Experienced recreational runners who gradually transitioned to Vibram FiveFingers over 10 weeks showed more bone marrow oedema on foot MRI than runners who stayed in their usual shoes: 10 of 19 had an increase in at least one bone (P = 0.009 vs control)
Runners had foot MRI before and after 10 weeks; one group kept running in traditional shoes, the other gradually transitioned to Vibram FiveFingers. Bone marrow oedema was scored 0-4 per bone (0 = none, 4 = oedema along more than 50% of the bone, representing a stress fracture).
Participants
n=36 (thirty-six) experienced recreational runners: 19 transition (Vibram), 17 control.
Protocol
10 weeks: control ran in traditional shoes only; experimental group transitioned gradually to Vibram FiveFingers.
MRI before and after; oedema graded 0-4 per bone.
Key Results
After 10 weeks, more runners in the Vibram group (10 of 19) showed increased bone marrow oedema in at least one bone than in the control group (P = 0.009).
Pre-training MRI scores did not differ between groups.
Authors' conclusion: transition to minimalist shoes very slowly and gradually to avoid stress injury in the foot.
Practical Application
Treat a move to minimalist shoes as a new bone load for the foot: here a gradual 10-week transition was still followed by increased oedema in 10 of 19 runners, and the authors advise transitioning very slowly and gradually. Inference: plan it over longer than 10 weeks.
The abstract does not report how many control runners showed increases, how many reached grade 4, or the transition schedule used.
Not from this paper; the base's own practice: localised bony foot pain during a footwear change means stopping the change and assessing for bone stress.
Limitations
n=36; MRI oedema is a surrogate, and its link to later injury is not shown here.
One shoe model (Vibram FiveFingers); transition protocol and weekly volume not given in the abstract.
Randomisation and blinding of MRI scoring are not described in the abstract.
How this entry was checked and changed
Why this level
small (n=36) RCT-indexed study, randomisation method not described, MRI surrogate rather than injury