Gymnasts' Ability to Modulate Sensorimotor Rhythms During Kinesthetic Motor Imagery of Sports Non-specific Movements Superior to Non-gymnasts

Abstract

Previous psychological studies using questionnaires have consistently reported that athletes have superior motor imagery ability, both for sports-specific and for sports-non-specific movements. However, regarding motor imagery of sports-non-specific movements, no physiological studies have demonstrated differences in neural activity between athletes and non-athletes. The purpose of this study was to examine the differences in sensorimotor rhythms during kinesthetic motor imagery (KMI) of sports-non-specific movements between gymnasts and non-gymnasts. We selected gymnasts as an example population because they are likely to have particularly superior motor imagery ability due to frequent usage of motor imagery, including KMI as part of daily practice. Healthy young participants (16 gymnasts and 16 non-gymnasts) performed repeated motor execution and KMI of sports-non-specific movements (wrist dorsiflexion and shoulder abduction of the dominant hand). Scalp electroencephalogram (EEG) was recorded over the contralateral sensorimotor cortex. During motor execution and KMI, sensorimotor EEG power is known to decrease in the α- (8-15 Hz) and β-bands (16-35 Hz), referred to as event-related desynchronization (ERD). We calculated the maximal peak of ERD both in the α- (αERDmax) and β-bands (βERDmax) as a measure of changes in corticospinal excitability. αERDmax was significantly greater in gymnasts, who subjectively evaluated their KMI as being more vivid in the psychological questionnaire. On the other hand, βERDmax was greater in gymnasts only for shoulder abduction KMI. These findings suggest gymnasts' signature of flexibly modulating sensorimotor rhythms with no movements, which may be the basis of their superior ability of KMI for sports-non-specific movements.

Keywords: athletes; electroencephalogram (EEG); event-related desynchronization (ERD); kinesthetic motor imagery (KMI); the Kinesthetic and Visual Imagery Questionnaire (KVIQ).

Figure 1

Experimental paradigm of the physiological experiment. Participants performed isometric contraction in the contraction phase and performed motor imagery of the same movement in the imagery phase. The diagram shows the flow in each trial, which was repeated five times within each set. Six sets were performed for each of the wrist dorsiflexion and shoulder abduction tasks.

Figure 2

Results of psychological experiment. Group data (mean ± S.D.) for visual motor imagery (VMI) (A) and kinesthetic motor imagery (KMI) (B) scores obtained from the Kinesthetic and Visual Imagery Questionnaire (KVIQ) are shown for both groups. The gray bars represent the data for non-gymnasts, while the black bars represents the data for gymnasts. *P < 0.05.

Figure 3

Results from physiological experiments for motor execution. Typical time courses of single-trial EEG, time-frequency map, α-band event-related desynchronization (ERD), and β-band in wrist dorsiflexion motor execution are shown for non-gymnast (A) and gymnast (B) participants. Note that participants performed wrist dorsiflexion motor execution from 0 to 5 s. Group data (mean ± S.D.) for the maximal peak of ERD both in the α- (αERDmax) (C) and in the β-bands (βERDmax) (D) during motor execution are shown across groups and tasks. The gray bars represent the data for non-gymnasts, while the black bars represent the data for gymnasts. No significant differences were observed across groups and tasks.

Figure 4

Results from physiological experiments for KMI. Typical time courses of single-trial EEG, time-frequency map, α-band ERD, and β-band in wrist dorsiflexion KMI are shown for non-gymnast (A) and gymnast (B) participants. Note that participants performed wrist dorsiflexion KMI from 0 to 5 s. Group data (mean ± S.D.) for αERDmax (C) and βERDmax (D) during KMI are shown across groups and tasks. The gray bars represent the data for non-gymnasts, while the black bars represent the data for gymnasts. *P < 0.05.

Figure 5

Results of the ratio of the α-band and the β-band power spectrum densities. Group data (mean ± S.D.) for the ratio of the α-band (A) and β-band power spectrum densities (PSD) (B) are shown for both groups. The gray bars represent the data for non-gymnasts, while the black bars represent the data for gymnasts. *P < 0.05.