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ASO ankle brace: what it is, how it is sized, and who it suits
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- ASO Ankle Stabilizer (Med Spec). Best for: People who want a lace up brace with full figure-eight straps that fits either foot. See options on Amazon
- Generic lace up ankle brace with figure-eight straps. Best for: People who want the same style from another maker. See options on Amazon
- Semi-rigid stirrup ankle brace. Best for: Early walking after a sprain when you want firm side shells. See options on Amazon
- Ankle compression sleeve. Best for: Mild swelling or achiness without instability. See options on Amazon
How the ASO is built
Med Spec describes the original ASO as a lace up boot with these features:
- Figure-eight stabilizing straps. Angled straps contour above the ankle bones and form a complete figure-eight, which the maker says helps stabilize the subtalar and talocrural joints (the two joints below and at the ankle).
- Elastic cuff. A woven elastic cuff with rounded edges wraps the top to keep laces and straps secure.
- CoolFlex padding. Padding with spandex fiber along the Achilles tendon and the top of the foot, and spacer mesh in the tongue.
- Centered lace. The shoe lace is attached to the tongue so it stays centered.
- No seam underfoot. The maker moved the seam to the back of the boot.
- Fits either foot. The maker says it is bilateral and fits left or right.
Who the maker designed it for
Med Spec lists these indications:
- Inversion or eversion ankle sprains (rolling in or out).
- Medial or lateral ankle instability.
- Subtalar joint instability.
That puts the ASO in the lace up category. The NATA position statement says both lace up and semi-rigid ankle braces, as well as taping, are effective at reducing recurrent sprains, and recommends that athletes with a history of sprains wear taping or bracing for all practices and games. For how lace ups compare with other styles, see our lace up ankle brace guide.
The maker's indications describe what the brace is designed to support, not a diagnosis. If you are not sure whether your ankle problem is a sprain, instability or something else, such as a tendon problem on the outside of the ankle, get it assessed first. Our ankle brace for peroneal tendonitis page covers outer ankle tendon pain.
ASO sizing chart, from the maker
| Size | Ankle circumference |
|---|---|
| XX-Small | 9 to 10 inches |
| X-Small | 10 to 11 inches |
| Small | 11 to 12 inches |
| Medium | 12 to 13 inches |
| Large | 13 to 14 inches |
| X-Large | 14 to 15 inches |
| XX-Large | 15 to 16 inches |
| 3X-Large | 16 inches and over |
The maker offers it in black and white and links a sizing and fitting video, instructions for use, and washing instructions on its product page. Measure with a soft tape and use the maker's instructions for where to measure; if you fall between sizes, check those instructions before ordering.
Putting it on and wearing it
- Follow Med Spec's instructions for use that come with the brace, since strap order matters on figure-eight designs.
- Wear a thin athletic sock underneath and your usual shoe over it.
- Snug, not tight: toes should stay warm, pink and with normal feeling.
- Recheck straps during breaks in play.
- A brace is one part of preventing repeat sprains. FootCareMD, from the American Orthopaedic Foot and Ankle Society, notes that bracing and physical therapy do not strengthen the ankle ligaments, and lists strengthening, Achilles stretching and balance training as rehabilitation for instability.
Alternatives if the ASO is not for you
If you want a similar lace up with a different fit, there are many figure-eight lace up braces. If you want firmer side shells for early walking after a sprain, see stirrup ankle brace. If you mainly want swelling control, see compression ankle brace and sleeve. Other brand explainers: McDavid, Aircast and Zamst.
What to look for when you buy
ASO Ankle Stabilizer (Med Spec)
Best for: People who want a lace up brace with full figure-eight straps that fits either foot
Med Spec lists it for inversion or eversion sprains and ankle instability, with figure-eight straps, an elastic cuff and no seam under the foot.
Watch out: Sized by ankle circumference, not shoe size. Measure before ordering.
See options on AmazonGeneric lace up ankle brace with figure-eight straps
Best for: People who want the same style from another maker
The lace up plus crossing strap design is the category NATA lists as effective against recurrent sprains.
Watch out: Sizing methods vary between makers; follow each chart.
See options on AmazonSemi-rigid stirrup ankle brace
Best for: Early walking after a sprain when you want firm side shells
Plastic shells on each side limit rolling, and NATA lists semi-rigid braces alongside lace ups as effective.
Watch out: Bulkier in shoes than a lace up.
See options on AmazonAnkle compression sleeve
Best for: Mild swelling or achiness without instability
A light, low-bulk option when you do not need to block rolling.
Watch out: Gives little protection against a sprain.
See options on AmazonQuestions people ask
- Is the ASO a lace up or a stirrup brace?
- It is a lace up brace. Med Spec describes a laced boot with angled stabilizing straps that form a figure-eight, rather than plastic side shells.
- How do I size an ASO ankle brace?
- By ankle circumference. The maker's chart runs from XX-Small at 9 to 10 inches to 3X-Large at 16 inches and over.
- Does the ASO fit the left or right foot?
- Either. Med Spec says the original ASO is bilateral and fits the left or right foot.
- What is the ASO ankle brace used for?
- The maker lists inversion or eversion ankle sprains, medial or lateral ankle instability, and subtalar joint instability.
- Can I wear an ASO brace in basketball or volleyball shoes?
- It is designed to be worn inside a shoe. Try it with your game shoes and socks, and loosen the shoe laces if the fit is tight.
Sources
- ASO Ankle Stabilizer (medspec.com), Medical Specialties (Med Spec)
- National Athletic Trainers' Association Position Statement: Conservative Management and Prevention of Ankle Sprains in Athletes (pmc.ncbi.nlm.nih.gov), Journal of Athletic Training, via PubMed Central (NIH)
- Ankle Instability Symptoms and Causes (footcaremd.org), FootCareMD (American Orthopaedic Foot and Ankle Society)