Let's face it Marathons (and most endurance events over 2 hours) are tough on the body. Markers of inflammation (C-Reactive Proteins), Cardiac and Muscular Stress (Creatine Kinase), Oxidation are all elevated for days or even weeks after a marathon. The general rule of thumb for recovery is one day per mile run which means, for a marathon, 26 days. Very few people who run marathons seem to have the patience for this type of break.
Let's digress for a moment. One nutrition concept that is gaining a lot more popularity at the moment is the use of a fast day where no calories are consumed - only water, black tea/coffee. The benefits of fasting have been well shown in studies.
- Reduction in Inflammation (C-Reative Proteins)
- Reduction in Cardiac Stress Marker (Creatine Kinase)
- Reduction in Oxidation Markers.
If we go back and re-read the first paragraph you will note that what has been proven to be decreased through the use of a Fast Day are exactly the same markers that are raised after the marathon.
Which means a specifically timed fast day after a marathon or Ironman can rapidly accelerate the recovery process.
It is important immediately after such an event to take in sufficient good carbs/fats to reload glycogen stores and also complete proteins for the rebuilding of muscle (this can also be supplemented with Branch Chain Amino Acids). A study from the Australian Institute of Sport showed that glycogen storage typically peaked after 24 hours which means immediately after the marathon and the following day load up with good quality carbohydrates, fats and proteins. A higher level of fat will increase the production of leptin (which manages the 'fullness' feeling) negating the hunger feeling on the fast day.
Even if you are not recovery from a marathon a fast day can be of benefit.