The effect of EVA and TPU custom foot orthoses on running economy, running mechanics, and comfort
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Date
2019-09-19Author
Van Alsenoy, Ken K.
Ryu, Joong Hyun
Girard, Olivier
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Van Alsenoy, K. K., Ryu, J. H. & Girard, O. (2019) The effect of EVA and TPU custom foot orthoses on running economy, running mechanics, and comfort. Frontiers in Sports and Active Living, 1:34.
Abstract
Custom made foot orthoses (CFO) with specific material properties have the potential to
alter ground reaction forces but their effect on running mechanics and comfort remains to
be investigated. We determined if CFO manufactured from ethyl-vinyl acetate (EVA) and
expanded thermoplastic polyurethane (TPU) materials, both compared to standardized
footwear (CON), improve running economy (RE), running mechanics, and comfort at two
running speeds. Eighteen well-trained, male athletes ran on an instrumented treadmill for
6min at high (HS) and low (LS) speeds corresponding to and 15% lower than their first
ventilatory threshold (13.8 ± 1.1 and 11.7 ± 0.9 km.h−1, respectively) in three footwear
conditions (CON, EVA, and TPU). RE, running mechanics and comfort were determined.
Albeit not reaching statistical significance (P = 0.11, !
2 = 0.12), RE on average improved
in EVA (+2.1 ± 4.8 and +2.9 ± 4.9%) and TPU (+0.9 ± 5.9 and +0.9 ± 5.3%) compared
to CON at LS and HS, respectively. Braking force was decreased by 3.4±9.1%at LS and
by 2.7 ± 9.8% at HS for EVA compared to CON (P = 0.03, !
2 = 0.20). TPU increased
propulsive loading rate by 20.2 ± 24 and 16.4 ± 23.1% for LS and HS, respectively
compared to CON (P = 0.01, !
2 = 0.25). Both arch height (P = 0.06, !
2 = 0.19) and
medio-lateral control (P = 0.06, !
2 = 0.16) showed a trend toward improved comfort
for EVA and TPU vs. CON. Compared to shoes only, mainly EVA tended to improve RE
and comfort at submaximal running speeds. Specific CFO-related running mechanical
adjustments included a reduced braking impulse occurring in the first 25% of contact
time with EVA, whereas wearing TPU increased propulsive loading rate.