This is positioned as the 2nd phase in a three-phase model. This particular training is called Pyramidal and focuses on building up overall fitness and your ability to recover day to day. This method is proven to increase performance gains from base training, but also provide a performance boost for the next training block (polarized third-phase).
This plan varies between 9 and 11 hours of training. It is meant to slowly build time at intensity as opposed to building volume at endurance. It is advised to completed 2-3months of base training before undergoing this type of training to maximize your benefits and reduce risk of injury.
The first meso-cycle begins building up volume at threshold to increase the load of stress the body can handle. Then a 4 day break is given to recover for the second meso-cycle. We call this extensive work.
The second meso-cycle now focuses on building up power at just above threshold. We call this VO2 max power. This will also increase one's maximum aerobic capacity and further pushes up threshold while preparing the body for the final phase of training. The meso-cycle uses varying length intervals to build the spectrum of VO2 power- as there are many energy systems that interchange between 2 and 6mins. We call this intensive work.
Why use this plan? This plan is best used 3months out from racing. It is best paired with high intensity the following block - to enable you to make the most out of your gains before your race!