Dandanell 2018 Scand J Med Sci Sports

Dandanell S, Meinild-Lundby AK, Andersen AB, Lang PF, Oberholzer L, Keiser S, Robach P, Larsen S, Rønnestad BR, Lundby C (2018) Determinants of maximal whole-body fat oxidation in elite cross-country skiers: role of skeletal muscle mitochondria. Scand J Med Sci Sports 28:2494-504.

» PMID: 30218613

Dandanell S, Meinild-Lundby AK, Andersen AB, Lang PF, Oberholzer L, Keiser S, Robach P, Larsen S, Roennestad BR, Lundby C (2018) Scand J Med Sci Sports

Abstract: Elite endurance athletes possess a high capacity for whole-body maximal fat oxidation (MFO). The aim was to investigate the determinants of a high MFO in endurance athletes. The hypotheses were that augmented MFO in endurance athletes is related to concomitantly increments of skeletal muscle mitochondrial volume density (Mito_VD) and mitochondrial fatty acid oxidation (FAO_p), that is, quantitative mitochondrial adaptations as well as intrinsic FAO_p per mitochondria, that is, qualitative adaptations. Eight competitive male cross-country skiers and eight untrained controls were compared in the study. A graded exercise test was performed to determine MFO, the intensity where MFO occurs (Fat_Max), and VO₂Max . Skeletal muscle biopsies were obtained to determine Mito_VD (electron microscopy), FAO_p, and OXPHOS_p (high-resolution respirometry). The following were higher (P < 0.05) in endurance athletes compared to controls: MFO (mean [95% confidence intervals]) (0.60 g/min [0.50-0.70] vs 0.32 [0.24-0.39]), Fat_Max (46% VO₂Max [44-47] vs 35 [34-37]), VO₂Max (71 mL/min/kg [69-72] vs 48 [47-49]), Mito_VD (7.8% [7.2-8.5] vs 6.0 [5.3-6.8]), FAO_p (34 pmol/s/mg muscle ww [27-40] vs 21 [17-25]), and OXPHOS_p (108 pmol/s/mg muscle ww [104-112] vs 69 [68-71]). Intrinsic FAO_p (4.0 pmol/s/mg muscle w.w/Mito_VD [2.7-5.3] vs 3.3 [2.7-3.9]) and OXPHOS_p (14 pmol/s/mg muscle ww/Mito_VD [13-15] vs 11 [10-13]) were, however, similar in the endurance athletes and untrained controls. MFO and Mito_VD correlated (r² = 0.504, P < 0.05) in the endurance athletes. A strong correlation between Mito_VD and MFO suggests that expansion of Mito_VD might be rate-limiting for MFO in the endurance athletes. In contrast, intrinsic mitochondrial changes were not associated with augmented MFO. • Keywords: Cross-country skiing, Endurance training, Intrinsic mitochondrial function, Mitochondrial fat oxidation, Mitochondrial volume density • Bioblast editor: Plangger M • O2k-Network Lab: DK Copenhagen Dela F, DK Copenhagen Lundby C, DK Copenhagen Larsen S

Labels: MiParea: Respiration, mt-Biogenesis;mt-density, Exercise physiology;nutrition;life style 

Organism: Human  Tissue;cell: Skeletal muscle  Preparation: Permeabilized tissue 

Coupling state: LEAK, OXPHOS, ET  Pathway: F, N, NS  HRR: Oxygraph-2k 

Labels, 2018-10