| Keywords |
accelerometer ; exercise intensity ; sex ; energy expenditure ; correlations |
| Abstract |
Physical activity provides various physiological and health promotional benefits. In promoting and monitoring physical activity, accelerometers are often employed. But the algorithm installed within the devices has not been throughly examined whether it reflects human activities sensitively. Currently introduced two accelerometers, Actical and Life Sense, were selected and the values obtained from these two devices and indirectly calorimetry (IC) were compared by sex and exercise intensity. Fifty nine young healthy adults (30 men, 28.3±4.2 yrs, 178.3±4.6 cm, 79.8±10.8 kg, 25.7±3.5 kg·m?2; 29 women, 27.7±5.1 yrs, 161.7±5.0 cm, 59.7±6.5 kg, 22.8±2.2 kg·m-2) participated in the study. They exercised on a treadmill at 6 different speed consecutively such as 3, 5, 7, 9, 10, 11 km·h-1 for men and 2, 4, 6, 8, 9, 10 km·h-1 for women. At each speed, they walked or ran for 5 min and rested 1 min before the next speed. During the exercise, they wore LS and Actical on their waistline. Also EE was measured using a metabolic measurement system. EE for men was 4.53±0.79, 6.17±0.96, 11.03±2.16, 14.80±2.25, 15.75±2.11, and 16.86±2.17 kcal·min?1 at 3, 5, 7, 9, 10, and 11 km·h?1 and EE for women was 2.58±0.56, 3.62±0.70, 5.69±1.01, 9.48±1.17, 10.53±1.37, and 11.25±1.43 kcal·min?1 at 2, 4, 6, 8, 9, and 10 km·h?1, respectively. Except at the lowest speed, EE obtained by three modalities showed high correlations. by sex and treadmill speed. According to Bland-Altman analyses, EE of Actical was consistently low compared to IC regardless sex and speed. Compared to IC, Life Sense showed a proportional error in moderate locomotive speed. Based on the results, Actical underestimated EE compared to IC in both man and woman over the course of treadmill speed. In particular, the two accelerometers do not appear to reflect actual EE sensitivity at low activity level. The sex differences in sensitivity may exist in high exercise intensity. |