Neural adaptations to long-term resistance training: evidence for the confounding effect of muscle size on the interpretation of surface electromyography

SKARABOT, Jakob, BALSHAW, Tom, MAEO, Sumiaki, MASSEY, Garry, BAHIA-LANZA, Marcel, MADEN-WILKINSON, Tom and FOLLAND, Jonathan (2021). Neural adaptations to long-term resistance training: evidence for the confounding effect of muscle size on the interpretation of surface electromyography. Journal of Applied Physiology.

[img]
Preview
PDF
Maden-Wilkinson-NeuralAdaptationsLong(AM).pdf - Accepted Version
All rights reserved.

Download (353kB) | Preview
Official URL: https://journals.physiology.org/doi/abs/10.1152/ja...
Link to published version:: https://doi.org/10.1152/japplphysiol.00094.2021

Abstract

This study compared elbow flexor (EF; Experiment 1) and knee extensor (KE; Experiment 2) maximal compound action potential (Mmax) amplitude between long-term resistance trained (LTRT; n=15 and n=14, 6±3 and 4±1 years of training) and untrained (UT; n=14 and n=49) men; and examined the effect of normalising electromyography (EMG) during maximal voluntary torque (MVT) production to Mmax amplitude on differences between LTRT and UT. EMG was recorded from multiple sites and muscles of EF and KE, Mmax was evoked with percutaneous nerve stimulation, and muscle size was assessed with ultrasonography (thickness, EF) and magnetic resonance imaging (cross-sectional area, KE). Muscle-electrode distance (MED) was measured to account for the effect of adipose tissue on EMG and Mmax. LTRT displayed greater MVT (+66-71%, p<0.001), muscle size (+54-56%, p<0.001), and Mmax amplitudes (+29-60%, p≤0.010) even when corrected for MED (p≤0.045). Mmax was associated with the size of both muscle groups (r≥0.466, p≤0.011). Compared to UT, LTRT had higher absolute voluntary EMG amplitude for the KE (p<0.001), but not the EF (p=0.195), and these differences/similarities were maintained after correction for MED; however, Mmax normalisation resulted in no differences between LTRT and UT for any muscle and/or muscle group (p≥0.652). The positive association between Mmax and muscle size, and no differences when accounting for peripheral electrophysiological properties (EMG/Mmax), indicates the greater absolute voluntary EMG amplitude of LTRT might be confounded by muscle morphology, rather than provide a discrete measure of central neural activity. This study therefore suggests limited agonist neural adaptation after LTRT.

Item Type: Article
Uncontrolled Keywords: Physiology; 06 Biological Sciences; 11 Medical and Health Sciences
Identification Number: https://doi.org/10.1152/japplphysiol.00094.2021
SWORD Depositor: Symplectic Elements
Depositing User: Symplectic Elements
Date Deposited: 28 Jun 2021 12:57
Last Modified: 24 Jun 2022 01:18
URI: https://shura.shu.ac.uk/id/eprint/28791

Actions (login required)

View Item View Item

Downloads

Downloads per month over past year

View more statistics