Morton Toe and Neuromuscular Performance

Morton Toe is Associated With Faster Contractile Properties and Superior Reactive Strength in Female Football Players

This cross-sectional observational study investigated whether female football players with Morton toe morphology differ from those with normal foot morphology in neuromuscular contractile properties and kinetic performance characteristics. Morton toe is a congenital foot variation in which the second toe is longer than the first. A total of 47 female football players were classified into two groups based on bilateral foot morphology: Morton foot group (n = 24) and normal foot group (n = 23). Neuromuscular properties of the dominant vastus lateralis muscle were assessed using tensiomyography, and kinetic performance was evaluated through a 40-cm drop jump test on dual force plates. The primary outcomes were contraction time (Tc) and reactive strength index (RSI). Secondary outcomes included relaxation time, delay time, sustain time, maximal displacement, jump height, peak power normalized to body mass, and landing net peak force normalized to body mass. Multiple linear regression models adjusted for age, body mass index, and mean arch index were used to evaluate whether group differences were independent of potential confounders. This study aimed to determine whether Morton toe morphology is associated with distinct neuromuscular and kinetic performance profiles in female athletes.

Study Overview

• Status: Completed
• Conditions: Foot Morphology; Morton Toe; Neuromuscular Properties

Detailed Description

Morton toe is a congenital foot morphology characterized by a longer second metatarsal relative to the first. Although traditionally regarded as a clinical or orthopedic variation associated with metatarsal stress fractures and balance difficulties, limited evidence from sprinter populations suggests that a longer second toe may be associated with superior athletic performance. However, no previous study has examined whether Morton toe morphology is related to neuromuscular contractile properties assessed via tensiomyography or kinetic performance derived from force plate testing in a controlled group comparison design.

Participants were screened from 97 female football players. Exclusion criteria included BMI outside the 18.5-29.9 range, bilateral arch index outside the 14-29% range, inconsistent bilateral foot morphology, lower-extremity injury within the past 12 months, neurological or orthopedic conditions, performance-affecting pharmacological use, and menstruation on the measurement day. Morton toe classification was based on the palpation method described by Davidson et al. (2007) with a minimal detectable change threshold of ±0.30 mm.

All measurements were conducted during the off-season to minimize training load interference. Testing followed a standardized sequence: foot morphology assessment, tensiomyography of the dominant vastus lateralis at rest, a 15-minute warm-up, and a 40-cm drop jump test. The assessor was blinded to group classification, and statistical analysis was performed by an independent researcher on a coded dataset. Primary outcome variables (Tc and RSI) were determined a priori. Secondary outcomes were corrected for multiple comparisons using the Holm-Bonferroni method. Regression analyses were performed to assess the independence of group effects from age, body mass index, and mean bilateral arch index.

• Study Type: Observational
• Enrollment (Actual): 47

Contacts and Locations

Study Locations

• Turkey (Türkiye)
  • Centre
    • Giresun, Centre, Turkey (Türkiye), 28100
      • Giresun University - Sports Science Faculty

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

• Sampling Method: Non-Probability Sample

Study Population

Female football players actively competing in organized leagues in Turkey, recruited from multiple teams during the 2025-2026 off-season period. A total of 97 players were initially screened; 47 met all eligibility criteria and were classified into Morton foot (n=24) and normal foot (n=23) groups.

Description

Inclusion Criteria:

• Active female football players with a valid sports license for the current season
• Regular participation in training and competitive matches
• Bilateral Morton toe morphology (Δ ≤ -0.30 mm on both feet) or bilateral normal foot morphology (Δ > +0.30 mm on both feet)
• Body mass index between 18.5 and 29.9 kg/m²
• Bilateral arch index between 14% and 29%
• Voluntary participation with written informed consent

Exclusion Criteria:

• Serious lower-extremity musculoskeletal injury within the past 12 months
• Neurological or orthopedic disease affecting measurement procedures
• Current use of pharmacological products affecting performance
• Acute pain, injury, or illness on the measurement day
• Menstruation on the measurement day (self-reported)
• Inconsistent bilateral foot morphology classification between feet
• Bilateral arch index below 14% (high arch) or above 29% (low arch)

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort
Morton Foot Group; Female football players with bilateral Morton toe morphology, defined as a second metatarsal protrusion distance exceeding the first by more than 0.30 mm bilaterally (Δ ≤ -0.30 mm). n = 24.
Normal Foot Group; Female football players with bilateral normal foot morphology, defined as a first metatarsal protrusion distance exceeding the second by more than 0.30 mm bilaterally (Δ > +0.30 mm). n = 23.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Contraction Time (Tc)	Tensiomyographic contraction time of the dominant vastus lateralis muscle, defined as the time between 10% and 90% of maximal radial displacement (ms).	Single measurement session
Reactive Strength Index (RSI)	Jump height divided by ground contact time during a 40-cm drop jump test (m/s). The trial with the highest RSI value out of three attempts was selected for analysis.	Single measurement session

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Maximal Displacement (Dm)	Peak radial displacement of the vastus lateralis muscle belly during tensiomyographic measurement (mm).	Single measurement session
Relaxation Time (Tr)	Time from 90% to 50% of maximal displacement during the relaxation phase of tensiomyographic measurement (ms).	Single measurement session
Delay Time (Td)	Time from electrical stimulus onset to 10% of maximal displacement during tensiomyographic measurement (ms).	Single measurement session
Sustain Time (Ts)	Duration the muscle response remains above 50% of maximal displacement during tensiomyographic measurement (ms).	Single measurement session
Jump Height (JH)	Vertical jump height calculated from flight time during a 40-cm drop jump test (cm).	Single measurement session
Peak Power Normalized to Body Mass (PPI)	Peak power output normalized to body mass during a 40-cm drop jump test (W/kg).	Single measurement session
Landing Net Peak Force Normalized to Body Mass (LPF)	Peak vertical ground reaction force at landing normalized to body mass during a 40-cm drop jump test (N/kg).	Single measurement session

Collaborators and Investigators

• Sponsor: Giresun University

Study record dates

Study Major Dates

• Study Start (Actual): January 10, 2026
• Primary Completion (Actual): March 15, 2026
• Study Completion (Actual): March 15, 2026

Study Registration Dates

• First Submitted: May 8, 2026
• First Submitted That Met QC Criteria: May 8, 2026
• First Posted (Actual): May 14, 2026

Study Record Updates

• Last Update Posted (Actual): May 14, 2026
• Last Update Submitted That Met QC Criteria: May 8, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: neuromuscular performance; tensiomyography; female football; drop jump; foot morphology; Morton toe; reactive strength index
• Additional Relevant MeSH Terms: Pain; Neurologic Manifestations; Musculoskeletal Diseases; Nervous System Diseases; Neuromuscular Diseases; Joint Diseases; Peripheral Nervous System Diseases; Foot Diseases; Metatarsalgia; Neuralgia; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Morton Neuroma
• Other Study ID Numbers: GRU-SBF-NS-06; 10/492 (Other Identifier: Giresun University Social Sciences, Natural Sciences and Engineering Research Ethics Committee)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No