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Shouting strengthens maximal voluntary force and is associated with augmented pupillary dilation
Yudai Takarada1, Daichi Nozaki2
1Faculty of Sports Sciences, Waseda University, 2-579-15 Mikajima, Tokorozawa, Saitama, 359-1192, Japan. takarada@waseda.jp.
Scientific Reports
|September 17, 2021
Summary
Shouting during maximal effort increases grip force by enhancing motor cortex excitability and pupil size. This suggests shouting modulates neural pathways, improving maximal voluntary contraction performance.
Area of Science:
- Neuroscience
- Motor Control
- Human Physiology
Background:
- Maximal voluntary force production in humans is typically limited by neural inhibition.
- Vocalization, such as shouting, during maximal exertion enhances force output.
- The precise neural mechanisms behind this force enhancement are not fully understood.
Purpose of the Study:
- To investigate how shouting influences the pupil-linked neuromodulatory system.
- To examine the effects of shouting on the motor system's state.
- To determine the relationship between shouting, neural activity, and maximal force production.
Main Methods:
- Measured handgrip maximal voluntary force.
- Assessed pupil size as an indicator of neuromodulatory activity.
- Used transcranial magnetic stimulation to evaluate motor evoked potentials and cortical silent period.
Main Results:
- Shouting significantly increased handgrip maximal voluntary force.
- Pupil size increased, and the cortical silent period decreased following a shout.
- These changes suggest enhanced motor cortical excitability.
Conclusions:
- Shouting enhances maximal voluntary force through increased motor cortical excitability.
- The effect may involve the noradrenergic system, indicated by pupil size changes.
- Shouting's force-enhancing effect is linked to both motor and pupil-linked neuromodulatory systems.
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