EFFECTS OF 6WEEKS OF DIFFERENT HIGH-INTENSITY INTERVAL AND MODERATE CONTINUOUS TRAINING ON AEROBIC AND ANAEROBIC PERFORMANCE MILE CAVAR, 1 TOSO MARSIC, 1,2 MARIN CORLUKA, 1 ZORAN CULJAK, 1 IVANA CERKEZ ZOVKO, 1 ALEX MU ¨ LLER, 3 GERHARD TSCHAKERT, 3 AND PETER HOFMANN 3 1 Department of Physical Culture, Faculty of Natural Science, Mathematics and Education, University of Mostar, Mostar, Bosnia and Herzegovina; 2 Faculty of Kineseology, University of Zagreb, Zagreb, Croatia; and 3 Exercise Physiology, Training & Training Therapy Research Group, Institute of Sports Science, University of Graz, Graz, Austria ABSTRACT Cavar, M, Marsic, T, Corluka, M, Culjak, Z, Cerkez Zovko, I, Mu ¨ ller, A, Tschakert, G, and Hofmann, P. Effects of 6 weeks of different high-intensity interval and moderate continuous train- ing on aerobic and anaerobic performance. J Strength Cond Res XX(X): 000–000, 2018—To provide practical data, we compared the training effects of 3 different programs, using a shuttle run stimulus, on aerobic and anaerobic performance, measured using the 20-m maximal shuttle run (Beep) test and 300-yd shuttle run, respectively. Forty-five physically trained men, with a mean age of 21.1 6 1.8 years, participated. The 6-week, 12-session training programs included 2 high-intensity interval training (HIIT) protocols, with either a short (SH) or long (LH) shuttle run interval, and a continuous shuttle run (CON), which was used as a control. The training intensity was based on the maximal shuttle run speed (MASS), measured on the Beep test, to elicit the relevant values of the time to exhaustion (TTE). Short (SH) training was performed at 115–120% (MASS), with a 10-second work to 10-second rest scheme, and the number of repetitions to be completed set to 70% of each participant’s maximum (;15 repetitions). LH training was performed at an intensity of 90–95%(MASS), with the duration set to 70%(TTE) (;4 minutes). For both SH and LH, 3 sets were completed at each session, with a 2–3 minutes of rest between sets. CON training consisted of continuous shuttle running for 35 minutes at an intensity of 70%(MASS). Both SH and LH yielded a large training effect (p , 0.01), with SH preferentially improving anaerobic performance and LH pref- erentially improving aerobic performance. No effect of CON training was identified. Our findings indicate that these differ- ent training protocols cannot be used interchangeably and that the Beep test is useful in prescribing the intensity and duration of HIIT. KEY WORDS HIIT, beep test, endurance training, time to exhaustion INTRODUCTION I n the science and practice of sport and exercises, par- ticular attention has been paid to the development of training strategies intended to improve performance- related physical qualities. High-intensity interval train- ing (HIIT) has been proposed as a time-saving strategy to improve both aerobic power (maximal oxygen consumption, V _ O 2 max) and anaerobic capacity (45). Therefore, HIIT has become a preferred method of endurance training for anaer- obically dominant sports (e.g., stop-and-go sports, such as soccer), in which V _ O 2 max influences performance (24) and occupations, such as the military, with a physiological profile that relies on diverse energetic sources and has time con- straints in achieving complex training aims. Despite the increasing interest in HIIT, its application and mechanisms remain poorly understood. Current literature on HIIT (14,18,36) has generally focused on V _ O 2 max, with interval training performed at intensities at or above the maximal aerobic velocity (MAV), where the MAV is defined, in laboratory procedures, as the minimal speed that yields V _ O 2 max. These training intensities are referred to as standard and supramaximal HIIT, respectively (18). Therefore, the HIIT concept covers a broad range of training parameters (intensity, duration of intervals and recovery, mode, work-to- rest ratio, type of rest, and mean intensity), which, in combination, produce specific effects that may lead to mis- interpretations of their effectiveness by practitioners. One clear example of this issue is Tabata HIIT, which has been incorrectly widely applied (e.g., in weight training and run- ning), with a 20-second work and 10-second rest schedule that was validated exclusively in cycling, with V _ O 2 max train- ing at 170% MAV (45). Furthermore, a lack of knowledge Address correspondence to Dr. Mile Cavar, mile.cavar@fpmoz.sum.ba. 00(00)/1–13 Journal of Strength and Conditioning Research Ó 2018 National Strength and Conditioning Association VOLUME 00 | NUMBER 00 | MONTH 2018 | 1 Copyright ª 2018 National Strength and Conditioning Association