Delayed onset muscle soreness intensity affects muscular performance / El Dolor muscular de aparición tardía afecta el desempeño muscular

Abstract Background: The study of functional impact of delayed onset muscle soreness has been limited to describe the decline on maximal isometric contraction, but muscular work and time to peak torque has not been examined yet. Purpose: To describe the changes induced by a session of lengthening contractions on muscle performance and delayed onset muscle soreness (DOMS). Methods: A quasi-experimental study was conducted in the Institutional laboratory; Twenty healthy men; mean age 21 SD 0.34 were recruited, all subjects performed 200 lengthening contractions of the quadriceps at 120°/s. Isometric and isokinetic peak torque, muscular work, time to peak torque, DOMS and creatine kinase activity were assessed at baseline, 48 h and 96 h post-exercise. The muscle performance was assessed with an isokinetic dynamometer and DOMS with a visual analog scale (VAS). Results: Relative to baseline, isometric and isokinetic peak torque and muscular work decreased in ~30% at 48 h post-exercise; delayed onset muscle soreness increased ~300%, which remained at 96 h post-exercise. Conclusions: These reflect that the decline in muscular performance is due to the changes in peak torque and muscular work, which has greater implications on muscle function. No changes were detected in time to peak torque. The alterations in muscular performance variables are accompanied by delayed onset muscle soreness which has also a negative impact on force production (29% of the drop on peak torque is explain by soreness intensity).

Resumen Introducción: Los estudios de impacto funcional del dolor muscular de aparición tardía (DMAT) se han limitado a describir la disminución de la contracción isométrica máxima, pero aún no se ha examinado el trabajo muscular y el tiempo del torque máximo. Objetivo: Describir los cambios inducidos por una sesión de ejercicio excéntrico sobre el rendimiento muscular y DMAT. Método: se realizó un estudio cuasi-experimental, los participantes fueron veinte hombres sanos; edad media 21 DE 0,34, todos los sujetos realizaron 200 contracciones excéntricas del cuádriceps a 120°/s. Se evaluó el torque pico isométrico e isocinético, el trabajo muscular, el tiempo hasta el torque máximo, DMAT y la actividad de la creatina quinasa al inicio, 48 h y 96 h después del ejercicio, el rendimiento muscular se evaluó con un dinamómetro isocinético y DOMS con una escala análoga visual (EAV). Resultados: en relación con la línea de base, el torque pico isométrico e isocinético y el trabajo muscular disminuyeron en ~ 30 % a las 48 h post-ejercicio; El dolor muscular de aparición tardía aumentó ~300 %, que permaneció 96 h después del ejercicio. Conclusiones: los resultados reflejan que la disminución del rendimiento muscular se debe a los cambios en el torque pico y trabajo muscular, lo que tiene mayores implicaciones en la función muscular. No se detectaron cambios en el tiempo hasta el torque máximo. Las alteraciones en las variables de rendimiento muscular se acompañan de DMAT que también tiene un impacto negativo en la producción de fuerza (el 29 % de la caída en el torque máximo se explica por la intensidad del dolor).

Kinesiotaping Diminishes Delayed Muscle Soreness but does not Improve Muscular Performance.

This study aimed at determining the effect of kinesio-taping (KT) on muscle performance and delayed onset muscle soreness (DOMS) after exercise induced muscle damaged. Sixty-six healthy men volunteered to participate (age:18-25 y/o), who performed 200 isokinetic lengthening contractions of the dominant quadriceps. Then subjects were randomized to either control (no treatment), sham (no tape tension), or KT (10% tape tension) groups. Muscle performance was assessed by peak torque and muscular work during maximal isometric and concentric isokinetic contractions. DOMS intensity was assessed using a visual analog scale. Measurements were taken pre-exercise (Pre), 48 h and 96 h post-exercise. Repeated measures ANOVA was used for comparisons within group, and ANCOVA for comparisons among groups. Muscle damage was confirmed in all participants by an increase in CK activity level (p<0.01). Decrease in isometric and isokinetic peak torque was detected at 48 h in the control and sham groups (p<0.01). Muscular work decreased in all groups at 48 h (p<0.01). No differences between groups were detected in muscular performance variables. Increase in DOMS intensity was determined in all groups at 48 h. Comparisons between groups showed lower DOMS intensity in the KT group at 48 h. KT decreased DOMS intensity perception after exercise-induced muscle damage; however, it did not impact muscular performance.

Continuous Ultrasound Decreases Pain Perception and Increases Pain Threshold in Damaged Skeletal Muscle.

OBJECTIVE: Determine whether therapeutic ultrasound (TUS) delivered in a continuous mode reduces pain perception after muscle injury. DESIGN: Randomized, double-blind trial. SETTING: Institutional laboratory. PARTICIPANTS: Twenty young healthy participants (11 females; 9 males; mean age ± SD, 24.1 ± 3.7 years). INTERVENTION: All subjects performed 50 maximal eccentric contractions of the biceps brachii on a Biodex dynamometer. Criterion measures of isometric force production and serum creatine kinase (CK) activity confirmed tissue damage. Both groups received either TUS or sham treatment everyday starting 24 hours after muscle damage. Muscle soreness and pain were assessed at baseline, 48 hours postdamage, and every other day for 8 days. MAIN OUTCOME MEASURES: Muscle pain was assessed with a battery of tests: visual analog scale (VAS), Short-form McGill Pain Questionnaire-2, joint angle changes, and mechanical pressure threshold. RESULTS: Confirmation of damage occurred with baseline compared to 48 hours after damage of isometric peak torque (N·m; P < 0.01) and CK activity (IU/I; P = 0.03). Our results showed significant treatment group differences in VAS (P = 0.01) and mechanical pressure threshold (P = 0.02) after the third TUS treatment in the distal bicep brachii region. CONCLUSIONS: Continuous TUS reduced pain perception and increased mechanical pressure threshold in the biceps brachii after muscle damage, specifically near the distal musculotendinous junction.

Resveratrol improves muscle function but not oxidative capacity in young mdx mice.

Patients with Duchenne muscular dystrophy (DMD) have reduced muscle function due to chronic muscle damage, inflammation, oxidative stress, and reduced oxidative capacity. Resveratrol reduces inflammation and oxidative stress, and increases oxidative capacity in other disease models. The purpose of this study was to determine the effects of resveratrol on muscle function, muscle pathology, and oxidative capacity in young mdx mice. For this, 4- to 5-week-old male mdx mice were randomized into control or resveratrol-treated groups and given resveratrol (100 mg/kg body mass) or an equal volume of water by gavage every other day for 8 weeks. Muscle function was assessed pre- and post-treatment. Central nucleation, total immune cell infiltrate, oxidative stress, and oxidative capacity were measured post-treatment. Resveratrol mediated substantial improvements in rotarod performance and in-situ peak tension by 53% and 17%, respectively, and slight improvements in central nucleation and oxidative stress. Resveratrol did not affect total immune cell infiltrate at 12 weeks of age, and had no effect on oxidative capacity. Resveratrol improves muscle function in mdx mice despite small changes in muscle pathology. The likely mechanism is a resveratrol-mediated reduction in immune cell infiltrate at the early stages of this disease, as previously reported by our laboratory.

Resveratrol decreases inflammation and increases utrophin gene expression in the mdx mouse model of Duchenne muscular dystrophy.

BACKGROUND & AIMS: Duchenne muscular dystrophy (DMD) is a lethal genetic disease with no cure. Reducing inflammation or increasing utrophin expression can alleviate DMD pathology. Resveratrol can reduce inflammation and activate the utrophin promoter. The aims of this study were to identify an active dose of resveratrol in mdx mice and examine if this dose decreased inflammation and increased utrophin expression. METHODS: 5-week old mdx mice were given 0, 10, 100, or 500 mg/kg of resveratrol everyday for 10 days. Sirt1 was measured by qRT-PCR and used to determine the most active dose. Muscle inflammation was measured by H&E staining, CD45 and F4/80 immunohistochemistry. IL-6, TNFα, PGC-1α, and utrophin gene expression were measured by qRT-PCR. Utrophin, Sirt1, and PGC-1α protein were quantified by western blot. RESULTS: The 100 mg/kg dose of resveratrol, the most active dose, increased Sirt1 mRNA 60 ± 10% (p < 0.01), reduced immune cell infiltration 21 ± 6% (H&E) and 42 ± 8% (CD45 immunohistochemistry (p < 0.05)), reduced macrophage infiltration 48 ± 10% (F4/80 immunohistochemistry (p < 0.05)), and increased IL-6, PGC-1α, and utrophin mRNA 247 ± 77%, 27 ± 17%, and 43 ± 23% respectively (p ≤ 0.05). Utrophin, Sirt1, and PGC-1α protein expression did not change. CONCLUSIONS: Resveratrol may be a therapy for DMD by reducing inflammation.

Six1 and Six1 cofactor expression is altered during early skeletal muscle overload in mice.

Six1 is a transcription factor that, along with cofactors (Eya1, Eya3, and Dach2), regulates skeletal muscle fiber-type and development. SIX1 (human) gene expression decreases after overload, but the time course of Six1 expression, if protein is affected, and if the response differs between muscles with differing phenotypes, is not known. Our purpose was to examine Six1 gene and protein expression and co-factor gene expression during the initiation of muscle overload, and determine if the muscle phenotype altered this response. The plantaris and soleus were functionally overloaded by synergistic ablation of the gastrocnemius, and Six1 gene and protein, and Six1 cofactor gene expression was measured. Six1 gene expression decreased at 1 day of overload 48 ± 9 and 47 ± 20 % (p < 0.01) in the plantaris and soleus. After 3 days of overload, Six1 protein expression increased 73 ± 17 and 168 ± 57 % in the plantaris and soleus (p < 0.05). After 1 day of overload, Dach2 gene expression decreased 56 ± 9 and 35 ± 3 % in both muscles (p < 0.001), while Eya1 decreased 33 ± 5 % only in the soleus (p < 0.01). Eya3 gene expression increased 127 ± 26 % (p < 0.05) and 76 ± 16 % (p < 0.05) in the plantaris and soleus, while Dach2 gene expression decreased 71 ± 4 % (p < 0.05) in the soleus after 3 days of overload. Six1 and Six1 co-factor expression is responsive to muscle overload in both fast and slow muscles. This indicates that this molecular program may affect overload adaptation regardless of muscle phenotype.

Therapeutic ultrasound affects IGF-1 splice variant expression in human skeletal muscle.

BACKGROUND: Animal models of skeletal muscle damage and repair demonstrate that therapeutic ultrasound (TUS) enhances muscle force recovery after damage, increases satellite cell proliferation, and decreases insulin-like growth factor (IGF)-1 splice variant (mechano growth factor) gene expression. However, these effects have not been verified in humans. PURPOSE: This study was undertaken to examine the 3 known splice variants of the IGF-1 gene in human skeletal muscle after damage and TUS treatment. STUDY DESIGN: Controlled laboratory study. METHODS: Sixteen healthy men (18-29 years of age), physically active, were randomized to either a control (CON) or experimental group (EXP). The EXP group underwent 200 lengthening contractions (muscle damage) of the quadriceps of both legs, 48 hours before TUS. Both groups received TUS, delivered for 10 minutes on a standardized area of the vastus lateralis of only 1 leg (1.0 MHz, 1.5 W/cm(2)). Bilateral muscle biopsy samples were taken from all participants, 6 hours after TUS. Total RNA was extracted, and quantitative real-time polymerase chain reaction conducted for each IGF-1 splice variant. RESULTS: Muscle damage was confirmed by a decrease in the isometric peak torque and increase in creatine kinase activity levels 48 hours after damage (P < .01). After muscle damage, gene expression of total IGF-1 and 2 IGF-1 splice variants increased. Therapeutic ultrasound induced significant increase in IGF-1Eb gene expression in undamaged muscle (1.4 ± 0.2-fold, P < 0.01). In damaged skeletal muscle, no significant change in gene expression attributable to TUS was determined. CONCLUSION: Insulin-like growth factor-1 splice variants are differentially regulated in human skeletal muscle in response to exercise-induced muscle damage and TUS treatment. A single treatment of TUS in damaged muscle induces no change in the gene expression of the 3 IGF-1 splice variants in humans. In contrast, in undamaged skeletal muscle, TUS significantly increased IGF-1Eb splice variant gene expression. CLINICAL RELEVANCE: These findings suggest that TUS may have additional therapeutic uses beyond its current common practice but may not be effective for muscle injury treatment in a young, healthy population.

La prueba de los monofilamentos: una alternativa para la detección oportuna del riesgo de pie diabético / The monofilament test: an alternative for early detection of diabetic foot risk

El principal factor desencadenante del pie diabético, complicación más común de la Diabetes Mellitus, es la Neuropatía Diabética (N.D), cuya patogénesis aún es ampliamente discutida. Un método simple, de bajo costo y reproducible para la evaluación de la alteración o ausencia de la sensación protectiva, es la prueba de sensibilidad realizada con los monofilamentos semmes-weinstein (S.W), recomendada como herramienta de tamizaje para la identificación de pacientes diabéticos en riesgo de ulceración. Sin embargo, algunos investigadores discuten su potencial clínico, debido a la falta de estandarización de la técnica de aplicación. Salud UIS 2004; 36:32-39.

The main factor for diabetic foot development, the most frequent complication in Diabetes Mellitus, is Diabetic Neuropathy (D.N), whose specific etiopathology is still unknown. A simple, inexpensive and reproducible method for assessing the sensorial component of D.N, defined as the absence of protective sensation, is the Semmes-Weinstein monofilament kit, which has been repeatedly recommended as a screening tool for identifying diabetic patients with risk of ulceration. However, several researchers discuss its clinical potential, because of the lack of a standardized application technique. Salud UIS 2004; 36:32-39.