Biomedical subjects

Kuan Zhang

Publications and source records attributed to Kuan Zhang.

4 recordsLinked to original sources

PubMed2005

Assessment of human locomotion by using an insole measurement system and artificial neural networks.

A new method for measuring and characterizing free-living human locomotion is presented. A portable device was developed to objectively record and measure foot-ground contact information in every step for up to 24h. An artificial neural network (ANN) was developed to identify the type and intensity of locomotion. Forty subjects participated in the study. The subjects performed level walking, running, ascending and descending stairs at slow, normal and fast speeds determined by each subject, respectively. The device correctly identified walking, running, ascending and descending stairs (accuracy 98.78%, 98.33%, 97.33%, and 97.29% respectively) among different types of activities. It was also able to determine the speed of walking and running. The correlation between actual speed and estimated speed is 0.98, p< 0.0001. The average error of walking and running speed estimation is -0.050+/-0.747 km/h (mean +/- standard deviation). The study has shown the measurement of duration, frequency, type, and intensity of locomotion highly accurate using the new device and an ANN. It provides an alternative tool to the use of a gait lab to quantitatively study locomotion with high accuracy via a small, light and portable device, and to do so under free-living conditions for the clinical applications.

Adolescent↗

PubMed2005

Energy balance in early-stage Huntington disease.

BACKGROUND: Huntington disease (HD) is a genetic neurologic disorder. Weight loss is common in HD and is related to progression of the disease, but the cause of weight loss remains unclear. OBJECTIVE: The study objective was to compare 24-h energy expenditure (EE) and energy intake in persons with early midstage HD with those of matched control subjects to determine how HD affects energy balance. DESIGN: EE was assessed in 13 subjects with early-stage HD and in 9 control subjects via indirect calorimetry in a human respiratory chamber. Energy intake was determined by weighing all food provided and all leftovers from an ad libitum diet. Body composition was measured via air-displacement plethysmography. Stage of disease was estimated on the basis of the Unified Huntington's Disease Rating Scale and modified Mini-Mental Status examinations. Regression analysis included all 13 HD subjects; t tests were used for the comparisons between matched HD and control subjects. RESULTS: 24-h EE was 11% higher in the HD subjects than in the control subjects (NS). This difference was due to a higher (P = 0.043) waking metabolic rate, which was related to a significantly greater displacement of the center of mass by HD subjects than by control subjects (P = 0.028). On average, both groups were in positive energy balance and exceeded their energy expenditure by 2510-2929 kJ. CONCLUSIONS: Higher 24-h EE in persons with early midstage HD is due to increased physical activity, both voluntary and involuntary. However, HD subjects are able to maintain positive energy balance when offered adequate amounts of food in a controlled setting.

Basal Metabolism↗

PubMed2004

Improving energy expenditure estimation for physical activity.

PURPOSE: The purpose of this study was to validate the Intelligent Device for Energy Expenditure and Activity (IDEEA) for estimation of energy expenditure during a variety of activities. An additional aim was to improve the accuracy of the estimation of energy expenditure of physical activity based on second-by-second information of type, onset, and duration of activity. METHODS: This study included two tests: a mask calorimetry test with 27 subjects [age = 33.7 +/- 13.8 (mean +/- SD) yr; BMI = 24.8 +/- 4.8 kg x m] and a respiratory chamber calorimetry test with 10 subjects (age = 32.9 +/- 12.4 yr; BMI = 26.1 +/- 5.6 kg x m). In the mask test, the subjects performed activities (sitting, standing, lying down, level treadmill walking, and running at different speeds) for 50-min durations. For the chamber test, subjects lived in the metabolic chamber for 23 h and performed three exercise sessions to compensate for the confined environment. RESULTS: The results showed significant correlations (P < 0.0001) between energy expenditure estimated by IDEEA and energy expenditure measured by the calorimeters with an accuracy >95%. After corrections for the decrease in sleeping metabolic rate, the estimation accuracy for the chamber test was increased by 1-96.2%, whereas the estimation accuracy for nighttime activity was significantly improved by 4-99%. CONCLUSION: IDEEA provides a suitable method for estimating the energy expenditure of physical activity. It provides both instantaneous and cumulative estimates of energy expenditure over a given period.

Adult↗

PubMed2003

Measurement of human daily physical activity.

OBJECTIVES: To validate a new device, Intelligent Device for Energy Expenditure and Activity (IDEEA), for the measurement of duration, frequency, and intensity of various types of human physical activity (PA). RESEARCH METHODS AND PROCEDURES: The ability of IDEEA to identify and quantify 32 types of PA, including the most common daily exercise and nonexercise PA, was tested in 76 subjects: Subjects included males (N = 33) and females (N = 43) ranging in age from 13 to 72 years with a mean body mass index (BMI) of 24.7 kg/m(2) (range: 18.4 to 41.0) [43 females: 13 to 72 years old and BMI 18.4 to approximately 41.0 kg/m(2) (mean = 24.7 kg/m(2)); 33 males: 15 to approximately 72 years old and BMI 21.0 to approximately 38.4 kg/m(2) (mean = 25.9 kg/m(2))]. Postures, limb movements, and jumping were tested using a timed protocol of specific activities. Walking and running were tested using a 60-meter track, on which subjects walked and ran at 6 self-selected speeds. Stair climbing and descending were tested by timing subjects who climbed and descended a flight of stairs at two different speeds. RESULTS: Correct identification rates averaged 98.9% for posture and limb movement type and 98.5% for gait type. Pooled correlation between predicted and actual speeds of walking and running was high (r = 0.986, p <or= 0.0001). DISCUSSION: IDEEA accurately measured duration, frequency, type, and intensity of a variety of daily PAs.

Adolescent↗