Unraveling the mystery of isocaloric endurance training - Influence of exercise modality, biological sex, and physical fitness

Adding LIT to HIIT: Is Low-Intensity Training Vital for Endurance-Trained Athletes during a 7-day HIIT Shock Microcycle?

“…The assessment of PPO has its origin in cycling-based incremental ramp tests and correlates strongly with V̇O 2max or TT performance and is therefore another important indicator of endurance performance (45,46). In a first attempt, we have transferred this principle to treadmill running using the WOODWAY formula applied in a ramp test protocol.…”

A training goal-oriented categorization model of high-intensity interval training

“…On the third level, aerobic HIIT can be categorized into several forms ( Figure 1 ). These include traditional or “long” aerobic intervals of 2–10 min, e.g., 4 × 4 min ( Helgerud et al, 2007 ; Sandbakk et al, 2013 ; Seiler et al, 2013 ; Rønnestad et al, 2014 ), and intermittent or “short” aerobic intervals ( Christensen et al, 1960 ; Laursen and Jenkins, 2002 ; Rønnestad et al, 2015 ) lasting around 15 s ( Helgerud et al, 2007 ; Dolci et al, 2020 ) to 60 s, e.g., 30 × 30 s ( Gibala et al, 2012 ; Stöggl et al, 2023 ). Short aerobic intervals are performed with a “high”, but not maximal target intensity enabling athletes to exercise at intensities at or above competition speed for extended durations ( Gullstrand, 1996 ) while long aerobic intervals are usually performed with slightly lower intensity compared to short aerobic intervals ( Rønnestad et al, 2015 ).…”

“…The following intensity targets are commonly applied for aerobic HIIT: ≥90% VO 2max or ≥90% maximal heart rate (HR max ) but not maximal intensity ( Laursen and Jenkins, 2002 ; Buchheit and Laursen, 2013a ; Buchheit and Laursen, 2013b ; Weston et al, 2014 ); 90%–120% power output/velocity at VO 2max (p/vVO 2max ), i.e., maximal aerobic power/speed (MAP/MAS) ( Hill and Rowell, 1996 ; Buchheit and Laursen, 2013a ); 70%–110% peak power output (PPO) determined by incremental exercise test ( Astorino et al, 2017 ; Stöggl et al, 2023 ); power output or speed above critical power/speed (CP/CS) ( Jones et al, 2010 ); rating of perceived exertion (RPE) exceeding 6 on the CR-10-BORG scale ( Buchheit and Laursen, 2013a ), or ranging between 15–18 (hard—very hard) on the 6 to 20-BORG scale ( Buchheit and Laursen, 2013a ; Ciolac et al, 2015 ; Foster et al, 2021 ; Coates et al, 2023 ); lactate concentration above the maximal lactate steady state ( Tschakert and Hofmann, 2013 ) or second lactate threshold ( Jamnick et al, 2020 ), greater than 4 mmol/L ( Mader, 1976 ) or even between 7 and 10 mmol/L ( Faude et al, 2013 ; Thum et al, 2017 ); above the respiratory compensation point/second ventilatory threshold ( Meyer et al, 2004 ).…”

“…In accordance with the differentiation into SIT and RSIT as mentioned above, SET can be further differentiated based on the recovery duration between the intervals ( Figure 1 ). Speed endurance production training (note, for reasons of consistency, we have added a T for “training” to the terminology, hence “SEPT” instead of SEP) is characterized by intervals of 10–40 s ( Iaia and Bangsbo, 2010 ) with highest possible mean power output/velocity (70%–100% V max ) and long recovery periods (4-6 times the interval duration ( Iaia and Bangsbo, 2010 ; Iaia et al, 2015 )) to allow for repeated intervals at the same quality, e.g., 40 s at 125% PPO with 260 s break ( Stöggl et al, 2023 ). Conversely, speed endurance maintenance training (SEMT) employs interval durations of up to 90 s ( Iaia and Bangsbo, 2010 ) (75 s in our model) with shorter recovery periods of 1–3 times the interval duration, e.g., 40 s passive recovery ( Iaia et al, 2015 ) to stress the repeatability with accumulated fatigue.…”