Fatigability & Running

Our muscles, tendons, ligaments, and bones adapt both positively and negatively to the level of stress we placed on them. Positive adaptation occurs when the applied stresses are repeated within the mechanical limits of a structure and adequate recovery time are provided between stress applications. On the other hand, negative adaptation (injuries) occurs when a stress is applied beyond the mechanical limits with insufficient recovery time between stress applications. The graph below shows the inverse relationship between Stress (training intensity) and Frequency. If training intensity and frequency are both high, runner will fall into the injury zone (increased likelihood of injuries due to negative adaptation). To identify a precise ratio of stress and frequency is never an easy task; it is a combination of running analysis, biomechanical assessment, and runner’s subjective feedbacks.  

Science is evolving very quickly to help us to understand the root cause of fatiguability and injuries. Traditional 2-dimensional video running analysis requires clumsy camera setup and can only be done on a treadmill. It sure does show the impact of the angles and lines on the video, but It is unable to provide clinicians any insights on resulting forces (ground reaction forces) of the runner- the potential consequences of the forces in the body which lead to injuries. High values of ground reaction force are associated with increased vertical displacement, which has been shown to reduce running economy.

Elite runners experience pain after mileage reaches certain thresholds. In most common scenarios, runners start to experience symptoms at 10k mark. However, their bodies may have already experienced breakdown (fatigue) at 8k mark. It important for us to identify when fatigue happens and fine tune the training and treatment program according.

In recent years, advanced technology such as 3D wearable sensor allows us to measure and analyze leg symmetry, ground reaction force, initial peak acceleration, cadence, and speed. This wireless technology allows runner to conduct their running assessment at their favorite terrains (i.e. sidewalks, trails, or tracks). The flexibility to remotely monitor an athlete allows us to observe the effects of terrain distance on runner’s running style. This provides us with valuable data to understand how fatigue and running environment affect runner’s performance over long distance. These data also allow us to gain valuable insights into a runner’s technique, strengths, and weaknesses, and more importantly to set safe training intensity and frequency for positive adaptation. Human bodies are highly adaptable on running long distance. With the latest technology and biomechanical treatment approach, runners will be able to enjoy running with less pain.

To learn more about how we incorporate 3D wearable sensors to all of our Running Analysis programs and how this can change how you train, run and compete, email me at simon@honsbergerphysio.com!

Written by: Simon Chow, BKin. RMT. CAT(C). R. Kin. 

Orthopedic Rehabilitation
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