Completed

NCT Number: NCT07439705

The Effect of Heel Skin Mechanoreceptors on Plantar Flexor Contraction Force

Previous studies have shown that stimulation of heel skin mechanoreceptors facilitates the soleus H-reflex, whereas stimulation of metatarsal region mechanoreceptors inhibits the soleus H-reflex. From this perspective, plantar cutaneous receptors may play an important role in the regulation of activities such as walking and running, as well as in the control of spasticity in patients with upper motor neuron lesions. Investigating the effect of heel skin mechanoreceptors on plantar flexor muscle contraction force may provide valuable insight into the potential influence of these mechanoreceptors on locomotor activities and muscle tone, and may offer a foundation for future studies directly addressing these topics.

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Key information

Conditions

Heel Skin Mechanoreceptors Plantar Flexion Contraction Force

Age range

20 year–40 year

Sex eligibility

Male

Study type

Interventional

Phase

Not applicable

Primary location

Istanbul Physical Medicine and Rehabilitation Training and Research Hospital

Istanbul, 34180, Turkey (Türkiye)

About this study

The aim of this study is to investigate the effect of heel skin mechanoreceptors on plantar flexor contraction force. The plantar flexor muscle strength of the participants was evaluated using a force sensor connected to a computer. For the isometric muscle strength measurement, the subjects were asked to perform maximal plantar flexion for 10 seconds. A 5-pulse stimulation package at 15% contraction level was delivered 10 times with a 4-6 second interval. The measurements were repeated 10 times with a 30-second interval. During the plantar flexion muscle strength measurement, the heel skin mechanoreceptors were stimulated at sensory threshold by a square wave electrical current with a pulse duration of 1 microsecond.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

Being healthy
Being between 20 and 40 years of age
Being female or male
Volunteering to participate

Exclusion criteria

Having a history of orthopedic conditions-particularly in the lower extremity-or residual neuromusculoskeletal problems due to previously experienced illnesses

Treatment and study plan

Assesment of Plantar Flexion Muscle Strength During Heel Skin Mechanoreceptor Stimulation

Other

For the measurement of isometric muscle strength, participants lying prone on an examination table were instructed to perform maximal plantar flexion for 10 seconds. To achieve a submaximal contraction corresponding to 15% of their maximal contraction force, they were asked to follow the 15% threshold reference line displayed on the force channel on the screen.

During the measurement of plantar flexion muscle strength, the cutaneous mechanoreceptors of the heel were stimulated with a square-wave electrical current with a pulse duration of 1 microsecond, at an intensity three times the sensory threshold. Electrical stimulation was delivered via a constant-current stimulator (Digitimer DS7A, Hertfordshire, United Kingdom). At the 15% contraction level, a train of five stimuli was delivered 10 times at intervals of 4-6 seconds. Measurements were repeated 10 times with 30-second intervals between each set.

Primary outcomes

Voluntary Contraction Force

Time frame: Day 1 (During a single experimental session)

While the participants were lying prone on the examination table, plantar flexion muscle strength was assessed using a computer-connected force sensor (SPIKE 2.7). For detailed analysis of the participant data using the SPIKE 2.7 force sensor software, an IIR digital filtering process was first applied to the force channel. During this procedure, a low-pass filter was selected. The filter settings were configured with a cutoff value of 100 and an order of 2. As a result of this filtering process, the newly generated filtered memory channel was labeled "ForceLP." Subsequently, the waveform average of the ForceLP channel was calculated with the following settings: width 4 s, offset 2 s, and trigger set to 6 stimuli (event+). From these averaged traces peak contraction force was determined.
Reflex Contraction Force

Time frame: Day 1 (During a single experimental session)

While the participants were lying prone on the examination table, plantar flexion muscle strength was assessed using a computer-connected force sensor (SPIKE 2.7). For detailed analysis of the participant data using the SPIKE 2.7 force sensor software, an IIR digital filtering process was first applied to the force channel. During this procedure, a low-pass filter was selected. The filter settings were configured with a cutoff value of 100 and an order of 2. As a result of this filtering process, the newly generated filtered memory channel was labeled "ForceLP." Subsequently, the waveform average of the ForceLP channel was calculated with the following settings: width 4 s, offset 2 s, and trigger set to 6 stimuli (event+). From these averaged traces reflex contraction force was determined.
Reflex Contraction Latency

Time frame: Day 1 (During a single experimental session)

While the participants were lying prone on the examination table, plantar flexion muscle strength was assessed using a computer-connected force sensor (SPIKE 2.7). For detailed analysis of the participant data using the SPIKE 2.7 force sensor software, an IIR digital filtering process was first applied to the force channel. During this procedure, a low-pass filter was selected. The filter settings were configured with a cutoff value of 100 and an order of 2. As a result of this filtering process, the newly generated filtered memory channel was labeled "ForceLP." Subsequently, the waveform average of the ForceLP channel was calculated with the following settings: width 4 s, offset 2 s, and trigger set to 6 stimuli (event+). From these averaged traces reflex contraction latency was determined.

Sponsors and collaborators

Lead sponsor

Istanbul Physical Medicine Rehabilitation Training and Research Hospital

Other Gov

Registry information

Important dates

Study start: 2025
Primary completion: 2026
Study completion: 2026
First posted: Feb 27, 2026
Registry last updated: Feb 27, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

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This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.