最大随意収縮の神経機構：中枢神経系調節による筋力増強の戦略

概要／Abstract

Maximal voluntary contraction (MVC) is central to human strength and function. Beyond muscle morphology, neural mechanisms—cortical and spinal excitability/inhibition, motor unit recruitment, and descending drive—critically constrain MVC. This narrative review integrates evidence on intracortical inhibition, afferent feedback, M1 neuroplasticity, and corticospinal dynamics, highlighting latent capacity to exceed conventional MVC via targeted modulation. We categorize translational strategies into four domains: cognitive-behavioral (verbal encouragement, goal priming), afferent-driven approaches, pharmacological agents (e.g., caffeine), and neuromodulatory stimulation. Evidence indicates these methods can acutely or subacutely enhance MVC, with promising relevance to older adults, athletes, and clinical populations. However, heterogeneity in protocols, dosing, and outcome measures limits comparability and mechanistic clarity. We outline priority directions to standardize metrics, refine neurophysiological endpoints (e.g., SICI, TMS silent period), and tailor context-specific

interventions. Advancing mechanism-based modulation of excitatory/inhibitory circuits may optimize rehabilitation and performance.

筋形態を超え、M1・皮質脊髄路の興奮/抑制がMVCを規定。認知・求心性・薬理・神経刺激で潜在力を引き出し、臨床・競技に応用可能。標準化と機序解明が課題。

これまでの研究で分かっていたこと（科学史的・歴史的な背景など）／Research Background

Morphology vs. neural drive: Muscle architecture, fiber types, and CSA underpin strength, yet complete motor-unit activation often fails even at maximal effort.

Supraspinal limitations: Insufficient descending drive and psychological inhibitory factors have been shown to cap MVC.

Inhibition/fatigue markers: SICI reductions and shorter TMS silent periods accompany strength training; supraspinal and central fatigue reduce voluntary activation.

今回の研究で新たに実現しようとしたこと、明らかになったこと／Findings

Integration: Synthesize neural substrates of MVC, emphasizing latent capacity beyond conventional thresholds.

Framework: Classify interventions into cognitive-behavioral, afferent-driven, pharmacological, and neuromodulatory domains with evidence of MVC enhancement.

Translational insights: Highlight applicability to aging, sports, and rehabilitation, and the need for standardized protocols.

そのために新しく開発した手法／Methods developed

This article is a narrative review; therefore, it does not report the development of novel measurement or intervention methods. However, from a neurophysiological perspective, it introduces potential intervention approaches that could be further developed in future research.

研究の波及効果や社会的影響／Research implications to the society

Clinical: Enhances rehabilitation outcomes and reduces fall risk and functional limitations.

Sports: Boosts acute performance and accelerates strength adaptations.

Aging: Improves gait stability and quality of life, potentially lowering healthcare burdens.

今後の課題／Future issues

Standardization: Harmonize protocols and outcome metrics; establish dose–response.
Mechanisms: Clarify causal roles of excitatory/inhibitory circuits and validate neurophysiological endpoints.
Context-specificity: Tailor interventions to populations and goals; assess durability.

研究者のコメント／Researcher’s Comment

Strength ceilings are set by neural circuits, not just muscle. By reducing inhibition and amplifying excitability, cognitive, afferent, pharmacological, and neuromodulatory interventions can safely unlock latent MVC capacity. Mechanism-driven neural modulation offers a path to clinically and athletically meaningful gains across aging, sport, and rehabilitation.

用語解説／Terminology

※1　MVC　（最大随意筋収縮）

※2　M1 （一次運動野）

※3　Transcranial Magnetic Stimulation（経頭蓋磁気刺激：TMS）

※4　Silent period　TMSでM1を刺激した後に、筋電図（EMG）活動が一時的に抑制されて「沈黙」する時間のこと。

論文情報（掲載された場合）／Journal Information (if published)

雑誌名／Journal： Frontiers in Physiology

論文名／Title： Enhancing Human Strength via Neural Modulation: Mechanisms of Maximal Voluntary Contraction and Translational Interventions

執筆者名・所属機関名／Authors and Affiliated Organization： Yudai Takarada (Waseda University)

Publishment Date（Local Time）：5 November 2025

Publishment Date（Japan Time）：

（オンライン掲載の場合／For online publication）

URL : https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2025.1695665/full

DOI：10.3389/fphys.2025.1695665

研究助成（外部資金による助成を受けた研究実施の場合）／Research Grant (in case of externally funded research)

研究費名／Research Fund：The Japan Society for the Promotion of Science (JSPS) KAKENHI Grant Number JP25K14752

研究課題名／Research Subject：局所的な血流制限下の筋収縮中の運動システム活動状態とは何か

研究代表者名・所属機関名／Research Representative and Affiliated Organization：Yudai Takarada (Waseda University)

 

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宝田　雄大

研究者詳細 – 宝田　雄大