendon adaptation.

Can I do the exercise without a step?

You can perform the exercise on flat ground, but you lose the eccentric lowering phase below neutral, which is part of the loading stimulus. A step, stair, or thick book provides the full range of motion.

What if the exercise is too painful to start?

Start with bilateral (two-leg) heel raises on flat ground without a towel. Once you can perform these comfortably, progress to the step, add the towel, and eventually move to single-leg. The key is finding a starting point that is challenging but tolerable.

Can I combine this with running or walking?

Yes, but monitor your total daily load. If running or long walks are significantly worsening your symptoms, reduce those activities while building up the heel raise protocol. As your tolerance improves, gradually reintroduce impact activities.

Is this the same as calf raises?

Mechanically similar, but with two key differences: the towel under the toes pre-tensions the plantar fascia (standard calf raises do not), and the tempo is deliberately slow (3 seconds up, 2 seconds hold, 3 seconds down) to maximize loading time on the tissues.

References

  • Rathleff MS, Molgaard CM, Fredberg U, et al. High-load strength training improves outcome in patients with plantar fasciitis: A randomized controlled trial with 12-month follow-up. Scandinavian Journal of Medicine and Science in Sports. 2015;25(3):e292-e300.
  • Riel H, Jensen MB, Olesen JL, et al. Self-dosed and pre-determined progressive heavy-slow resistance training have similar effects in people with plantar fasciopathy: a randomised trial. Journal of Physiotherapy. 2019;65(3):154-161.
  • Riel H, Vicenzino B, Olesen JL, et al. Corticosteroid injection plus exercise versus exercise, beyond advice and a heel cup for patients with plantar fasciopathy: protocol for a randomised clinical superiority trial (the FIX-Heel trial). Trials. 2020;21(1):49.
  • Riel H, Vicenzino B, Olesen JL, et al. Does a corticosteroid injection plus exercise or exercise alone add to the effect of patient advice and a heel cup for patients with plantar fasciopathy? A randomised clinical trial. British Journal of Sports Medicine. 2023;57(22):1438-1444.
  • Moller M, Riel H, Wester JU, et al. Surgical or non-surgical treatment of plantar fasciopathy (SOFT): study protocol for a randomized controlled trial. Trials. 2022;23(1):835.

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