Food for thought on structuring microcycles (weekly training structure):
In a study examining training load and overtraining, Bruin et al. (1994) trained 7 male athletes on a treadmill for 272 days straight. Prior to testing and training, the athletes were screened for their ability to run on a treadmill, and all athletes followed a low intensity three month training program of five 30-45min sessions of walking and running per week.
Training lasted 272 days, 7 days a week, alternating one day of interval training, and one day of light endurance training. Training intensities were set by heart rate: v140, v180 and v200, where "v" indicates the velocity which elicited the target heart rate of 140, 180 or 200 beats per minute. Interval training began with 4x(3'@v200 with 3'@v140) and increased to 6x(3'@v200 with 3'@v140) + 6x(0:60" sprint with 4min recovery). During all interval training, the treadmill was set at a 6.25% incline. Training intensities/velocities were continuously revised based on frequent testing (every 4 weeks until day 187, and then every 2 weeks thereafter).
The alternating endurance days consisted of 20mins of v140 from day 0 to day 260.
For the first 260 days, all athletes were able to handle the increasing training load, without injury, illness, or reduced performance.
Before any of you try this at home, I should probably mention that the athletes were horses.
Noting that none of the horses were demonstrating the expected signs of overtraining, the researchers changed the training program on day 261. Instead of further increasing the training load of the interval sessions, the authors increased the training load of the endurance sessions (ie. the rest days got harder). Specifically, they increased the intensity from v140 to v180, but kept the duration (20mins) the same.
Ten days later, "the training was discontinued because the horses showed progressive and marked irritability and increased difficulty in completing the training sessions. In addition, they did not consume the usual amount of food provided."
Horses who were able to adapt to a progressively harder training load over the course of 260 consecutive days of training, failed after only 10 days of increased training intensity on the easy days.
Interesting. More soon.
Bruin, G., H. Kuipers, H. A. Keizer, and G. J. Vandervuisse. Adaptation and overtraining in horses subjected to increasing training loads. Journal of Applied Physiology, 76:1908-1913, 1994. Abstract.