Objectives:Aerobic exercise training can increase skeletal muscle mitochondrial content.Supine exercise training with legs above the heart potentially augments these increases.However,the impact of supine exercise tra...Objectives:Aerobic exercise training can increase skeletal muscle mitochondrial content.Supine exercise training with legs above the heart potentially augments these increases.However,the impact of supine exercise training on mitochondrial biogenesis and cardiovascular adaptations remains unclear.Methods:In this single-centred,randomized,parallel arm trial,19 recreationally active individuals underwent seven sessions of either supine with legs up(SUP;n=9,6 females)or upright with legs down(UP;n=10,7 females)aerobic training on a recumbent bike at 71±7%and 71±2%of peak work rate(WRpeak),respectively.The study aimed to test the effects of training with decreased muscle oxygenation on indices of muscle mitochondrial remodelling.Secondary outcomes included exercise performance,muscle oxygenation,and cardiovascular responses.Results:Secondary outcomes revealed significant interaction effects for time to fatigue(TTF)and WRpeak in the SUP group during supine testing,suggesting enhanced exercise tolerance and performance.No between group interaction effects were observed for upright testing.No clear effects on mitochondrial biogenesis were observed based on expression of mitochondrial protein subunits and transcriptional regulators.Acutely,HRpeak was lower during the SUP Test compared to the UP Test.No central cardiovascular adaptations were observed following training.Conclusions:Our exploratory analyses showed that supine aerobic training more effectively improves supine exercise tolerance and performance compared with upright training,despite no differences in measured proteins related to mitochondrial biogenesis.Further research is needed to elucidate the mechanisms underlying these postural-specific training effects.Registration:clinicaltrials.gov:NCT04151095.展开更多
Background:It remains unclear whether studies comparing _(max)imal oxygen uptake(VO_(2max))response to sprint interval training(SIT)vs.moderate-intensity continuous training(MICT)are associated with a high risk of bia...Background:It remains unclear whether studies comparing _(max)imal oxygen uptake(VO_(2max))response to sprint interval training(SIT)vs.moderate-intensity continuous training(MICT)are associated with a high risk of bias and poor reporting quality.The purpose of this study was to evaluate the risk of bias and quality of reporting in studies comparing changes in VO_(2max) between SIT and MICT.Methods:We conducted a comprehensive literature search of 4 major databases:AMED,CINAHL,EMBASE,and MEDLINE.Studies were excluded if participants were not healthy adult humans or if training protocols were unsupervised,lasted less than 2 weeks,or utilized mixed exercise modalities.We used the Cochrane Collaboration tool and the CONSORT checklist for non-pharmacological trials to evaluate the risk of bias and reporting quality,respectively.Results:Twenty-eight studies with 30 comparisons(3 studies included 2 SIT groups)were included in our meta-analysis(n=360 SIT participants:body mass index(BMI)=25.9±3.7 kg/m^(2),baseline VO_(2max)=37.9±8.0 mL/kg/min;n=359 MICT participants:BMI=25.5±3.8 kg/m^(2),baseline VO_(2max)=38.3±8.0 mL/kg/min;all mean±SD).All studies had an unclear risk of bias and poor reporting quality.Conclusion:Although we observed a lack of superiority between SIT and MICT for improving VO_(2max)(weighted Hedge’s g=0.004,95%con-fidence interval(95%CI):-0.08 to 0.07),the overall unclear risk of bias calls the validity of this conclusion into question.Future studies using robust study designs are needed to interrogate the possibility that SIT and MICT result in similar changes in VO_(2max).展开更多
Objectives To determine how the anti-inflammatory actions of interleukin-10(IL-10)and IL-6 differ across age and physical activity levels.Methods Using a cross-sectional design,fasted blood samples were obtained from ...Objectives To determine how the anti-inflammatory actions of interleukin-10(IL-10)and IL-6 differ across age and physical activity levels.Methods Using a cross-sectional design,fasted blood samples were obtained from younger physically inactive(YI:n=10,age:22.7±3.7 years,BMI:24.8±4.8 kg/m^(2),<150 min of weekly moderate-to-vigorous physical activity[MVPA]),younger highly active(YA:n=11 varsity cross country running athletes,20.7±2.7 years,21.1±1.8 kg/m^(2),>300 min of weekly MVPA),and older highly active(OA:12,56.0±10.3 years,22.8±3.2 kg/m^(2),>300 min of weekly MVPA)individuals and analyzed for leukocyte counts,IL-10 and IL-6-related signaling,and cytokine secretion ex vivo.Results Total white blood cells and monocytes were similar between groups(p=0.8)but YA and OA had lower lymphocyte counts than YI(p<0.01).The ability of IL-10(1 ng/mL)to phosphorylate signal transducer and activator of transcription 3(STAT3)in CD14 monocytes was greater in YA vs.YI(p<0.03)despite YA having lower IL-10 receptor expression(p<0.01).IL-6(10 ng/mL)mediated STAT3 phosphorylation in CD4 lymphocytes was higher in OA compared YI(p<0.01),with a similar tendency observed for YA vs.YI(p=0.08).Despite enhanced responsiveness of STAT3 to IL-10/6 in active individuals,the ability of IL-10/6 to inhibit tumor necrosis factor-alpha(TNF-⍺)secretion from lipopolysaccharide-stimulated whole-blood was similar between groups.Conclusions Highly active younger and older individuals demonstrate enhanced IL-10-and IL-6-mediated activation of immune cell STAT3.Although the ability of IL-10/6 to inhibit TNF-⍺secretion appeared unimpacted by activity level,anti-inflammatory cytokine actions were preserved in older active individuals.展开更多
Objectives To investigate the impact of acute energetic stress(acute HIIE and fasting)on ERRγ,PPARβ,NR1D1,NR4A1,and TFEB in human skeletal muscle.Methods The current study performed secondary analyses using muscle b...Objectives To investigate the impact of acute energetic stress(acute HIIE and fasting)on ERRγ,PPARβ,NR1D1,NR4A1,and TFEB in human skeletal muscle.Methods The current study performed secondary analyses using muscle biopsy samples from two previously published studies:study 1)leg muscle biopsies from nine men and eight women were obtained pre and 3 h following acute high-intensity interval cycling exercise(HIIE);study 2)leg muscle biopsies were obtained from nine men pre-,during,and post-an 8 h fast with or without 2 h of arm ergometer exercise.RT-PCR was performed on samples from each study to determine the mRNA expression of ERRγ,PPARβ,NR1D1,NR4A1,and TFEB.Additionally,we retrieved data from meta-analyzed human muscle gene expression using the publicly available database MetaMex.Results PGC-1α(p<0.01,d=1.98)and NR4A1(p<0.01,d=1.36)mRNA expression significantly increased while TFEB(p≤0.05,d=0.70)decreased following HIIE.Significant decreases in NR4A1 and NR1D1 mRNA expression were observed following an 8 h fast.Our MetaMex analyses revealed significant increases(p<0.05)in PGC-1αand NR4A1 expression following aerobic and resistance exercise,and in PPARβexpression following resistance exercise.Conclusions Our data indicate that acute HIIE stimulates increases in NR4A1 and PGC-1αand decreases in TFEB mRNA expression in human skeletal muscle.Additionally,a short term(8 h)fast reduced the mRNA expression of the transcriptional regulators NR4A1 and NR1D1–potentially as a mechanism of decreasing mitochondrial biogenesis to reduce energy expenditure during a period of restricted energy availability.展开更多
Background:Insufficient physical activity and prolonged sedentary behavior have emerged as major global public health challenges.Short bouts(≤10 min)of accumulated exercise(SBAE)throughout the day may be a promising ...Background:Insufficient physical activity and prolonged sedentary behavior have emerged as major global public health challenges.Short bouts(≤10 min)of accumulated exercise(SBAE)throughout the day may be a promising strategy to mitigate the adverse effects of prolonged sitting and promote physical activity,ultimately promoting overall health.However,previous ambiguity in defining this concept has resulted in a fragmented and inconsistent evidence base,impeding practical applications,the development of guidelines,and policymaking.The purpose of this study is to establish an operational definition of SBAE by synthesizing systematic reviews and research trials alongside an expert consensus.Additionally,it seeks to evaluate acute and long-term efficacy and feasibility,providing evidence-based recommendations for practice and future research directions.Methods:A literature search was performed across PubMed and Web of Science,followed by systematic screening and summarization of eligible studies based on predefined inclusion criteria.Inclusion criteria encompassed various modes/types of SBAE(bouts lasting≤10 min,performed multiple times daily with≥30 min intervals);both aerobic and resistance exercise were considered.Relevant systematic reviews and research trials were included.Methodological quality,risk of bias,and evidence certainty were assessed.Expert consensus was obtained through a survey to evaluate recommendations and agreement levels on findings.Results:After analyzing 27 systematic reviews,135 research studies,and an expert consensus involving 48 researchers from 11 countries,SBAE is defined as any exercise mode of activity,regardless of intensity,that is accumulated in either continuous or intermittent bouts lasting≤10 min per session(including multiple intermittent sets)that are performed multiple times(≥2 sessions/day)per day,with intervals of≥30 min between bouts or otherwise sufficient time for recovery.When used to interrupt prolonged periods of sedentary time,SBAE mitigates the acute adverse effects of sedentary behavior on more than 10 clinical biomarkers of endocrine,cardiovascular,and brain health/function among adults of diverse ages and conditions.Moreover,SBAE was superior for improving acute glycemic control compared to a single continuous exercise session.As a long-term intervention(average of 11 weeks),SBAE can improve over 20 health outcomes,including peak oxygen uptake,resting blood pressure,and metabolic health.Additionally,SBAE might be more effective than continuous exercise for improving longer-term glycemic control and body composition.Long-term completion rates for SBAE interventions are generally high(95%),with low dropout rates(12%)and high adherence rates even without supervision(85%),and its safety has been preliminarily validated.Conclusion:An operational definition of SBAE is provided along with its classification and acute and long-term efficacy.Practical exercise prescription recommendations and evidence-based strategies for various populations and contexts are provided.Future research should focus on generating high-quality evidence for SBAE in 5 key areas:quantification and monitoring,population-specific responses,optimization of exercise prescriptions,intervention efficacy,and practical implementation.Additionally,addressing policy,environmental,and promotional barriers is crucial for transitioning from expert consensus to public consensus,and for facilitating the application of this strategy in real-world environments.展开更多
High-intensity and sprint interval training(HIIT and SIT,respectively)enhance insulin sensitivity and glycemic control in both healthy adults and those with cardiometabolic diseases.The beneficial effects of intense i...High-intensity and sprint interval training(HIIT and SIT,respectively)enhance insulin sensitivity and glycemic control in both healthy adults and those with cardiometabolic diseases.The beneficial effects of intense interval training on glycemic control include both improvements seen in the hours to days following a single session of HIIT/SIT and those which accrue with chronic training.Skeletal muscle is the largest site of insulin-stimulated glucose uptake and plays an integral role in the beneficial effects of exercise on glycemic control.Here we summarize the skeletal muscle responses that contribute to improved glycemic control during and following a single session of interval exercise and evaluate the relationship between skeletal muscle remodelling and improved insulin sensitivity following HIIT/SIT training interventions.Recent evidence suggests that targeting skeletal muscle mechanisms via nutritional interventions around exercise,particularly with carbohydrate manipulation,can enhance the acute glycemic benefits of HIIT.There is also some evidence of sex-based differences in the glycemic benefits of intense interval exercise,with blunted responses observed after training in females relative to males.Differences in skeletal muscle metabolism between males and females may contribute to sex differences in insulin sensitivity following HIIT/SIT,but well-controlled studies evaluating purported muscle mechanisms alongside measurement of insulin sensitivity are needed.Given the greater representation of males in muscle physiology literature,there is also a need for more research involving female-only cohorts to enhance our basic understanding of how intense interval training influences muscle insulin sensitivity in females across the lifespan.展开更多
基金supported by funding provided to BJG from the Natural Sciences and Engineering Research Council of Canada(NSERCgrant no.402635).
文摘Objectives:Aerobic exercise training can increase skeletal muscle mitochondrial content.Supine exercise training with legs above the heart potentially augments these increases.However,the impact of supine exercise training on mitochondrial biogenesis and cardiovascular adaptations remains unclear.Methods:In this single-centred,randomized,parallel arm trial,19 recreationally active individuals underwent seven sessions of either supine with legs up(SUP;n=9,6 females)or upright with legs down(UP;n=10,7 females)aerobic training on a recumbent bike at 71±7%and 71±2%of peak work rate(WRpeak),respectively.The study aimed to test the effects of training with decreased muscle oxygenation on indices of muscle mitochondrial remodelling.Secondary outcomes included exercise performance,muscle oxygenation,and cardiovascular responses.Results:Secondary outcomes revealed significant interaction effects for time to fatigue(TTF)and WRpeak in the SUP group during supine testing,suggesting enhanced exercise tolerance and performance.No between group interaction effects were observed for upright testing.No clear effects on mitochondrial biogenesis were observed based on expression of mitochondrial protein subunits and transcriptional regulators.Acutely,HRpeak was lower during the SUP Test compared to the UP Test.No central cardiovascular adaptations were observed following training.Conclusions:Our exploratory analyses showed that supine aerobic training more effectively improves supine exercise tolerance and performance compared with upright training,despite no differences in measured proteins related to mitochondrial biogenesis.Further research is needed to elucidate the mechanisms underlying these postural-specific training effects.Registration:clinicaltrials.gov:NCT04151095.
基金supported by an operating grant from the Natural Science and Engineering Research Council of Canada (NSERCgrant number:402635) to BJG+2 种基金JTB was supported by a NSERC Vanier Canada Graduate ScholarshipHI was supported by NSERC PGS-DNP was supported by NSERC CGS-M。
文摘Background:It remains unclear whether studies comparing _(max)imal oxygen uptake(VO_(2max))response to sprint interval training(SIT)vs.moderate-intensity continuous training(MICT)are associated with a high risk of bias and poor reporting quality.The purpose of this study was to evaluate the risk of bias and quality of reporting in studies comparing changes in VO_(2max) between SIT and MICT.Methods:We conducted a comprehensive literature search of 4 major databases:AMED,CINAHL,EMBASE,and MEDLINE.Studies were excluded if participants were not healthy adult humans or if training protocols were unsupervised,lasted less than 2 weeks,or utilized mixed exercise modalities.We used the Cochrane Collaboration tool and the CONSORT checklist for non-pharmacological trials to evaluate the risk of bias and reporting quality,respectively.Results:Twenty-eight studies with 30 comparisons(3 studies included 2 SIT groups)were included in our meta-analysis(n=360 SIT participants:body mass index(BMI)=25.9±3.7 kg/m^(2),baseline VO_(2max)=37.9±8.0 mL/kg/min;n=359 MICT participants:BMI=25.5±3.8 kg/m^(2),baseline VO_(2max)=38.3±8.0 mL/kg/min;all mean±SD).All studies had an unclear risk of bias and poor reporting quality.Conclusion:Although we observed a lack of superiority between SIT and MICT for improving VO_(2max)(weighted Hedge’s g=0.004,95%con-fidence interval(95%CI):-0.08 to 0.07),the overall unclear risk of bias calls the validity of this conclusion into question.Future studies using robust study designs are needed to interrogate the possibility that SIT and MICT result in similar changes in VO_(2max).
基金H.I.was supported by a Natural Sciences and Engineering Council(NSERC)postdoctoral fellowship and a Michael Smith Health Research BC Research Trainee AwardJ.B.was supported by and NSERC Undergraduate Student Research Award+2 种基金G.S.J.was supported by an Indigenous Scholar’s AwardJ.P.L is supported by an NSERC Discovery Grant(RGPIN-2019-05204)Killam Accelerator Research Fellowship(AWD-018101).
文摘Objectives To determine how the anti-inflammatory actions of interleukin-10(IL-10)and IL-6 differ across age and physical activity levels.Methods Using a cross-sectional design,fasted blood samples were obtained from younger physically inactive(YI:n=10,age:22.7±3.7 years,BMI:24.8±4.8 kg/m^(2),<150 min of weekly moderate-to-vigorous physical activity[MVPA]),younger highly active(YA:n=11 varsity cross country running athletes,20.7±2.7 years,21.1±1.8 kg/m^(2),>300 min of weekly MVPA),and older highly active(OA:12,56.0±10.3 years,22.8±3.2 kg/m^(2),>300 min of weekly MVPA)individuals and analyzed for leukocyte counts,IL-10 and IL-6-related signaling,and cytokine secretion ex vivo.Results Total white blood cells and monocytes were similar between groups(p=0.8)but YA and OA had lower lymphocyte counts than YI(p<0.01).The ability of IL-10(1 ng/mL)to phosphorylate signal transducer and activator of transcription 3(STAT3)in CD14 monocytes was greater in YA vs.YI(p<0.03)despite YA having lower IL-10 receptor expression(p<0.01).IL-6(10 ng/mL)mediated STAT3 phosphorylation in CD4 lymphocytes was higher in OA compared YI(p<0.01),with a similar tendency observed for YA vs.YI(p=0.08).Despite enhanced responsiveness of STAT3 to IL-10/6 in active individuals,the ability of IL-10/6 to inhibit tumor necrosis factor-alpha(TNF-⍺)secretion from lipopolysaccharide-stimulated whole-blood was similar between groups.Conclusions Highly active younger and older individuals demonstrate enhanced IL-10-and IL-6-mediated activation of immune cell STAT3.Although the ability of IL-10/6 to inhibit TNF-⍺secretion appeared unimpacted by activity level,anti-inflammatory cytokine actions were preserved in older active individuals.
基金supported by Brendon Gurd’s Discovery Grant from NSERC.
文摘Objectives To investigate the impact of acute energetic stress(acute HIIE and fasting)on ERRγ,PPARβ,NR1D1,NR4A1,and TFEB in human skeletal muscle.Methods The current study performed secondary analyses using muscle biopsy samples from two previously published studies:study 1)leg muscle biopsies from nine men and eight women were obtained pre and 3 h following acute high-intensity interval cycling exercise(HIIE);study 2)leg muscle biopsies were obtained from nine men pre-,during,and post-an 8 h fast with or without 2 h of arm ergometer exercise.RT-PCR was performed on samples from each study to determine the mRNA expression of ERRγ,PPARβ,NR1D1,NR4A1,and TFEB.Additionally,we retrieved data from meta-analyzed human muscle gene expression using the publicly available database MetaMex.Results PGC-1α(p<0.01,d=1.98)and NR4A1(p<0.01,d=1.36)mRNA expression significantly increased while TFEB(p≤0.05,d=0.70)decreased following HIIE.Significant decreases in NR4A1 and NR1D1 mRNA expression were observed following an 8 h fast.Our MetaMex analyses revealed significant increases(p<0.05)in PGC-1αand NR4A1 expression following aerobic and resistance exercise,and in PPARβexpression following resistance exercise.Conclusions Our data indicate that acute HIIE stimulates increases in NR4A1 and PGC-1αand decreases in TFEB mRNA expression in human skeletal muscle.Additionally,a short term(8 h)fast reduced the mRNA expression of the transcriptional regulators NR4A1 and NR1D1–potentially as a mechanism of decreasing mitochondrial biogenesis to reduce energy expenditure during a period of restricted energy availability.
文摘Background:Insufficient physical activity and prolonged sedentary behavior have emerged as major global public health challenges.Short bouts(≤10 min)of accumulated exercise(SBAE)throughout the day may be a promising strategy to mitigate the adverse effects of prolonged sitting and promote physical activity,ultimately promoting overall health.However,previous ambiguity in defining this concept has resulted in a fragmented and inconsistent evidence base,impeding practical applications,the development of guidelines,and policymaking.The purpose of this study is to establish an operational definition of SBAE by synthesizing systematic reviews and research trials alongside an expert consensus.Additionally,it seeks to evaluate acute and long-term efficacy and feasibility,providing evidence-based recommendations for practice and future research directions.Methods:A literature search was performed across PubMed and Web of Science,followed by systematic screening and summarization of eligible studies based on predefined inclusion criteria.Inclusion criteria encompassed various modes/types of SBAE(bouts lasting≤10 min,performed multiple times daily with≥30 min intervals);both aerobic and resistance exercise were considered.Relevant systematic reviews and research trials were included.Methodological quality,risk of bias,and evidence certainty were assessed.Expert consensus was obtained through a survey to evaluate recommendations and agreement levels on findings.Results:After analyzing 27 systematic reviews,135 research studies,and an expert consensus involving 48 researchers from 11 countries,SBAE is defined as any exercise mode of activity,regardless of intensity,that is accumulated in either continuous or intermittent bouts lasting≤10 min per session(including multiple intermittent sets)that are performed multiple times(≥2 sessions/day)per day,with intervals of≥30 min between bouts or otherwise sufficient time for recovery.When used to interrupt prolonged periods of sedentary time,SBAE mitigates the acute adverse effects of sedentary behavior on more than 10 clinical biomarkers of endocrine,cardiovascular,and brain health/function among adults of diverse ages and conditions.Moreover,SBAE was superior for improving acute glycemic control compared to a single continuous exercise session.As a long-term intervention(average of 11 weeks),SBAE can improve over 20 health outcomes,including peak oxygen uptake,resting blood pressure,and metabolic health.Additionally,SBAE might be more effective than continuous exercise for improving longer-term glycemic control and body composition.Long-term completion rates for SBAE interventions are generally high(95%),with low dropout rates(12%)and high adherence rates even without supervision(85%),and its safety has been preliminarily validated.Conclusion:An operational definition of SBAE is provided along with its classification and acute and long-term efficacy.Practical exercise prescription recommendations and evidence-based strategies for various populations and contexts are provided.Future research should focus on generating high-quality evidence for SBAE in 5 key areas:quantification and monitoring,population-specific responses,optimization of exercise prescriptions,intervention efficacy,and practical implementation.Additionally,addressing policy,environmental,and promotional barriers is crucial for transitioning from expert consensus to public consensus,and for facilitating the application of this strategy in real-world environments.
基金supported by the Natural Sciences and Engineering Research Council of Canada(RGPIN-2020-05779).
文摘High-intensity and sprint interval training(HIIT and SIT,respectively)enhance insulin sensitivity and glycemic control in both healthy adults and those with cardiometabolic diseases.The beneficial effects of intense interval training on glycemic control include both improvements seen in the hours to days following a single session of HIIT/SIT and those which accrue with chronic training.Skeletal muscle is the largest site of insulin-stimulated glucose uptake and plays an integral role in the beneficial effects of exercise on glycemic control.Here we summarize the skeletal muscle responses that contribute to improved glycemic control during and following a single session of interval exercise and evaluate the relationship between skeletal muscle remodelling and improved insulin sensitivity following HIIT/SIT training interventions.Recent evidence suggests that targeting skeletal muscle mechanisms via nutritional interventions around exercise,particularly with carbohydrate manipulation,can enhance the acute glycemic benefits of HIIT.There is also some evidence of sex-based differences in the glycemic benefits of intense interval exercise,with blunted responses observed after training in females relative to males.Differences in skeletal muscle metabolism between males and females may contribute to sex differences in insulin sensitivity following HIIT/SIT,but well-controlled studies evaluating purported muscle mechanisms alongside measurement of insulin sensitivity are needed.Given the greater representation of males in muscle physiology literature,there is also a need for more research involving female-only cohorts to enhance our basic understanding of how intense interval training influences muscle insulin sensitivity in females across the lifespan.
