Thursday, January 6, 2011

Your Training Plan: Periodization (Say what?)

Pe-ri-od-i-za-tion |ˌpi(ə)rēədəˈzā sh ən| noun - refers to the way some portion of time is divided into periods. 

Through a combination of exercise physiology theory and experience with preparation for endurance events, competitive athletes and coaches have learned that their workout schedule works best for them when properly periodized. This post is about the rationale behind the structure of a training plan. In later posts, I may talk more about the specifics of putting a custom plan together.

Assuming there is enough time to prepare for a target race (12-18 weeks or more), a complete training cycle (the "Macrocycle") is generally broken down into four to five smaller periods, called "Mesocycles," which are then further broken into "Microcycles." The purpose is to distribute the different types of workouts among the Microcycles and Mesocycles, so that workout intensity can build and taper optimally without overtraining and/or undue risk of injury.

Training schemes I have seen involve 3 to 4 periods, referred to usually as "phases" or "mesocycles" leading up to the target event, then some include a recovery phase for after the target event.

The pre-event mesocycles invariably include a greater proportion of "endurance" work to start, and then an increase in proportion of speed work (intervals) and threshold (tempo) workouts, followed by an increase in the volume of speed and threshold work consistent with the distance of the target race, and finally tapers by decreasing total running volume, while increasing the proportion of training volume dedicated to higher-intensity work (example: Table 1).

Table 1. Pfitzinger & Douglas 2001 Advanced Marathoning training system. Mesocycles in a marathon training macrocycle.

Mesocycle        Training Emphasis
        1                Endurance
        2                Lactate Threshold (stamina) and Endurance
        3                Race Specific Training
        4                Taper and Race
        5                Recovery

This structure isn't arbitrary. As observed at the start of this post, the logic  is derived both from the experiences of athletes and coaches, as well as a working understanding of exercise physiology. There is a very good reason to do endurance work throughout the entire macrocycle, for example. The useful changes that result in our hard and soft tissues and circulatory systems that result from endurance training take time. They involves a building of strength and resilience in bones and cartilage, ligaments, tendons and muscles, increasing the vascularization of muscle tissues that allows for better oxygen delivery and increasing in the cellular fat-burning machinery that allows us to maintain aerobic activities for long periods of time. Of all the changes that occur in our tissues during training, these are the ones that take the longest time, so it's important to do endurance work throughout a training macrocycle to build and maintain aerobic endurance.

Whereas aerobic running increases aerobic endurance, speed work, or VO2 Max training (interval training) is useful for increasing aerobic capacity. That is, it builds strength and improves metabolic efficiency by stimulating further increases in the cellular machinery in our muscles that is required for aerobic metabolism. This basically means that it improves the speed we can run aerobically. When and how much VO2 Max training is emphasized can be related to the target race distance. If the target race is a relatively short long distance race, like 3-10K, your plan might include speed work that increases throughout the first three mesocycles of the training macrocycle. If your race is a marathon, you might not gain as much benefit from it, so the overall proportion of speed work might be lower, however.

Although aerobic endurance and capacity are important for being able to go the distance, the greatest limitation in our performance during a race is the fastest pace we can maintain without the build-up of lactic acid in our muscles tissues that is indicative of the acidosis that inhibits muscle contraction and forces us ultimately to stop and rest. This pace is commonly called out "Lactate Threshold" pace. Fortunately, we can improve our lactate threshold relatively quickly, because most of the machinery required is all at the cellular level. To accomplish this we need our muscles to be able to process the byproducts of anaerobic metabolism more quickly and build a greater tolerance in our muscle tissues for acidosis. No major growth or reorganization of muscle tissue is required for this. The body can build the tiny machinery needed in muscle cells relatively quickly. So, while it's important to include tempo or threshold training in the macrocycle if we want to perform at our peak on race day, we don't need to emphasize this kind of work over the entire macrocycle. As a result, training plans usually start with some modest tempo work, and increase the length of tempo workouts gradually throughout the the third mesocycle.

Cellular machinery, which we build with speed and tempo work is not only relatively quick to develop when we challenge our muscles appropriately, it is also quick to dissolve. Our bodies don't like to maintain a lot of unused machinery. It's why we lose condition when we stop working out. the first thing distance runners lose is their speed over distances (aerobic capacity and lactate threshold), followed a little later by losses in aerobic endurance.

Speed training, not to be confused with VO2 Max training, involves short sprints or strides. Primarily, this type of work is intended to improve strength, neuromuscular coordination, and thus form and turnover. The benefits of speed training are real, but subtle. Training plans usually maintain a relatively little of this kind of work overall, and keep it relatively constant (a maintenance activity).  Since it is done at almost maximum intensity, it can be overdone and result in soreness, fatigue, and injury that prevents endurance and stamina training from being as fruitful.

The steps in a training macrocycle aren't all that different from the steps of sharpening a steel blank into a sharpened blade. First you have to make it thin enough to function reliably as a blade (endurance), then you need to bevel the edge to make it thin enough to hold and edge (stamina), then you need to hone the edge until until it's sharp (race-specific), but then some amount of minor strafing and touchup may be needed for it to make the cut smoothly (taper). It's not a perfect analogy, but it's close enough.

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