Physical activity engagement outside of college physical education: Application of the transtheoretical model

Objective: In this study, we examined physical activity (PA) engagement outside of college physical education (PE) classes using the Transtheoretical Model (TTM). Methods: Overall, 414 university students enrolled in PE classes voluntarily participated in this study. Participants were asked to complete a survey packet to measure 4 core constructs of TTM and their PA level performed outside of PE classes. Among the participants, 150 randomly selected students were asked to wear a triaxial accelerometer for 7 consecutive days to identify their PA level. Descriptive statistics and multivariate analyses of variance were used to determine the association between stages of motivational readiness and other strategic core constructions. Results: We categorized 77% of respondents into either the 'action' stage or the 'maintenance' stage for engaging in additional PA outside of the classes. Behavioral processes of change showed a graded and significant association with the stages. Both self-efficacy and decisional balance were significantly higher in students at higher stages. Conclusion: Our findings showed that most students enrolled in college PE classes had additional PA outside of the class participation. In addition, behavioral processes may be effective strategies for this specific target group to promote PA.Peer reviewedCommunity Health Sciences, Counseling and Counseling Psycholog

Myonuclear accretion is a determinant of exercise-induced remodeling in skeletal muscle.

Skeletal muscle adapts to external stimuli such as increased work. Muscle progenitors (MPs) control muscle repair due to severe damage, but the role of MP fusion and associated myonuclear accretion during exercise are unclear. While we previously demonstrated that MP fusion is required for growth using a supra-physiological model (Goh and Millay, 2017), questions remained about the need for myonuclear accrual during muscle adaptation in a physiological setting. Here, we developed an 8 week high-intensity interval training (HIIT) protocol and assessed the importance of MP fusion. In 8 month-old mice, HIIT led to progressive myonuclear accretion throughout the protocol, and functional muscle hypertrophy. Abrogation of MP fusion at the onset of HIIT resulted in exercise intolerance and fibrosis. In contrast, ablation of MP fusion 4 weeks into HIIT, preserved exercise tolerance but attenuated hypertrophy. We conclude that myonuclear accretion is required for different facets of exercise-induced adaptive responses, impacting both muscle repair and hypertrophic growth

ERK1/2 signaling induces skeletal muscle slow fiber-type switching and reduces muscular dystrophy disease severity

© 2019 American Society for Clinical Investigation. MAPK signaling consists of an array of successively acting kinases. ERK1 and -2 (ERK1/2) are major components of the greater MAPK cascade that transduce growth factor signaling at the cell membrane. Here, we investigated ERK1/2 signaling in skeletal muscle homeostasis and disease. Using mouse genetics, we observed that the muscle-specifc expression of a constitutively active MEK1 mutant promotes greater ERK1/2 signaling that mediates fber-type switching to a slow, oxidative phenotype with type I myosin heavy chain expression. Using a conditional and temporally regulated Cre strategy, as well as Mapk1 (ERK2) and Mapk3 (ERK1) genetically targeted mice, MEK1-ERK2 signaling was shown to underlie this fast-to-slow fber-type switching in adult skeletal muscle as well as during development. Physiologic assessment of these activated MEK1-ERK1/2 mice showed enhanced metabolic activity and oxygen consumption with greater muscle fatigue resistance. In addition, induction of MEK1-ERK1/2 signaling increased dystrophin and utrophin protein expression in a mouse model of limb-girdle muscle dystrophy and protected myofbers from damage. In summary, sustained MEK1-ERK1/2 activity in skeletal muscle produces a fast-to-slow fber-type switch that protects from muscular dystrophy, suggesting a therapeutic approach to enhance the metabolic effectiveness of muscle and protect from dystrophic disease

New models of regenerating VML injured rat skeletal muscle : single muscle fiber injection and resistance exercise

Volumetric muscle loss (VML) is a traumatic soft tissue injury that is common in recent battle fields and causes permanent losses of muscle mass and function in affected muscle. Since a new VML injury model has been developed in our lab which defects large mass of rat lateral gastrocnemius (LGAS), several sources of extracellular matrix (ECM) and stem cells including adipose tissue derived stem cells and mesenchymal stem cells have been utilized to enhance the regeneration of defected muscle. In the current study, regenerative effects of resistance exercise and satellite cells injection after the VML injury were tested. Satellite cells transplanted via single muscle fiber injection significantly enhanced generation of a specific force of defected muscle possibly via suppressing fibrotic tissue build-up and inducing significant hypertrophy of regenerating muscle at the sites of injury. However it did not increase muscle mass and tetanic force of the defected LGAS. Resistance exercise intervention after the injury improved all morphological and functional recoveries. Defected muscle mass and functions (tetanic and specific forces) were significantly increased in the resistance exercised group compared to the non-exercised. Cross sectional area (CSA) of mature and regenerating muscle fibers in injured muscle were also significantly increased by the resistance training. Single muscle fiber injection with resistance exercise did not further increase muscle mass or functions, but it had an impact on decreasing accumulation of the non-functional (fibrotic tissue and residual injured) area. These results indicate that resistance exercise is a great rehabilitative intervention after traumatic muscle injury to enhance muscle mass and function with or without satellite cells injection.Kinesiology and Health Educatio

Effects of a Tai Chi-Based Stroke Rehabilitation Program on Symptom Clusters, Physical and Cognitive Functions, and Quality of Life: A Randomized Feasibility Study

Stroke survivors suffer from disease-associated symptoms. Tai Chi can be a beneficial approach to provide an adapted form of intervention to manage their symptoms. The study aimed to determine the effects of a Tai Chi-based stroke rehabilitation program on symptom clusters, physical and cognitive functions, and stroke-specific quality of life among stroke survivors in Korea. Thirty-four stroke survivors were randomly assigned to receive either the Tai Chi-based program or the stroke-symptom management program. The feasibility of the program and its effects on the outcomes were assessed at baseline, 3 months, and 6 months. Repeated measures ANOVA showed that most symptoms improved in both groups during the 6-month period, but swallowing-related symptoms improved significantly in the Tai Chi group. Based on the interaction effect, Tai Chi was more effective on flexor muscle strength, ambulation, and activities of daily living and cognitive function over 6 months than their counterparts. Among SS-QOL dimensions, the Tai Chi group showed significant improvements in the thinking and self-care dimensions. The Tai Chi-based stroke rehabilitation program was feasible and safely applicable to stroke survivors in the community settings. This program could improve symptoms, physical and cognitive function, leading to improvements in the self-care dimension of the SS-QOL among stroke survivors

Dilated cardiomyopathy-mediated heart failure induces a unique skeletal muscle myopathy with inflammation

Abstract Background Skeletal muscle myopathy and exercise intolerance are diagnostic hallmarks of heart failure (HF). However, the molecular adaptations of skeletal muscles during dilated cardiomyopathy (DCM)-mediated HF are not completely understood. Methods Skeletal muscle structure and function were compared in wild-type (WT) and cardiac myosin binding protein-C null mice (t/t), which develop DCM-induced HF. Cardiac function was examined by echocardiography. Exercise tolerance was measured using a graded maximum treadmill running test. Hindlimb muscle function was assessed in vivo from measurements of plantar flexor strength. Inflammatory status was evaluated from the expression of inflammatory markers and the presence of specific immune cell types in gastrocnemius muscles. Muscle regenerative capacityat days 3, 7, and 14 after eccentric contraction-induced injury was determined from the number of phenotypically new and adult fibers in the gastrocnemius, and functional recovery of plantar flexion torque. Results t/t mice developed DCM-induced HF in association with profound exercise intolerance, consistent with previous reports. Compared to WT, t/t mouse hearts show significant hypertrophy of the atria and ventricles and reduced fractional shortening, both systolic and diastolic. In parallel, the skeletal muscles of t/t mice exhibit weakness and myopathy. Compared to WT, plantar flexor muscles of t/t null mice produce less peak isometric plantar torque (Po), develop torque more slowly (+ dF/dt), and relax more slowly (− dF/dt, longer half-relaxation times,1/2RT). Gastrocnemius muscles of t/t mice have a greater number of fibers with smaller diameters and central nuclei. Oxidative fibers, both type I and type IIa, show significantly smaller cross-sectional areas and more central nuclei. These fiber phenotypes suggest ongoing repair and regeneration under homeostatic conditions. In addition, the ability of muscles to recover and regenerate after acute injury is impaired in t/t mice. Conclusions Our studies concluded that DCM-induced HF induces a unique skeletal myopathy characterized by decreased muscle strength, atrophy of oxidative fiber types, ongoing inflammation and damage under homeostasis, and impaired regeneration after acute muscle injury. Furthermore, this unique myopathy in DCM-induced HF likely contributes to and exacerbates exercise intolerance. Therefore, efforts to develop therapeutic interventions to treat skeletal myopathy during DCM-induced HF should be considered

Comparative analysis of growth-phase-dependent gene expression in virulent and avirulent Streptococcus pneumoniae using a high-density DNA microarray

The global pattern of growth-dependent gene expression in Streptococcus pneumoniae strains was evaluated using a high-density DNA microarray. Total RNAs obtained from an avirulent S. pneumoniae strain R6 and a virulent strain AMC96-6 were used to compare the expression patterns at seven time points (2.5, 3.5, 4.5, 5.5, 6.0, 6.5, and 8.0 h). The expression profile of strain R6 changed between log and stationary growth (the Log-Stat switch). There were clear differences between the growth-dependent gene expression profiles of the virulent and avirulent pneumococcal strains in 367 of 1,112 genes. Transcripts of genes associated with bacterial competence and capsular polysaccharide formation, as well as clpP and cbpA, were higher in the virulent strain. Our data suggest that late log or early stationary phase may be the most virulent phase of S. pneumoniae.