Mark Sprowls | Biodesign Center for Bioelectronics and Biosensors

Physical fitness assessments provide immense value to athletes in both terms of direct sport practice by tracking the effectiveness of training and also in research informing coaching decisions for the most effective training regiments. The most common type of physical fitness assessment, a VO2 Max test, works by measurement of a person’s maximal oxygen consumption. Despite accepted validity, the test is cumbersome and consequently limited in application for 2 primary reasons: (1) it requires the usage of wearable equipment that interferes with true free-living exercise patterns (do you run the same wearing a mask with connected tubes?) and therefore accuracy of true free-living VO2 (additionally, wearable equipment significantly increases the risk of SARS-CoV-2 transmission) and (2) many persons cannot safely reach maximal effort levels on a fixed bike (e.g. post-surgery individuals, respiratory illness affected individuals, at-risk populations for heart attacks). As such, our team proposes to use GSI seed funding to investigate the viability of a completely novel physical fitness assessment, the first-ever “contactless physical fitness assessment”, hereby referred to as the “contactless thermodynamic efficiency test” or cTET. cTET is based on an intuitive scientific quantity, the thermodynamic efficiency of a body, which is the ratio of the energy “investment” of a system (the “calories burned”, i.e. energy expenditure [kcal/min]) to the energy output of that system (thermodynamic work done by the person on a treadmill, fixed bike, etc.) obtained under unconstrained physical condition. Our SmartPad system is able to measure energy expenditure with no wearable equipment by measurement of breath gas accumulation rates in the ambient environment of a room with over 90% accuracy (validated in a randomized controlled trial involving 20 subjects and a gold standard reference instrument). The power output can be calculated using the load resistance and speed on a bike or treadmill. The ratio of these two terms, energy exergy expenditure to power output, results in a simple and intuitive cTET value. In this proposal, we propose to test 24 subjects using our contactless physical fitness assessment, using a Modified Bruce Protocol where treadmill speed is ramped up in a stepwise fashion and simultaneous lactic acid blood concentrations are measured after each step. Twenty-four subjects are asked to continuously ramp up their speed and be measured for lactic acid (via fingerprick) until their maximum allowable thermodynamic efficiency value to minimize subject risk for subjects that cannot achieve high effort levels. An analysis of cTET and lactic acid threshold (determined from contactless assessed energy expenditure from SmartPad (kcal/day) vs lactic acid levels) will be performed in connection with age segments and sex, using 12 males and 12 females. The results of this comparison will help the scientific community unveil differences in physical performance for low-intensity exercise. This system and a new method for physical fitness assessment will provide a massive benefit to the sports research community, as high-risk individuals can finally track physical fitness over time after medical intervention, e.g. progression of an injured athlete recovering from surgery.

Last updated April 2021.