高能雷射治療對運動引發疲勞後肌肉位移特徵與被動移行量的改變

Abstract

研究背景：肌肉疲勞指急性運動中或後肌肉力量或功率的下降，易增加受傷風險，因此運動前的肌肉疲勞預防策略至關重要。高能雷射治療已被證實可減少疲勞後的力量流失，同時可是一種可以用於操控肌肉疲勞的工具。評估肌肉疲勞的非侵入性量測工具中，超音波斑點追蹤技術是一種能即時量測深層肌肉在動態主動收縮下位移特徵的工具，並能定量評估疲勞狀態下肌肉被動伸展的移行特徵。目前已有文獻發現，疲勞後肌肉在收縮時會出現主動收縮位移量下降的現象。然而，目前針對高能雷射是否是一種可以用於操控疲勞後肌肉主動收縮之收縮位移量以及被動伸展之移行量的研究仍相對有限，此外，也無相關研究證實，以上肌肉收縮位移量以及肌肉被動移行量恢復到疲勞前狀態，在時序上，與其他可用於監測肌肉疲勞的神經肌肉量測工具相比，是否有所不同。改善以上現況除可探討高能雷射治療對肌肉收縮位移量與肌肉被動移行量的影響外，並有助於解釋肌肉疲勞恢復到疲勞前狀態的過程中，神經肌肉依序恢復的順序。 研究目的：本研究旨在探討高能雷射治療在減緩或操控肌肉疲勞後肌肉收縮位移量與被動移行量的效果，以及分析各項監測肌肉疲勞之工具，其有關神經肌肉之數據，在恢復到肌肉疲勞前狀態的時序，以及肌力與各量測工具結果之相關性。本研究企圖透過肌肉收縮位移量定量評估疲勞狀態下肌肉的主動收縮能力，並以肌肉被動移行量測量肌肉在被伸展之條件下其被動延展之大小。本研究同時量測肌肉的力量輸出、神經肌肉活化程度及肌肉微循環的變化，以分析有無高能雷射治療介入時，在肌肉疲勞時與後，以上數據的特徵及恢復的作用，並且分析肌力與肌肉收縮位移量、被動移行量與其他動態生理指標（如表面肌電訊號之中位頻率變化、峰值力矩等）之間的相關性，以確認超音波影像技術在運動疲勞評估中的適用性。 研究方法：本研究採隨機、交叉、虛假療法對照實驗設計，預計收錄20位健康生理男性，將隨機分為A、B兩組，並進行兩次間隔15天的等速向心收縮運動（疲勞運動），其中A組會先接受高能雷射介入，15天後接受虛假雷射介入；B組則是先接受虛假雷射介入，15天後接受高能雷射介入。兩組均以等速向心運動誘發疲勞，兩組均於運動前、運動後立即、5、10、20分鐘測量：股外側肌肌肉收縮位移量、股外側肌肌肉被動移行量、膝伸直最大自主等長收縮力矩、表面肌電訊號、肌肉微循環。 結果：肌肉組織在經由高能雷射介入的條件下，在肌肉疲勞後，於等長收縮時，向近端移動的收縮位移量顯著大於虛假雷射（高能雷射介入：8.61 ± 3.15 mm、虛假雷射介入：5.71 ± 2.82 mm，P 值 < 0.001），且發現在高能雷射介入條件下，其肌肉收縮位移量在疲勞前後的變化量顯著小於虛假雷射介入（高能雷射介入：2.56 ± 2.12 mm、虛假雷射介入：5.30 ± 2.41 mm，P 值 < 0.001）；此外，於被動屈曲時，向遠端移動的被動移行量顯著大於較虛假雷射（高能雷射介入：16.01 ± 5.05 mm、虛假雷射介入：13.89 ± 6.16 mm，P 值 < 0.001），同時發現在高能雷射介入條件下，其肌肉被動移行量在疲勞前後的變化量顯著大於虛假雷射介入（高能雷射介入：3.56 ± 2.17 mm、虛假雷射介入：1.48 ± 2.46 mm，P 值 < 0.001）。同時發現在中位頻率、膝伸直力矩、帶氧血紅素、氧飽和度等數據，皆在高能雷射介入後，其結果下降或改變之幅度顯著低於虛假雷射介入。針對以上各項參數恢復到疲勞前狀態之時序，發現在高能雷射介入後，肌肉收縮位移量與膝伸直力矩於運動後5分鐘內恢復到疲勞前狀態，早於虛假雷射介入；中位頻率、帶氧血紅素與氧飽和度在兩個介入條件中皆於5分鐘內恢復，且中位頻率於20分鐘後顯著上升；肌肉被動移行量則在兩個介入條件中皆未於20分鐘內恢復。最後，透過皮爾森相關性分析發現肌肉收縮位移量的變化量與峰值力矩變化量呈現低度負相關（r = -0.238，P值 = 0.005）。 結論：高能雷射治療介入可有效減緩肌肉疲勞後在肌肉機械行為與神經生理參數上的變化，並加速肌肉收縮位移量與膝伸直力矩的恢復。其潛在機制可能包括促進局部血液循環、提升粒線體活化、加速代謝副產物的清除，以及增強神經肌肉活化表現。整體而言，本研究結果發現高能雷射治療介入具作為非侵入性疲勞恢復介入方式的可能途徑，並提出以超音波斑點追蹤技術作為監測肌肉動態收縮與疲勞狀態工具的可行性。

Background: Muscle fatigue is defined as a decline in muscle force or power during or after acute exercise, which increases the risk of injury and highlights the importance of implementing preventive strategies before exercise. High-intensity laser therapy (HILT) has been shown to attenuate strength loss induced by fatigue and may serve as a potential tool for modulating muscle fatigue; however, its effects on muscle contractile behaviors—specifically muscle shortening and displacement during fatigue—remain unclear. Several non-invasive tools are available to assess muscle fatigue, each providing unique insights into the fatigue process. Among these, speckle tracking ultrasonography is a promising technique that allows real-time, quantitative measurement of muscle displacement during dynamic active contractions. It can also evaluate muscle contractility and passive excursion during fatigue. However, limited research has investigated the effects of HILT on muscle displacement and muscle excursion. Moreover, limited research has examined whether the recovery timeline of these parameters differs from other neuromuscular indicators used to monitor muscle fatigue. Addressing these knowledge gaps not only helps to clarify the biomechanical and neurophysiological mechanisms of HILT during recovery but also contributes to understanding the chronological recovery processes of neuromuscular function following fatigue. Purpose: This study aimed to investigate the effects of high-intensity laser therapy (HILT) on the modulation of muscle displacement and muscle excursion after fatigue. Additionally, analyze the recovery timelines of neuromuscular parameters in comparison with baseline states. Moreover, correlation among muscle strength and various fatigue-related indicators were explored. Muscle displacement was quantitatively assessed to evaluate active contractile capacity under fatigued conditions, while muscle excursion was measured to assess passive mobility. Simultaneously, muscle force output, neuromuscular activation, and microcirculatory changes were measured to characterize the fatigue response and recovery process, with and without HILT. Correlations between muscle force output, muscle displacement, muscle excursion and other physiological indicator – such as surface electromyography (median frequency) and peak torque – were examined to evaluate the feasibility of ultrasound imaging for fatigue monitoring. Methods: A randomized, crossover, sham-controlled design was employed with 20 healthy male participants. Each participant was randomly assigned to two group (Group A and Group B) and completed two fatigue protocols, 15 days apart, receiving either HILT or a sham laser (SHAM) intervention in a randomized order. Measurements were taken at baseline and at multiple time points post-fatigue (immediately, and at 5, 10, and 20 minutes), including vastus lateralis muscle displacement, muscle excursion, maximal isometric knee extension torque, neuromuscular activation, and microcirculation. Results: Under the HILT conditions, the muscle displacement during maximal voluntary isometric contraction testing at immediately post-fatigue significantly greater than SHAM (HILT: 8.61 ± 3.15 mm; sham: 5.71 ± 2.82 mm). The study also found that under HILT conditions, the change in muscle displacement before and immediately after fatigue was significantly smaller than that under SHAM conditions (HILT: 2.56 ± 2.12 mm, SHAM: 5.30 ± 2.41 mm). Moreover, during the passive knee flexion testing, muscle excursion was significantly greater than SHAM (HILT: 16.01 ± 5.05 mm; sham: 13.89 ± 6.16 mm; P < 0.001). Also, under HILT conditions, the change in muscle excursion before and immediately after fatigue was significantly greater than that under SHAM conditions (HILT: 3.56 ± 2.17 mm, SHAM: 1.48 ± 2.46 mm). Additionally, HILT resulted in significantly attenuated reduction or changes in peak torque, median frequency, oxygenated hemoglobin, and oxygen saturation compared to SHAM. Regarding recovery timelines, muscle displacement and torque returned to baseline within 5 minutes post-exercise under HILT, earlier than under SHAM. Median frequency, oxygenated hemoglobin, and oxygen saturation recovered within 5 minutes under both conditions. However, muscle excursion did not fully recover within 20 minutes. A weak negative correlation was found between the change of muscle displacement and peak torque (r = -0.238, P = 0.005). Conclusion: HILT effectively attenuates alterations in muscle mechanical behavior and neurophysiological parameters following muscle fatigue, and accelerates the recovery of muscle displacement and knee extension torque. The underlying mechanisms may involve enhanced local blood circulation, improved mitochondria activation, accelerated clearance of metabolic byproducts, and enhanced neuromuscular activation. Overall, these findings highlight the potential of HILT as a non-invasive intervention to promote fatigue recovery and support the use of speckle tracking ultrasonography as a reliable tool for monitoring dynamic muscle contraction to provide real-time information on muscle fatigue.