PhD defence: Optimizing Training Strategies and Exercise Performance in Athletes
Jan Sommer Jeppesen
PhD thesis
The primary aim of the thesis was to evaluate the effects of two distinct training strategies aimed at enhancing exercise performance in male (Study I) and female (Study II) endurance athletes.
In Study I, highly trained male cyclists underwent either high or low volume speed endurance training over a period of 6 weeks, during which the overall training volume was markedly reduced. In Study II, female endurance athletes underwent a 14-day period of low energy availability to investigate the effects of a rapid lowering of body weight while maintaining training volume.
In addition to examining the effects of intensified training and low energy availability on exercise performance, the underlying physiological mechanisms governing potential adaptations related to muscle metabolism and fatigue resistance were assessed.
The two studies allowed for an examination of whether athletes could benefit from adapting such strategies in their pursuit to optimize exercise performance.
The main findings of Study I were that highly trained athletes can improve their sprinting ability and short-intense exercise performance by implementing a low volume of speed endurance training, whereas performing a higher volume did not yield similar improvements. Moreover, implementing speed endurance training can compensate for a reduction in training volume by preserving endurance exercise performance and underlying physiological mechanisms such as maximal oxygen consumption and skeletal muscle metabolism.
The main findings of Study II were that 14 days of low energy availability impairs endurance and short-intense exercise performance, even when normalized to the reduction in body weight and furthermore, following three days of sufficient energy, performance remained impaired.
Notably, the impaired performance was not attributed to reduced glycogen, changes in skeletal muscle metabolism but possibly linked to changes in substrate metabolism. Furthermore, low energy availability was associated with increased oxidative stress in isolated immune cells, suggesting a potential increase in susceptibility to acute infections.
The thesis concluded that highly trained cyclists can derive benefits from implementing speed endurance training into their training regimen, whereas rapid weight loss directly impairs exercise performance.
2024, 183 pages.
Time
10 June 2024, 14:00
Venue
Auditorium 1, August Krogh Building, Universitetsparken 13, DK-2100 Copenhagen, Denmark.
Opponents
Associate Professor Anne Yaël Nossent (chair), Department of Nutrition, Exercise and Sports, University of Copenhagen, Denmark.
Assistant Professor Karsten Koehler, Technical University of München, Department of Sports and Health Sciences.
Professor Niels Ørtenblad, University of Southern Denmark, Department of Sport Science and Clinical Medicine.
Main supervisor
Professor Ylva Hellsten, The August Krogh Section for Human Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Denmark.
Co supervisor
Professor Jens Bangsbo, The August Krogh Section for Human Physiology, Department of Nutrition, Exercise and Sports, University of Copenhagen, Denmark.