Benítez-Flores, Stefano; Castro, Flávio A. de S.; Lusa Cadore, Eduardo; Astorino, Todd A.

Journal of Strength and Conditioning Research 37(5):p 1070-1078, May 2023. | DOI: 10.1519/JSC.0000000000004358

PURPOSE:

To compare the acute cardiovascular and neuromuscular effects of 3 time-matched sessions of high-intensity training.

PROCEDURES:

Nine women and nine men age ~23 years with an average Vo2max of ~47.6 ml·kg−1·min−1 performed three less-than-9:00 sessions of the following in a randomized order:

  1. Sprint interval training (SIT) @ 10 x :05 work with :35 rest between each.

  2. Burpee interval training (BIT) @ same as SIT.

  3. Vigorous intensity continuous training (VICT) @ running 6:05 @ ∼85% of peak heart

rate [HRpeak]).

Monitored during exercise were indices related to heart rate (HR), neuromuscular performance (counter movement jump height [CMJheight] and squat and bench press power), and autonomic balance (heart rate recovery and heart rate variability [HRR and HRV]).

CONCLUSIONS:

• SIT and VICT elicited a higher HRmean and time of ≥90% HRpeak compared to BIT.

• SIT exhibited a slower HRR and lower HRV than BIT and VICT post-session.

• Only SIT resulted in a significant decline in CMJheight, relative squat mean power, and relative bench press peak power.

• SIT diminishes the sympathovagal reactivation and neuromuscular performance compared with work-matched BIT and VICT.

IN PLAIN ENGLISH:

• SIT efforts were all-out for the :05 which would increase the recruitment of the more fatigable type IIX muscle fibers.

• Doing BIT would involve the more fatigable type IIX muscle fibers, but during the process from getting to the ground, standing up, then initiating the next burpee offers a slight “rest” between each segment, just enough to allow for a tincture of ATP energy recovery.

• VICT involved constant movement during the 6:05 of work time, but it was not all-out like the SIT thus not as demanding on the type IIX muscle fibers.

• For maximum recovery of the type IIX muscle fibers, at least 2:00 recovery would be needed.

• The :35 recovery between the 10 bouts in the SIT and BIT was not optimally maximal, thus greater fatigue from H+ accumulation over the total work time negatively affected the performance on the CMJ height, squat, and bench, especially from SIT.