Interactions between training sessions – Part II: Timing of adaptations

In the first instalment of this series, I talked a bit about the importance of modeling the response to training load, fatigue and recovery, to the correct prescription of training. Today I will talk a bit about the temporal evolution of fatigue/recovery, which will influence adaptation to training.

After each training session, fatigue sets in and performance is diminuished. The recovery process also starts as performance will slowly increase towards a higher level. The recovery phase allows for several biological adaptations to occur:

- normalization of the cell environment.
- recovery of neuromuscular stimulation processes
- concentration and activity of enzymes and hormones will be restored
- energy sources are replenished

As these processes evolve, adaptation to the stimulus (training session) is marked by an increase of performance. This is usually called the principle of super-compensation.

As fatigue is directly related to performance, and performance related to adaptation to training, then one way of monitoring adaptation would be to measure performance. However, measuring performance has its own impact on the training process. Therefore, a non-intrusive way of monitoring adaptation to training is the qualitative monitoring of an athlete’s level of fatigue.

In order for adaptation to training to occur, some requiments need to be met:
- A healthy body: Inflammation, infection, mental stress, etc strongly reduce the possibility for adaptation.
- Adequate training load: This is the most crucial aspect of successful training.
- Enough recovery: rest or regenerative workouts will make up most of an athlete’s time.

The timing for adaptation is the deciding factor when planning training on the short-term (1-7 days). For a healthy athlete, this timing depends on several factors:

- the type and duration of the workout
- the conditioning level of the athlete
- the recovery level of the athlete

If an athlete has a high conditioning level and/or is well rested, time for adaptation will be shorter. On the other hand, mental stress or lack of rest will slow down the process necessary to achieve super-compensation. The differences in timing for adaptation are due to various biological regeneration processes that take place during the recovery phase. The replenishment of creatine phosphate will take only a few seconds to a couple of minutes to return to normal levels, but the glycogen-reloading process in the muscle may last 24 hours; in some cases, it may last even longer. The production of new enzymes (proteins) may also take hours, sometimes even days, to complete (Olbrecht 2000).

According to Olbrecht (2000), the time for different types of training to reach the maximal supercompensation are:

- Extensive Endurance: 8 to 12 hours.
- Intensive Endurance: 24 to 30 hours.
- Sprints/Short sets: 30 to 40 hours.
- Extensive Anaerobic Training: 36 to 48 hours.
- Extensive Strength Training: 40 to 60 hours.
- Intensive Anaerobic Training: 36 to 48 hours.
- Intensive/Strength Training/Competition: 48-72 hours.

When designing a training plan, the time intervals between consecutive training sessions should be selected in order to respect the timings of adaptation to training for the different training methods used. Working out these timings is possibly the most difficult part of planning and it is the "art" part of coaching.

In the last part of this series, I will talk a bit about interactions between swim, bike and run training sessions.


Olbrecht, J., (2000), The Science of Winning – Planning, Periodizing and Optimizing Swim Training.