Evaluation of three methodologies to estimate the VO 2max in people of different ages C. Balderrama a, * , G. Ibarra b , J. De La Riva c , S. López a a Department of Industrial Design, Universidad Autónoma de Ciudad Juárez, Av. del Charro Num. 450 norte, Ciudad Juárez Chihuahua, C.P. 32310, Mexico b Department of Industrial and Manufacturing Engineering, Universidad Autónoma de Ciudad Juárez, Av. del Charro Num. 450 norte, Ciudad Juárez Chihuahua, C.P. 32310, Mexico c Department of Industrial Engineering, InstitutoTecnológico de Ciudad Juárez, Av. Tecnológico 1340, Cd. Juárez Ch., C.P. 32500, Mexico article info Article history: Received 11 December 2007 Accepted 29 June 2010 Keywords: Maximal oxygen consumption Submaximal test Metabolic rate abstract Aging and gender are factors that affect the variation of physical work capacity. The present paper highlights the importance of the metabolism used by ergonomics to establish the appropriate limits of loads at work. This study compares the aerobic capacity of people from 20 to 71 years old split in 5 different groups. The laboratory experiment tested 33 volunteers (19 women and 14 men). A submaximal step test was used to measure the VO 2 using a portable breath by breath metabolic system and a telemetric heart rate monitor. Three methods to estimate the VO 2max were compared: 1) a direct measurement of VO 2 , 2) estimation by heart rate, and 3) a step test method using predetermined charts. Significant difference was encountered among the estimation methods as well as among the age ranges (F 2,92 ¼ 6.43, p < 0.05 y F 4,92 ¼ 7.18, p < 0.05 respectively). The method of direct measurement and the method of predetermined charts were different for the estimation of the VO 2max with a confidence level of 95%. The method of predetermined charts is better adapted for males and people younger than 30 years. The estimation through non invasive heart rate apparatus was a good appraiser of the maximal oxygen consumption considering both genders and all the age groups. Ó 2010 Elsevier Ltd. All rights reserved. 1. Introduction The ISO-8996, 2004 categorizes in three different levels of the determination of metabolic rate in work task; such categorization is derived from different estimation methods. Methods used in the first two levels are based on classification according to either occupation or type of physical activity. The third level, which is based on direct measurements of oxygen consumption (VO 2 ) is considered to be the most accurate. According to Capodaglio et al. (1997), measurement of energy expenditure can be per- formed using four different approaches: 1) direct measurement; 2) indirect calculation using standardized values; 3) estimation derived from the linear relationship between heart rate (HR) and VO 2 while performing at medium-to-high intensity effort under steady state conditions, and 4) using predictive formulas of energy expenditure during elemental components of a complex work cycle. New and easier systems for direct metabolic rate assessment resulted from the advent of computerized applications for data acquisition, the development of rapidly responding gas analyzers, and electronically activated gas volume sensing devices (Wilmore et al., 1976). In a few words, VO 2 is the fraction of oxygen (O 2 ) consumed by the muscle while performing work. Being highly correlated to maximal cardiac output, the assessment of maximal oxygen consumption (VO 2max ) provides a measure of the maximal energy output during aerobic processes and of the functional capacity of the cardiovascular system (Astrand and Rodahl, 2003). The cardiovascular and lung systems capacity of a person restricts the delivery of O 2 to the cells (Pollice et al., 1998). Furthermore, esti- mation VO 2 max is considered the most reliable factor to determine a person’s aerobic capacity, which is useful in the assessment of cardio respiratory fitness and has been widely used in sportsmen, patients, and workers while performing physical tasks. Devices that measure and quantify inhaled and exhaled air constitute a more reliable method to estimate VO 2max . These apparatuses use a sensor that measures the concentration of oxygen in both inhaled and exhaled air while using a mask placed on the subjects face, then estimate the difference usually in units of liters per minute. Portable apparatuses are available that are fairly light weight, resembling an adjustable back pack. These appara- tuses have a reliability level of between 5 and 10% (Galindez, 2007). One example of these portable instruments is Cosmed’s K4b2, * Corresponding author. Tel./fax: þ52 656 199 5567. E-mail address: cesar.balderrama@uacj.mx (C. Balderrama). Contents lists available at ScienceDirect Applied Ergonomics journal homepage: www.elsevier.com/locate/apergo 0003-6870/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.apergo.2010.06.017 Applied Ergonomics 42 (2010) 162e168