Aerobic high-intensity intervals are superior to improve V̇O2max compared with sprint intervals in well-trained men

Abstract

Maximal oxygen uptake (V̇O_2max ) may be the single most important factor for long-distance running performance. Interval training, enabling high intensity, is forwarded as the format that yields the largest increase in V̇O_2max . However, it is uncertain if an optimal outcome on V̇O_2max , anaerobic capacity, and running performance is provided by training with a high aerobic intensity or high overall intensity. Thus, we randomized 48 aerobically well-trained men (23 ± 3 years) to three commonly applied interval protocols, one with high aerobic intensity (HIIT) and two with high absolute intensity (sprint interval training; SIT), 3× week for 8 weeks: (1) HIIT: 4 × 4 min at ~95% maximal aerobic speed (MAS) with 3 min active breaks. (2) SIT: 8 × 20 s at ~150% MAS with 10 s passive breaks. (3) SIT: 10 × 30 s at ~175% MAS with 3.5 min active breaks. V̇O_2max increased more (p < 0.001) following HIIT, 4 × 4 min (6.5 ± 2.4%, p < 0.001) than SIT, 8 × 20 s (3.3 ± 2.4%, p < 0.001) and SIT, 10 × 30 s (n.s.). This was accompanied by a larger (p < 0.05) increase in stroke volume (O₂ -pulse) following HIIT, 4 × 4 min (8.1 ± 4.1%, p < 0.001) compared with SIT, 8 × 20 s (3.8 ± 4.2%, p < 0.01) and SIT, 10 × 30 (n.s.). Anaerobic capacity (maximal accumulated oxygen deficit) increased following SIT, 8 × 20 s (p < 0.05), but not after HIIT, 4 × 4 min, nor SIT, 10 × 30 s. Long-distance (3000-m) endurance performance increased (p < 0.05-p < 0.001) in all groups (HIIT, 4 × 4 min: 5.9 ± 3.2%; SIT, 8 × 20 s: 4.1 ± 3.7%; SIT, 10 × 30 s: 2.2 ± 2.2%), with HIIT increasing more than SIT, 10 × 30 s (p < 0.05). Sprint (300-m) performance exhibited within-group increases in SIT, 8 × 20 s (4.4 ± 2.0%) and SIT, 10 × 30 s (3.3 ± 2.8%). In conclusion, HIIT improves V̇O_2max more than SIT. Given the importance of V̇O_2max for most endurance performance scenarios, HIIT should typically be the chosen interval format.

Keywords: HIIT; MAOD; SIT; Tabata; aerobic power; anaerobic capacity; running economy; running performance.

FIGURE 1

Flow chart of the study.

FIGURE 2

Representative examples of the three exercise interventions. Dotted line (‐ ‐ ‐) represents heart rate whereas solid line (–) represents oxygen uptake. Notice how the heart rate typically relates to oxygen uptake during the three interval formats. Gray area represents ≥90% of maximum. (A) HIIT 4 × 4 min running at ~95% of maximal aerobic speed (MAS) interspersed by 3 min active recovery. (B) SIT 8 × 20 s exhaustive running at ~150% of MAS interspersed by 10 s passive recovery. (C) SIT 10 × 30 s maximal running (average of ~175% MAS) interspersed by 3.5 min active recovery. During these training sessions, accumulated time ≥90% of V̇O_2max was 7 min (A), 1.5 min (B), and 0 min (C).

FIGURE 3

Percentage change in V̇O_2max (A), O₂ pulse (B), 3000‐meter running performance, (C) and 300‐m running performance (D) from pre‐ to posttest. 4 × 4 min, 4 × 4 min running at ~95% of maximal aerobic speed (MAS) interspersed by 3 min active recovery; 8 × 20 s, 8 × 20 s exhaustive running at ~150% of MAS interspersed by 10 s passive recovery; 10 × 30 s, 10 × 30 s maximal running (average of ~175% MAS) interspersed by 3.5 min active recovery. Data presented as mean and standard error of the mean. Significant different change from pre‐ to posttest within group (*p ≤ 0.05, **p ≤ 0.01, ***p ≤ 0.001), compared to 10 × 30 s (^a p ≤ 0.05, ^aaa p ≤ 0.001), compared to 8 × 20 s (^b p ≤ 0.05, ^bbb p ≤ 0.001).

FIGURE 4

Illustration of the calculation of maximal accumulated oxygen deficit (MAOD) for a subject, with a V̇O_2max of 65.5 ml kg⁻¹ min⁻¹. The subject ran at 118% of maximal aerobic speed (16.0 km h⁻¹ at 3° inclination) and with a theoretical O₂ cost of 76.1 ml kg⁻¹ min⁻¹. During the time to exhaustion of 157 s, the total accumulated O₂ cost (white and gray area combined) was calculated to equal 199.2 ml kg⁻¹. The accumulated VO₂ (gray area) during the 157 s was 116.2 ml kg⁻¹, giving a MAOD (white area) of 83.0 ml kg⁻¹.