Lundby, Carsten

Atrial natriuretic peptide (ANP) is suggested to stimulate lipolysis, which has been demonstrated using supraphysiological doses of ANP. We explored the effects of physiological doses of ANP, as observed during an acute exercise bout, on lipolysis, ketogenesis, and glucose metabolism. Ten healthy men was randomized to infusion of ANP vs. placebo using stable isotope labeled tracers. The present study indicates that lipid metabolism does not seem to be regulated by ANP in men.

This paper reports temporal changes in physiological measurements of exercise performance in a young man transitioning from alpine skiing until he became a world junior champion time trial cyclist after only 3 yr of bike-specific training. At the time he became World Champion he also achieved among the highest reported maximal oxygen uptake (V̇o2max) value, 96.7 ml·min−1·kg−1, or 7,397 ml/min in absolute terms at 76.5 kg, which had increased by 29.6% from 74.6 ml·min−1·kg−1 pre-bike-specific training. After 15 mo with almost no structured exercise training, V̇o2max returned to 77.0 mL·min−1·kg−1 and was similar to the value reported before specific bike training, albeit with absolute term (6,205 ml/min) still being 11.3% higher. Part of the explanation for his athletic achievements is likely also related to the up to 20.9% improvement in Power@4 mmol/l (W). Although genetic profiles of endurance athletes have not generated data suggesting a shared genetic signature associated with elite endurance performance, this case study highlights the importance of intrinsic biological factors in elite endurance performance. NEW & NOTEWORTHY This study shows that very high V̇o2max values (>70 ml·min−1·kg−1) can be found in individuals not previously specializing in aerobic training and that values of >90 ml·min−1·kg−1, as well as a cycling world junior champion title, can be achieved in such individuals with just 3 yr of dedicated exercise training.

Some individuals show little or no increase in maximal oxygen consumption (V˙O 2max ) in response to training programs consistent with public health guidelines. However, results from studies using more intense programs challenge the concept that some humans have limited trainability. We explore the implications of these divergent observations on the biology of trainability and propose a new set of twin studies to explore them.

AbstractIn this review, we argue that several key features of maximal oxygen uptake (VO2max) should underpin discussions about the biological and reductionist determinants of its interindividual variability: (i) training‐induced increases in VO2max are largely facilitated by expansion of red blood cell volume and an associated improvement in stroke volume, which also adapts independent of changes in red blood cell volume. These general concepts are also informed by cross‐sectional studies in athletes that have very high values for VO2max. Therefore, (ii) variations in VO2max improvements with exercise training are also likely related to variations in these physiological determinants. (iii) All previously untrained individuals will respond to endurance exercise training in terms of improvements in VO2max provided the stimulus exceeds a certain volume and/or intensity. Thus, genetic analysis and/or reductionist studies performed to understand or predict such variations might focus specifically on DNA variants or other molecular phenomena of relevance to these physiological pathways.