At the recent ASCA conference Kristie-Lee Taylor presented:
Monitoring Neuromuscular Fatigue and Training
Responses using Vertical Jumps
The presentation summarised findings from a series of studies exploring practical methods for monitoring neuromuscular fatigue in the daily training environment.
With the increasing professionalism of sports, the volume and frequency of training required for competitive performances at the elite level have also amplified. Athletes involved in high performance sports programs are required to train meticulously in order to continuously improve or maintain performance across long competitive seasons. The consequence of such high loading is an increased level of fatigue and parallel loss in performance capacity while the body is attempting to re-establish homeostasis. It is well accepted that if exercise periods are too frequent, intense and/or long, with insufficient recovery between sessions, a state of non-functional overreaching or overtraining may occur, prohibiting athletes from reaching their potential during important competitions. Coaches of high performance athletes are therefore interested in methods for determining the optimal workload and recovery needed to induce positive training adaptations, while also avoiding the accumulation of excessive residual fatigue that is responsible for limiting the adaptive response.
The first half of the presentation covered in detail the work done to establish current best practice methods for training monitoring in high performance programs in Australia and New Zealand. The remainder of the presentation focused on attempts to validate such approaches.
The following methodological considerations were examined regarding the use of vertical jumps for monitoring neuromuscular fatigue and associated training responses:
- The magnitude of practically important changes in vertical jump performance for monitoring fatigue.
- Methods for reducing measurement error to improve our ability of detecting small but practically important changes.
- The sensitivity of jump variables in detecting fatigue.
- The mechanisms responsible for reduced jump performance during heavy training.
- The ability to predict non-functional overreaching or overtraining.
The validation work was rigorous and very well designed and executed.
In summing up Kristie was able to make these recommendations:
- Measure performance as frequently as possible after an adequate warm-up.
- Use the average value of a minimum of 4-6 trials of unloaded CMJs.
- Monitor mean power, jump height, peak velocity and/or eccentric displacement as they are most sensitive to fatigue induced by deliberate overreaching.
- Flag important changes in relation to trend line rather than point to point. Moderate to large changes are in the range of 3-6%.
- Calculate trends for different phases of training (e.g. pre-season, comp phase)
- Don’t rely on changes in isometric strength and high force low velocity movements for monitoring fatigue since they are not affected in the same way as high velocity movements – most athletes can maintain this type of performance through high levels of fatigue.
- While mean force is most reliable variable, it barely changes in response to training and is therefore not a good indicator of fatigue or training adaptations.
- Be aware that changes in CMJ performance are not necessarily indicative of peripheral neuromuscular fatigue as previously postulated – central fatigue may also play an important role.
- Further investigations are still needed to develop systems for the early detection of non-functional overreaching and overtraining.
This work was done over a three year period as a major component of Kristie’s PhD. She used GymAware to measure the performance variables mentioned above.