Biomedical subjects

Lana J Nysse

Publications and source records attributed to Lana J Nysse.

4 recordsLinked to original sources

PubMed2005

Laboratory measurement of posture allocation and physical activity in children.

PURPOSE: The purpose of this study was to validate the combined use of inclinometers and accelerometers to measure body posture and movement in children in a laboratory setting. METHODS: We performed two separate experiments. In the first experiment, we tested the hypothesis that four inclinometers (tilt sensors) could be used to capture body posture in children. We observed and recorded body posture in eight healthy children (mean +/- SD; body mass index (BMI), 18 +/- 3 kg x m(-2)) on 2880 occasions and compared these records with the inclinometer data. In the second experiment, the hypothesis was that two inclinometers could be used to determine whether 18 children (BMI, 21 +/- 5 kg x m(-2)) were sedentary. We observed and recorded sedentariness (sitting/lying compared to standing) on 5575 occasions and compared these records with the inclinometer data. In both of these experiments, we also addressed the hypothesis that accelerometer output, when measured at varying velocities, correlated with walking energy expenditure. RESULTS: In experiment 1, body posture was correctly identified in 2880 out of 2880 inclinometer measurements. In experiment 2, sedentary behavior was correctly identified in 5575 out of 5575 occasions. For the entire group, acceleration and body weight correlated well with energy expenditure (r2 = 0.84). CONCLUSION: The inclinometer-accelerometer system that we tested can be used to measure body posture and movement. We can measure sedentary behavior using two inclinometers instead of four inclinometers. This monitoring system may be useful for measuring energy expenditure, body posture, and physical activity in children.

Calorimetry, Indirect↗

PubMed2004

Commercially available pedometers: considerations for accurate step counting.

BACKGROUND: Many commercially available pedometers undercount, especially at slower speeds. We examined the effects of age, obesity, and self-selected walking speed on pedometer accuracy. We also compared the accuracy of piezoelectric and spring-levered pedometers at slow walking speeds. METHODS: Study 1: 259 subjects walked on a motorized treadmill at two self-selected walking speeds. Steps were counted using a spring-levered pedometer. Study 2: 32 subjects walked on a motorized treadmill at slow walking (1.0-2.6 MPH) speeds. Steps were counted using spring-levered and piezoelectric pedometers. RESULTS: Study 1: self-selected walking speed and pedometer accuracy decreased with increasing age, weight, and body mass index (BMI). Accuracy was 71% below 2.0 MPH, 74-91% between 2.0 and 3.0 MPH, and 96% above 3.0 MPH. Decreased accuracy was best predicted by increasing age. Study 2: between 1.8 and 2.0 MPH, the accuracy of the piezoelectric pedometer (>97%) exceeded that of the spring-levered pedometers (52-95%). Even at 1.0 MPH, accuracy of the piezoelectric pedometer (56.4 +/- 33.8%) was superior to the spring-levered pedometers (7-20%). CONCLUSION: Accuracy of all pedometers tested exceeded 96% at speeds 3.0 MPH, but decreased at slower walking speeds. In individuals that naturally ambulate at slower walking speeds (e.g., elderly), we recommend the use of more sensitive (e.g., piezoelectric) pedometers.

Adult↗

PubMed2003

Labor saved, calories lost: the energetic impact of domestic labor-saving devices.

OBJECTIVE: As the prevalence of obesity has increased, so has sedentariness. Progressive sedentariness has been attributed to greater use of labor saving devices, such as washing machines, and less nonexercise walking (e.g., walking to work). However, there is a paucity of data to support this conclusion. In this study, we address the hypothesis that domestic mechanization of daily tasks has resulted in less energy expenditure compared with performing the same tasks manually. RESEARCH METHODS AND PROCEDURES: Energy expenditure was measured in four groups of subjects (122 healthy adult men and women total) from Rochester, Minnesota. Energy expenditure was measured using indirect calorimetry while subjects performed structured tasks such as cleaning dishes and clothes, stair climbing, and work-associated transportation, and these values were compared with the respective mechanized activity. RESULTS: Energy expenditure was significantly greater and numerically substantial when daily domestic tasks were performed without the aid of machines or equipment (clothes washing: 45 +/- 14 vs. 27 +/- 9 kcal/d; dish washing: 80 +/- 28 vs. 54 +/- 19 kcal/d; transportation to work: 83 +/- 17 vs. 25 +/- 3 kcal/d; stair climbing: 11 +/- 7 vs. 3 +/- 1 kcal/d; p < 0.05). The combined impact of domestic mechanization was substantial and equaled 111 kcal/d. DISCUSSION: The magnitude of the energetic impact of the mechanized tasks we studied was sufficiently great to contribute to the positive energy balance associated with weight gain. Efforts focused on reversing sedentariness have the potential to impact obesity.

Adult↗

PubMedDate not supplied

Precision and accuracy of an ankle-worn accelerometer-based pedometer in step counting and energy expenditure.

BACKGROUND: Walking is a widely used approach to increase physical activity levels in obese patients. In this paper, we investigate the precision and accuracy of an ankle-worn dual-axis accelerometer (Stepwatch) and investigate its potential application as a predictor of energy expenditure. METHODS: Twenty healthy subjects (10 lean, 10 obese) wore spring-levered (Accusplit), piezoelectric (Omron HF-100), and Stepwatch pedometers. Subjects walked on a treadmill at 1, 2, and 3 mph and in a hallway at 1 and 1.85 mph, during which energy expenditure was measured. RESULTS: The Stepwatch counted 99.7 +/- 0.67% (mean +/- SEM) of the manual counts. In comparison, the Omron pedometer counted 61 +/- 3.3% and the Accusplit counted 26 +/- 2.8% of the manual counts at 1 mph although all pedometers were accurate (> 98% of counts) at 3 mph. In repeated measures, the Stepwatch produced negligible variance (SD = 0.36) over all speed whereas the other pedometers showed a large amount of variance at all speed (SD = 4-13). Stepwatch counts were predictive of walking energy expenditure corrected by weight (r2 > 0.8). CONCLUSION: The counts from the Stepwatch were virtually identical to the manual counts from a trained investigator and provided a reliable predictor of walking energy expenditure.

Adult↗