It is relatively common to use high intensity interval training (HIIT) sessions in the same session as strength training with other muscle groups.
The results of a study have recently been published (Andrade et al, 2021; J Sports Med Phys Fitness 61: 803; doi: 10.23736 / S0022-4707.20.11458-0) whose objective was to compare the effects of performing a HIIT running on subsequent performance in strength exercises with upper limbs.
Seventeen young men (24.8 ± 5.2 years) participated who completed: 1) control session of strength exercises with bench press; 2) treadmill interval running protocol followed by bench press session; and 3) protocol of continuous treadmill running followed by the bench press session. Four sets of the bench press exercise were performed at 80% of 1RM until failure. In the HIIT protocol, eight sprints of 40 s were performed at 100% of the maximum aerobic speed, with a 20 s passive interval between them, while the continuous protocol consisted of 30 min running on a treadmill at 90% of the frequency corresponding to the second ventilatory threshold. The number of maximal repetitions completed in each set and condition was recorded and compared using a two-way repeated measures ANOVA.
The results showed that the interval protocol (18.7 ± 4.9 repetitions) resulted in a reduction in the number of bench press repetitions compared to the control protocol (21.4 ± 5.4 repetitions) (P = 0.002); while continuous running did not affect bench press performance (20.6 ± 4.4 repetitions). The total number of repetitions decreased from set to set in all protocols (P <0.001).
The authors evidenced a deterioration in upper limb strength performance after HIIT, but not after continuous moderate intensity running, which has implications for the planning and prescription of concurrent training.
JL. Chicharro (PhD) Opinion:
Concurrent training (aerobic + strength) in the same session is the most common in fitness rooms, but it is also very common in sports performance.
Athletes usually try to distance aerobic training at least 6 hours from strength training, but in the fitness area they are usually grouped in the same session to save time. It is important for athletes to be aware of this possible interference between training modalities. In the field of fitness or therapeutic exercise these possible interferences are not so important.