Neural Adaptations to Metronome-Paced Strength Training

Neural Adaptations to Metronome-Paced Strength Training: Insights From Neuroscience and Human Movement Variability

The aim of the study is to investigate the effects of incorporating variability within Resistance Training (RT) methods on the neural adaptations along the corticospinal tract and on neuromuscular function. The literature suggests that RTis one of the most common modalities to enhance and restore muscle function and its practice results in adaptation in neural and morphological adaptations. It is also known that conditions such as ageing and injury have a negative impact on neural drive to the muscles with consequences at motor control level that are not addressed by traditional RT. Recent approaches such as metronome paced strength training have been used to cover this motor control dimension through a greater control and consciousness of movement. However, this methodology tends not to incorporate the inherent variability and complex, fractal-like fluctuations that characterize human movement. The investigators propose that incorporating variability through a fractal-like metronome approach will speed up the neural adaptations which will be useful in injury rehab.

Study Overview

• Status: Recruiting
• Conditions: Healthy
• Intervention / Treatment: Other: Fractal Paced; Other: Isochronous Paced; Other: Self Paced

• Study Type: Interventional
• Enrollment (Estimated): 60
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: João H Oliveira, MSc; Phone Number: +351 913266232; Email: joao.henriques.oliveira@gmail.com
• Study Contact Backup: Name: João R Vaz, PhD; Phone Number: +351 967096444; Email: jvaz@egasmoniz.edu.pt

Study Locations

• Portugal
  • Monte de Caparica
    • Almada, Monte de Caparica, Portugal, 2829-699
      • Recruiting
      • Egas Moniz School of Health & Science
      • Contact: João R. Vaz, PhD; Phone Number: +351 967096444; Email: jvaz@egasmoniz.edu.pt

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

• aged between 18 and 40 years

Exclusion Criteria:

• Neurologic conditions;
• Lower limb disabilities or disease;
• Not able to provide informed consent;
• Have an implanted device (e.g. pacemakers) or any metal in the body;
• Medication advised against the application of Transcranial Magnetic Stimulation;
• History/family history of seizures, brain lesions or head trauma, neurological or psychiatric diseases, epilepsy, migraine

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Fractal Paced; Strength training in single leg extension machine, synchronizing each repetition with a fractal-like visual metronome, i.e., a metronome presenting visual external cues with variability within its temporal structure.	Other: Fractal Paced; The intervention consists in a metronome-paced strength training session performed 3 times per week (with 48h of rest between sessions), during 4 weeks. Each session consists in 4 sets of 15 repetitions at 65% of the one-repetition maximal (1RM) in single leg extension machine, synchronizing each repetition with fractal external cues presented by a visual metronome. The rest between sets will be set at 2 minutes of rest between sets.
Experimental: Isochronous Paced; Strength training in single leg extension machine, synchronizing each repetition with a isochronus visual metronome, i.e., a metronome presenting visual external cues withthe same pace in each repetition (without variability)	Other: Isochronous Paced; The intervention consists in a metronome-paced strength training session performed 3 times per week (with 48h of rest between sessions), during 4 weeks. Each session consists in 4 sets of 15 repetitions at 65% of the one-repetition maximal (1RM) single in leg extension machine, synchronizing each repetition with isochronus external cues presented by a visual metronome. The rest between sets will be set at 2 minutes of rest between sets.
Experimental: Self Paced; Strength training in single leg extension machine at participants self pace.	Other: Self Paced; The intervention consists in a metronome-paced strength training session performed 3 times per week (with 48h of rest between sessions), during 4 weeks. Each session consists in 4 sets of 15 repetitions at 65% of the one-repetition maximal (1RM) in single leg extension machine, at their own self pace (with no metronome). The rest between sets will be set at 2 minutes of rest between sets.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Corticospinal Excitability (CSE) changes across the 4-weeks intervention (PRE to Week1, Week 2, Week 3, POST and follow-up) both within and between Fractal paced, Isochronus Paced and Self paced groups	CSE is a parameter extracted through the application of Transcranial Magnetic Stimulation (TMS). This parameter provides information regarding the level of excitability of the corticospinal tract.	PRE (baseline), W1 (week 1), W2 (week 2), W3 (week 3), POST (week 4), FUP (follow-up 4 weeks after the end of intervention)
Short-interval Intracortical Inhibition (SICI) changes across the 4-weeks intervention (PRE to Week1, Week 2, Week 3, POST and follow-up) both within and between Fractal paced, Isochronus Paced and Self paced groups	SICI is a parameter extracted through the application of Transcranial Magnetic Stimulation (TMS). This parameter provides information regarding the level of inhibition within the motor cortex.	PRE (baseline), W1 (week 1), W2 (week 2), W3 (week 3), POST (week 4), FUP (follow-up 4 weeks after the end of intervention)
Corticospinal Silent Period (CSP) changes across the 4-weeks intervention (PRE to Week1, Week 2, Week 3, POST and follow-up) both within and between Fractal paced, Isochronus Paced and Self paced groups	CSP is a parameter extracted through the application of Transcranial Magnetic Stimulation (TMS). This parameter provides information regarding the level of inhibition along the corticospinal tract.	PRE (baseline), W1 (week 1), W2 (week 2), W3 (week 3), POST (week 4), FUP (follow-up 4 weeks after the end of intervention)
Intracortical Facilitation (ICF) changes across the 4-weeks intervention (PRE to Week1, Week 2, Week 3, POST and follow-up) both within and between Fractal paced, Isochronus Paced and Self paced groups	ICF is a parameter extracted through the application of Transcranial Magnetic Stimulation (TMS). This parameter provides information regarding the level of facilitation within the motor cortex.	PRE (baseline), W1 (week 1), W2 (week 2), W3 (week 3), POST (week 4), FUP (follow-up 4 weeks after the end of intervention)
Lumbar Evoked Potentials (LEP) changes across the 4-weeks intervention (PRE to Week1, Week 2, Week 3, POST and follow-up) both within and between Fractal paced, Isochronus Paced and Self paced groups	LEP is a measure extracted through the aplication of Lumbar stimulation. This measure allow to distinguish the adaptations that occur at spinal level as a result of strength training.	PRE (baseline), W1 (week 1), W2 (week 2), W3 (week 3), POST (week 4), FUP (follow-up 4 weeks after the end of intervention)
Maximal Compound Action Potentials (Mmax) changes across the 4-weeks intervention (PRE to Week1, Week 2, Week 3, POST and follow-up) both within and between Fractal paced, Isochronus Paced and Self paced groups	Mmax is a measure assessed through peripheral nerve stimulation and represents the maximal capacity of recruit the motoneurons that innerve a muscle.	PRE (baseline), W1 (week 1), W2 (week 2), W3 (week 3), POST (week 4), FUP (follow-up 4 weeks after the end of intervention)
StartReact Gain changes across the 4-weeks intervention (PRE to Week1, Week 2, Week 3, POST and follow-up) both within and between Fractal paced, Isochronus Paced and Self paced groups	StartReact gain is a measure that is calculated following the StartReact protocol. It consists in measuring the participants' reaction times in response to visual stimuli (visual reaction time [VRT]), visual stimuli combined with a quiet sound (visual auditory reaction time [VART]) and visual startling stimuli (visual startling reaction time [VSRT]) and, then, apply the following formula: StartReact gain = ([VRT - VSRT]/[VRT - VART]).	PRE (baseline), W1 (week 1), W2 (week 2), W3 (week 3), POST (week 4), FUP (follow-up 4 weeks after the end of intervention)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Single leg extension 1RM changes after 4-weeks intervention (PRE to POST and follow-up) both within and between Fractal paced, Isochronus Paced and Self paced groups	Single leg 1RM is defined as the maximal load that each participant mobilized in a single maximum dynamic knee extension.	PRE (baseline), POST (week 4), FUP (follow-up 4 weeks after the end of intervention)
Maximal Voluntary Isometric Contraction (MVIC) changes across the 4-weeks intervention (PRE to Week1, Week 2, Week 3, POST and follow-up) both within and between Fractal paced, Isochronus Paced and Self paced groups	MVIC is defined as the maximal force an individual can produce against an immovable resistance	PRE (baseline), W1 (week 1), W2 (week 2), W3 (week 3), POST (week 4), FUP (follow-up 4 weeks after the end of intervention)
Sample Entropy (SampEn) changes across the 4-weeks intervention (PRE to Week1, Week 2, Week 3, POST and follow-up) both within and between Fractal paced, Isochronus Paced and Self paced groups	SampEn is a non-linear measure of the temporal structure of force output, being an indicator of the regularity of this physiological output. It is obtained from sustained submaximal isometric contractions and it has been proposed as an indirect index of the capacity of the neuromuscular system to adapt the force output to changes in environment, i.e., its adaptability.	PRE (baseline), W1 (week 1), W2 (week 2), W3 (week 3), POST (week 4), FUP (follow-up 4 weeks after the end of intervention)
Coefficient ov variation (CV) changes across the 4-weeks intervention (PRE to Week1, Week 2, Week 3, POST and follow-up) both within and between Fractal paced, Isochronus Paced and Self paced groups	CV is a common linear measure that translates the amount of variability within the signal and is calculated through the standard deviation normalised to the mean of a time series	PRE (baseline), W1 (week 1), W2 (week 2), W3 (week 3), POST (week 4), FUP (follow-up 4 weeks after the end of intervention)
Motor Unit Action Potentials (MUAP) changes across the 4-weeks intervention (PRE to Week1, Week 2, Week 3, POST and follow-up) both within and between Fractal paced, Isochronus Paced and Self paced groups	MUAP is obtained through the decomposition of electromyographic (EMG) signals collected using High-density surface EMG electrodes and is an index of motor unit recruitment.	PRE (baseline), W1 (week 1), W2 (week 2), W3 (week 3), POST (week 4), FUP (follow-up 4 weeks after the end of intervention)
Firing Rate (FR) changes across the 4-weeks intervention (PRE to Week1, Week 2, Week 3, POST and follow-up) both within and between Fractal paced, Isochronus Paced and Self paced groups	FR is obtained through the decomposition of electromyographic (EMG) signals collected using High-density surface EMG electrodes and is a measure of intramuscular coordination	PRE (baseline), W1 (week 1), W2 (week 2), W3 (week 3), POST (week 4), FUP (follow-up 4 weeks after the end of intervention)

Collaborators and Investigators

• Sponsor: Egas Moniz - Cooperativa de Ensino Superior, CRL
• Collaborators: Fundação para a Ciência e a Tecnologia

Study record dates

Study Major Dates

• Study Start (Actual): September 15, 2024
• Primary Completion (Estimated): August 30, 2026
• Study Completion (Estimated): December 31, 2026

Study Registration Dates

• First Submitted: July 29, 2024
• First Submitted That Met QC Criteria: July 29, 2024
• First Posted (Actual): August 1, 2024

Study Record Updates

• Last Update Posted (Estimated): January 16, 2026
• Last Update Submitted That Met QC Criteria: January 14, 2026
• Last Verified: January 1, 2026

More Information

Terms related to this study

• Keywords: Transcranial Magnetic Stimulation; Neuroscience; Motor Control; Neural Adapatations; Dynamic Systems; Metronome Paced Strength Training
• Other Study ID Numbers: METROTRAIN - 1403

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