scholarly journals The role of skeletal muscle contractile duration throughout the whole day: reducing sedentary time and promoting universal physical activity in all people

2017 ◽  
Vol 596 (8) ◽  
pp. 1331-1340 ◽  
Author(s):  
Marc T. Hamilton
Keyword(s):  
Physical Activity ◽  
Skeletal Muscle ◽  
Sedentary Time ◽  
Muscle Contractile

Skeletal Muscle Adaptations to Prolonged Exposure to Extreme Altitude: A Role of Physical Activity?

2008 ◽  
Vol 9 (4) ◽  
pp. 311-317 ◽  
Author(s):  
Masao Mizuno ◽  
Gabrielle K Savard ◽  
Nils-Holger Areskog ◽  
Carsten Lundby ◽  
Bengt Saltin
Keyword(s):  
Physical Activity ◽  
Skeletal Muscle ◽  
Prolonged Exposure ◽  
Muscle Adaptations ◽  
Extreme Altitude ◽  
Skeletal Muscle Adaptations

Role of myokines in exercise and metabolism

2007 ◽  
Vol 103 (3) ◽  
pp. 1093-1098 ◽  
Author(s):  
Bente Klarlund Pedersen ◽  
Thorbjörn C. A. Åkerström ◽  
Anders R. Nielsen ◽  
Christian P. Fischer
Keyword(s):  
Skeletal Muscle ◽  
Skeletal Muscles ◽  
Contractile Activity ◽  
Endocrine Effects ◽  
Skeletal Muscle Function ◽  
The Past ◽  
Exercise Induced ◽  
Immune Changes ◽  
Muscle Contractile

During the past 20 yr, it has been well documented that exercise has a profound effect on the immune system. With the discovery that exercise provokes an increase in a number of cytokines, a possible link between skeletal muscle contractile activity and immune changes was established. For most of the last century, researchers sought a link between muscle contraction and humoral changes in the form of an “exercise factor,” which could mediate some of the exercise-induced metabolic changes in other organs such as the liver and the adipose tissue. We suggest that cytokines and other peptides that are produced, expressed, and released by muscle fibers and exert either paracrine or endocrine effects should be classified as “myokines.” Since the discovery of interleukin (IL)-6 release from contracting skeletal muscle, evidence has accumulated that supports an effect of IL-6 on metabolism. We suggested that muscle-derived IL-6 fulfils the criteria of an exercise factor and that such classes of cytokines should be named “myokines.” Interestingly, recent research demonstrates that skeletal muscles can produce and express cytokines belonging to distinctly different families. Thus skeletal muscle has the capacity to express several myokines. To date the list includes IL-6, IL-8, and IL-15, and contractile activity plays a role in regulating the expression of these cytokines in skeletal muscle. The present review focuses on muscle-derived cytokines, their regulation by exercise, and their possible roles in metabolism and skeletal muscle function and it discusses which cytokines should be classified as true myokines.

Role of Extracellular Matrix in Adaptation of Tendon and Skeletal Muscle to Mechanical Loading

2004 ◽  
Vol 84 (2) ◽  
pp. 649-698 ◽  
Author(s):  
MICHAEL KJÆR
Keyword(s):  
Physical Activity ◽  
Mechanical Properties ◽  
Skeletal Muscle ◽  
Extracellular Matrix ◽  
Connective Tissue ◽  
Mechanical Loading ◽  
Collagen Synthesis ◽  
Cross Linking ◽  
Collagen Turnover

Kjær, Michael. Role of Extracellular Matrix in Adaptation of Tendon and Skeletal Muscle to Mechanical Loading. Physiol Rev 84: 649–698, 2004; 10.1152/physrev.00031.2003.—The extracellular matrix (ECM), and especially the connective tissue with its collagen, links tissues of the body together and plays an important role in the force transmission and tissue structure maintenance especially in tendons, ligaments, bone, and muscle. The ECM turnover is influenced by physical activity, and both collagen synthesis and degrading metalloprotease enzymes increase with mechanical loading. Both transcription and posttranslational modifications, as well as local and systemic release of growth factors, are enhanced following exercise. For tendons, metabolic activity, circulatory responses, and collagen turnover are demonstrated to be more pronounced in humans than hitherto thought. Conversely, inactivity markedly decreases collagen turnover in both tendon and muscle. Chronic loading in the form of physical training leads both to increased collagen turnover as well as, dependent on the type of collagen in question, some degree of net collagen synthesis. These changes will modify the mechanical properties and the viscoelastic characteristics of the tissue, decrease its stress, and likely make it more load resistant. Cross-linking in connective tissue involves an intimate, enzymatical interplay between collagen synthesis and ECM proteoglycan components during growth and maturation and influences the collagen-derived functional properties of the tissue. With aging, glycation contributes to additional cross-linking which modifies tissue stiffness. Physiological signaling pathways from mechanical loading to changes in ECM most likely involve feedback signaling that results in rapid alterations in the mechanical properties of the ECM. In developing skeletal muscle, an important interplay between muscle cells and the ECM is present, and some evidence from adult human muscle suggests common signaling pathways to stimulate contractile and ECM components. Unaccostumed overloading responses suggest an important role of ECM in the adaptation of myofibrillar structures in adult muscle. Development of overuse injury in tendons involve morphological and biochemical changes including altered collagen typing and fibril size, hypervascularization zones, accumulation of nociceptive substances, and impaired collagen degradation activity. Counteracting these phenomena requires adjusted loading rather than absence of loading in the form of immobilization. Full understanding of these physiological processes will provide the physiological basis for understanding of tissue overloading and injury seen in both tendons and muscle with repetitive work and leisure time physical activity.

scholarly journals FRI0384 BODY COMPOSITION AS A MEDIATOR IN THE RELATIONSHIP BETWEEN PHYSICAL ACTIVITY AND PHYSICAL FUNCTION IN LOWER-LIMB OSTEOARTHRITIS: RESULTS FROM THE KHOALA COHORT

2020 ◽  
Vol 79 (Suppl 1) ◽  
pp. 789.1-790 ◽  
Author(s):  
M. Wieczorek ◽  
C. Rotonda ◽  
J. Sellam ◽  
F. Guillemin ◽  
A. C. Rat
Keyword(s):  
Physical Activity ◽  
Skeletal Muscle ◽  
Muscle Mass ◽  
Fat Mass ◽  
Skeletal Muscle Mass ◽  
Weight Bearing ◽  
Fat Mass Index ◽  
Mediating Role ◽  
Skeletal Muscle Mass Index

Background:Many trials investigated the beneficial effect of physical activity (PA) on physical function (PF) in people with osteoarthritis (OA), but factors involved in this relationship are poorly understood. Considering the link between OA and obesity and obesity-related disorders, body composition (BC) could be one of these factors.Objectives:To examine the relationships between baseline components of PA and 5-year PF scores, considering BC variables measured at 3 years as potential mediators in theses associations (Figure).Methods:We used data from the KHOALA cohort, a French population-based multicenter cohort of 878 patients with symptomatic knee and/or hip OA, aged between 40 and 75 years old. Baseline PA intensity (Metabolic Equivalent of Task, MET), frequency (times/week), duration (hours/week) and type (weight-bearing or not) were assessed by the Modifiable Activity Questionnaire. PF was measured with the WOMAC questionnaire at 5 years (higher scores = greater functional limitations).Skeletal muscle mass (grams) and fat mass (grams) were measured by dual X-ray absorptiometry (DXA) in 358 patients at 3 years. Fat mass index (kg/m2), appendicular fat mass (kg), % of fat mass, lean mass index (kg/m2), appendicular muscle mass (kg), skeletal muscle mass index (kg/m2or %) were calculated based on DXA data. Sarcopenia was defined according to the FNIH Sarcopenia Project recommendations.A causal mediation analysis was used to highlight the mediating role of BC variables. Bivariate analyses (multiple linear and logistic regressions) were performed to select the variables of interest. Separate generalized linear models were used to describe the relationships between PA components, PF and selected BC variables. Unadjusted and adjusted for baseline confounders (age, gender, number of comorbidities, disease duration, mental health and vitality scores) models were ran.Results:A 1-MET increase in baseline PA intensity was significantly associated with an improvement in PF at 5 years (-3 points). Weight-bearing PA was also significantly associated with better PF scores (-5 points).A 1-MET-increase in PA intensity at baseline was associated with a subsequent decrease at 3 years in fat mass index (-0.86 k/m2), an increase in skeletal muscle mass index (≥ 6%), and a decrease in % of fat mass (-2%). Non-weight-bearing PA was significantly associated with a decrease in fat mass index (-2.5 kg/m2).A 1-point increase in PF score was associated with a reduction in skeletal muscle mass index (calculated from body mass index, -0.3%) and an increase in skeletal muscle mass index (calculated from height, +3 kg/m2). The presence of sarcopenia was significantly associated with a degradation of PF (+7 points).Crude analyses indicated that 20.4% of the effect of baseline PA intensity on PF scores at 5 years was mediated by skeletal muscle mass index (calculated from height), 23.2% by fat mass index and 26.6% by % of fat mass. Similarly, 19.3% of the effect of baseline PA type on PF scores at 5 years was mediated by fat mass index and 15.1% by % of fat mass. After adjustment, we found no longer evidence of a mediating role of BC variables in these associations.Conclusion:We found significant associations between a 1-MET increase in PA intensity, weight-bearing PA at baseline and improvement in PF at 5 years, without any mediating role of BC variables. Further studies are needed to better understand the factors involved in these associations, especially psychosocial variables.Disclosure of Interests:Maud Wieczorek: None declared, Christine Rotonda: None declared, Jérémie SELLAM: None declared, Francis Guillemin Grant/research support from: Francis Guillemin received a grant from Expanscience paid to his institution., Anne-Christine Rat: None declared

scholarly journals Relationship between Physical Performance and Frailty Syndrome in Older Adults: The Mediating Role of Physical Activity, Sedentary Time and Body Composition

2020 ◽  
Vol 18 (1) ◽  
pp. 203
Author(s):  
Irene Rodríguez-Gómez ◽  
Asier Mañas ◽  
José Losa-Reyna ◽  
Luis M. Alegre ◽  
Leocadio Rodríguez-Mañas ◽  
...  
Keyword(s):  
Physical Activity ◽  
Older Adults ◽  
Body Composition ◽  
Physical Performance ◽  
Healthy Aging ◽  
Sedentary Time ◽  
Vigorous Physical Activity ◽  
Skeletal Muscle Index ◽  
The Relationship

The objectives were to clarify whether the relationship between physical performance and frailty was independently and jointly mediated by movement behaviors and body composition. We analyzed 871 older adults (476 women) from The Toledo Study for Healthy Aging. Skeletal muscle index (SMI) and fat index (FI) were determined using bone densitometry. Sedentary time (ST) and moderate-to-vigorous physical activity (MVPA) were assessed using accelerometry. The Frailty Trait Scale and The Short Physical Performance Battery (SPPB) were used to evaluate frailty and physical performance, respectively. Simple and multiple mediation analyses were carried out to determine the role of movement behaviors and body composition, adjusted for potential confounders. ST and MVPA acted independently as mediators in the relationship between SPPB and frailty (0.06% for ST and 16.89% for MVPA). FI also acted as an independent mediator in the same relationship (36.47%), while the mediation role of SMI was not significant. MVPA and FI both acted jointly as mediators in this previous relationship explaining 58.15% of the model. Our data support the fact that interventions should simultaneously encourage the promotion of MVPA and strategies to decrease the FI in order to prevent or treat frailty through physical performance improvement.

Risk for losing physical independence in older adults: The role of sedentary time, light, and moderate to vigorous physical activity

Maturitas ◽  
2014 ◽  
Vol 79 (1) ◽  
pp. 91-95 ◽  
Author(s):  
Elisa A. Marques ◽  
Fátima Baptista ◽  
Diana A. Santos ◽  
Analiza M. Silva ◽  
Jorge Mota ◽  
...  
Keyword(s):  
Physical Activity ◽  
Older Adults ◽  
Sedentary Time ◽  
Vigorous Physical Activity ◽  
Physical Independence

Selective Carbonylation Of The Skeletal Muscle Mitochondrial Proteome In Aging Mice: The Role Of Lifelong Physical Activity

2010 ◽  
Vol 42 ◽  
pp. 21
Author(s):  
Jose A. Duarte ◽  
Renato M. Alves ◽  
Pedro A. Figueiredo ◽  
Rui Vitorino ◽  
Rita M. Ferreira ◽  
...  
Keyword(s):  
Physical Activity ◽  
Skeletal Muscle ◽  
Mitochondrial Proteome

scholarly journals Adiposity and High Blood Pressure during Childhood: A Prospective Analysis of the Role of Physical Activity Intensity and Sedentary Time in the GECKO Drenthe Cohort

2020 ◽  
Vol 17 (24) ◽  
pp. 9526
Author(s):  
Rikstje Wiersma ◽  
Esther Hartman ◽  
Hendrika Marike Boezen ◽  
Eva Corpeleijn
Keyword(s):  
Physical Activity ◽  
Blood Pressure ◽  
Sedentary Time ◽  
Strong Predictor ◽  
Physical Activity Intensity ◽  
Logistic Regression Models ◽  
Activity Intensity ◽  
Z Scores ◽  
Expert Center

Whereas in adults, physical inactivity is strongly related to obesity and hypertension, in young children the evidence is inconsistent and scarce. We examined the association between physical activity (PA) behaviours at 5–6 years of age and adiposity and blood pressure (BP) at 10–11 years in 947 children (51% boys) from the Groningen Expert Center for Kids with Obesity (GECKO) Drenthe cohort. Sedentary time (ST) and light, moderate, and vigorous PA were assessed using accelerometry (ActiGraph GT3X, wear time > 600 min/day, ≥3 days). Body mass index (BMI), waist circumference (WC), and systolic and diastolic BP were measured at 5–6 and 10–11 years of age and standardized as age- and sex-adjusted (and height-adjusted, for BP) z-scores. Adjusted linear and logistic regression models showed that most PA behaviours were not related to standardized BMI or WC, overweightness/obesity, abdominal overweightness/obesity, standardized systolic or diastolic BP, pulse pressure, or prehypertension at 10–11 years of age. Only if children spent more time in vigorous PA was WC slightly lower (B (95% CI) = −0.08 (−0.16, −0.01) SD, stdβ = −0.068) and the increase in WC over the years was less (B (95% CI) = −0.10 (−0.18, −0.01) SD; stdβ = −0.083). To conclude, at this very young age, PA behaviours are not a strong predictor for overweightness/obesity or hypertension later in childhood.

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