Abstract
This chapter reviews new quantification possibilities for the assessment of physical activity, a variable intimately related to good health. First, a variety of existing instruments are described with regard to their validity and functionality. Then, their applications are analyzed and categorized into two broad branches: sedentary lifestyle prevention and applications in special population segments. The authors’ intention is to make existing possibilities for assessment of physical activity known to researchers and public health professionals, as it is important for the achievement and promotion of active and healthy lifestyles in the population.
TopTechnological investigation has been innovating and implementing new physical activity registration systems for many years. The pulsometer and portable metabolic units have, without a doubt, revolutionized the ability to study physiological parameters, sport, and physical training. However, these instruments, in spite of their objectivity, are difficult to apply and manage in large samples. Moreover, it turns out to be very difficult to document physical activity without interruption over a multiple-day period, which is what really interests us when attempting to quantify lifestyles. For this reason accelerometers came onto the market in the early 1980’s and continue to be innovated to better achieve this outcome. As Puyau et al. indicate (2002), activity monitors were developed in response to the lack of reliability of self-report measures, the intrusiveness of direct observation, and the complexity of heart rate monitoring. With the advent of small accelerometer-based activity monitors, the ability to monitor personal activity has improved greatly, both quantitatively and qualitatively.
Key Terms in this Chapter
Energy Expenditure: The amount of energy used by the body at any point of time... at work or at rest. It is usually expressed in terms of kilocalories per minute (kcal/min) or in terms of the amount of oxygen used (liters of O2).
Accelerometer: An accelerometer is a device that registers physical activity via body movement (acceleration) produced during a limited period of time.
Calibration: Related to accelerometers, calibration object is to determine the relationship between raw accelerometer output (counts) and actual levels of physical activity.
Epoch: An epoch is the time period over which accelerometer counts are averaged.
Portable Metabolic Unit: A portable metabolic unit is an instrument to assess oxygen consumption in subjects, when they are performing their true exercise outside of the laboratory.
Counts: counts are the summation of the measured accelerations by an accelerometer, during a certain period of time.
Cut-Off Points: Related to accelerometers, the cut-off points are different values defining energy expenditure levels.