Achilles tendon · Research & rehabilitation

Achilles tendon.
Understand the load.

A walk through the clinic tells only part of the story. Explore how force and pressure measurements can help you study Achilles tendon loading, follow changes in movement and put rehabilitation into context.

Explore the applications Read the research

With loadsol®, pedar® and emed® by novel.

Runner in a navy kit mid-stride, isolated from the supplied stadium image.

Questions worth measuring

From everyday steps
to rehabilitation research.

The most useful measurement starts with a clear question. These are the most relevant applications in the research reviewed here, from patient monitoring to exploratory laboratory studies.

01 Daily activity · loadsol

What happens between appointments?

Step counts tell you how much someone moves. Force measurements add information about how each step is loaded. Researchers have used loadsol with a biomechanical model to study daily Achilles loading in people with tendinopathy.

A study of 15 people, with 6–14 recorded days each across two weeks, linked some higher-load exposure measures with better calf function. It did not establish an ideal daily dose or show that increasing load caused recovery. Daily-life tendinopathy study

Useful for: studying loading exposure, variation between days and relationships with function.

02 Rupture rehabilitation · loadsol

How does a walking boot change loading?

Boot angle, construction and walking speed can all influence estimated Achilles tendon force. Instrumented-boot studies help researchers compare these conditions and understand what an external weight-bearing instruction actually means for tendon loading.

Studies in healthy volunteers show that boot settings matter. These findings support controlled comparisons; they do not prescribe a safe setting for a healing tendon. Boot configuration study Instrumented-boot method

Useful for: evaluating rehabilitation protocols and documenting loading under defined boot conditions.

03 Running & exercise · loadsol

What changes when the task changes?

In-shoe measurements let researchers compare the same person across controlled conditions. An outdoor study in 30 healthy runners found that longer ground contact time reduced estimated peak Achilles tendon force. It examined an immediate mechanical response, not injury prevention. Outdoor running study

For exercise research, a three-zone insole algorithm has also been validated for estimating plantarflexion moments during walking, running and selected tasks including heel raises and jumps. Exercise measurement study

Useful for: comparing gait cues and exercise demands, with analysis suited to the task and population.

04 Pressure transfer in recovery · pedar

Is heel-to-toe loading returning?

After a rupture, walking can look different even as symptoms improve. pedar shows how pressure travels under the foot inside the shoe. In an early-recovery study, researchers followed pressure progression alongside ultrasound and patient-reported function over 12 weeks. Gait recovery study

A separate study in healthy adults used pedar with ultrasound and muscle-activity measurements to compare ankle-foot orthosis settings. This adds a view of pressure redistribution, rather than a direct measure of tendon healing. Orthosis study

Useful for: repeated gait assessment, tracking push-off patterns and comparing braces or footwear.

05 Barefoot function · emed

Are loading differences still present?

Returning to activity does not necessarily mean both feet load in the same way. An emed study within a doctoral thesis found regional barefoot loading differences in six male athletes around two years after Achilles repair. Its small sample makes this exploratory evidence. Post-repair gait thesis

emed can help document these patterns in a standardized assessment. A second thesis combines barefoot pressure with ultrasound in diabetic-foot research, providing broader context rather than evidence for Achilles injury prediction. Diabetes and tissue-properties thesis

Useful for: investigating residual regional asymmetry and compensatory foot loading.

06 Muscle–tendon mechanics · loadsol

How do anatomy and tissue properties matter?

Force measurements become more informative when combined with other methods. Researchers have paired loadsol with ultrasound, muscle-activity recordings and metabolic measurements to investigate running mechanics and hypermobility-related conditions.

These studies explore tendon moment arms, calf muscle force and walking tolerance. They show the value of a combined research setup; the ultrasound and other systems supply information that a force insole alone cannot provide. Running mechanics Muscle force in hypermobility Walking tolerance

Useful for: studying individual muscle–tendon mechanics and connective-tissue disorders.

From a sensor signal to a research result

Foot loading is measured.
Tendon force is estimated.

This distinction is central to interpreting Achilles research. None of these three systems measures force inside the Achilles tendon directly.

  1. 01 / Measure

    Capture the foot–surface interaction

    loadsol records normal force beneath the foot. pedar and emed record plantar pressure distribution, from which regional loading measures can be calculated.

  2. 02 / Model

    Estimate the tendon’s mechanical demand

    In the cited loadsol studies, algorithms combine three-zone force data with lever arms and other assumptions to estimate ankle moment and tendon force. Boot protocols may require additional sensors and calibration. Moment algorithm Boot protocol

  3. 03 / Interpret

    Connect the result with the person

    Consider symptoms, calf strength, walking conditions, clinical examination and, where relevant, imaging. A loading trace alone cannot tell you whether a tendon has healed.

Three systems. Different questions.

Choose the measurement
that fits your study.

Start with the outcome you need, then choose the sensor layout, recording setup and analysis method.

Mobile in-shoe force

loadsol®

For questions about force over time, loading across steps and activity outside the laboratory.

Measures
Normal plantar force; regional force with an appropriate multi-zone insole.
Achilles research fit
Daily loading exposure, boot studies and model-based estimates during walking or running.
Plan for
The correct sensor zones, calibration and a validated analysis protocol. A research model is not automatically a standard product output.
Explore loadsol

In-shoe pressure distribution

pedar®

For questions about where the foot loads the shoe and how that distribution changes.

Measures
Dynamic plantar pressure distribution inside footwear.
Achilles research fit
Heel-to-toe pressure progression, regional loading and orthosis comparisons.
Plan for
Consistent footwear, anatomical regions and walking or running speed. Tendon properties in the cited studies were assessed with separate ultrasound methods.
Explore pedar

Barefoot pressure platform

emed®

For questions about barefoot foot function and regional plantar loading in a controlled setting.

Measures
Plantar pressure distribution during barefoot standing or movement across the platform.
Achilles research fit
Complementary foot-function assessment and research relating plantar loading to tissue measurements.
Plan for
A repeatable platform protocol. Ultrasound or elastography measures tendon properties separately.
Explore emed

What the evidence can tell us

Can we predict
an Achilles injury?

The studies reviewed here support measuring foot loading and developing models of tendon loading. They do not establish a validated tool that predicts an individual’s future tendinopathy, rupture or re-rupture.

Estimating load is already a valuable step.

In wearable research, “prediction” often refers to estimating a mechanical quantity. A 2026 study used boot accelerometry to estimate per-step peak Achilles tendon load in rupture patients, with insole-based estimates as the reference. That is different from predicting who will sustain an injury. Wearable load-estimation study

Injury prediction remains a research question.

Following loading alongside symptoms and function could help future studies investigate risk or recovery. Establishing clinical prediction would require prospective outcome data, independent validation and useful decision thresholds.

Use loading data to inform an assessment. These studies do not provide a universal safe-load threshold or a stand-alone return-to-sport clearance rule.

Make comparisons meaningful

Build a repeatable
measurement routine.

For research or clinical monitoring, a consistent setup makes change easier to interpret.

  1. Define the question. Separate tendinopathy, rupture rehabilitation and healthy-participant studies. Decide whether you need force, regional pressure or a model-derived tendon outcome.
  2. Record the conditions. Keep track of footwear, boot angle, walking speed, sensor layout and calibration. Document meaningful changes between visits.
  3. Pair loading with function. Add the clinical or research outcomes relevant to the question, such as symptoms, heel-raise performance, strength or imaging.
  4. Look at the whole pattern. Compare repeated measurements with the person’s own baseline. Limb symmetry or a lower peak alone does not establish recovery.

Let’s talk about your research

What would you like
to measure?

Tell us about your participants, activities and intended outcomes. We can help you choose a suitable novel measurement setup.

Discuss your application

The evidence behind the page

Research & references.

Explore the publications, conference abstracts, theses and open research materials. Journal articles are listed separately from preliminary work. Linked preprints and later journal versions describe the same research, not independent confirmation.

Journal articles12 references
  1. In-Vivo Force-Length Relationship of the Medial Gastrocnemius Muscle in Hypermobile Ehlers-Danlos Syndrome and Hypermobility Spectrum DisordersJournal article

    Golden DW, Oliemans JP, Ladell AJM, Walls KD, Bennett EC, Skaper SJ, Asmussen MJ, Manocha RHK, Fletcher JR · 2026. Journal of Musculoskeletal and Neuronal Interactions. 2026;26(1):1–12.

    Force measurement combined with ultrasound to study calf muscle mechanics in hypermobility; not an Achilles injury-prediction study.

  2. Increasing ground contact time reduces Achilles tendon forces during rearfoot strike running outdoorsJournal article

    Aubol KG, Grävare Silbernagel K, Baxter JR, Shewokis PA, Milner CE · 2026. Journal of Science and Medicine in Sport. 2026;29(1):100–105. Online August 21, 2025.

    Outdoor running experiment in healthy adults. Review based on the published abstract and publisher excerpts; complete article unavailable.

  3. Two-week cumulative tendon load estimated from insole sensor contact forces is associated with plantar flexor function in Achilles tendinopathyJournal article

    Song K, Kwon MP, Smith AK, Pohlig RT, Grävare Silbernagel K, Baxter JR · 2026. Scientific Reports. 2026;16:9495.

    Daily-life study of 15 people with tendinopathy. Associations with function do not establish a treatment dose or causal effect.

  4. To what extent do the muscles and tendons influence metabolic cost and exercise tolerance in the hypermobile Ehlers-Danlos Syndrome and Hypermobility Spectrum Disorders?Journal article

    Sheehan DS, Oliemans JP, Golden DW, Walls KD, Bennett EC, Skaper SJ, Asmussen MJ, Manocha RHK, Fletcher JR · 2026. Clinical Biomechanics. 2026;131:106695. Online November 13, 2025.

    Combined force, ultrasound and physiological measurements in hypermobility. Publisher-indexed sections reviewed; complete publisher file unavailable.

  5. How do differences in Achilles’ tendon moment arm lengths affect muscle-tendon dynamics and energy cost during running?Journal article

    Bennett EC, Machado E, Fletcher JR · 2023. Frontiers in Sports and Active Living. 2023;5:1125095.

    Running study combining loadsol, ultrasound and other measurements to investigate tendon moment arms and muscle–tendon mechanics.

  6. The Difference in Achilles Tendon Loading within Immobilizing Boots Based on Ankle Angle, Boot Type, and Walking SpeedJournal article

    Hullfish TJ, Woods MM, Kwon MP, Boakye LAT, Humbyrd CJ, Baxter JR · 2024. Orthopaedic Journal of Sports Medicine. 2024;12(10):23259671241283806.

    Healthy-volunteer comparison of boot angle, construction and walking speed. No patient healing or re-rupture outcomes tested.

  7. Continuous Estimation of Achilles Tendon Loading in Rupture Patients Using a Single Boot-Mounted AccelerometerJournal article

    Godshall S, Boakye LAT, Halilaj E, Humbyrd CJ, Baxter JR · 2026. IEEE Transactions on Neural Systems and Rehabilitation Engineering. 2026;34:3245–3254.

    Personalized estimation of per-step peak load in 19 rupture patients. Published abstract and matching preprint reviewed; journal full text unavailable.

  8. Wearable sensor and machine learning estimate tendon load and walking speed during immobilizing boot ambulationJournal article

    Kwon MP, Hullfish TJ, Humbyrd CJ, Boakye LAT, Baxter JR · 2023. Scientific Reports. 2023;13:18086.

    Boot-mounted motion-sensor models trained against force-derived tendon-load estimates. Healthy participants; load estimation, not injury prediction.

  9. A simple instrumented insole algorithm to estimate plantar flexion momentsJournal article

    Todd J. Hullfish, Josh R. Baxter · 2020. Gait & Posture 79:92-95

    Validates plantarflexion-moment estimation in seven healthy adults across walking, running and selected exercises.

  10. Instrumented immobilizing boot paradigm quantifies reduced Achilles tendon loading during gaitJournal article

    Todd J. Hullfish, Kathryn M. O'Connor, Josh R. Baxter · 2020. Journal of Biomechanics 109:109925

    Five healthy participants; custom instrumented boot and model-based tendon-load estimates.

  11. Relationship between tendon structure, stiffness, gait patterns and patient reported outcomes during the early stages of recovery after an Achilles tendon ruptureJournal article

    Didier Laurent, Lorcan Walsh, Amir Muaremi et al. · 2020. Scientific Reports 10:20757

    Small early-recovery cohort followed with in-shoe pressure, ultrasound and patient-reported outcomes over 12 weeks.

  12. The Effect of Ankle Foot Orthosis' Design and Degree of Dorsiflexion on Achilles Tendon Biomechanics—Tendon Displacement, Lower Leg Muscle Activation, and Plantar Pressure During WalkingJournal article

    Åsa Fröberg, Mattias Mårtensson, Anton Arndt · 2020. Frontiers in Sports and Active Living 2:16

    Healthy-volunteer comparison of orthosis settings using pedar, ultrasound and muscle-activity recordings.

Conference abstracts9 preliminary reports
  1. Cross-System Agreement of Relative Achilles Loading Levels in Dynamic TasksConference abstract

    John F. Drazan; Melanie Napierala; Joseph P. Duszak; Matthew J. Manduca; Jack T. Felipe; Stephanie G. Cone · 2025. ORS conference abstract 883; not a full journal article

    Preliminary comparison of relative Achilles loading across movements using force insoles and shear-wave tensiometry.

  2. Peak Achilles Tendon Loading During On-Court Basketball Activities Vary by Prior Formal Basketball Experience, not Age, Across College-Aged and Middle-Aged AdultsConference abstract

    Matthew J. Manduca; Aidan P. Rahill; Roy F. Cook; Demia Bland; John F. Drazan · 2025. ORS conference abstract 1722

    Exploratory on-court loading comparisons in recreational male basketball players; no prospective injury outcomes.

  3. Sensor-Measured Achilles Tendon Load is Associated with Plantarflexor Dynamic Function in Achilles TendinopathyConference abstract

    Ke Song; Michelle P. Kwon; Andy K. Smith; Ryan T. Pohlig; Karin Grävare Silbernagel; Josh R. Baxter · 2025. ORS conference abstract 317

    Earlier report from the daily-life tendinopathy study. Use final journal article daily-life loading for principal findings and statistics.

  4. Using An Instrumented Insole To Detect Changes In Achilles Tendon Loading Between Pregnant Women In Their First Trimester And Pregnant Women In Their Third TrimesterConference abstract

    Afua Nkansah-Andoh; Michelle Meyers; Devyn Russo; Ke Song; Casey Humbyrd; Josh Baxter · 2025. ORS conference abstract 1978

    Exploratory comparison of first- and third-trimester walking. Proposed pain prediction was not tested.

  5. Two weeks of Achilles tendon loading monitored by instrumented insole is associated with plantarflexor functionConference abstract

    Ke Song; Michelle P. Kwon; Andy K. Smith; Karin Grävare Silbernagel; Josh R. Baxter · 2024. ASB conference abstract; PDF page 97

    Earlier report from the 15-person tendinopathy cohort; related to final journal article daily-life loading.

  6. Tendon Loads Measured over 2 Weeks of Daily Living are Associated with Achilles Tendinopathy Patient OutcomesConference abstract

    Ke Song; Michelle P. Kwon; Andrew K. Smith; Karin Grävare Silbernagel; Josh R. Baxter · 2024. ORS conference abstract 1708

    Small daily-life monitoring pilot; related to later work daily-life loading, not independent confirmation.

  7. Using an instrumented insole to estimate Achilles tendon loading in pregnant women during walkingConference abstract

    Afua Nkansah-Andoh; Michelle Meyers; Devyn Russo; Casey Humbyrd; Josh Baxter · 2024. BMES Annual Meeting poster CC2, 26 October 2024

    Preliminary pregnancy-versus-control walking comparison; different comparison groups from trimester comparison.

  8. Estimating tendon load and walking speed using an instrumented immobilizing bootConference abstract

    Michelle P. Kwon; Todd J. Hullfish; Lorraine A.T. Boakye; Josh R. Baxter · 2023. ASB conference abstract; PDF page 7

    Earlier boot-model analysis from the research programme subsequently reported in wearable boot-sensor models.

  9. Achilles Tendon Loading During Walking Differs Between Commonly Used Immobilizing BootsConference abstract

    Josh R. Baxter; Todd J. Hullfish; Daniel C. Farber; Casey J. Humbyrd · 2022. Foot & Ankle Orthopaedics conference abstract/supplement; first online 10 November 2022 despite DOI suffix containing 21

    Very small boot-comparison pilot in two healthy men. See the larger published study boot configuration.

Doctoral theses2 theses
  1. Elastography and Ultrasound of the Plantar Soft Tissues and Achilles Tendon in DiabetesDoctoral thesis

    Benedictine Yen Chen Khor · 2024. PhD thesis, Glasgow Caledonian University

    Contextual diabetic-foot thesis; emed pressure measurements were paired with separate ultrasound methods. Not Achilles injury-prediction evidence.

  2. Gait analysis and muscoloskeletal modelling used in athletes recovery from Achilles tendon ruptureDoctoral thesis

    Dong Sun · 2020. PhD thesis, University of Pannonia

    Exploratory post-repair research in six male athletes. Barefoot pressure measurements and separate movement/modeling methods.

Preprints & open data3 preprints + 1 dataset; linked to journal articles above
  1. Two-week cumulative tendon load estimated from insole sensor contact forces is associated with plantar flexor function in Achilles tendinopathyDataset

    Ke Song; Michelle P. Kwon; Andy K. Smith; Ryan T. Pohlig; Karin Grävare Silbernagel; Josh R. Baxter · 2026. Open dataset, version 1, posted 11 February 2026

    Companion dataset and analysis code for daily-life loading. Repository metadata reviewed; raw data were not reanalysed.

  2. Continuous Estimation of Achilles Tendon Loading in Rupture Patients Using a Single Boot-Mounted AccelerometerPreprint

    Stanton Godshall; Lorraine A.T. Boakye; Eni Halilaj; Casey Jo Humbyrd; Josh R. Baxter · 2026. medRxiv preprint, 11 March 2026; subsequently published

    Preprint version of the subsequently published journal article accelerometer-based load estimation. Not an additional independent study.

  3. Two weeks of cumulative tendon load monitored by insole sensors is associated with plantar flexor function in Achilles tendinopathyPreprint

    Ke Song; Michelle P. Kwon; Andy K. Smith; Ryan T. Pohlig; Karin Grävare Silbernagel; Josh R. Baxter · 2025. medRxiv preprint, 2 July 2025; subsequently published

    Preprint version of the subsequently published journal article daily-life loading. Final wording and statistics may differ.

  4. Wearable sensor and machine learning accurately estimate tendon load and walking speed during immobilizing boot ambulationPreprint

    Michelle P. Kwon; Todd J. Hullfish; Casey J. Humbyrd; Lorraine A.T. Boakye; Josh R. Baxter · 2023. medRxiv preprint, 5 June 2023; subsequently published

    Preprint version of the subsequently published journal article wearable boot-sensor models. Final journal article preferred for claims.