What is Impact Load?
Impact Load is the sum of the intensities created from every impact measured at the lower limbs during an IMU Step session. Total Impact Load is the sum of the left and right limb Impact Loads.
Impact Load is comparable within and between sessions, allowing you to examine the loading outcomes of specific activities, drills, sessions, and training days – and their respective effects on an athlete’s workload.
As an example, if an athlete took 500 steps at 1g, 1000 steps at 2g and 2000 steps at 3g, the Impact Load calculation would look like so:
Impact Load = (500 x 1g) + (1000 x 2g) + (2000 x 3g) = 8500 (8.5k)
How do I Interpret Impact Load?
Impact Load is directly proportional to number of impacts and intensity of impacts. Impact Load will increase with more impacts as well as with higher intensity impacts.
This makes Impact Load useful as a cumulative lower limb load metric. If you want to look at the total load sustained from a session or drill, Impact Load is a good indicator for this.
To inspect the intensity of an activity or drill, we suggest using Impact Load per minute from the first graph in the Session Breakdown section. This is the rate at which Impact Load is accumulated.
Percentage of high intensity steps and number of high intensity steps are also good indicators of session intensity.
Note that a level of session intensity will carry different weight for different athletes depending on their capabilities and circumstances.
Why use Impact Load?
Including Impact Load in the IMU Step suite of metrics adds a new perspective to IMU Step lower limb load insights.
We know that the loading outcomes of a session are dependent on the number of steps taken as well as the intensity of those steps. Impact Load is a simple, easy to use metric that can be used to compare different loading outcomes between left and right limbs, drills, activities, sessions, and athletes.
Impact Load is a calculated and defined metric based on known athlete motion, in this case steps, making it relevant to the actual movements conducted by the athlete and represents the specific loading outcomes of those movements.
Detecting specific events such as steps via sensors on each inner ankle makes Impact Load non-arbitrary, and directly related to the way an athlete’s legs land on the ground. This provides a relevant, objective, comparable view on each limb in any training session.
What is Total Impact Load?
Total Impact Load combines the Impact Load from both the left and right legs.
It is the total Impact Load accumulated in both the lower limbs for a whole session, day, or week.
You can look at the Total Impact Load for a whole day or week in the All Sessions Summary or All Sessions Asymmetry sections of the Dashboard.
How is Impact Load different to Bone Stimulus?
Bone Stimulus is a scientific model interpreting the tibia’s response to cyclic mechanical loading. This response is non-linear, and changes over time as the bone experiences more impacts.
Bone Stimulus is most relevant for answering the following questions:
- How does an injured bone’s response compare to a non-injured bone
- When has the bone received enough stimulus for remodeling?
You can read more about Bone Stimulus on our website here.
Impact Load is a linear sum of all the impacts measured, allowing you to measure and compare loading outcomes within or between sessions. This makes Impact Load a versatile, comparable, and useful metric for directly comparing activities that may happen at the start vs. the end of a session e.g. different drills, small sided games, various running intensities.
This allows you to ask and answer questions such as:
- Between Drill A and Drill B, which was of higher load on my athlete?
- What was the Total Impact Load sustained by my athlete today, and how does that compare to other training days?
- There is a difference in Impact Load between the left and right limbs for my athlete – is this an expected representation of their current form? If so, how is this reflected in the Asymmetry Graph?
Impact Load is NOT a representation of the body’s response to load but is simply a direct measure of cumulative impacts entering the body over time.
Learn More
If you want to know how you can use Impact Load within your load monitoring system, check out our latest article, 5 Ways to Use Impact Load.
