Who, why and what?
Intuitively, it would seem that if time is limited, you should be better off doing as much ‘quality’ work as possible with those hours rather than spending 80% at a pace which hardly seems to hurt at all (thus breaking the ‘no pain no gain’ mantra). Yet it has been reported anecdotally for a long time that the best endurance athletes train not only with high volumes, but that they maintain a disciplined program of relatively low intensity training 80% of the time and with high intensity for only about 20%. This contrasts with many amateur endurance athletes, who tend to spend most of their time in the middle ground – hard enough to push themselves out of the comfort zone, but not so hard that they become exhausted.
High intensity means above lactate turn point (VT2), when talking is almost impossible and sustained effort is very uncomfortable. By low intensity, we are referring to intensity below lactate threshold (VT1) – i.e. talking pace.
Researchers from the University of Stirling set out to discover not only which type of training program produced the biggest gains, but also whether a polarised program would be effective at all for athletes who have limited time to train i.e. about 7 hrs per week, implying that the quality portion would be only 1.5hrs per week.
12 trained cyclists each performed two blocks of 6 weeks of either polarised or threshold training, separated by 4 weeks of detraining to wash out the effects. 40 km Time Trial, muscle biopsy and other peak power measures were used to assess the effectiveness of the training.
What did they find?
Both training periods produced gains in performance, but as the table below indicates, the performance changes were all larger for the polarised training program compared to the threshold one. This is especially surprising since the total training time spent in the conventional threshold program (7.4hrs) was 1hr longer per week than on the polarised one.
In summary, comparing the gains form the polarised vs. threshold programs: Peak power output PPO [mean (±SE) change of 8 (±2)% vs. 3 (±1)%, power at lactate threshold LT [9 (±3)% vs. 2 (±4)%, and high-intensity exercise capacity [85 (±14)% vs. 37 (±14)%, P < 0.05].
The authors concluded these main findings:
1. The study confirmed the effectiveness of a polarised training model in well trained endurance athletes. Even when absolute training time spent in zone one is matched (this is the reason for the slightly greater total time per week spent in the threshold program).
2. Zone 1 is sufficient to maximise the increase in mitochondria in type 1 (slow twitch) muscle fibres, mainly used in endurance sports, such as cycling, running and long distance swimming.
3. The time spent in zone 3 may stimulate greater adaptations than the same (or even greater) time spent in zone 2. This would be in line with current thinking on High Intensity Training (HIT) which has been shown to produce significant benefits from short but intense training bouts. In order to sustain these high efforts though, the athlete needs to be well recovered. This limits the number of sessions that can be carried out per week.
Overall, they said that ‘a polarised training model is recommended for trained cyclists wishing to maximally improve performance and physiological adaptation over a short term training period.
Implications for training with Heart Rate Variability (HRV):
1. In a previous blog post it was shown that in trained athletes, HRV recovery following Zone 1 training is almost immediate. This implies that large volumes in this zone are not going to result in HRV decreasing, and in fact over periods of several weeks should cause HRV to rise steadily, pushing baseline values higher.
Studies on runners (e.g. Martin Buchheit) and swimmers (e.g. Chalencon) have shown a clear relation between improvements in HRV and increases in aerobic performance.
2. The high intensity Zone 3 training should cause a dip in HRV if performed correctly. If not, it’s possible that they are not being performed sufficiently intensely. The authors of this paper used interval sets of 4 minutes full-on followed by 2 minutes rest as an example of high intensity training that had been effective at producing performance gains in cyclists that were already well trained.
If we take the example of the 7 hours per week total then over 20 of these 4 min intervals have to be performed, probably spread over 2 or 3 sessions. Needless to say that if HRV is back to or above baseline, these sessions will be easier to perform to the required intensity than if you try to do them tired!
As usual, we would be interested to hear from ithlete users who have personal experience to either back up or dispute these findings.
To read the research paper
Six weeks of a polarized training-intensity distribution leads to greater physiological and performance adaptations than a threshold model in trained cyclists.