Scand J Med Sci Sports 2016: : – ª 2016 John Wiley & Sons A/S. doi: 10.1111/sms.12660 Published by John Wiley & Sons Ltd Effects of submaximal and supramaximal interval training on determinants of endurance performance in endurance athletes M. Paquette1,2, O. Le Blanc1,2, S. J. E. Lucas 3,4, G. Thibault1, D. M. Bailey5,6, P. Brassard1,2 1Department of Kinesiology, Faculty of Medicine, Universite Laval, Quebec, QC, Canada, 2Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de Quebec, Quebec, QC, Canada, 3School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, UK, 4Department of Physiology, University of Otago, Dunedin, New Zealand, 5Neurovascular Research, Laboratory, Faculty of Life Sciences and Education, University of South Wales, South Wales, UK, 6Sondes Moleculaires en Biologie, Laboratoire Chimie Provence UMR 6264 CNRS, Universite de Provence Marseille, Marseille, France Corresponding author: Patrice Brassard, PhD, Department of Kinesiology, Faculty of Medicine, PEPS – Universite Laval, 2300 rue de la Terasse, room 2122, Quebec, QC, Canada GIV OA6. Tel.: 418 656-2131 (5621), Fax: 418-656-4908, E-mail: patrice. [email protected] Accepted for publication 19 January 2016 We compared the effects of submaximal and increased VO2max (HIIT85: +3.3 Æ 3.1 mL/kg/min; supramaximal cycling interval training on determinants of HIIT115: +3.3 Æ 3.6 ml/kg/min; Time effect P = 0.002; exercise performance in moderately endurance-trained Group effect: P = 0.95), Ppeak (HIIT85: +18 Æ 9W; men. Maximal oxygen consumption (VO2max), peak power HIIT115: +16 Æ 27 W; Time effect P = 0.045; Group output (Ppeak), and peak and mean anaerobic power were effect: P = 0.49), and mean anaerobic power (HIIT85: measured before and after 6 weeks (3 sessions/week) of +0.42 Æ 0.69 W/kg; HIIT115: +0.55 Æ 0.65 W/kg; Time submaximal (85% maximal aerobic power [MP], HIIT85, effect P = 0.01; Group effect: P = 0.18). Six weeks of n = 8) or supramaximal (115% MP, HIIT115, n = 9) submaximal and supramaximal interval training performed interval training to exhaustion in moderately endurance- to exhaustion seems to equally improve VO2max and trained men. High-intensity training volume was 47% anaerobic power in endurance-trained men, despite half the lower in HIIT115 vs HIIT85 (304 Æ 77 vs 571 Æ 200 min; accumulated time spent at the target intensity. P < 0.01). Exercise training was generally associated with In endurance sports such as cycling, maximal oxygen put to that produced at VO2max); thus, the optimal consumption (VO2max), endurance capacity, anaero- exercise training stimulus remains equivocal. bic fitness, and movement efficiency are important Submaximal interval training can improve endur- determinants of endurance performance (Joyner & ance performance in highly endurance-trained Coyle, 2008). Evidence strongly suggests that both cyclists (Westgarth-Taylor et al., 1997; Kristoffersen high-volume, low-intensity and low-volume, high- et al., 2014; Stoggl€ & Sperlich, 2014). Accumulating intensity training (Londeree, 1997; Buchheit & evidence indicates that supramaximal interval train- Laursen, 2013) are important in order to optimize ing can also increase maximal aerobic capacity in adaptations in endurance athletes (Stoggl€ & Sperlich, moderately active adults (Rodas et al., 2000; Gist 2014). High-intensity training, although representing et al., 2014; Weston et al., 2014), although the bene- a smaller proportion of athletes’ training volume, is ficial impact of interval training in that intensity a critical component in the training of all successful domain remains ambiguous in athletic men main- endurance athletes (Seiler, 2010). High-intensity taining usual low-intensity base-training (Weston training is usually performed using interval training, et al., 2014). which involves repeated short-to-long bouts of Few studies have directly compared submaximal, rather high-intensity exercise interspersed with maximal, and supramaximal interval training in recovery periods (Buchheit & Laursen, 2013). Vari- endurance-trained athletes (Stepto et al., 1999; Laur- ous high-intensity interval training (HIIT) protocols sen et al., 2002; Esfarjani & Laursen, 2007), and are utilized in athletes’ training programs, including those that have report equivocal findings. For exam- submaximal training (below VO2max), VO2max train- ple, Stepto et al. (1999) reported greatest improve- ing, and supramaximal training (superior power out- ments in cycling endurance performance following 1 Paquette et al. six HIIT sessions over 3 weeks performed at 85% were road cyclists (n = 9), triathletes (n = 7), mountain bikers peak power (P , i.e., submaximal interval training) (n = 2), and a cross-country skier, who were training peak Æ and 175% P (i.e., supramaximal interval train- 8.4 2.7 h/week in the month before the study, and were tak- peak ing part in 0 to 2 interval training sessions/week (0.5 Æ 0.7 ing), compared to HIIT performed at 80%, 90%, or HIIT sessions/week on average). This study was approved by 95% Ppeak. In contrast, others report that interval the local ethics committee and was conducted in accordance training at VO2max performed twice a week for 4 to the principles established in the Declaration of Helsinki, (Laursen et al., 2002) or 10 weeks (Esfarjani & Laur- with verbal and written informed consent provided by all sen, 2007) shows larger beneficial effects on perfor- participants. mance and key physiological determinants of performance (e.g., VO2max and 3000 m running time) Experimental design in trained athletes compared to supramaximal inter- Participants reported to the laboratory on four separate occa- val training at 130% of maximal aerobic speed sions over a period of 2 weeks to perform: (a) anthropometric (Laursen et al., 2002; Esfarjani & Laursen, 2007) and resting measurements, (b) an incremental cycling test to and 175% Ppeak (Laursen et al., 2002; Esfarjani & determine VO2max and Ppeak, (c) a maximal aerobic power Laursen, 2007). Furthermore, 6 weeks of supramaxi- (MP) stepwise intermittent protocol, and (d) a 30-s Wingate mal running interval training (3 sessions/week at test to assess sprint performance (peak and mean anaerobic power). Participants were asked to refrain from training for at 130% 3000-m running speed) provided greater bene- least 12 h and to avoid alcohol and caffeine consumption for fits for endurance, sprint, and repeated sprint perfor- 24 h before each visit. All sessions were performed in the same mance than submaximal interval training (at 3000-m order for all participants and there was at least 24 h between running speed) in physically active but not endur- testing sessions. After these four preliminary evaluation ses- ance-trained individuals (Cicioni-Kolsky et al., sions, participants were matched according to their age and VO2max before one from each pair was randomly assigned to 2013). Accordingly, whether submaximal or supra- one of two training groups: submaximal (HIIT ) or supra- maximal interval training elicits the greatest benefits 85 maximal (HIIT115). By study design, participants in both in endurance-trained athletes remains uncertain. groups had similar age (HIIT85:26Æ 6years, HIIT115: Æ Æ Most studies comparing different training intensi- 27 6 years), height (HIIT85:1.77 0.08, HIIT115: Æ ties usually match sessions based on achieving the 1.78 0.08 m), body mass, % body fat, and VO2max (Tables 1 and 2). The four evaluation sessions were repeated 48–96 h fol- same energy consumption across interventions. lowing the end of a 6-week training program (see Fig. 1). However, Seiler et al. (2013) has suggested that matching training regimens on energy consumption induces different overall effort between interval regi- Training interventions mens, with total effort or fatigue being lower when Training consisted of three HIIT sessions per week over a per- energy expenditure is achieved with lower intensity iod of 6 weeks, with 48–72 h between sessions. On remaining exercise. Importantly, as pointed out by Seiler et al. days, participants were asked to avoid high-intensity exercise, (2013) and Rønnestad et al. (2015), athletes match but to maintain a similar low and/or moderate intensity train- their HIIT sessions for overall effort and accumu- ing volume typically performed prior to the study. The HIIT85 group performed repeated 1- to 7-min effort bouts, depending lated fatigue in real life situations, not for total work. on the session, at 85% MP, separated by half the effort time Thus, effort matching appears a more valid way to of active recovery (150 W or 50% MP if MP <300 W) until compare intensities, as they would be used in real- exhaustion. The HIIT115 group performed repeated 30-s to 1- world settings. min effort bouts, depending on the session, at 115% MP, sep- Therefore, the aim of this study was to assess the arated by twice the effort time of active recovery (150 W or 50% MP if MP <300 W) until exhaustion. Table 3 outlines impact of effort-matched submaximal and supra- the 18 sessions performed in a randomized order during the maximal interval training on determinants of endur- 6 weeks by participants from HIIT85 and HIIT115 groups. The ance performance in moderately endurance-trained reasons for alternating exercise bout duration from one ses- adults. We hypothesized that, notwithstanding a sion to another throughout the 6-week training period in both lower training volume, supramaximal interval train- groups were to reduce monotony of exercise training and to focus on exercise intensity, e.g., 85 vs 115% MP, and not exer- ing would increase to a greater extent aerobic capac- cise duration. Trainings were performed on Tacx Bushido ity compared to submaximal interval training. We trainers (Tacx, Terneuzen, The Netherlands). also expected an improvement in anaerobic capacity HIIT85 and HIIT115 protocols were matched for total effort following supramaximal, but not submaximal inter- rather than for total work, which is closer to what athletes val training. typically do when performing hard interval sessions at various intensities (Seiler et al., 2013).