Effects of shoe-length mismatch on gait speed and sagittal-plane lower-limb joint motion in healthy adults

Abstract

[Purpose] This study examined the impact of shoe–foot length mismatch on gait speed and sagittal-plane lower-limb joint motion in healthy adults during comfortable and maximal-effort walking. [Participants and Methods] Thirty healthy adults participated in the study. Four shoe-length conditions were tested: an appropriately fitted condition and oversized conditions in which shoes were 1-, 2-, and 3 cm longer than the appropriate length. Shoe width was standardized to the appropriate-size for each participant. Gait speed was assessed via 10 m gait time under comfortable and maximal-effort conditions. Sagittal-plane motion of the hip, knee, and ankle joints was recorded. [Results] 10 m gait time increased with shoe length. During comfortable walking, 10 m gait time was significantly longer in the 2- and 3 cm longer conditions, whereas no significant difference was observed in the 1 cm longer condition. During maximal-effort walking, 10 m gait time was significantly longer in all oversized conditions. Sagittal-plane joint motion also increased with shoe length, particularly at the hip and knee, with significant increases primarily observed in these joints. [Conclusion] Shoe–foot length mismatch prolonged 10 m gait time and increased sagittal-plane lower-limb joint motion. Clinicians should recognize that even minor shoe–foot length mismatch may reduce gait efficiency.

INTRODUCTION

Wearing ill-fitting shoes is a globally recognized issue, with particularly high prevalence among older adults^{1, 2)}. Poorly fitting footwear is linked to foot problems, such as pain, calluses, and corns^{3, 4)}. In Japan, few individuals wear correctly sized shoes, regardless of age^5,6,7,8). The country’s hot and humid climate⁹⁾ and the widespread use in homes of raised wooden floors with comfortable underfloor ventilation¹⁰⁾ influence footwear choices. Cultural norms, including the common practice of removing shoes at the house entrance, may also encourage selection of shoes larger than actual foot size for ease of removal. This practice may encourage the selection of oversized shoes to facilitate quick donning and doffing in daily life. Limited shoe-related education may further exacerbate this issue, as instruction on proper fit and size is rarely provided from kindergarten through high school¹¹⁾.

Given the widespread prevalence of oversized shoes, quantitatively assessing their impact on gait is clinically important. Gait speed is a key indicator of physical function, fall risk, and survival, and the 10 m walk test is widely used in clinical and research settings with validated reliability across populations^12,13,14). However, gait speed alone cannot fully reveal the kinematic mechanisms underlying gait changes caused by incorrectly sized footwear, as it varies with joint motion. Sagittal-plane motion during gait is a fundamental kinematic parameter directly contributing to anterior–posterior propulsion and forward limb advancement; therefore, it should be evaluated alongside gait speed. Previous studies on oversized shoes have primarily focused on gait speed, exercise tolerance, and ground reaction forces^15,16,17,18). However, their effects on lower-limb joint kinematics remain less well understood, and detailed shoe-length conditions have rarely been reported. Understanding the effects of shoe–foot length mismatch can help improve footwear guidance for safer walking and support fall-prevention efforts. Thus, the purpose of this study was to examine the effects of shoe–foot length mismatch on gait speed and sagittal-plane lower-limb joint motion in healthy adults during comfortable and maximal-effort walking, with joint motion quantified as the sagittal-plane range of motion (ROM) of the hip, knee, and ankle.

PARTICIPANTS AND METHODS

To account for potential missing data, 35 healthy adults (17 males and 18 females; mean age: 21.1 ± 1.5 years; mean height: 164.9 ± 8.1 cm; mean weight: 58.3 ± 12.5 kg) were initially recruited. However, 5 participants (2 males and 3 females) were excluded owing to improper fit of appropriate-size shoes, leaving 30 participants for final analysis. An a priori sample size calculation was performed using G*Power 3.1 (Heinrich Heine University, Düsseldorf, Germany) for a one-way repeated-measures ANOVA to test the main effect of shoe length (four conditions). The assumptions were an effect size of f=0.25, α=0.05, power (1 − β)=0.80, a correlation among repeated-measures of 0.70, and ε=1.0, which yielded a minimum required sample size of approximately 20 participants. The study was approved by the Research Ethics Committee of Kinjo University (Approval no. 2024-07). All participants received verbal and written explanations of the study and provided written informed consent. Healthy participants who could walk independently without assistive devices were included in the study, whereas those with conditions that could affect gait (e.g., neurological or musculoskeletal disorders) were excluded. Foot length was measured using a foot measurement device [Ashimori measurement box; Japan Educational Shoes (JES), Chiyoda, Tokyo, Japan], and foot circumference was measured using a tape measure at the maximum breadth across the first and fifth metatarsal heads. Educational shoes (JES-005; JES, Tokyo, Japan) were selected according to Japanese Industrial Standards and JASPE foot education guidance materials¹⁹⁾.

Four shoe-length conditions were tested: an appropriately fitted condition and shoe-length oversized conditions in which shoes were 1-, 2-, and 3 cm longer than the appropriate length. Participants wore socks of identical material, matched to foot length across all conditions. Shoelace and hook-and-loop fastener tightness was standardized to 2.0 kgf using a digital hanging scale (WORLDBOSS DHS-020; Takamori Kohki Co., Ltd., Niigata, Japan) at the uppermost eyelet and fastener. All shoe fittings were performed by a single examiner. Walking tasks included comfortable and maximal-effort walking, with the order of shoe-length conditions and task type randomized. The walking path was a 16 m long, with 3 m acceleration and deceleration zones at each end, and the central 10 m segment was used for analysis. After one practice trial per condition, a single measurement trial was recorded.

Primary outcomes were 10 m gait time and sagittal-plane hip, knee, and ankle joint motion quantified as ROM. Three-dimensional kinematic data were collected using seven wireless inertial measurement units (IMUs; Ultium Motion, Noraxon USA Inc., Scottsdale, AZ, USA) at 100 Hz. IMUs were attached with dedicated straps at the midpoint of the sacrum’s upper edge, the proximal two-thirds of the femur length, the distal one-third of the tibia length, and a point 10 cm anterior to the midpoint between the medial and lateral malleoli of both feet. Prior to data collection, participants stood in an anatomical position for calibration following the manufacturer’s standard static protocol.

Hip, knee, and ankle sagittal-plane angles were measured continuously across each walking trial. ROM was defined as the difference between maximum and minimum joint angles during a single gait cycle, representing flexion-extension angular displacement for the hip and knee and dorsiflexion–plantarflexion displacement for the ankle. ROM values were extracted from the middle 10 m segment of the analysis zone and averaged across valid trials per shoe condition. The 10 m gait time was measured by the same examiner using a stopwatch.

Statistical analyses were performed using R (v4.2.1; R Foundation for Statistical Computing, Vienna, Austria), with significance set at 5%. One-way repeated-measures analysis of variance was conducted to test the effect of shoe length, and when significant, multiple comparisons were performed using Shaffer’s modified Bonferroni method to compare the appropriate-size condition with each longer condition. Sphericity was assessed using Mendoza’s test; when it was violated, the Greenhouse–Geisser correction was applied.

RESULTS

Mean 10 m gait times for each shoe length are presented in Table 1. During comfortable walking, 10 m gait time was significantly longer in the +2 cm (p=0.027) and +3 cm (p=0.017) conditions compared with the appropriate-size condition, whereas no significant difference was observed between the appropriate-size and +1 cm conditions (p=0.577). During maximal-effort walking, gait time was significantly prolonged in all oversized conditions compared with the appropriate-size condition (all p<0.001). During comfortable walking, the 10 m gait time was 6.8 ± 0.8 s under the appropriate-size condition and increased to 7.0 ± 0.9 s (+2 cm) and 7.2 ± 1.0 s (+3 cm). During maximal-effort walking, it increased from 5.1 ± 0.7 s to 5.3 ± 0.7 s (+1 cm), 5.4 ± 0.7 s (+2 cm), and 5.6 ± 0.8 s (+3 cm).

Table 1. Results of the 10 m gait time (s) assessment.

Walking condition	Shoe size
	Appropriate	+1 cm	+2 cm	+3 cm
Comfortable	6.8 ± 0.8	6.9 ± 0.9	7.0 ± 0.9*	7.2 ± 1.0*
Max effort	5.1 ± 0.7	5.3 ± 0.7*	5.4 ± 0.7*	5.6 ± 0.8*

Values are means ± standard deviation (SD). Comfortable, self-selected comfortable walking; max effort, maximal-effort walking (as fast as possible). *p<0.05 compared with the appropriate shoe-length condition under the same walking condition.

Mean ROM values for each shoe-length condition are shown in Table 2. During comfortable walking, significant increases relative to the appropriate-size condition were observed in the left hip at +2 cm (p=0.042) and +3 cm (p=0.009), the left knee at +1 cm (p=0.014), +2 cm (p=0.002), and +3 cm (p<0.001), the right knee at +2 cm (p=0.036) and +3 cm (p<0.001), and the right ankle at +3 cm (p=0.032). During maximal-effort walking, significant increases relative to the appropriate-size condition occurred in the left knee at +2 cm (p=0.022) and +3 cm (p<0.001) as well as the right knee at +1 cm (p=0.003), +2 cm (p<0.001), and +3 cm (p<0.001).

Table 2. Sagittal-plane joint range of motion (°) during walking under two conditions with differing shoe lengths.

Joint	Walking condition	Shoe size
		Appropriate	+1 cm	+2 cm	+3 cm
Hip (Left)	Comfortable	56.1 ± 4.1	56.4 ± 5.3	57.5 ± 4.6*	58.1 ± 5.2*
	Max effort	62.1 ± 5.8	62.7 ± 6.7	62.1 ± 5.8	62.9 ± 6.6
Hip (Right)	Comfortable	56.4 ± 4.9	56.6 ± 4.8	57.8 ± 4.9	57.7 ± 5.4
	Max effort	61.8 ± 6.2	62.4 ± 6.4	61.9 ± 5.1	62.2 ± 5.3
Knee (Left)	Comfortable	70.3 ± 4.3	71.7 ± 4.2*	72.9 ± 4.9*	74.8 ± 4.8*
	Max effort	72.0 ± 5.8	73.3 ± 5.3	74.3 ± 6.9*	76.6 ± 6.8*
Knee (Right)	Comfortable	69.5 ± 3.8	70.4 ± 4.6	71.5 ± 5.4*	74.3 ± 4.9*
	Max effort	70.5 ± 6.5	72.6 ± 6.8*	73.4 ± 7.0*	75.8 ± 7.7*
Ankle (Left)	Comfortable	35.0 ± 5.3	35.9 ± 5.4	37.0 ± 6.7	37.4 ± 6.4
	Max effort	38.6 ± 7.2	38.8 ± 5.7	38.6 ± 6.6	40.1 ± 9.6
Ankle (Right)	Comfortable	35.0 ± 5.2	35.4 ± 5.6	36.9 ± 6.6	37.5 ± 5.8*
	Max effort	38.8 ± 5.8	38.4 ± 6.2	38.3 ± 7.5	39.6 ± 6.2

Values are means ± SDs. Range of motion (ROM) was defined as the difference between the maximum and minimum joint angles during a single gait cycle. Comfortable, self-selected comfortable walking; max effort, maximal-effort walking (as fast as possible). *p<0.05 compared with the appropriate shoe-length condition under the same walking condition.

DISCUSSION

This study demonstrated that 10 m gait time and sagittal-plane flexion-extension ROM increased with shoe length. Significant effects were associated with the +1 cm and +2 cm conditions during maximal-effort walking and comfortable walking, respectively. These findings indicate that even mild shoe–foot length mismatch can impair walking performance, particularly when greater propulsive force is required. The results align with previous reports linking ill-fitting shoes to decreased gait parameters^{15, 16)}. This pattern suggests that the threshold for oversizing effects is lower during maximal-effort walking than during comfortable walking.

Two mechanisms may account for the prolonged gait time under oversized shoe conditions. First, forward foot sliding within the shoe (foot slip) likely occurs. Excess shoe-length worsens the foot–shoe fit, allowing the foot to slide forward during late-stance push-off and impairing efficient force transfer to the ground^{17, 18)}. Second, diminished toe function may contribute. Although shoes were heel-fitted and secured with standardized shoelace and hook-and-loop fastener tension, oversized lengths increased forefoot space and shifted the shoe shank anteriorly relative to the anatomical metatarsophalangeal joint position. Consequently, the windlass mechanism and arch support function may be underutilized, and as reported by Scott et al.²⁰⁾, toe grip strength aiding late-stance propulsion may not be fully exerted, thereby weakening push-off.

Reduced propulsive force may also impair foot clearance and forward limb advancement during swing, prompting compensatory adjustments. Prior studies have shown that swing initiation depends not only on active hip flexor contraction but also on momentum generated by late-stance propulsion and passive limb dynamics^{21, 22)}. When push-off is inadequate, insufficient initial limb momentum may necessitate greater joint motion to achieve clearance and advancement. Moreover, minimum toe clearance is associated with tripping risk, and the importance of swing-phase kinematics in evaluating abnormal gait has been emphasized^23,24,25). Overall, the increased ROM, particularly in the knee joint, suggests that compensatory movement adjustments may offset the mechanical disadvantage imposed by oversized shoes. These findings may have important implications for older adults. Because older adults exhibit greater gait variability and reduced gait reproducibility compared with younger adults²⁶⁾, shoe–foot length mismatch may further compromise gait efficiency and stability in this population. Therefore, future studies should examine whether similar or greater effects occur in older adults.

This study has several limitations. Because participants were healthy adults, the magnitude and clinical significance of the effects may differ in older individuals or populations with pathological conditions. Additionally, reduced propulsive efficiency was inferred from previous studies, as foot movement within the shoe, ground reaction forces, and muscle activity were not directly measured. Future research should incorporate foot slip distance, plantar pressure, electromyography, and force plate assessments to clarify the mechanisms linking shoe-length mismatch to gait changes. Finally, the study’s results may depend on shoe design, warranting caution when generalizing to other footwear types.

In conclusion, shoe–foot length mismatch prolongs 10 m gait time and increased lower-limb ROM. During maximal-effort walking, effects appeared even with mild oversizing (+1 cm condition), confirming that small shoe length differences can compromise gait efficiency and kinematics. Clinicians assessing and instructing gait in physical therapy should recognize that even minor shoe–foot length mismatches may act as biomechanical factors that reduce gait efficiency.

Funding

The author, their immediate family, and any research foundations with which they are affiliated have not received any financial payments or other benefits from any commercial entity related to the subject of this article. The author has not received any funding related to the subject matter of this article.

Conflict of interest

None.