Comparative Analysis of User Perception and Step Length Using
Toe Separating, Contoured Sandals versus Thong Style Flip-Flops
INTRODUCTION
Thong style flip-flops have become a very common
form of footwear in modern society, with reported
rates of use as high as 43% in women [1] . However,
minimal support offered by the common flip-
flop presents concerns with regard to normal foot
biomechanics, maintaining normal gait, overall
satisfaction, and comfort. Previous research has
explored the relationship of foot pathologies and the
use of thong style flip-flops, which require the wearer
to dorsiflex the ankle in order to prevent the sandal
from falling off [2] . Criticism of the thong style flip-
flops is inherent in the design. The thin rubber soles
with uniform thickness frequently associated with
traditional flip-flops are just one of the shortcomings
responsible for the biomechanical deficit. Due to lack
of support and adaptation through the weight-bearing
portion of gait, soles of traditional flip-flops are unable
to maintain proper foot biomechanics throughout the
gait cycle. This use of out-of phase musculature can
lead to overuse and alteration of normal gait patterns
[3]
.
Sandals lay claim to being both the oldest as well as
the most familiar foot covering used throughout the
world [4] . One advantage of sandal-wear is the lack
of restriction in the transverse (horizontal) plane. In
contrast, closed-toe shoes are more likely to constrict
the toe box, which has been attributed to several
forefoot pathologies [5] . Previous research has found
that young adults increase their step length when
wearing shoes as compared to walking barefoot [3,6] .
Toe separating, contoured sandals (TSCS) are an
emerging footwear product composed of four soft
fabric loops that are configured to separate the toes.
The material used in the toe separators of the sandal
examined in this article is composed of visco-elastic
polyurethane foam surrounded by an antimicrobial
fabric. The lower element of the sandal is made of
50
Pedorthic Footcare Association | www.pedorthics.org
either cork or rubber and features a foot bed that has
a deep heel pocket and a built-in medial arch support
[7]
. Dorsal and superior views of the experimental
TSCS product are shown in Figures 1a and 1b, the
control sandal is shown in Figure 1c. Currently
there are no studies examining the biomechanical
effects of TSCS on lower extremity function or
user perceptions. The objective of this study was to
determine if TSCS provide benefit to its wearers in
terms of comfort, perceived stability, and step length
measures, as compared to a traditional thong style
flip-flop.
METHODS
Participants
Female students at the New York College of Podiatric
Medicine (NYCPM) were invited to participate in the
study via email. Approval to conduct this study was
obtained from NYCPM’s Institutional Review Board
prior to commencing study recruitment. Inclusion
criteria included female subjects between the ages
of 20 and 30 that had no known health conditions
involving complications of the foot, and no prior
foot pathologies. Twenty (20) female students were
enrolled into the study by signing the consent form to
participate, which described complete details of the
study protocol. Subjects were assigned a randomized
ID number in order to maintain confidentiality.
Assessment of volunteer shoe size and
instructions to volunteer participants
Participants’ weight was obtained using a Health–o–
meter® Professional scale. Each participant had both
feet measured using the Brannock Foot Measuring
device, which provides an accurate measure for shoe
fit and size. Volunteers were allotted one pair of
TSCS according to the measured shoe size and were
instructed that the sandal must be worn 15 minutes