Objective:In this review,we critically evaluate studies directly comparing the effects of plyometric vs.resistance training on skeletal muscle hypertrophy.Methods:We conducted electronic searches of PubMed/MEDLINE,Sco...Objective:In this review,we critically evaluate studies directly comparing the effects of plyometric vs.resistance training on skeletal muscle hypertrophy.Methods:We conducted electronic searches of PubMed/MEDLINE,Scopus,SPORTDiscus,and Web of Science to find studies that explored the effects of plyometric vs.resistance training on muscle hypertrophy.Results:Eight relevant studies were included in the review.Six studies compared the effects of plyometric vs.resistance training on muscle hypertrophy,while 2 studies explored the effects of combining plyometric and resistance training vs.isolated resistance training on acute anabolic signaling or muscle hypertrophy.Based on the results of these studies,we conclude that plyometric and resistance training may produce similar effects on whole muscle hypertrophy for the muscle groups of the lower extremities.Therefore,it seems that plyometric training has a greater potential for inducing increases in muscle size than previously thought.Despite the findings observed at the whole muscle level,the evidence for the effects of plyometric training on hypertrophy on the muscle fiber level is currently limited for drawing inferences.Compared to isolated resistance training,combining plyometric and resistance exercise does not seem to produce additive effects on anabolic signaling or muscle growth;however,this area requires future study.The limitations of the current body of evidence are that the findings are specific to(a)musculature of the lower extremities,(b)short-term training interventions that lasted up to 12 weeks,and(c)previously untrained or recreationally active participants.Conclusion:This review highlights that plyometric and resistance training interventions may produce similar effects on whole muscle hypertrophy,at least for the muscle groups of the lower extremities,in untrained and recreationally trained individuals,and over short-term(i.e.,≤12 weeks)intervention periods.展开更多
Skeletal muscle stiffness is altered after spinal cord injury(SCI).Assessing muscle stiffness is essential for rehabilitation and pharmaceutical interventions design after SCI.The study used magnetic resonance elastog...Skeletal muscle stiffness is altered after spinal cord injury(SCI).Assessing muscle stiffness is essential for rehabilitation and pharmaceutical interventions design after SCI.The study used magnetic resonance elastography to assess the changes in stiffness after chronic SCI compared to matched able-bodied controls and determine its association with muscle size,spasticity,and peak torque in persons with SCI.Previous studies examined the association between muscle stiffness and spasticity,however,we are unaware of other studies that examined the effects of muscle composition on stiffness after SCI.Ten participants(one female)with chronic SCI and eight(one female)matched able-bodied controls participated in this cross-sectional study.Magnetic resonance elastography was utilized to monitor stiffness derived from shear waves propagation.Modified Ashworth scale was used to evaluate spasticity scores in a blinded fashion.Peak isometric and isokinetic torques were measured using a biodex dynamometer.Stiffness values were non-significantly lower(12.5%;P=0.3)in the SCI group compared to able-bodied controls.Moreover,stiffness was positively related to vastus lateralis whole muscle cross-sectional area(CSA)(r2=0.64,P<0.005)and vastus lateralis absolute muscle CSA after accounting for intramuscular fat(r2=0.78,P<0.0007).Stiffness was also positively correlated to both isometric(r2=0.55-0.57,P<0.05)and isokinetic peak(r2=0.46-0.48,P<0.05)torques.Our results suggest that larger clinical trial is warranted to confirm the preliminary findings that muscle stiffness is altered after SCI compared to healthy controls.Stiffness appeared to be influenced by infiltration of intramuscular fat and modestly by the spasticity of the paralyzed muscles.The preliminary data indicated that the relationship between muscle stiffness and peak torque is not altered with changing the frequency of pulses or angular velocities.All study procedures were approved by the Institutional Review Board at the Hunter Holmes McGuire VA Medical Center,USA(IRB#:02314)on May 3,2017.展开更多
Purpose:We aimed to perform a systematic review and meta-analysis of the effects of training to muscle failure or non-failure on muscular strength and hypertrophy.Methods:Meta-analyses of effect sizes(ESs)explored the...Purpose:We aimed to perform a systematic review and meta-analysis of the effects of training to muscle failure or non-failure on muscular strength and hypertrophy.Methods:Meta-analyses of effect sizes(ESs)explored the effects of training to failure vs.non-failure on strength and hypertrophy.Subgroup meta-analyses explored potential moderating effects of variables such as training status(trained vs.untrained),training volume(volume equated vs.volume non-equated),body region(upper vs.lower),exercise selection(multi-vs.single-joint exercises(only for strength)),and study design(independent vs.dependent groups).Results:Fifteen studies were included in the review.All studies included young adults as participants.Meta-analysis indicated no significant difference between the training conditions for muscular strength(ES=-0.09,95%confidence interval(95%CI):-0.22 to 0.05)and for hypertrophy(ES=0.22,95%CI:-0.11 to 0.55).Subgroup analyses that stratified the studies according to body region,exercise selection,or study design showed no significant differences between training conditions.In studies that did not equate training volume between the groups,the analysis showed significant favoring of non-failure training on strength gains(ES=-0.32,95%CI:-0.57 to-0.07).In the subgroup analysis for resistance-trained individuals,the analysis showed a significant effect of training to failure for muscle hypertrophy(ES=0.15,95%CI:0.03-0.26).Conclusion:Training to muscle failure does not seem to be required for gains in strength and muscle size.However,training in this manner does not seem to have detrimental effects on these adaptations,either.More studies should be conducted among older adults and highly trained individuals to improve the generalizability of these findings.展开更多
文摘Objective:In this review,we critically evaluate studies directly comparing the effects of plyometric vs.resistance training on skeletal muscle hypertrophy.Methods:We conducted electronic searches of PubMed/MEDLINE,Scopus,SPORTDiscus,and Web of Science to find studies that explored the effects of plyometric vs.resistance training on muscle hypertrophy.Results:Eight relevant studies were included in the review.Six studies compared the effects of plyometric vs.resistance training on muscle hypertrophy,while 2 studies explored the effects of combining plyometric and resistance training vs.isolated resistance training on acute anabolic signaling or muscle hypertrophy.Based on the results of these studies,we conclude that plyometric and resistance training may produce similar effects on whole muscle hypertrophy for the muscle groups of the lower extremities.Therefore,it seems that plyometric training has a greater potential for inducing increases in muscle size than previously thought.Despite the findings observed at the whole muscle level,the evidence for the effects of plyometric training on hypertrophy on the muscle fiber level is currently limited for drawing inferences.Compared to isolated resistance training,combining plyometric and resistance exercise does not seem to produce additive effects on anabolic signaling or muscle growth;however,this area requires future study.The limitations of the current body of evidence are that the findings are specific to(a)musculature of the lower extremities,(b)short-term training interventions that lasted up to 12 weeks,and(c)previously untrained or recreationally active participants.Conclusion:This review highlights that plyometric and resistance training interventions may produce similar effects on whole muscle hypertrophy,at least for the muscle groups of the lower extremities,in untrained and recreationally trained individuals,and over short-term(i.e.,≤12 weeks)intervention periods.
文摘Skeletal muscle stiffness is altered after spinal cord injury(SCI).Assessing muscle stiffness is essential for rehabilitation and pharmaceutical interventions design after SCI.The study used magnetic resonance elastography to assess the changes in stiffness after chronic SCI compared to matched able-bodied controls and determine its association with muscle size,spasticity,and peak torque in persons with SCI.Previous studies examined the association between muscle stiffness and spasticity,however,we are unaware of other studies that examined the effects of muscle composition on stiffness after SCI.Ten participants(one female)with chronic SCI and eight(one female)matched able-bodied controls participated in this cross-sectional study.Magnetic resonance elastography was utilized to monitor stiffness derived from shear waves propagation.Modified Ashworth scale was used to evaluate spasticity scores in a blinded fashion.Peak isometric and isokinetic torques were measured using a biodex dynamometer.Stiffness values were non-significantly lower(12.5%;P=0.3)in the SCI group compared to able-bodied controls.Moreover,stiffness was positively related to vastus lateralis whole muscle cross-sectional area(CSA)(r2=0.64,P<0.005)and vastus lateralis absolute muscle CSA after accounting for intramuscular fat(r2=0.78,P<0.0007).Stiffness was also positively correlated to both isometric(r2=0.55-0.57,P<0.05)and isokinetic peak(r2=0.46-0.48,P<0.05)torques.Our results suggest that larger clinical trial is warranted to confirm the preliminary findings that muscle stiffness is altered after SCI compared to healthy controls.Stiffness appeared to be influenced by infiltration of intramuscular fat and modestly by the spasticity of the paralyzed muscles.The preliminary data indicated that the relationship between muscle stiffness and peak torque is not altered with changing the frequency of pulses or angular velocities.All study procedures were approved by the Institutional Review Board at the Hunter Holmes McGuire VA Medical Center,USA(IRB#:02314)on May 3,2017.
文摘Purpose:We aimed to perform a systematic review and meta-analysis of the effects of training to muscle failure or non-failure on muscular strength and hypertrophy.Methods:Meta-analyses of effect sizes(ESs)explored the effects of training to failure vs.non-failure on strength and hypertrophy.Subgroup meta-analyses explored potential moderating effects of variables such as training status(trained vs.untrained),training volume(volume equated vs.volume non-equated),body region(upper vs.lower),exercise selection(multi-vs.single-joint exercises(only for strength)),and study design(independent vs.dependent groups).Results:Fifteen studies were included in the review.All studies included young adults as participants.Meta-analysis indicated no significant difference between the training conditions for muscular strength(ES=-0.09,95%confidence interval(95%CI):-0.22 to 0.05)and for hypertrophy(ES=0.22,95%CI:-0.11 to 0.55).Subgroup analyses that stratified the studies according to body region,exercise selection,or study design showed no significant differences between training conditions.In studies that did not equate training volume between the groups,the analysis showed significant favoring of non-failure training on strength gains(ES=-0.32,95%CI:-0.57 to-0.07).In the subgroup analysis for resistance-trained individuals,the analysis showed a significant effect of training to failure for muscle hypertrophy(ES=0.15,95%CI:0.03-0.26).Conclusion:Training to muscle failure does not seem to be required for gains in strength and muscle size.However,training in this manner does not seem to have detrimental effects on these adaptations,either.More studies should be conducted among older adults and highly trained individuals to improve the generalizability of these findings.
