ippon blade® Official Running Safety Guidelines

Enjoy your practice safely, and learn to move without unnecessary strain.

ippon blade is intended to help you learn how to use your body without unnecessary strain and develop your movement and balance. Notice your body’s responses, use the effort you need while reducing excessive tension, and adapt to your condition and surroundings.

Forcing yourself to use ippon blade for longer, or continuing through fatigue or discomfort, does not mean you will gain greater benefits. Walking, resting, shortening a session and stopping are all appropriate choices. Value controlled, adaptable movement rather than distance or finishing alone.

TENARI establishes these official recommendations for personal running practice and participation in running events. They are TENARI’s own usage guidelines, not an independent safety certification.

Scope: These guidelines cover adult road running and event participation using the ZEN and MIROKU models.

Issued: 18 October 2026 · Revised: 19 October 2026 · TENARI Co., Ltd. · English edition

Experience behind these guidelines

Over approximately ten years of single-tooth geta practice, developer TEN completed 100 km events at Okuizumo in 2017, Hakusan–Shirakawago in 2018, and Tobishima Kaido in 2022. The 2017 result predates the introduction of ippon blade in 2018.

Approximately eight years of product development, improvement, teaching, daily use and users’ event participation have accumulated since ippon blade was introduced. Decisions to stop partway through a run, and changes made in response to the body, also inform these guidelines.

These achievements belong to particular practitioners under particular conditions. They neither establish the same recommended distance for everyone nor guarantee safety. A 100 km run is not a standard or a target for general users.

1. Upper distance guideline for choosing a running event

For well-prepared general users entering a running event, the upper distance guideline is approximately 20 km, including events up to one half marathon: 21.0975 km (approximately 13.1 miles).

This is an upper guideline for choosing an event, not a recommendation to run 20 km in everyday practice. Neither 20 km nor a half marathon is a goal or quota you need to reach. Choose a shorter event that suits you, and participate only when skill, health, equipment and environmental conditions are appropriate.

This is an operational upper guideline set by TENARI for event participation. It is not a scientifically established threshold at which running becomes safe or unsafe. Shorten or stop a run whenever your condition or circumstances require it, even within this event-distance guideline.

Shorter runs can still involve substantial effort at higher speeds. Consider slopes, surfaces, weather, time on your feet and fatigue together. Breaks or splitting a session do not remove the need to assess the total load.

2. Skills to establish before running

Even experienced runners need to learn ippon blade-specific skills progressively. Follow the intended use, sizing and instructions for your model. Before running, you should be able to:

• Fit and adjust the straps so that your feet do not slip excessively and there is no compression or numbness.
• Stand, walk, stop and turn in control, and deliberately slow down or change from running to walking.
• Maintain contact through the tooth without repeatedly striking the front or rear edge of the platform against the ground.
• Observe your surroundings and foot placement, leave space around people and obstacles, and adapt speed and stride to changes in slope or surface.

Begin on a level, clearly visible surface away from traffic and crowded areas. Review official instructions and any lecture videos supplied with your purchase. If you are unsure about fit or technique, consult TENARI or an authorized instructor who provides ippon blade running instruction.

3. Everyday practice: start short and finish with capacity to spare

There is no fixed recommended distance or distance target for everyday practice. The approximately 20 km event-distance guideline does not describe your daily training volume.

Start with brief sessions and short distances suited to your current condition and proficiency. Focus on moving without unnecessary strain, rather than running farther. Finish before exhaustion, while you still have capacity for controlled movement and clear judgment. A short session or walking alone is a valid choice.

Keep enough capacity to notice your breathing, contact with the ground and balance, and make adjustments. Progress also means moving more comfortably over the same distance and adapting to changing conditions.

Progress from walking to short runs. Check how you feel during practice, after it and over the following days. Increase time or distance gradually only when appropriate. Do not increase distance, speed and slope together, or increase the load while significant fatigue or pain remains.

Prepare suitable clothing, fluids and fuel, a way to contact help and a return plan. Change your route or stop if slippery or icy surfaces, poor visibility, traffic or crowds prevent controlled running.

These guidelines are for adult road running. Do not directly apply them to mountain or trail activities, competitive high-speed running, or long-distance running by minors.

4. Inspect your ippon blade before each use

• Check the platform and tooth for cracks, chips and looseness.
• Check the sole for excessive wear or separation.
• Check straps for damage, looseness and appropriate fit.

Stop using the product if you find a problem and seek advice about repair or replacement. Do not continue running with unapproved structural modifications or temporary repairs.

After changing model, size or adjustment, start again with short practice sessions. A lower model or a finish achieved in another model does not by itself establish safety.

5. Before entering a running event

• Event rules and entry requirements: Before entering, read the event rules and entry information, and follow any footwear or equipment restrictions and participation conditions. These guidelines do not require every participant to contact the organizer or obtain individual permission. If the event rules require advance confirmation or an application, follow that procedure.
• Relevant preparation: Practice with the same model, adjustment and carried equipment, preparing for the expected surfaces, slopes and time on your feet. Choose a shorter event for your first participation. A pre-event assessment by an instructor who teaches ippon blade running is recommended.
• Time limits: Allow for drinking, fueling, walking and rest without relying on forced acceleration. Do not ignore a stopping condition to reach a cutoff.
• Other participants: Leave space at starts and aid stations. Avoid sudden changes of direction and risky overtaking. Follow organizers’, officials’ and medical staff’s instructions.

Do not start when you have a fever, chest symptoms, dizziness, illness, pain affecting movement or substantial fatigue. If you have an ongoing medical condition, a history of chest pain or fainting during exercise, or concerns identified at a health check, discuss participation with a medical professional beforehand.

6. When to slow down, rest or stop

Absence of pain alone is not a reason to continue. Monitor leg movement, contact, balance, breathing and attention. The following decisions take priority over distance and finishing.

Slow down, walk or rest as your capacity decreases

If breathing becomes harder to regulate, fatigue increases or tension builds, slow down and switch to walking or rest. End the session if controlled movement and clear judgment do not return.

End ippon blade running for the day if control is lost

Stop if your legs no longer respond or transmit force as expected, your hips or knees become stiff and difficult to move, contact repeatedly becomes unstable, or slowing and stopping become difficult.

Stop for pain or injury affecting movement

Stop running if pain, swelling, numbness or skin injury changes how you move. Seek medical assessment if symptoms are severe or persist.

Seek help for chest symptoms or altered awareness

Stop immediately and seek medical help for chest pain or discomfort, cold sweats, severe breathlessness, unsteadiness or altered awareness. Call the local emergency number for altered consciousness or severe or persistent symptoms. In Japan, call 119; outside Japan, use the emergency number for your location.

End the day’s ippon blade running after a fall or equipment problem

After a fall, stop running in ippon blade for the day and check your body and equipment. Stop for breakage, looseness or sole separation as well.

When a condition requires ending the session, do not restart simply because you feel better after a brief rest. If you cannot move safely, request assistance or transport.

7. Considering events beyond a half marathon

Events beyond a half marathon exceed the general-user event-distance upper guideline. Experienced runners considering them need consistent ippon blade practice, experience of running and recovering from approximately a half marathon, and plans for fueling, rest and withdrawal appropriate to the intended distance. Assess the course and time limits as well.

Advance consultation with an authorized instructor who teaches ippon blade running is recommended. Consultation or a technique assessment does not bring that event distance within the general-user guideline.

Finishing a full marathon is not a required step toward longer distances. Choose a range in which you can enjoy practice and deepen your understanding of movement.

8. TENARI-organized events

These guidelines also apply when TENARI plans general-user running events. General-user distances are limited to a half marathon or less, with shorter distances for beginners as appropriate to their skills and local conditions.

Organizers should arrange pre-event skill checks, assess the route, crowds and weather, allow slowing down and walking, provide withdrawal and return arrangements, and prepare emergency communication and medical support. Encouraging a finish must never interfere with a participant’s decision to stop.

Longer events require a separate framework addressing participant eligibility, route, medical assistance, transport and cancellation criteria. These guidelines alone do not authorize such events or participation.

9. Safety, warranty and future review

These guidelines aim to reduce the risk of accidents and injury and support enjoyable, continuing practice. They do not guarantee injury-free use or a finish. When exceeding the event-distance upper guideline, or running beyond what their condition allows, even experienced users may encounter loads they cannot manage, falls, injury or deteriorating health.

Exceeding the event-distance upper guideline does not automatically exclude every form of compensation or responsibility. Product warranties, accident liability and event insurance are determined under the relevant terms, circumstances and applicable law.

TENARI will review these guidelines in light of experience, including model, proficiency, distance and duration, surface and weather, changes during a run, reasons for stopping, falls or injuries, and recovery afterward.

Notice your body’s responses and learn to choose the practice that suits you. Develop that ability while enjoying movement with ippon blade.

Related information

Japanese edition

General marathon health guidance from the Japanese Society of Physical Fitness and Sports Medicine and Japan Association of Athletics Federations (Japanese PDF)

The external resource provides general health and emergency guidance. It is not a certification or endorsement of ippon blade or of the distance limits in this document.