Morelli Andrea, Sassi Aldo, Rampinini Ermanno, Giglio Paolo, Impellizzeri Franco

The portable, indirect calorimeters can be used to estimate the energy expenditure (EE) during occupational activities. The precise quantification of the daily EE is necessary to investigate the amount of physical activity required to assess health outcomes. Therefore, it is very important to determine the absolute EE of occupational activities. With this aim, it is possible to quantify the EE of occupational activities using the “Compendium of the Physical Activities”, (Ainsworth et al., 1993), which includes the METs of several physical activities. The aim of this study was to collect data about the EE of an occupational activity which had not been included in the compendium: tile laying.3 floor-layers were involved in the study (age 36 ± 5, height 174 ± 5 cm, weight 87 ± 3, BMI 28.6 ± 2.3, estimated VO2max 32.4 ± 0.8 ml•kg-1•min-1). Each subject randomly carried out 2 trials (completing 12.5 m2), by simulating 2 typical work activities of this occupational activity: laying cement and laying adhesive. The activity investigated was divided into 2 phases:1)construction of a cement base (mixing the cement, transporting the cement with a wheelbarrow and, finally, leveling the cement);2) tile laying. Respiratory gas were measured using a portable metabolic cart.The EE required to complete one square meter of cement base (71.1 ± 12.7 kJ•m-2, or 17.4 ± 3.1 kcal•m-2) and of tile laying (32.3 ± 12.5 kJ• m-2, or 7.9 ± 3.1 kcal•m-2) were also calculated. The EE of “construction of cement” phase was 6.1 ± 0.7 MET, or 38.0 ± 4.2 kJ•min-1, or 9.3 ± 1.0 kcal•min-1, with a final [La] of 2.9 ± 0.6 mmol•l-1. The EE of “tile laying” phase was 5.6 ± 0.8MET, or 35.1 ± 5.0kJ•min-1, or 8.6 ± 1.2 kcal•min-1, with a final lactate of 2.9 ± 0.6 mmol•l-1.This occupational activity can be classified as Very Heavy (EE > 31.4 KJ•min-1) or Heavy (MET between 4.8 and 7.1) (Bouchard and Shepard, 1994). Considering that each floor-layer usually completes a surface area of about 35 m2•day-1, the daily EE for this occupational activity (including both the construction of a cement base and tile laying) ranges from 3619 kJ, or 887 kcal. However, as the whole tile-laying procedure is sometimes carried out by two or more workers, those who only constructed the cement base (50-60 m2•day-1) reach a daily EE of 3555-4266 kJ•day-1, or 870-1044 kcal•day-1. In conclusion, this study provides useful information for a more precise determination of the total daily physical activity of floor-layers.