Montero 2015 J Physiol
Montero D, Cathomen A, Jacobs RA, FlΓΌck D, de Leur J, Keiser S, Bonne T, Kirk N, Lundby AK, Lundby C (2015) Haematological rather than skeletal muscle adaptations contribute to the increase in peak oxygen uptake induced by moderate endurance training. J Physiol [Epub ahead of print]. |
Montero D, Cathomen A, Jacobs RA, Flueck D, de Leur J, Keiser S, Bonne T, Kirk N, Lundby AK, Lundby C (2015) J Physiol
Abstract: KEY POINTS: This study assessed the respective contributions of haematological and skeletal muscle adaptations to any observed improvement in peak oxygen uptake (VO2 peak ) induced by endurance training (ET). VO2 peak , peak cardiac output (QΜ peak ), blood volumes and skeletal muscle biopsies were assessed prior (pre) to and after (post) 6 weeks of ET. Following the post-ET assessment, red blood cell volume (RBCV) reverted to the pre-ET level following phlebotomy and VO2 peak and QΜ peak were determined again. We speculated that the contribution of skeletal muscle adaptations to an ET-induced increase in VO2 peak could be identified when offsetting the ET-induced increase in RBCV. VO2 peak , QΜ peak , blood volumes, skeletal muscle mitochondrial volume density and capillarization were increased after ET. Following RBCV normalization, VO2 peak and QΜ peak reverted to pre-ET levels. These results demonstrate the predominant contribution of haematological adaptations to any increase in VO2 peak induced by ET.
ABSTRACT: It remains unclear whether improvements in peak oxygen uptake (VΜO2 peak ) following endurance training (ET) are primarily determined by central and/or peripheral adaptations. Herein, we tested the hypothesis that the improvement in VΜO2 peak following 6 weeks of ET is mainly determined by haematological rather than skeletal muscle adaptations. Sixteen untrained healthy male volunteers (age = 25 Β± 4 years, VΜO2 peak = 3.5 Β± 0.5 l min-1 ) underwent supervised ET (6 weeks, 3-4 sessions per week). VΜO2 peak , peak cardiac output (QΜ peak ), haemoglobin mass (Hbmass ) and blood volumes were assessed prior to and following ET. Skeletal muscle biopsies were analysed for mitochondrial volume density (MitoVD ), capillarity, fibre types and respiratory capacity (OXPHOS). After the post-ET assessment, red blood cell volume (RBCV) was re-established at the pre-ET level by phlebotomy and VΜO2 peak and QΜ peak were measured again. We speculated that the contribution of skeletal muscle adaptations to the ET-induced increase in VΜO2 peak would be revealed when controlling for haematological adaptations. VΜO2 peak and QΜ peak were increased (P < 0.05) following ET (9 Β± 8 and 7 Β± 6%, respectively) and decreased (P < 0.05) after phlebotomy (-7 Β± 7 and -10 Β± 7%). RBCV, plasma volume and Hbmass all increased (P < 0.05) after ET (8 Β± 4, 4 Β± 6 and 6 Β± 5%). As for skeletal muscle adaptations, capillary-to-fibre ratio and total MitoVD increased (P < 0.05) following ET (18 Β± 16 and 43 Β± 30%), but OXPHOS remained unaltered. Through stepwise multiple regression analysis, QΜ peak , RBCV and Hbmass were found to be independent predictors of VΜO2 peak . In conclusion, the improvement in VΜO2 peak following 6 weeks of ET is primarily attributed to increases in QΜ peak and oxygen-carrying capacity of blood in untrained healthy young subjects.
β’ O2k-Network Lab: CH Zurich Gassmann M, CH Zurich Lundby C, CH Zurich University of Zurich Physiology
Labels: MiParea: Respiration, Exercise physiology;nutrition;life style
Organism: Human
Tissue;cell: Skeletal muscle
Preparation: Permeabilized tissue
Coupling state: OXPHOS, ETS"ETS" is not in the list (LEAK, ROUTINE, OXPHOS, ET) of allowed values for the "Coupling states" property.
HRR: Oxygraph-2k
[Epub ahead of print]