If you change your running shoe adjust you training volume
A new study examined the morphology of selected intrinsic and extrinsic foot muscles, the plantar fascia, Achilles tendon and heel pad and compared four groups of runners using different running shoe types.
(neutral shoes, motion control shoes, minimalistic shoes and neutral shoes with insoles).
The movement restriction and cushioning provided by conventional running shoes has been slated to reduce the workload of foot muscles, and thus may potentially weaken these muscles.
This study, therefore, hypothesized that runners using minimalistic shoes would demonstrate larger foot muscles and thicker tendons compared to those using other shoes and that runners using motion control shoes and neutral shoes with custom-made insoles would be associated with smaller foot muscles and thinner tendons.
And, that is exactly what the researchers found.
The morphology of foot soft tissues is associated with running shoe type in healthy recreational runners,
Zhang et al,
Journal of Science and Medicine in Sport, July 2018 Volume 21, Issue 7, Pages 686–690
To determine the differences in the morphology of foot soft tissues between runners using different types of running shoes.
Thirty-eight recreational runners were divided into four groups based on running shoe type, namely, neutral shoes, motion control shoes, minimalistic shoes and neutral shoes with custom-made insoles. An arch height index and a relative arch deformation index were calculated for each participant. An ultrasound device was used to measure the cross-sectional area and/or the thickness of selected intrinsic foot muscles (abductor hallucis, flexor hallucis brevis and flexor digitorum brevis) and extrinsic foot muscles (flexor digitorum longus, tibialis anterior and the peroneus muscles), and the thickness of the plantar fascia, Achilles tendon and heel pad.
Recreational runners using minimalistic shoes demonstrated stiffer foot arches than those using neutral shoes. Among the selected foot muscles, only abductor hallucis showed a significant morphological difference between shoe groups. Runners using minimalistic shoes had the thickest abductor hallucis. The minimalistic shoe runners also showed a thinner proximal plantar fascia and a thicker Achilles tendon than other runners. Insole runners had a thinner heel pad than neutral shoe runners.
This study suggests that the morphology of foot soft tissues is associated with running shoe type in recreational runners. A sudden change in running shoe type without adjusting training volume should be undertaken with caution, since it may take time for foot soft tissues to adapt to a new shoe condition.
I did find this study a bit all over the place, mixed results and conclusions, for example, whilst changes in cross-sectional area of AbH (and ONLY AbH) were found in the minimalist running group, the authors say that a limitation of the study is that "compression applied on the skin during the ultrasound measurement might have led to underestimating the thickness of heel pad and foot muscles".
Read it for yourselves and make your own mind up.
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Director of Bartold Clinical