|Surrender bro, women are tougher than we'll ever be... and let's not talk about the other tactics by the means of which they trick us into doing whatever they want without us even noticing :-o|
Men are different, women too
The results of previous experiments suggest that women are tougher than men, when it comes to steady state high intensity exercise at a self-selected pace. In their most recent study that involved 16 subjects (8 men and 8 women) between 19 and 30 years of age who had been participating in at least one session of interval training per week within the past months, Laurent et al. set out to test whether this would apply to HIIT sessions with fixed rest periods, but also variable, self-selected intensities. To this end, they had their subjects perform three bouts of HIIT.
"Each session consisted of 6, 4-minute intervals interspersed with either 1, 2, or 4 minutes of recovery. The recovery duration was counterbalanced and subjects were informed of the specific work-to-rest ratio prior to performing each session. Each trial began with a 5-minute warm-up that consisted of walking 4.8 km/h at 5% incline."
|Suggested read: "8x Increase in PGC1-Alpha Cycling in Glycogen Depleted State" (read more)|
The treadmill remained elevated at 5% incline for the duration of the whole session. Prior to each interval, subjects estimated their level of readiness using a perceived readiness scale.
Throughout and at the end of each interval, VO2(ml/kg/min), heart rate (bpm), and rate of perceived exertion (RPE) were measured, recorded and statistically processed.
At the conclusion of the fourth minute, the treadmill was slowed to 4.8 km/h for an active recovery.
"These procedures were followed identically for each of the 6 intervals and across all 3 trials. At the conclusion of the final interval of each session, subjects were disconnected from the metabolic system and sat quietly in a chair in the laboratory for approximately 15-20 minutes whereupon they provided a session RPE (SRPE) using the OMNI scale. "All subjects were given at least 72 hours but no more than 10 days of rest between HIIT sessions, at the end of which the scientists had made the following observations:
Triple your energy expenditure by doing shorter shuttle runs (learn more)
- The same velocity and effect size advantage for the strong sex was evident during the trial with 2 min rest times, as well, but in this case the difference was no longer significant.
- Even during the 4-minute recovery trial, men ran at higher velocities but the values were not significantly different and the effect size was considerably low.
"Apropos active rest - what's the best?"
If you take a closer look at the data in figure 1, you will realize that the 4-min-condition with a work-to-rest ratio of 4:2 (in other words, the 2min rest-condition) appears to have a slight advantage over the other conditions. While the VO2 max may be ~1% higher in the short rest condition (VO2 data not shown), this is not worth the increased exertion both men and women experienced when they ran their 4-min intervals with only 1min of active rest in-between.
|(Re)read the SuppVersity HIIT Series and learn about the optimal interval:rest ratios for your personal training goals (click here)|
Once you've figured out what works best for you, stick to it! I don't care if it's 2:1 or 30s:1min, as long as it works for you and you don't have to drag yourself to the track or the gym, whenever your HIIT sessions are due, that's your personal optimum. You should still keep in mind that this optimum may change with your current performance / weight loss / hypertrophy goals and the corresponding amount of energy you consume. Previous research, for example, suggests that long(er) intervals (in the 4min range) could have a slight edge over very short ultra-intense ones, especially when your primary goal is to shed body fat (learn more in the HIIT Special Part I & Part II)
- Laurent CM, Vervaecke LS, Kutz MR, Green JM. Sex specific responses to self-paced, high-intensity interval training with variable recovery periods. J Strength Cond Res. 2013 Jul 8. [Epub ahead of print]