Improving Foot Strength in Vocational Ballet Dancers

NCT06589050 | Completed

• 1 other identifier: 5/24/AS/UOW
• Study Type: interventional
• Target: 49
• Locations: 1 country
• Sites: 1

Brief Summary

Professional dancers subject their feet to high forces through frequent jumping, repeated heel rises, insufficient shoe cushioning, and a high degree of foot mobility. To prevent injuries and improve jumping performance, dancers are recommended to strengthen the muscles of the lower extremities. The foot muscles, especially the toe flexors, play an important role as shock absorbers and motors for the foot by absorbing and generating mechanical energy, which is essential for human locomotion. Furthermore, they serve as a link between the powerful leg extensor muscles and the ground, transmitting the energy generated by the larger muscle groups. This makes them essential components of overall athletic performance. However, the impact of foot muscle strength on dancers´ jumping performance remains uncertain. Therefore, the aim of this study is to investigate the effectiveness of two training programs designed to strengthen the toe flexor muscles in dancers. For this project, a 6.5-week intervention with ballet students from a vocational ballet school is planned. Before and after the intervention, all study participants will perform tests to assess foot muscle strength and jumping performance.

Conditions

Toe Flexor Strength

Keywords

Toe flexor strength; Foot; Dance; Jumping performance

Outcome Measures

Primary Outcomes (1)

• Maximal voluntary isometric contraction (MVIC) of the toe flexors muscles

  The post-intervention difference between the three groups in MVIC of the toe flexors measured with a custom-made toe flexor dynamometer in a seated position (90° angle in the hips and knees) where the foot is secured with a strap. Participants will push with their toes against a pedal and hold this isometric contraction for 2-3 seconds. The strength will be normalized by body weight (N/kg).

  Measurements will be performed one week prior to and one week after the intervention.

Secondary Outcomes (5)

• Vertical jump - Countermovement jump (CMJ) - Jump height (cm)

  Measurements will be performed one week prior to and one week after the intervention.

• Vertical jump - CMJ - changes in force parameters

  Measurements will be performed one week prior to and one week after the intervention.

• Vertical jump - Sauté jump - jump height (cm)

  Measurement will be performed one week prior to and one week after the intervention.

• Vertical jump - Sauté - changes in force parameters

  Measurements will be performed one week prior to and one week after the intervention.

• Horizontal jump - Long jump - jump distance (cm)

  Measurements will be performed one week prior to and one week after the intervention.

Other Outcomes (1)

• End User Questionnaire

  After the intervention, up to one hour.

Study Arms (3)

"Toe flexor device" experimental group

EXPERIMENTAL

Participants will complete: * 3 sets of 15 repetitions with a 90-second break between each set. * Tempo 2-0-2-0 * 4 times per week * Progression will be achieved by increasing the stiffness of the elastic band whenever the participant can perform 15 repetitions without great effort.

Other: "Toe flexor device" experimental group

"Inclined Heel Rise" experimental group

EXPERIMENTAL

Participants will complete: * 3 sets of 10 to 15 repetitions with a 90-second break between each set. * Tempo 2-0-2-0 * 4 times per week * Progression will be achieved by increasing the number of repetitions to 15 and then adding weights to be held in the ipsilateral hand.

Other: "Inclined Heel Rise" experimental group

Control group

NO INTERVENTION

The control group will continue with the ballet school's normal training schedule.

Interventions

"Toe flexor device" experimental group OTHER

This intervention group will perform toe flexion using a toe flexor (TF) device, which facilitates the shortening and stretching of the TF muscle-tendon units (MTUs) against resistance bands. While seated, participants will push a pedal down with their toes over two counts and release it over two counts.

"Toe flexor device" experimental group

"Inclined Heel Rise" experimental group OTHER

This intervention group will perform single-leg heel rises on an inclined platform. Participants will place their hands against a barre for balance support, lift their heels over two counts, and lower them over two counts.

"Inclined Heel Rise" experimental group

Eligibility Criteria

• Age: 14 Years - 19 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Child (0-17), Adult (18-64)

You may qualify if:

• Being a ballet student at the Elmhurst Ballet School.
• Aged 14 to 19.
• Written informed consent (by the participant and/or their legal guardian).

You may not qualify if:

• Any recent lower leg or foot injuries.
• Chronic pain in the lower extremities.

Sponsors & Collaborators

• University of Bern: lead
• Elmhurst Ballet School, Birmingham: collaborator
• German Sport University, Cologne: collaborator

Study Sites (1)

Elmhurst Ballet School

Birmingham, B57UH, United Kingdom

Location

Related Publications (7)

• Goldmann JP, Bruggemann GP. The potential of human toe flexor muscles to produce force. J Anat. 2012 Aug;221(2):187-94. doi: 10.1111/j.1469-7580.2012.01524.x.

  PMID: 22747582 BACKGROUND

• Goldmann JP, Sanno M, Willwacher S, Heinrich K, Bruggemann GP. The potential of toe flexor muscles to enhance performance. J Sports Sci. 2013;31(4):424-33. doi: 10.1080/02640414.2012.736627. Epub 2012 Oct 30.

  PMID: 23106289 BACKGROUND

• Chiu LZF, Daehlin TE. Midfoot and Ankle Mechanics in Block and Incline Heel Raise Exercises. J Strength Cond Res. 2021 Dec 1;35(12):3308-3314. doi: 10.1519/JSC.0000000000004145.

  PMID: 34570059 BACKGROUND

• Jarvis DN, Kulig K. Kinematic and kinetic analyses of the toes in dance movements. J Sports Sci. 2016 Sep;34(17):1612-8. doi: 10.1080/02640414.2015.1126672. Epub 2015 Dec 21.

  PMID: 26691227 BACKGROUND

• Smith R, Lichtwark G, Farris D, Kelly L. Examining the intrinsic foot muscles' capacity to modulate plantar flexor gearing and ankle joint contributions to propulsion in vertical jumping. J Sport Health Sci. 2023 Sep;12(5):639-647. doi: 10.1016/j.jshs.2022.07.002. Epub 2022 Jul 21.

  PMID: 35872091 BACKGROUND

• Tourillon R, Gojanovic B, Fourchet F. How to Evaluate and Improve Foot Strength in Athletes: An Update. Front Sports Act Living. 2019 Oct 11;1:46. doi: 10.3389/fspor.2019.00046. eCollection 2019.

  PMID: 33344969 BACKGROUND

• Willemse L, Wouters EJM, Pisters MF, Vanwanseele B. Plantar intrinsic foot muscle activation during functional exercises compared to isolated foot exercises in younger adults. Physiother Theory Pract. 2024 Aug;40(8):1656-1668. doi: 10.1080/09593985.2023.2204947. Epub 2023 Apr 26.

  PMID: 37126537 BACKGROUND

Study Officials

• Anna Schrefl, MSc

  University of Bern

  PRINCIPAL INVESTIGATOR

• Daniel Erlacher, PhD

  University of Bern

  STUDY CHAIR

• Andrea Schaerli, PhD

  University of Bern

  STUDY CHAIR

• Nico Kolokythas, PhD

  Elmhurst Ballet School

  STUDY CHAIR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Masking Details: After the participants have completed the pre-measurements, they will be assigned to their group allocation. The intervention´s nature precludes blinding the participants and the trainer; however, a supervisor will monitor data collection.
• Purpose: BASIC SCIENCE
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Model Details: This is a parallel-group randomized controlled study. Participants will be randomly assigned to one of three parallel groups (two experimental groups and one control group) with a 1:1:1 ratio. To balance the covariates of age and sex among the three groups, a computer-based program will perform stratified randomization within three blocks.

Study Record Dates

• First Submitted: September 5, 2024
• First Posted: September 19, 2024
• Study Start: September 10, 2024
• Primary Completion: December 5, 2024
• Study Completion: December 15, 2024
• Last Updated: March 26, 2025

Record last verified: 2025-03

Data Sharing

• IPD Sharing: Will not share

Locations

GB (1)