The magnitude of the resulting voltage is directly related to the extension of the deformation. Accelerometers are electronic motion sensors with a major property of evoking a charge when deformed in a special direction.
Further, field methods could be coupled with the use of accelerometers to provide continuous information on body posture and activity allowing objective assessment of subjects' activity and levels of fitness. 5, 6 Field methods on the other hand are much cheaper than the doubly labelled water method, and are faster to employ compared to both the cycle ergometer and treadmill test because one can handle multiple subjects at a time. The doubly labelled water calorimetry, which gives a direct determination of VO 2max, is time consuming and requires expensive equipment as well as highly trained technicians, and is further impracticable for use with large groups. Methods for these measurements include the use of laboratory based doubly labelled water calorimetry, 4 a cycle ergometer, treadmill test and the now increasingly popular field tests such as the 20 m shuttle run test (SRT). These markers are crucial in assessment of cardio-respiratory fitness (CF). 1 – 3 Various valid techniques for its assessment exist and include measurement of physiological markers of BP, heart rate (HR) and aerobic capacity - percentage of maximal oxygen uptake (VO 2max). Physical fitness (PF) is crucial to health among all age brackets, with benefits such as maintenance of lipid profile, regulation of blood pressure (BP) and control of cardiovascular ailments.