Author(s): LENS-VALES, A., VARELA-SANZ, A., FARIÑAS, J., OVIES-GUTIÉRREZ, F., NINE, I., RIAL-VÁZQUEZ, J., IGLESIAS-SOLER, E., Institution: DEPARTMENT OF PHYSICAL EDUCATION AND SPORTS, Country: SPAIN, Abstract-ID: 1161

INTRODUCTION:
Aerobic interval training (AIT) is a method commonly used for accumulating a great exercise volume at a targeted intensity (i.e., above 90% of VO₂max) within a single training session by interspersing high-intensity exercise bouts (i.e., work intervals longer than 60 s) with pauses (i.e., rest intervals) (Sánchez-Otero et al., 2022; Varela-Sanz et al., 2023). Classical recommendations for developing aerobic power involve the implementation of work intervals lasting 2–3 minutes, performed at maximal aerobic speed (MAS), with a work-to-rest ratio (w:r) of 1:1 and a total accumulated exercise volume of at least 15 min (Sánchez-Otero et al., 2022; Varela-Sanz et al., 2023). To the best of our knowledge, no studies have investigated individualized interval durations based on a time-to-exhaustion running test (Tlim) close to MAS. This study aimed to examine the acute cardiometabolic and perceptual responses to three individualized AIT running sessions with different intensities of effort based on the individual Tlim.
METHODS:
Fourteen Sports Science students performed the Universitè de Montréal Track Test (UMTT) (Léger and Boucher, 1980) on a treadmill to determine MAS and VO₂max. After 48 hours, participants' Tlim was determined at an intensity close to the MAS. 48 hours later, they randomly performed three AIT running sessions, each accumulating 15 min but differing in intensity of effort based on Tlim: AIT30 (work intervals lasting 30% of Tlim), AIT50 (work intervals lasting 50% of Tlim) and AIT75 (work intervals lasting 75% of Tlim). Rating of perceived exertion (RPE) was recorded after each work interval and for the entire session. Heart rate (HR) was monitored throughout all sessions, while lactatemia was measured at the beginning and the end of AIT.
RESULTS:
Both average RPE and HR were lower during AIT30 (RPE: 6.30 ± 1.55, HR: 170.14 ± 8.95 bpm) compared to the other configurations (AIT50, RPE: 7.54 ± 1.17, HR: 175.02 ± 9.02 bpm; AIT75, RPE: 8.44 ± 0.75, HR: 175.69 ± 9.58 bpm; p<.001 for all). Lactatemia was also lower after AIT30 (9.41 ± 2.68 mMol·L-1) compared to AIT75 (13.55 ± 3.70 mMol·L-1; p=.011). In contrast, completed training time was greater in AIT30 (900.00 ± 0.00 s) compared to the other configurations (AIT50: 880.29 ± 73.76 s; AIT75: 723.57 ± 150.93 s) (p<.001).
CONCLUSION:
Our results suggest that AIT running sessions implementing work intervals lasting 30% of Tlim may attenuate cardiometabolic and perceptual responses compared with longer interval configurations, although the accumulated training volume is higher.

Léger, L., & Boucher, R. (1980). An indirect continuous running multistage field test: the Université de Montréal track test. Canadian journal of applied sport sciences. Journal canadien des sciences appliquees au sport, 5(2), 77–84. Sánchez-Otero, T., Tuimil, J. L., Boullosa, D., Varela-Sanz, A., & Iglesias-Soler, E. (2022). Active vs. Passive Recovery During an Aerobic Interval Training Session in Well-trained Runners. Eur J Appl Physiol, 122(5), 1281–1291. Varela-Sanz, A., Sánchez-Otero, T., Tuimil, J. L., Boullosa, D., & Iglesias-Soler, E. (2023). Influence of Recovery Mode on the Maximum Number of Intervals Until Exhaustion During an Aerobic Interval Training Session. J Strength Cond Res, 37(9), e510-e520.