Here’s the paper using paragraphs so that a human can read it:
The purpose of this study was to compare the effect of two different methods of organizing endurance training in trained cyclists.
One group of cyclists performed block periodization, wherein the first week constituted five sessions of high-intensity aerobic training (HIT), followed by 3 weeks of one weekly HIT session and focus on low-intensity training (LIT) (BP; n = 10, VO2max = 62 ± 2 mL/kg/min).
Another group of cyclists performed a more traditional organization, with 4 weeks of two weekly HIT sessions interspersed with LIT (TRAD; n = 9, VO2max = 63 ± 2 mL/kg/min).
Similar volumes of both HIT and LIT was performed in the two groups.
While BP increased VO2max , peak power output (Wmax) and power output at 2 mmol/L [la(-)] by 4.6 ± 3.7%, 2.1 ± 2.8%, and 10 ± 12%, respectively (P < 0.05), no changes occurred in TRAD.
BP showed relative improvements in VO2max compared with TRAD (P < 0.05). Mean effect size (ES) of the relative improvement in VO2max , Wmax , and power output at 2 mmol/L [la(-)] revealed large to moderate effects of BP training compared with TRAD training (ES = 1.34, ES = 0.85, and ES = 0.71, respectively).
The present study suggests that block periodization of training provides superior adaptations to traditional organization during a 4-week endurance training period, despite similar training volume and intensity.
So all I need to do to improve is 3 weeks of 5 HIIT sessions a week? Am I reading this correctly? 
Study Design Details:
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Block Periodization (BP) Group (n=10): Performed 5 HIT sessions in the first week, followed by 3 weeks of only 1 weekly HIT session, with the rest of the time focused on low-intensity training.
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Traditional (TRAD) Group (n=9): Performed a steady schedule of 2 HIT sessions per week interspersed with low-intensity training for all 4 weeks.
No. It’s 5 HIT first week then 1 per week after.
You’re all correct. I misread. Whew!
Did they just do one 4 week block or did they follow a longer plan with rest weeks etc?
Just the one 4-week block.
FWIW full paper readable here:
If not already clear to anyone reading, both groups did the same type and volume of training, just organised differently (to investigate front-loading of the intensity):
In order to investigate the effect of block periodization per se, the same volume of both HIT and low intensity training was performed in both groups during this 4-week intervention period.
Purely speculating as a punter, it seems to me that if doing just one 4-week block, then packing more of your intensity into the beginning of that block would provide more time for adaptations to have occurred by the time you come to test at end of that block. So perhaps that’s what’s going on here?
When referencing previous studies in the Discussion, this study goes on to say…
In fact, studies lasting 7–8 weeks with two to three HIT sessions (4 ¥ 4 min) per week have reported change in VO2max (5–7%) similar to those found for the BP group in the present study (Helgerud et al., 2007; Seiler et al. 2011). This could be taken to indicate that longer training intervention periods are needed for the TRAD group to show performance improvements.
So for those of us with training plans lasting multiple months (as opposed to doing a single 4-week block, then nothing thereafter…), then maybe the benefits of front-loading intensity loses relevance?
Regardless, I’m never doing 5 HIIT sessions in a week🤮, even if that meant I got to do only 1 HIIT/week for the following few weeks.
I assume that there wasn’t any rest week involved here because 1) the wording implies as much (four weeks of training), 2) in research they are trying to complete the study quickly so they don’t lose participants, 3) they weren’t doing many sessions per week.
I wish they had stated what the actual training hours were and the split of LIT vs HIT.
It looks like they actually ran the study for 12 weeks and the 4 week paper was an intermediate result (both to pad the author’s CV and to hedge against losing some of their only 20 participants, which they did end up with only 15 by the end).
Here’s the 12 week study. Again it seems like they didn’t do any recovery weeks, but if the volume was low and the subjects were college students that was probably reasonable.
The results:
BP achieved a larger relative improvement in VO2max than TRAD (8.8 ± 5.9% vs 3.7 ± 2.9%, respectively, < 0.05) and a tendency toward larger increase in power output at 2 mmol/L [la(-)] (22 ± 14% vs 10 ± 7%, respectively, P = 0.054). Mean effect size (ES) of the relative improvement in VO2max , power output at 2 mmol/L [la(-)], hemoglobin mass, and mean power output during 40-min all-out trial revealed moderate superior effects of BP compared with TRAD training (ES range was 0.62-1.12). The present study suggests that BP of endurance training has superior effects on several endurance and performance indices compared with TRAD.
Was just about to link that lol.
IMO it’s probably more reliable to stick to traditional periodization for most people. However if one is plateaued and can’t add more time then it’s definitely worth trying a similar intervention on themselves.
I think there’s a lot of evidence to support using block periodization. Dylan Johnson did a video on it looking at many studies.
If you think about it it’s the same principle as base, build, specialty but on a smaller scale. And I have noticed that my nervous system prefers one short term shock rather than continuous bouts of higher stress. So I’m giving BP a shot this year.
The science of block periodization video is here. Dylan explains his training for 2024 and his block that he used to prep for his 10th place at Unbound here (at ~22 mins), although that was a volume block rather than an intensity block.
Actually rewatching the DJ BP videos he ends up citing both of these studies. Of course he had the whole paper not just the summary.
These were competitive cyclists that were already well trained, so that’s good. I doubt how much studying untrained people matters to trained athletes trying to optimize their training.
It also confirms my assumption of no rest weeks.
There’s also a similar newer study from 2022 which this time included threshold training and progressive overload for the linear traditional periodizarion group. The block periodization group also did threshold training on their 3rd week.
This time there were no significant differences between the two groups and the conclusion was that both methods work. Here’s the paper:
That’s an interesting study, but I would have been surprised if they had found any difference between the groups.
Both groups were prescribed the same total number of HIT,
MIT, and LIT sessions during each 4-week mesocycle and the
HIT and MIT were made up of the same total number of
efforts and had the same total duration.
The average weekly training volume (hrs·wk.−1) during the
intervention was not different between groups (p = 0.571) with
an average of 7.5 ± 2.0 h·wk.−1 in TP and 8.0 ± 2.7 h·wk.−1 in
BP, respectively
The training load (i.e., iTRIMP scores) for the whole
intervention period was not different between the groups (p = 0.820)
and there was no difference in the average iTRIMP score from the LIT and MIT sessions…
While the quest for the ideal training plan continues we can always fall back on those immortal words - “Ride lots.”
But on this chart there is simply more stimulus in the block periodisation treatment? I’ve had a read of various papers and not sure theres much difference, generally. I imagine for some people though, big stimulus works well. I know my biggest ftp gains have come from big volume - cycling trips basically - followed by rest.
The chart illustrates intensity distribution. Both groups did the same amount of workouts and the same overall volume.
Thats what i thought. The visuals look off though. Or my eyes are playing up.
So it seems that block periodization’s primary benefit is by having a temporary increase in volume above baseline. If during the other weeks rather than going back to normal volume to go to below normal volume, you’re not getting much benefit.
So it seems to reinforce the stage race or team camp training benefits that have been anecdotally observed.