To analyze the acute physiological response to aerobic short-interval training (AESIT) at various high-intensity running speeds. A minor anaerobic glycolytic energy supply was aimed to mimic the characteristics of slow continuous runs.
Eight trained male runners (maximal oxygen uptake [VO2max] 55.5 ± 3.3 mL · kg−1 · min−1) performed an incremental treadmill exercise test (increments: 0.75 km · h−1 · min−1). Two lactate turn points (LTP1, LTP2) were determined. Subsequently, 3 randomly assigned AESIT sessions with high-intensity running-speed intervals were performed at speeds close to the speed (v) at VO2max (vVO2max) to create mean intensities of 50%, 55%, and 60% of vLTP1. AESIT sessions lasted 30 min and consisted of 10-s work phases, alternated by 20-s passive recovery phases.
To produce mean velocities of 50%, 55%, and 60% of vLTP1, running speeds were calculated as 18.6 ± 0.7 km/h (93.4% vVO2max), 20.2 ± 0.6 km/h (101.9% vVO2max), and 22.3 ± 0.7 km/h (111.0% vVO2max), which gave a mean blood lactate concentration (La) of 1.09 ± 0.31 mmol/L, 1.57 ± 0.52 mmol/L, and 2.09 ± 0.99 mmol/L, respectively. La at 50% of vLTP1 was not significantly different from La at vLTP1 (P = .8894). Mean VO2 was found at 54.0%, 58.5%, and 64.0% of VO2max, while at the end of the sessions VO2 rose to 71.1%, 80.4%, and 85.6% of VO2max, respectively.
The results showed that AESIT with 10-s work phases alternating with 20 s of passive rest and a running speed close to vVO2max gave a systemic aerobic metabolic profile similar to slow continuous runs.
Wallner and Simi are with the Sports Science Laboratory, FH Joanneum University of Applied Science, Bad Gleichenberg, Austria. Tschakert and Hofmann are with the Exercise Physiology and Training Research Group, University of Graz, Graz, Austria. Address author correspondence to Dietmar Wallner at firstname.lastname@example.org.