Towel Scrunch

The evidence

Weak intrinsic foot muscles are increasingly recognised as part of the plantar fasciitis picture, they share load with the fascia in supporting the medial longitudinal arch, so when they fail to do their share, the fascia takes more force. Towel scrunches train the foot intrinsics in a closed-chain pattern. Note: this is a strengthening exercise, not a stretch, framed accordingly in the routine.

Intrinsic foot muscles are the small muscles whose origins and insertions both sit inside the foot. The four layers of the plantar intrinsics (the abductor hallucis and flexor digitorum brevis most superficially, the quadratus plantae and lumbricals beneath, the flexor hallucis brevis and adductor hallucis next, and the interossei deepest) form what McKeon, Hertel and colleagues termed the "foot core" — a local stabiliser system structurally analogous to the lumbar multifidus / transverse abdominis system at the spine (see the McKeon citation below for the framing paper). When the foot core is weak, the plantar fascia, as a passive structure, absorbs the load that active muscle should be sharing.

Towel scrunch is one of the simplest closed-chain ways to load the foot core. As you scrunch, the metatarsophalangeal joints flex actively under the body of the long flexor tendons running over them. The movement recruits the flexor digitorum brevis (which lies directly under the central band of the fascia) and the lumbricals. Doing it heel-anchored on a hard floor adds an isometric arch-support demand against gravity, training the muscles in something closer to the position they need to work in during gait.

Dosing guideline: a common practical convention is 3 sets of 20 to 30 seconds, daily, progressing the load each week. We are not aware of a single canonical randomised-controlled trial that fixes the exact protocol for towel scrunch in isolation; the dosing above is conservative practice extrapolated from the broader intrinsic-foot-muscle strengthening literature (notably the "short foot" exercise work). If your physiotherapist gives you a different dose for your specific case, follow theirs.

Progression ladder, from easiest to hardest: toe curls in the air with no resistance, towel scrunch with a thin towel, towel scrunch with a weighted towel (a small tin on the far end), "short foot" exercise (lifting the medial longitudinal arch actively without curling the toes — much harder than it sounds) and finally single-leg balance on a foam surface barefoot, which integrates the intrinsics into postural control.

Timing expectations: patients commonly report noticeable arch fatigue within the first week and perceived improvement in morning step pain over 4 to 8 weeks of consistent practice. Structural change (visible on ultrasound) takes longer. The exercise pairs naturally with the Rathleff high-load heel-drop protocol (see the heel-drops stretch page) because the two address different parts of the same problem — heel drops remodel the fascia tissue itself under load; intrinsic strengthening reduces the load the fascia has to carry.

What NOT to do: do not actively extend the toes hard ("scrunch the towel back out") between reps — that turns the exercise into a generic flexor stretch and dilutes the strengthening stimulus. Let the toes loosely return to neutral, then scrunch again. Pain inside the foot during the exercise is unusual and should be checked against your contraindications; aching arch fatigue is the desired feedback.

Citation: McKeon PO, Hertel J, et al. (2015). The foot core system: a new paradigm for understanding intrinsic foot muscle function. British Journal of Sports Medicine · DOI: 10.1136/bjsports-2013-092690

Common questions

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Routines that use this