Response of the Cerebral Cortex to Resistance and Non-resistance Exercise Under Different Trajectories: A Functional Near-Infrared Spectroscopy Study

Abstract

Background: At present, the effects of upper limb movement are generally evaluated from the level of motor performance. The purpose of this study is to evaluate the response of the cerebral cortex to different upper limb movement patterns from the perspective of neurophysiology. Method: Thirty healthy adults (12 females, 18 males, mean age 23.9 ± 0.9 years) took resistance and non-resistance exercises under four trajectories (T1: left and right straight-line movement; T2: front and back straight-line movement; T3: clockwise and anticlockwise drawing circle movement; and T4: clockwise and anticlockwise character ⁕ movement). Each movement included a set of periodic motions composed of a 30-s task and a 30-s rest. Functional near-infrared spectroscopy (fNIRS) was used to measure cerebral blood flow dynamics. Primary somatosensory cortex (S1), supplementary motor area (SMA), pre-motor area (PMA), primary motor cortex (M1), and dorsolateral prefrontal cortex (DLPFC) were chosen as regions of interests (ROIs). Activation maps and symmetric heat maps were applied to assess the response of the cerebral cortex to different motion patterns. Result: The activation of the brain cortex was significantly increased during resistance movement for each participant. Specifically, S1, SMA, PMA, and M1 had higher participation during both non-resistance movement and resistance movement. Compared to non-resistance movement, the resistance movement caused an obvious response in the cerebral cortex. The task state and the resting state were distinguished more obviously in the resistance movement. Four trajectories can be distinguished under non-resistance movement. Conclusion: This study confirmed that the response of the cerebral motor cortex to different motion patterns was different from that of the neurophysiological level. It may provide a reference for the evaluation of resistance training effects in the future.

Keywords: functional near-infrared spectroscopy; motor cortex; neurophysiology; resistance movement; upper limb movement.

Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Copyright © 2021 Shi, Li and Yu.

Figures

FIGURE 1

The task paradigm. (A) The experiment consists of two parts: non-resistance movement and resistance movement. Each task contains three periodic motions: rest for 30 s and exercise for 30 s. The interval between the two exercises is 600 s. (B) Four trajectories.

FIGURE 2

Basic experimental setup. (A) Cerebral cortical channel placement; (B) a map of the regions of the brain covered by light poles. Blue: supplementary motor area (SMA) and pre-motor area (PMA); green: the primary somatosensory cortex (S1); and red: primary motor cortex (M1). (C) Experimental environment and process diagram; (D) schematic diagram of 27 channels. Yellow circles: 10 transmitters; blue circles: 8 receivers; and white circles: 27 channels.

FIGURE 3

Activation maps of cerebral cortex from trajectory 1 to trajectory 4. (A) Non-resistance movement; (B) resistance movement. The change from red to yellow indicates that the degree of activation is from low to high. The coordinates in the figure show the activation range of the cerebral cortex in each mode. The data are t values, t:statistical value of sample t-test [with a significance level of p < 0.05, Lipschitz-Killing curvature (LKC)-based expected Euler characteristics (EC) correction]. The data and maps are calculated and generated by SPM_NIRS.

FIGURE 4

Symmetric heat maps of T1, T2, T3, and T4, which represent the Pearson correlation index of 27 channels. (A) Non-resistance movement; (B) resistance movement. The change from white to dark blue indicates that the correlation level is from negative 0.8 to positive 1.

FIGURE 5

Correlation heat map of regions of interests (ROIs) in T1, T2, T3, and T4 for the primary somatosensory cortex (S1), supplementary motor area (SMA), pre-motor area (PMA), primary motor cortex (M1), and dorsolateral prefrontal cortex (DLPFC). (A) Non-resistance movement; (B) resistance movement. The color bar from yellow to dark blue indicates the correlation from –1 to 1.

FIGURE 6

The HbO concentration (ΔHbO) in the cerebral cortex of regions of interests (ROIs) in T1, T2, T3, and T4. (A) Non-resistance movement; (B) resistance movement. Values were shown with mean + SD.

FIGURE 7

β values of four trajectories under two movement modes. The abscissa shows four trajectories. The coordinate is the value of β. β was extracted from the general linear analysis model (GLM). The bar indicates the errors. ∗∗p < 0.01, ∗∗∗∗p < 0.0001.

FIGURE 8

Time series of oxyhemoglobin changes during the task. (A) Non-resistance movement; (B) resistance movement. The gray area is the stimulus period. The solid line in the figure represents the average value of concentration, and the upper and lower shaded parts represent the error (mean ± SD) (n = 24).