Training structure: plan for long-term performance gains

The polarized theory of training uses the concept of ‘intensity zones’. Basically, this concept assigns your time spent training into three zones - 1, 2 and 3 - which refer to easy, moderately hard and extremely hard intensities of training respectively (see below). Advocates of polarized training suggest that the best way of maximizing endurance potential is to spend the bulk of training time in zone 1, some time in zone 3 but not too much time in zone 2 (the moderately hard zone).

In this study, researchers found that increasing the work and training time below the first ventilatory threshold (zone-1 training, easy-to-moderate intensity) and also increasing time spent above the second ventilatory threshold (zone-3, very intense work) while reducing the proportion of time spent in zone-2 (threshold training, moderate-hard intensity) correlated with a significant improvement in MMP at 2, 5 and 12 minutes over the course of a season, without harming MMP over longer durations. Unfortunately however, there is no further evidence on how MMP values could be enhanced through the manipulation of training loads/intensities over the course of a season, or from one season to the next.

New research

In many sports science studies, athletes undergo a training intervention and the before/after results are compared with another group of athletes who undergo a different or no intervention. When it comes to progression of MMP over the course of a season or two however, there are very few athletes who would be willing to put themselves through a 12 or 24-month experiment, especially when that intervention might produce no performance gains or even performance losses compared to their normal training habits!

Fortunately, there is another approach that can be used to explore this topic, which is to record real-world data and observe correlations – ie to take a group of endurance athletes who have recorded MMP data over the course of a couple of seasons, find out which athletes have made the most progression in MMP over time, and then look at the training structure differences between those athletes and other athletes who made little or no progression. This was the line of approach of a new study that aimed to analyze the evolution of the MMP in competitive triathletes between seasons, and to examine its relationship with training characteristics based on the external load. It was hypothesized that MMP improvements would be positively related to an increased in high-intensity training volume.

Published two months ago in the Journal of Functional Morphology and Kinesiology, this research took the form of a longitudinal study, which tracked the same group of 14 international-level junior and under-23 triathletes over three consecutive competitive seasons to see which particular training habits most positively affected cycling performance⁽⁸⁾. This was done by tracking changes in the athletes’ MMP profiles over the 3-year period and mapping those changes against the volume, frequency and intensity of their training to see which parameters most positively influenced MMP profiles. In particular, the researchers wanted to test the polarized theory out by seeing if the improvements in sustained cycling capacity were primarily driven by an increase in the proportion of high/very-high intensity training time.

What they did

The researchers recruited 14 triathletes for the study who were highly experienced, averaging five years of international racing, and all of whom had a history of uninterrupted training prior to the study. The individual training data from each of the triathletes over three complete annual cycles (with each season defined as running from November 1st to October 31^st of the following year) was collected. The athletes’ training volume and intensity data were recorded in the form of the total time (hours), total distance (kms), and the proportion of time spent within key power output bands relative to the total training time across that triathlete’s season. These training power bands were defined as follows:

·        Low output intensity – less than or equal to 2 watts per kilo.

·        Moderate-high output intensity – 2-6 watts per kilo.

·        Very high output intensity - more than 6 watts per kilo.

In all cases, this power output data was measured and recorded using ‘Assioma Duo’ power meters (important to ensure measurement consistency across all athletes).

At key points in each season, the triathletes underwent testing to evaluate MMP outputs for a variety of different durations designed to reflect the competitive demands of triathlon cycle racing, which is characterized periods of steady effort but with a range of higher-intensity bursts steady effort needed for sprint finishes, hill climbing, breakaways etc. These MMP durations were 10 seconds, 30 seconds, 1 minute, 5 minutes, 10 minutes, 20 minutes, 40 minutes and 60 minutes. The researchers then mapped the MMP results achieved by each triathlete in each season to their patterns of training intensity in each season, and the progression over consecutive seasons to build up a picture of how effective different proportions of training intensity were for longer-term development.

What they found

There were a number of findings that emerged from the data, some expected and some unexpected:

·        When measured across the three seasons as a whole, the triathletes experienced marked power output gains averaged across the MMP durations, boding well for increased competitive performance. Within this overall improvement however, it was the longer duration MMPs (10, 20, 40 and 60 minutes) that showed significant improvements (from 0.9% to 4.8%) with the 10-second, 30-second, and 5-minute MMP values showing less improvement.

·        Total training time across the three seasons increased by an average of 22.1% and annual cycling mileage grew by 32.8%. Note that because these triathletes were young (under-23s), some of this training volume and time increase would be expected anyway since the athletes’ bodies were becoming more mature and physically able to handle higher workloads.

·        There seemed to be a step change between season #2 and #3; during the final year, the triathletes significantly increased the proportion of their total training time spent within the 4.0-6.0 watts/kg training intensity (moderate to hard, zone-2 work). This shift was strongly correlated to a big improvement in 1-minute, 10-minute, and 20-minute MMP values (see figure 1), indicating a significant boost in the aerobic power.

·        In contrast to the polarized training theory, long-term improvements in the longer MMP durations (over 1 minute) were negatively correlated to the proportion of time spent in zone 1 (easy to moderate intensity). Put simply, the bigger the proportion of zone-1 training, the smaller the gains in MMP! Instead, MMP values improved the most when the triathletes increased their total training volume and dedicated a bigger proportion of that time performing zone-2 training (exactly the opposite of what the polarized theory predicts).

·        Sprint performance (ie MMP durations of 10 and 30 seconds) was only improved by very-high intensity training (at 12-14 watts/kg). But while this type of incredibly high-intensity training was extremely effective at boosting sprint performance, it did not give any endurance performance benefits – ie for power outputs at longer-duration MMPs.

Figure 1: Changes in MMP scores between season #1/#2 and #2/#3

Implications for amateur endurance athletes

Before we tease out the practical implications of this new research, it’s important to reiterate that these triathletes were at the young end of the spectrum and highly trained. Therefore, the progression they observed may have been more rapid than in an older cohort because their relatively young bodies were still maturing. Despite this however, the underlying physiological principles can still provide a practical roadmap for amateur endurance athletes who are keen to obtain performance improvements over successive seasons.

The first point to emerge is that long-term progression in endurance performance is not amenable to a ‘quick fix’. The significant increase in aerobic power in these athletes seen by the third year was only possible by a gradual and systematic build up total training volume and distance. Yes, the triathletes stepped up their zone-2 training in year three, but that was introduced following the foundations built over the previous two years. If amateurs wish to progress across successive seasons, a yearly increase in total training volume and training time is likely to help, but this needs to be restricted to annual increases of no more than 10% to ensure the skeletal system can adapt without injury, and to reduce the risk of overtraining and burnout.

A second key point is that while the polarized approach to training intensities has a lot going for it, this does NOT meant that zone-2 work become unimportant. In fact, more recent research shows that for amateur athletes, a polarized approach may not be best after all (see this article)^(9,10). The problem is that it’s all too easy for amateur athletes to fall in the ‘polarized trap’ where the large majority of training consists of sessions that are comfortable and without any challenge (junk miles), and where moderate to hard intensities are almost completely avoided. What this research shows is that that for true endurance performance gains that translate into improved race performance, a significant amount of work must be done in zone 2 (moderate to hard intensity) in order to make progress. In practical terms, this means performing structured, sustained tempo work, and interval sessions consisting of 1 to 4-minute intervals, which elevate and sustain heart rates of around 85-90% of maximum heart rate.

Thirdly, and related to the above point, this research observed that the greater the proportion of time spent in zone 1, the less the performance gains. Therefore, while easy recovery rides most definitely have a place in a training program, cyclists in particular need to be aware that spending too much training time coasting, freewheeling, or riding at a leisurely pace can eat into your time where productive fitness-boosting training could be taking place. For example, if your training time is limited to eight hours per week, spending six of those hours doing easy rides with lots of freewheeling or leisurely-paced riding is not going to get you very far.

Finally, this study found that endurance performance and sprint ability are trained completely differently. To improve your sprinting (under 30 seconds) ability, you need to perform sprints at an extremely high intensity in training. But while this is a good aspect of fitness to train – eg to help you outpace your opponent in the final dash to the finish line – don’t kid yourself that it will help with your endurance performance. This means that an athlete aiming to improvement half-marathon or 25-mile time trial performance should focus mainly on the types of training outlined above, not on a program of sprint training! Sprint training should be kept away from your endurance work (and conducted while you’re fresh) with your main focus directed on building your sustainable power outputs over the 10-60 minute time periods.

References

1.       Int. J. Sports Physiol. Perform. 2021;17:22–30

2.       Int. J. Sports Physiol. Perform. 2014;9:732–734

3.       Int. J. Sports Physiol. Perform. 2022;17:1558–1564

4.       Int. J. Sports Physiol. Perform. 2023;18:1141–1144

5.       Int. J. Sports Physiol. Perform. 2006;1:324–335

6.       SportRxiv. 2023 doi: 10.51224/SRXIV.317

7.       Sports. 2020;8:167. doi: 10.3390/sports8120167

8.       J Funct Morphol Kinesiol. 2026 Mar 26;11(2):138

9.       Journal of Sports Science and Medicine (2019) 18, 708-715

10.     Front Physiol. 2020 Nov 12;11:534688. doi: 10.3389/fphys.2020.534688