Author(s): ZACHAROGIANNIS, E., PARADISIS, G., DALLAS, G., TSOPANIDOU, A., ZACHAROGIANNI, A., Institution: NATIONAL AND KAPODISTRIAN UNIVERSITY OF ATHENS, Country: GREECE, Abstract-ID: 805

INTRODUCTION:
Sprint interval (SIT, intensities 140-170%VO2max with short work bouts <30s and long recovery periods 4min) and high intensity interval (HIIT, intensities 90-100%VO2max with work bouts 30s-5min and recovery periods 30s-5min) training have been proposed to improve cardiorespiratory endurance performance in untrained as well as elite distance runners. However prolonged (>90min) running endurance performance directly depends on the rate of carbohydrate (rCHO) metabolism due to limited CHO storage. Purpose: The purpose of the present research was to study the effect of SIT and HIIT training methods on rCHO use at a submaximal (mean marathon pace) running velocity corresponding with 75%VO2max.
METHODS:
Twenty-two trained endurance runners (15 males and 7 females, mean ± sd age 33.6±12.1 years, body mass 74.5±10.7 kg, stature 176.5±6.7 cm, % body fat 12.9±3.2 and VO2max 54.33±5.1 ml.kg-1.min-1) assigned randomly to participate either in SITG (n=11) or HIITG (n=11) group. Each experimental group added for 8 weeks (2 days/week) either SIT or HIIT training sessions together with the rest of their training routine. Pre and post training subjects performed incremental test to determine VO2max and one 6 min continuous submaximal run at a speed corresponding with 75%VO2max 48 hours after VO2max trial. Submaximal run speed was the same during post measurement. Oxygen consumption and respiratory exchange ratio (RER) were monitored in 60 s intervals during maximal and submaximal exercise trials. CHO oxidation was calculated using stoichiometric equations (Frayn, 1983) with the assumption that urinary nitrogen was negligible.
RESULTS:
Anova analysis showed that 8 weeks application of HIIT lowered 20% mean ± sd (pre 2.92±0.8 V post 1.9±0.47 g.min-1) rCHO at the same mean±sd (11.7±1.24 km.h-1) running speed (p<0.05) for the HIITG. The SITG (pre 3.56±1.01 V post 3.52±0.89 g.min-1) lowered only 1% rCHO (p>0.05) at the same pre and post mean±sd (12.2±1.3 km.h-1) running speed.
CONCLUSION:
Although SIT may be recommended as a time saving mode of interval training to improve running endurance performance, for prolonged though endurance running maximal effort its effectiveness regarding CHO sparing adaptations is limited. The results of the present study support the use of HIIT instead of SIT during marathon and ultramarathon training.