title: Can we optimise the exercise training prescription to maximise improvements in mitochondria function and content?
abstract: BACKGROUND
  While there is agreement that exercise is a powerful stimulus to increase both mitochondrial function and content, we do not know the optimal training stimulus to maximise improvements in mitochondrial biogenesis.
  
  
  METHODS
  This review will focus predominantly on the effects of exercise on mitochondrial function and content, as there is a greater volume of published research on these adaptations and stronger conclusions can be made.
  
  
  CONCLUSIONS
  The results of cross-sectional studies, as well as training studies involving rats and humans, suggest that training intensity may be an important determinant of improvements in mitochondrial function (as determined by mitochondrial respiration), but not mitochondrial content (as assessed by citrate synthase activity). In contrast, it appears that training volume, rather than training intensity, may be an important determinant of exercise-induced improvements in mitochondrial content. Exercise-induced mitochondrial adaptations are quickly reversed following a reduction or cessation of physical activity, highlighting that skeletal muscle is a remarkably plastic tissue. Due to the small number of studies, more research is required to verify the trends highlighted in this review, and further studies are required to investigate the effects of different types of training on the mitochondrial sub-populations and also mitochondrial adaptations in different fibre types. Further research is also required to better understand how genetic variants influence the large individual variability for exercise-induced changes in mitochondrial biogenesis.
  
  
  CONCLUSIONS
  The importance of mitochondria for both athletic performance and health underlines the importance of better understanding the factors that regulate exercise-induced changes in mitochondrial biogenesis. This article is part of a Special Issue entitled Frontiers of Mitochondrial Research.
authors.affiliation: Institute of Sport, Exercise and Active Living (ISEAL), Victoria University, Australia. Electronic address: David.Bishop@vu.edu.au.
authors.forename: David J
authors.initials: DJ
authors.lastname: Bishop
authors.affiliation: Institute of Sport, Exercise and Active Living (ISEAL), Victoria University, Australia.
authors.forename: Cesare
authors.initials: C
authors.lastname: Granata
authors.affiliation: Institute of Sport, Exercise and Active Living (ISEAL), Victoria University, Australia.
authors.forename: Nir
authors.initials: N
authors.lastname: Eynon
mesh_terms: D000818:Animals; D054874:Athletic Performance / Q000502:physiology / Q000592:standards; D002138:Calibration; D019069:Cell Respiration / Q000502:physiology; D002950:Citrate (si)-Synthase / Q000032:analysis / Q000378:metabolism; D015444:Exercise / Q000502:physiology*; D005081:Exercise Therapy / Q000379:methods / Q000592:standards*; D006801:Humans; D008931:Mitochondria, Muscle / Q000737:chemistry / Q000502:physiology*; D010805:Physical Conditioning, Animal / Q000379:methods / Q000592:standards; D051381:Rats
chemical_list: D002950:Citrate (si)-Synthase
keywords: Exercise; Mitochondrial biogenesis; Mitochondrion; Trainability