Tam 2016 Eur J Appl Physiol

Tam E, Bruseghini P, Calabria E, Sacco LD, Doria C, Grassi B, Pietrangelo T, Pogliaghi S, Reggiani C, Salvadego D, Schena F, Toniolo L, Verratti V, Vernillo G, Capelli C (2016) Gokyo Khumbu/Ama Dablam Trek 2012: effects of physical training and high-altitude exposure on oxidative metabolism, muscle composition, and metabolic cost of walking in women. Eur J Appl Physiol 116:129-44.

» PMID: 26349745

Tam E, Bruseghini P, Calabria E, Sacco LD, Doria C, Grassi B, Pietrangelo T, Pogliaghi S, Reggiani C, Salvadego D, Schena F, Toniolo L, Verratti V, Vernillo G, Capelli C (2016) Eur J Appl Physiol

Abstract: We investigated the effects of moderate-intensity training at low and high altitude on V_O2 and Qa_O2 kinetics and on myosin heavy-chain expression (MyHC) in seven women (36.3 yy ± 7.1; 65.8 kg ± 11.7; 165 cm ± 8) who participated in two 12- to 14-day trekking expeditions at low (598 m) and high altitude (4132 m) separated by 4 months of recovery.

Breath-by-breath V_O2 and beat-by-beat Qa_O2 at the onset of moderate-intensity cycling exercise and energy cost of walking (C_w) were assessed before and after trekking. MyHC expression of vastus lateralis was evaluated before and after low-altitude and after high-altitude trekking; muscle fiber high-resolution respirography was performed at the beginning of the study and after high-altitude trekking.

Mean response time of V_O2 kinetics was faster (P = 0.002 and P = 0.001) and oxygen deficit was smaller (P = 0.001 and P = 0.0004) after low- and high-altitude trekking, whereas Qa_O2 kinetics and C_w did not change. Percentages of slow and fast isoforms of MyHC and mitochondrial mass were not affected by low- and high-altitude training. After training altitude, muscle fiber ADP-stimulated mitochondrial respiration was decreased as compared with the control condition (P = 0.016), whereas LEAK respiration was increased (P = 0.031), leading to a significant increase in the respiratory control ratio (P = 0.016).

Although training did not significantly modify muscle phenotype, it induced beneficial adaptations of the oxygen transport–utilization systems witnessed by faster V_O2 kinetics at exercise onset. • Keywords: Exercise training, Aerobic metabolism, Chronic hypoxia, Women, VO2max, Energy cost of walking, Cryopreserved muscle fibers

• O2k-Network Lab: IT Verona Calabria E, IT Udine Grassi B

Labels: MiParea: Respiration, Exercise physiology;nutrition;life style 

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

Regulation: Coupling efficiency;uncoupling  Coupling state: LEAK, OXPHOS  Pathway: N, S, NS, ROX  HRR: Oxygraph-2k 

BMI, VO2max 

Discussion related to: significant increase in the respiratory control ratio

E Gnaiger (2015-12-08)

The 'respiratory control ratio' or 'respiratory acceptor control ratio' has been defined as the ratio of State 3/State 4 respiration (Chance and William 1955), analogous to the P/L ratio (Gnaiger 2009). With a decrease of P and and increase of L, the P/L ratio decreases.

There are statistical arguments to express the coupling control ratio as the inverse of the respiratory acceptor control ratio (Gnaiger 2020). The L/P coupling control ratio has lower and upper limits from 0.0 to 1.0 and increases with an increase of L and a decrease of P.

References

1. Chance B, Williams GR (1955) Respiratory enzymes in oxidative phosphorylation: III. The steady state. J Biol Chem 217:409-27. - »Bioblast link«
2. Gnaiger E (2009) Capacity of oxidative phosphorylation in human skeletal muscle. New perspectives of mitochondrial physiology. Int J Biochem Cell Biol 41:1837–45. - »Bioblast link«
3. Gnaiger E (2020) Mitochondrial pathways and respiratory control. An introduction to OXPHOS analysis. 5th ed. Bioenerg Commun:112 pp. - »Bioblast link«

Further details

» Respiratory acceptor control ratio

» L/P coupling control ratio

» OXPHOS-coupling efficiency