Strenuous resistance exercise effects on magnetic resonance diffusion parameters and muscle–tendon function in human skeletal muscle

Abstract

Purpose: To assess the effects of strenuous exercise on magnetic resonance diffusion parameters and muscletendon complex function in skeletal muscle. Materials and Methods:Six men performed ankle plantar flexion exercises with eccentric contraction. The fractional anisotropy (FA), l 1 , l 2 , l 3 , mean diffusivity (MD), and T 2 values in the triceps surae muscles were measured by magnetic resonance diffusion tensor and spinecho imaging. Passive torque of plantar flexors, maximal voluntary isometric plantar flexion torques (MVIP), and Achilles tendon stiffness during MVIP were measured by combined ultrasonography and dynamometry. Plasma creatine kinase and muscle soreness were also assessed. These parameters were measured before and 1-8 days postexercise. Results:The medial gastrocnemius exhibited significantly decreased FA 2-5 days after, increased l 2 3 days after, and increased l 3 2 and 3 days after exercise. This muscle also showed significantly increased MD and T 2 values 3 days postexercise. MVIP significantly decreased 2 and 3 days postexercise, while passive torque significantly increased 2 days postexercise. Creatine kinase and muscle soreness increased 3-5 days and 1-5 days postexercise, respectively.Conclusion: Exercise-induced muscle damage manifested as significant changes in muscle diffusion parameters with muscle-tendon complex dysfunction and delayedonset muscle soreness.

Muscle Changes Detected with Diffusion-Tensor Imaging after Long-Distance Running

“…Previous research established DTI as a reproducible and valid technique (23,24,26) to evaluate muscle status (10,11,(27)(28)(29). We extended the clinical applicability of this technique by developing a protocol that covers both upper legs from hip to knee in one examination.…”

“…The DTI-derived parameters-eigenvalues (l 1 , l 2 , and l 3 ), mean diffusivity, and fractional anisotropy (FA)-are sensitive to changes in the tissue microstructure. Previous studies showed increase of mean diffusivity and decrease of FA within skeletal muscle tissue after mechanical injury and exercise-induced trauma (10)(11)(12). However, these studies measured the diffusion in small parts of muscles with known abnormalities.…”

Localization of damage in the human leg muscles induced by downhill running

“…To support the usefulness of T 2 as an index of muscle damage, high correlation ( r  > 0.9) has been reported between changes in T 2 and plasma CK activity measured within several days after eccentric exercises 30, 38 . Some studies demonstrated that T 2 increased heterogeneously within the KEs 11, 31, 37 or PFs 39, 40 after eccentric or strenuous resistance exercises. To the authors knowledge, however, no studies have examined localization of muscle damage within the KEs and PFs induced by DR. Clarifying this would provide insight into which site or muscle should be given particular care and/or focus when conducting DR in a practical or experimental setting.…”

Assessment of Postoperative Tendon Quality in Patients With Achilles Tendon Rupture Using Diffusion Tensor Imaging and Tendon Fiber Tracking

“…FA will show the degree of water diffusion anisotropy according to the muscle fiber direction. Thus, the FA value is a robust intravoxel measure that yields values between 0 (perfectly isotropic) and 1 (perfectly anisotropic) (19,20).…”

“…Hence, combining these per-voxel data sets will permit the construction of 3-dimensional fiber tracts Furthermore, the parameters FA and ADC can be evaluated from these data sets, supplying a quantitative description of tissue organization and integrity (13,14,24). DTI is based on the fact that cell membranes and other structures restrict water diffusion through the tissues, leading to anisotropic diffusion (19). DTI anatomically represents the diffusion along the main direction of the muscle fiber (20).…”