Furthermore, in a subsequent study using a similar low volume high intensity interval sprint training, exercise capacity (maximal oxygen consumption, V ˙O 2peak), and markers of oxidative capacity have been shown to increase along with other metabolic adaptations as seen after endurance training ( Burgomaster et al., 2008). (2006) could demonstrate that a low volume sprint interval training can elicit increases in exercise capacity, markers of oxidative capacity, resting muscle glycogen content, and buffering capacity, all of these changes being comparable to those induced by a high volume endurance training. This was based on a study demonstrating that sprint interval training can improve cycle endurance time significantly ( Burgomaster et al., 2005). Sprint interval training has been predicted to be a potent and time-efficient means of improving endurance exercise performance ( Coyle, 2005). The latter might be explained by the well-known effects of hypervolemia on exercise performance. HIHVT induced a nearly complete slow-to-fast fiber type transformation on the mRNA level, which, however, cannot account for the improvements of performance parameters. However, mRNA expression levels of glycolytic marker enzyme glyceraldehyde-3-phosphate dehydrogenase did not change after the first and second training set. In agreement, a significant decrease was also found for citrate synthase mRNA after the second training set, indicating reduced oxidative capacity. The mRNA expression of peroxisome proliferator-activated receptor gamma coactivator 1α (PGC-1α), a master regulator of oxidative energy metabolism, decreased after the second training set. A shift from slow MHCI/β to fast MHCIIa mRNA expression occurred after the first and second training set. Training-induced decreases of hematocrit indicate hypervolemia. No changes in blood levels of lipid metabolites were detected.
Prolonged time-to-exhaustion was found in endurance tests with 65 and 80% P max at INT and END. In incremental tests peak power (P peak) was increased, whereas V ˙O 2peak was unaltered. vastus lateralis biopsies by quantitative real-time PCR. The mRNA expression levels of myosin heavy chain (MHC) isoforms and markers of energy metabolism were analyzed in M. HIHVT was evaluated by comparing performance tests before and after the entire training (baseline, BSL, and endpoint, END) and between the two training sets (intermediate, INT). We present here a longitudinal study determining the effects of two 3 week-periods of high intensity high volume interval training (HIHVT) (90 intervals of 6 s cycling at 250% maximum power, P max/24 s) on a cycle ergometer. 5Molecular and Cell Physiology, AG Vegetative Physiology, Hannover Medical School, Hannover, Germany.4Institute of Sports Science, Leibniz University Hannover, Hannover, Germany.3Institute of Clinical Pharmacology, Hannover Medical School, Hannover, Germany.2Clinical Research Center Hannover, Hannover Medical School, Hannover, Germany.1Institute of Sports Medicine, Hannover Medical School, Hannover, Germany.Julian Eigendorf 1, Marcus May 2, Jan Friedrich 1, Stefan Engeli 3, Norbert Maassen 1,4 *, Gerolf Gros 5 and Joachim D.