Wheels, water and poles: load cells and Paralympics classifications
Watching the Paris Paralympic coverage, it struck us how diverse the level of impairment could be within a single event. So, how does the Paralympic classification system work, and what role do load cells play?
According to the Paralympics website:
“The Paralympic system of classification intends to guarantee fair competition between all athletes. Athletes go through the classification process before taking part in a Paralympic competition, during which they are assessed and allocated a sport class in accordance with the degree and nature of their eligible impairments.
This classification is carried out by a panel of medical and technical experts responsible for evaluating the impact of their impairment(s) on specific tasks and activities fundamental to the sport and the athlete’s sporting performance.”
Wheelchair rugby
If like us you’ve been enjoying the fast and furious sport of wheelchair rugby you’ll know what a physically demanding sport it must be. As the World Wheelchair Rugby Federation (IWRF) website says:
“Wheelchair rugby is not your typical Para sport. It’s a high impact, competitive, contact sport that is not for the faint of heart.”
A team from the University of Padua in Italy studied sixteen elite players of the Italian wheelchair rugby team to try and correlate individual performance test with the IWRF classification.
Each athlete performed a test to the point of exhaustion:
“Tests were all performed on a non-motorized ergometer developed by the University of Padova for wheelchair users. Briefly, the bench is composed of two independent drums connected by a shaft and can simulate the equivalent linear inertia of the wheelchair-athlete system detected in the court. Two electromechanical brakes restrained by two load cells are employed to increment the load.”
The team concluded that the results of “Only the most significant anaerobic and sport-specific performance parameters” should be included in the classification process to make it more effective.
Para swimming
It was a swimming medal final early in this year’s Paralympics that prompted our thoughts about classification and the division of athletes into sports classes. An article in Aspetar Sports Medicine Journal explained that:
“The use of different sport classes in World Para Swimming is crucial to ensure a fair and equitable field of play, considering the diversity of impairment types and severity in the sport.”
The important role of load cells is to provide reliable evidence for each athlete to ensure they are placed in the fairest class.
“The development of instrumented strength tests using relatively inexpensive load cell technology has also represented significant progress towards the development of evidence-based classification in para athletes.”
Load cells are also used in passive drag assessments. Para swimmers with low passive drag may have a performance advantage. The article explains how an in-line waterproof load cells was used in a electro-mechanical towing device to “measure para swimmers’ drag at a known towing velocity.” Equally, by attaching an in-line load cell to a fixed point, assessments can include measurements from fully tethered swimming trials.
Seated shot put pole forces
Paralympic Seated Shot Put involving athletes throwing the shot from a special seat frame with the aid of a holding pole. Here’s how they do it:
A research team from the University of Adelaide, Australia realised that in competition, athletes used the pole in a variety of ways. So they looked at two ways of measuring pole forces. For the first method of testing, load sensing, the team needed to address some specific challenges with the load cell itself:
“The primary force measurement is achieved using a 3- component load cell and pivot joint at the base of the pole with an overhanging knife-edge support arrangement … The cantilever support configuration was considered due to the scarcity of load cells that could measure the bending moment directly at the magnitude expected (estimated based on 0.5-1.0× bodyweight), i.e., the pivot-joint results in zero moment at the load cell.”
Now the team have these unique measurements, they will interpret the data to answer key questions raised, such as:
- Do higher pole forces benefit an athlete?
- If so, what’s the effect of different pole positions and grips?
Want to check out these and other Paralympic sports?
Schedules for all Paralympic events can be found here.
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