How to Train (Part 2)

How to Train (Part 2)

Ok so I was going to do a two-part series on How to Train, I’m now making it a three-part series. Why? Because I can…and because I didn’t realise quite how much there is to write about in this series! So apologies for that…and please keep reading. In part two of this How to Train series, I’ll introduce four different running training models and thereafter I will evaluate the scientific evidence behind them. Hopefully you will be able to better understand what type of training model you should be using going forward. On a side note, be sure to check out Part 1 before going forward in this post.


Let’s start out with a concession. Optimal volume and training-intensity distributions among runners is an elusive matter. In my opinion, anyone who tells you this type of training is better than that type is talking tripe. I am a firm believer that variation in training is the number one most critical factor in improving performance (a topic I will discuss at a later stage), and therefore the key is not in what model of training you are using, but when to use which model and whether or not you are implementing it correctly.


I will be using and discussing four main training models over the following few blog posts to be consistent with terminology currently used in research (Haff & Triplett, 2016) (Hydren & Cohen, 2015) (Stoggl & Splerich, 2015). These models are; Polarized training (PT), Threshold training (THR), High volume training (HVT), and High-intensity interval training (HIIT). To help you understand the training intensity distribution of all four models better, see Table 1 below adapted from Hydren & Cohen (2015):


Table 1: Endurance Training Models and Their Training Time at Varying Intensities

Training Model % Training Time at

RPE ⥶13

% Training Time at RPE 14 – 16 % Training Time at RPE ⥸ 17
Polarized Training 75 – 80 0 – 10 15 – 20
Threshold Training 50 – 60 40 – 60 0
High Volume Training 100 0 0
High-Intensity Interval Training 50 0 50


The four models above are characterized by the amount of time spent in different intensity zones. For the sake of ease of understanding, I have chosen to use Rating of Perceived Exertion (RPE) to explain the amount of time spent in different intensity zones. For those of you familiar with Borg’s RPE scale from 6 (rest) to 20 (maximum exertion), you will know that an RPE score of ⥶13 is considered light intensity exercise, whereas and RPE of 14 – 16 is considered hard or race pace and a score of ⥸17 is considered very hard (Hydren & Cohen, 2015). For the remainder of this post I will refer to these intensity zones as zone 1, 2, and 3 respectively. It is extremely important to distinguish between these training zones and Joe Friel’s training zones, so take a look at table 2 below to help better understand the matter.


Table 2: Agreement Between RPE Training Zones, Joe Friel’s Training Zones and Type of Session

Joe Friel’s Zones Training Zone 1 (RPE ⥶13) Training Zone 2 (RPE 14 – 16) Training Zone 3 (RPE ⥸ 17)
1 Long, Slow Distance
2 Long, Slow Distance
3 Steady Tempo
4 Intermittent Tempo
5a, b, c Intervals & HIIT

*Fartlek training can fit into any of the above categories owing to its varying training intensities.


For those of you who have read Part 1 of this series, you might be wondering about now, “where does part 1 fit into what’s been covered so far here?”. In part 1 I introduced different types of training sessions (individual sessions that you might do on any given training day), and which training zone (according to Joe Friel’s training zones, not the three zones mentioned above) each respective session falls into. In this blog I am now addressing the ratio of time spent in three specific intensity zones (light, hard, very hard). In other words, the amount of any individual training sessions you do in a given training week will determine the training model that you are currently using – you might just not know what that is yet. For the remainder of this post I’m going to focus on one of my favourite training models: Polarized Training or PT.


PT is a training model used by all types of endurance athletes – including runners – which requires the athlete to spend the vast majority of their weekly training time at low intensity/pace and the remainder of the weekly training time at very hard intensity/pace (see table 1 above). In other words, runners would spend the large majority of their weekly training doing long, slow distance training (see part 1) which is in Joe Friel’s zone 1 and 2 and a small portion of training time doing interval training which is Joe Friel’s zone 4 and 5, but very little to no tempo training or Joe Friel’s zone 3. Typically, when doing any type of training, high-intensity training sessions (>17) are separated by one or more very light training sessions (Hydren & Cohen, 2015).


Researchers at the department of sport science and kinesiology – University of Salzburg state that elite endurance athletes tend to train at 80% low intensity and 20% high intensity (weekly mileage), and typically that includes at least two HIIT sessions per week (Stoggl and Sperlich 2015). They go on further to state that after comprehensive analysis of the four training models above, PT appears to be the best type of training model in terms of improvement in several key components of endurance performance, namely; peak oxygen uptake (VO2 Peak), velocity at lactate threshold, work economy, peak running velocity, and time to exhaustion.


The reason there are ranges in percentage training time at particular intensities given in Table 1 above, is because exactly how much training done in each intensity zone is dependent on what period of the training calendar you find yourself in. Typically, high-level endurance athletes tend to spend; 84 – 95%, 2 – 11%, and 2 – 9% of their training time in zones 1, 2 and, 3 respectively during the preparation period of their seasons (Stoggl & Sperlich, 2015). This is a relatively larger portion of time spent in training zone 1 in comparison to training intensity distribution before the competition phase of the season. In the pre-competition phase, runners tend to shift to a more pronounced polarized training intensity distribution with 75 – 78%, 4 – 10%, and 15-20% of training spent in zones 1, 2, and 3 respectively (Stoggl & Sperlich, 2015). There is an apparent shift towards a greater portion of training time spent in zone 3 during this phase of the season. It is currently unclear exactly how training intensity distribution is split during competition phase for high-level endurance athletes owing to the difficulty of recording this information during this phase (Stoggl & Sperlich, 2015).


While many international, Olympic, and high-level athletes make use of PT as their preferred training model (Stoggl & Sperlich) (Hydren & Cohen, 2015), this is not reason enough to state unequivocally that PT is the best training model. However, several experimental studies have been conducted in the past decade which provide such evidence. In Table 3 below, I have summarized the key aspects of these studies.


Table 3: Summary of Recent Experimental Research on PT

Author Endurance Sport Level of Athlete Research Question Findings
Neal et al. (2013) Cycling Well trained Does PT or THR training improve physiological adaptations more? Peak Power Output (PPO), time to exhaustion (TTE) & lactate threshold (LT) significantly improved in PT vs THR.
Munoz et al. (2014) Running Recreational Does PT improve performance in recreational runners in comparison to THR training? Both PT and THR training improves 10km time, but more so in PT training.
Stoggl & Splerich (2014) Runners, cyclists, triathletes, cross-country skiers Well trained Which training model (PT, THR, HVT, HIIT) provides the greatest response on key endurance components? PPO/ Peak Velocity Output (PVO), TTE, and VO2 Peak all improved after PT training. Velocity/power at LT increased after both PT and THR.   


Now another warning, the next three paragraphs have some serious scientific content in them, and I have included them in this post for those who want to know why and how PT works (i.e. what is the mechanism behind it). If you are not interested in that, skip to the last paragraph which is an important summary.


In the study by Neal et al. (2013), several possible reasons were given for the improved training response in PT vs THR training. Neal et al. (2013) suggest that improvements in PPO, TTE and LT come from improved mitochondrial density and a resulting improvement in production of ATP in PT compared to THR. Athletes with an already high mitochondrial energy production capacity may achieve relative improvement in PPO, TTE and LT owing to the HIIT (zone 3) done in PT compared to moderate intensities (zone 2), done in THR training. The ability of athletes to transport and oxidate lactate (use lactate as a source of energy) is cited as one of the chief reasons for the improved LT, TTE and PPO following PT compared to THR training (Neal et al. 2013). This improved use of lactate and other exercise substrates helps maintain pH within cells and delay the onset of fatigue during high-intensity tasks (Neal et al. 2013). The ability to maintain cellular pH, improved capillarity (ability of your cells to use oxygen and create energy), and other cardiovascular adaptations are further contributing factors to improved LT, TTE and PPO. These adaptations are notably stimulated in zone 3 training compared to zone 2 training – another potential reason why PT may improve training adaptation compared to THR. The final mechanism suggested by Neal et al. (2013) as to why PT improved PPO, LT, and TTE in trained cyclists compared to THR training is due to relative recovery. Recovering from zone 1 training takes quicker than recovering from zone 2 and zone 3 training. However, recovery from zone 2 training has no difference to recovery required after zone 3 training (Neal et al. 2013). Therefore it makes sense that if there are larger physiological adaptations in type 3 training compared to type 2, and the recovery requirements are similar, that type 3 (PT) training is more effective than type 2 (THR) training.


In research on recreational runners, Munoz et al. (2014) found that runners taking part in PT training significantly improved their 10km time trial by approximately 5% or 119 seconds. This is in agreement with Stoggl and Splerich (2015), who state that longitudinal research suggests that PT has a positive effect on the performance of endurance athletes. Both groups of researchers are in agreement that PT is not the only way to train, however, and that THR type training is also an adequate method of training for endurance athletes yielding similar improvements in performance – for example, 3.5% or 84 seconds for recreational runners in their respective 10km time trial (Munoz et al. 2014).


In the study by Stoggl and Splerich (2014), it is suggested that PT is the superior training model for endurance athletes. While THR and PT resulted in increased velocity at LT (running at high intensity), PT resulted in superior improvement in VO2 Peak (highest VO2 value obtained on a running test), TTE, and PPO/PVO. PT athletes in this study did approximately 68% of their training in zone 1, 6% in zone 2, and 26% in zone 3 over 9 weeks for the PT model. The authors suggest that training in zone 1 (HVT) improves metabolic and hemodynamic (dynamics of blood flow) adaptations, VO2 Peak and ability to utilize fat and glucose for energy. However, there comes a point where VO2 Peak and performance will plateau, in which case HIIT sessions are needed to stimulate further improvements in endurance performance – in other words – PT (Stoggl & Splerich, 2014). Adding HIIT training to your training program will result in increased stroke volume (amount of blood pumped by your heart) and total blood volume, as well as your ability to use oxygen, and enhanced aerobic (oxygen dependent) and anaerobic (not-dependent on oxygen) energy systems. The improvements in these systems are attributed to increased mitochondrial biogenesis/density and oxidative capacity which is in agreement with the findings of Neal et al. (2013).   


In summary, a polarized training model is a great way of training, regardless of your gender, age, sport, or competition level (Hydren & Cohen, 2015). The tricky part is actually sticking to a training program that does <10% exercise time in zone 2. Runners seeking to use PT should make use of heart rate monitors, pace, and ratings of perceived exertion to help gauge whether they are in zone 2 or not. Hydren and Cohen (2015) recommend that during competition season, the natural tendency of races to take place in zone 2, means PT should be used during training to prevent too much relative training time taking place in zone 2. Furthermore, switching the training model from time to time may prove fruitful for runners and endurance athletes (i.e. not only using PT throughout the year) (Stoggl & Splerich, 2015).




Haff, G. G., and Triplett, N. T. (2016). Essentials of strength training and conditioning. Human Kinetics. 4(20) p. 559-581.


Hydren, J. R., and Cohen, B. S. (2015). Current scientific evidence for a polarized cardiovascular endurance training model. Journal of Strength and Conditioning Research. 29(12) p. 3523-3530.


Munoz, I., Seiler, S., Bautista, J., et al. (2014). Does polarized training improve performance in recreational runners? International Journal of Sports Physiology and Performance. 9 p. 265-272.


Neal, C. M., Hunter, A. M., Brennan L., et al. (2013). Six weeks of a polarized training-intensity distribution leads to greater physiological and performance adaptations than a threshold model in trained cyclists. Journal of Applied Physiology. 114 p. 461-471.


Stoggl, T., and Splerich, B. (2014). Polarized training has greater impact on key endurance variables than threshold, high intensity, or high volume training. Frontiers in Physiology. 5(33) p. 1-9.
Stoggl, T. L., and Sperlich, B. (2015). The training intensity distribution among well-trained and elite endurance athletes. Frontiers in Physiology. 6(295) p. 1-14.

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