Subject's Waist Research Articles

Relationship Between Anthropometric Variables Among Hypertensive and Type 2 Diabetes Patients Attending a Nigerian Tertiary Hospital

Background A myriad of discrepancies abounds as to which anthropometric measures have the best marker for assessing obesity a major risk factor for hypertension and Type 2 diabetes. This study sought to determine the strength of the relationship between the following obesity risk factors, including, Waist circumference, body mass index, and Waist Hip Ratio. Their predictive ability of obesity in these subjects were also determined. Methods A total of two hundred and one (201) male and female hypertensive (n=122) and type 2 diabetes (n=79) subjects participated in this study. Blood pressure, anthropometric measurements, blood glucose were obtained from each subject. Data were analyzed using, descriptive statistics, Spearman’s, and Pearson’s correlation. Results The mean age, weight, and height of the subjects were 53.02±12.02 years, 72.91±15.68kg, and 1.66±0.08m, respectively. In the hypertensive subject Waist Hip Ratio indicated that 71.35% were obese, Waist Circumference indicated 39.3% and Body mass Index indicated 25.4% obesity. For the subject with type 2 diabetes, Waist Hip Ratio indicated 75.9% obesity, Waist Circumference (40.5%), and Body Mass Index (22.8%). A strong positive relationship (r=0.85) was found between Waist Circumference and Body Mass Index in the hypertensive subject and a strong positive relationship (r=0.72) between WHR and BMI in the subjects with type 2 diabetes. Conclusion Overall, the study affirms that the Waist Hip Ratio is a better anthropometric measure for assessing obesity and that it predicts obesity in hypertensive and type 2 diabetes subjects better than other measures.

The Mobile Lower Body Negative Pressure Gravity Suit for Long-Duration Spaceflight.

Spaceflight Associated Neuro-ocular Syndrome, bone decalcification, and muscle atrophy are among the most prevalent risks associated with long-duration spaceflight. Implementing the lower body negative pressure (LBNP) method is a potential countermeasure for these risks. LBNP counteracts head-ward fluid shifts and generates ground-reaction forces (GRFs). GRFs are beneficial for maintaining bones and muscles by producing gravity-like loads experienced on Earth. Currently, LBNP devices are large/bulky, and usually require the subject to maintain a stationary position. However, our new mobile gravity suit is relatively small, untethered, and flexible in order to improve mobility in space. We hypothesized that this novel mobile gravity suit generates greater GRFs than a standard LBNP chamber. While lying supine, GRF data were recorded in both devices using foot sole sensors and a weight scale. At -40 mmHg, the gravity suit generated a mean maximum bodyweight of 125 ± 22% (P < 0.02) whereas the standard LBNP chamber generated 91 ± 24%. The standard LBNP chamber generated a single force on the stationary subject, which was expressed as AW(LBNP) = GRF, where Aw = cross-sectional area (CSA) of subject’s waist. However, the mobile gravity suit generated an additional force based on the following equation, (AF + AW)LBNP = GRF, where AF = CSA of subject’s feet. The additional force was further expressed as F1 + F2 = AF × LBNP, where F1 = spinal loading force, F2 = waist shear force, and AF × LBNP = the total downward foot force. Thus, the mobile gravity suit produces higher percentages of bodyweight due to the suit’s novel design.

Ground Reaction Forces generated by a Lower Body Negative Pressure Exercise Device for Space Flight

Loss of bone and muscle are leading concerns among astronauts during prolonged space flight. Lower body negative pressure (LBNP) chambers generate gravitational and cardiovascular stresses to maintain musculoskeletal strength and fitness by means of suction pressure. Ground reaction forces (GRFs) generated underneath the user’s feet are directly proportional to the level of negative pressure applied. However, the exact mechanism of GRF generation remains unresolved. We hypothesize that increasing the cross‐sectional area (CSA) of the user’s waist in contact with a flexible waist seal will increase the GRFs generated at a given vacuum pressure. To test our hypothesis, we collected GRFs generated by 6 healthy subjects under two conditions: original (unchanged) CSA of their waist and a greater waist CSA using expanded cushioning around waist of the same subjects. GRFs were measured with LBNP levels ranging from 0 (ambient pressure) to 50 mmHg with subjects lying in supine position to simulate microgravity. The original CSA of 467.7 cm2 ± 69.0 cm2 generated 118 % ± 31 % body weight at −50 mmHg. However, the larger CSA of 1,451.0 cm2 ± 331.0 cm2 generated a mean GRF of 146 % ± 31% body weight at −50 mmHg. A one‐way ANOVA test resulted in p‐values &lt; 0.05 for all pressures, denoting statistically significant increases in larger compared with original CSA GRF. The GRF generated with larger CSA followed this equation GRF = −1.8211 (LBNP) + 0.7899 while the GRF generated with original CSA followed the equation: GRF = −1.5079 (LBNP) + 0.3995. These data support our hypothesis that GRFs generated by LBNP are directly proportional to the waist CSA. Using this new concept, astronauts may generate GRFs at lower LBNP levels to prevent pre‐syncopal symptoms during exercise in space.Support or Funding InformationSupported by NASA grants NNX13AJ12G and NSSC19K0409.Average weight measurements with varying pressures for six volunteers; red is original CSA of subject's waist and blue is larger CSA.Figure 1

Quantitative assessment of motor function in patients with Parkinson's disease using wearable sensors

Motor dysfunction is the main clinical symptom and diagnosis basis of patients with Parkinson's disease (PD). A total of 30 subjects were recruited in this study, including 15 PD patients (PD group) and 15 healthy subjects (control group). Then 5 wearable inertial sensor nodes were worn on the bilateral upper limbs, lower limbs and waist of subjects. When completing the 6 paradigm tasks, the acceleration and angular velocity signals from different parts of the body were acquired and analyzed to obtain 20 quantitative parameters which contain information about the amplitude, frequency, and fatigue degree of movements to assess the motor function. The clinical data of the two groups were statistically analyzed and compared, and then Back Propagation (BP) Neural Network was used to classify the two groups and predict the clinical score. The final results showed that most of the parameters had significant difference between the two groups, ten times of 5-fold cross validation showed that the classification accuracy of the BP Neural Network for the two groups was 90%, and the predictive accuracy of Hoehn-Yahr (H-Y) staging and unified PD rating scale (UPDRS) Ⅲ score of the patients were 72.80% and 68.64%, respectively. This study shows the feasibility of quantitative assessment of motor function in PD patients using wearable sensors, and the quantitative parameters obtained in this paper may have reference value for future related research.

Biomechanical Analysis of a Dynamic Stability Test System to Evoke Sway and Step Recovery.

This paper reports on the dynamic analysis and experimental validation of a method to perturb the balance of subjects in quiet standing. Electronically released weights pull the subject's waist through a specified displacement sensed by a photoelectric sensor. A dynamic model is derived that computes the force applied to the subject as a function of waist acceleration. This model accurately predicts the acceleration of mock subjects (suspended masses) with high repeatability. The validity and simplicity of this model suggest that this method can provide a standard for provocation testing on stable surfaces. Proof-of-concept trials on human subjects demonstrate that the device can be used with a force platform and motion tracking and that the device can induce both sway and step recoveries in healthy male adults.

Ideal Ergonomical Design for Light Hand Activities in Standing

AIM: To find out ideal ergonomic position for light hand work activities in standing. Objectives: 1. To find out the co-relation between person's height and distance of the platform for performing hand activities in standing. 2. To find out the common area of pain for three different platforms for different distances. Purpose of Study: The purpose of the study is to know whether hand activities which are involved in standing are causing any musculoskeletal discomfort or not. Methodology: a) Study Design: Cross sectional study, b) Sample Population: PCMC AreaaSample Size: 100, c) Sampling Technique: Random sampling, d) Inclusion Criteria: Healthy subjects (both malesafemales) between the of 25-50 years are selectedafurther divided in 4 groups. Exclusion Criteria: 1.Acute injury to back 2. Infection (unhealed / healing ) 3. Congenital deformities 4. Spinal upper and lower limb deformities 5. Neurological deficit e) Outcome Measures : VAS, Timing, Repetitions and Area of pain f) Data CollectionaAnalysis: ANOVA and POST HOC TEST is used for seeing correlation between person's height and distance of the platform for performing hand activities in standing. Results: a) Subjects in group 1, performed better at distance of 4 inch on 30a32 inch platforms (p values are 0.000a0.032), b) Subjects in group 2, performed better at distance of 4 inch on 32 inch platform (p value 0.032), c) Subjects in group 3, performed better at distance of 4 inch on 32a34 inch platforms ( p values are 0.032a0.690), d) For 4th group people no platform was found to be comfortable. Conclusion: The study concluded that,light handwork activities if performed at waist level and at nearest distance;activities can be performed comfortably without causing much of musculoskeletal discomfort.The commonest area of pain noticed was lowback pain. Clinical Significance : The study can be implemented while designing a platform for hand activities.The height of platform at which the activities are going to be performed should be at subject's waist level.

Quantitative analysis of fall risk using TUG test

We examined falling risk among elderly using a wearable inertial sensor, which combines accelerometer and gyrosensors devices, applied during the Timed Up and Go (TUG) test. Subjects were categorised into two groups as low fall risk and high fall risk with 13.5 s duration taken to complete the TUG test as the threshold between them. One sensor was attached at the subject's waist dorsally, while acceleration and gyrosensor signals in three directions were extracted during the test. The analysis was carried out in phases: sit-bend, bend-stand, walking, turning, stand-bend and bend-sit. Comparisons between the two groups showed that time parameters along with root mean square (RMS) value, amplitude and other parameters could reveal the activities in each phase. Classification using RMS value of angular velocity parameters for sit-stand phase, RMS value of acceleration for walking phase and amplitude of angular velocity signal for turning phase along with time parameters suggests that this is an improved method in evaluating fall risk, which promises benefits in terms of improvement of elderly quality of life.

Discrimination between Upstairs and Downstairs Based on Accelerometer

An algorithm for the discrimination between human upstairs and downstairs using a tri-axial accelerometer is presented in this paper, which consists of vertical acceleration calibration, extraction of two kinds of features (Interquartile Range and Wavelet Energy), effective feature subset selection with the wrapper approach, and SVM classification. The proposed algorithm can recognize upstairs and downstairs with 95.64% average accuracy for different sensor locations, i.e. located on the subject's waist belt, in the trousers pocket, and in the shirt pocket. Even for the mixed data from all sensor locations, the average recognition accuracy can reach 94.84%. Experimental results have successfully validated the effectiveness of the proposed method.

가속도 신호를 이용한 걸음걸이 패턴 분류

걸음걸이 패턴 분류는 많은 응용분야가 있을 뿐만 아니라 매우 중요한 연구 분야이다. 따라서 본 연구에서는 허리에 부착된 가속도 모듈로부터 획득된 신호를 이용하여 천천히 걷기(slow walking, S.W), 일반 걷기(normal walking, N.W), 빠르게 걷기(fast walking, F.W) 등의 보행 패턴을 분류하고자한다. 11명의 성인으로부터 블루트스 모듈을 이용하여 100Hz로 샘플링된 3축 가속도 신호를 획득하였다. 획득된 데이터는 웨이브렛 변환을 이용하여 분석하였다. 걸음걸이 패턴은 두가지의 파라미터들을 이용하여 분석되어지는데, 하나는 운동에 해당하는 웨이브렛 계수의 에너지(power)와 전 후방향의 전체 에너지사이의 비율(RPA)이고, 다른 파라미터는 전 후 방향과 상 하 수직 방향 사이에서 웨이브렛 계수의 제곱근 평균 비율(RAV)이다. 천천히 걷기는 다른 걷기와 비교했을 때 작은 RPA값을 가지게 되어 분류가 용이하며, 천천히 걷기는 RAV를 이용하여 일반 걷기와 구별되어 질 수 있었다. 따라서 본연구는 건강한 성인에게서 3축 가속도 신호를 획득한 후 웨이브렛 파라미터를 이용하여 걷기 패턴을 잘 구별할 수 있는 연구임을 확인 하였다. This classification of walking patterns is important and many kinds of applications. Therefore, we attempted to classify walking on level ground from slow walking to fast walking using a waist acceleration signal. A tri-axial accelerometer was fixed to the subject's waist and the three acceleration signals were recorded by bluetooth module at a sampling rate of 100 Hz eleven healthy. The data were analyzed using discrete wavelet transform. Walking patterns were classified using two parameters; One was the ratio between the power of wavelet coefficients which were corresponded to locomotion and total power in the anteroposterior direction (RPA). The other was the ratio between root mean square of wavelet coefficients at the anteroposterior direction and that at the vertical direction(RAV). Slow walking could be distinguished by the smallest value in RPA from other walking pattern. Fast walking could be discriminated from level walking using RAV. It was possible to classify the walking pattern using acceleration signal in healthy people.

Barometric Pressure and Triaxial Accelerometry-Based Falls Event Detection

Falls and fall related injuries are a significant cause of morbidity, disability, and health care utilization, particularly among the age group of 65 years and over. The ability to detect falls events in an unsupervised manner would lead to improved prognoses for falls victims. Several wearable accelerometry and gyroscope-based falls detection devices have been described in the literature; however, they all suffer from unacceptable false positive rates. This paper investigates the augmentation of such systems with a barometric pressure sensor, as a surrogate measure of altitude, to assist in discriminating real fall events from normal activities of daily living. The acceleration and air pressure data are recorded using a wearable device attached to the subject's waist and analyzed offline. The study incorporates several protocols including simulated falls onto a mattress and simulated activities of daily living, in a cohort of 20 young healthy volunteers (12 male and 8 female; age: 23.7 ±3.0 years). A heuristically trained decision tree classifier is used to label suspected falls. The proposed system demonstrated considerable improvements in comparison to an existing accelerometry-based technique; showing an accuracy, sensitivity and specificity of 96.9%, 97.5%, and 96.5%, respectively, in the indoor environment, with no false positives generated during extended testing during activities of daily living. This is compared to 85.3%, 75%, and 91.5% for the same measures, respectively, when using accelerometry alone. The increased specificity of this system may enhance the usage of falls detectors among the elderly population.

Child Voice and Noise: A Pilot Study of Noise in Day Cares and the Effects on 10 Children's Voice Quality According to Perceptual Evaluation

The purpose of this investigation was to study children's exposure to background noise at the ears during a normal day at the day care center and also to relate this to a perceptual evaluation of voice quality. Ten children, from three day care centers, with no history of hearing and speech problems or frequent infections were selected as subjects. A binaural recording technique was used with two microphones placed on both sides of the subject's head, at equal distance from the mouth. A portable digital audio tape (DAT) recorder (Sony TCD-D 100, Stockholm, Sweden) was attached to the subject's waist. Three recordings were made for each child during the day. Each recording was calibrated and started with three repetitions of three sentences containing only sonorants. The recording technique allowed separate analyses of the background noise level and of the sound pressure level (SPL) of each subjects' own voice. Results showed a mean background noise level for the three day care centers at 82.6dBA Leq, ranging from 81.5 to 83.6dBA Leq. Day care center no. 2 had the highest mean value and also the highest value at any separate recording session with a mean background noise level of 85.4dBA Leq during the noontime recordings. Perceptual evaluation showed that the children attending this day care center also received higher values on the following voice characteristics: hoarseness, breathiness, and hyperfunction. Girls increased their loudness level during the day, whereas for boys no such change could be observed.

Anticipatory postural adjustments and the latency of compensatory stepping reactions in humans

A compensatory stepping response is a commonly used strategy in recovering balance control after a postural perturbation. Unlike gait initiation, the compensatory stepping often occurs without an anticipatory postural adjustment (APA), in which body weight is shifted to the swing leg first and then back to the stance leg prior to foot lifting. In postural perturbation studies using a moving platforms stepping responses without an APA were found to have shorter latency to foot lifting than trials with an APA. We studied stepping responses of healthy young adults under postural perturbation of a pulling force impulse on the subject's waist. In contrast to previous studies, the latency of foot lifting was found in the current study to be shorter in the trials with an APA than trials without an APA. Furthermore, greater amplitude of an APA was associated with a shorter latency of foot lifting. Response with an APA of large amplitude may indicate high level of determinant for foot lifting. A pause as to whether or not to initiate/complete a stepping response is suggested to be partially the cause of delayed foot lifting in trials without an APA or with small amplitude of the APA.

Vocal Behavior and Vocal Loading Factors for Preschool Teachers at Work Studied with Binaural DAT Recordings

Preschool teachers are at risk for developing voice problems such as vocal fatigue and vocal nodules. The purpose of this report was to study preschool teachers' voice use during work. Ten healthy female preschool teachers working at daycare centers (DCC) served as subjects. A binaural recording technique was used. Two microphones were placed on both sides of the subject's head, at equal distance from the mouth, and a portable DAT recorder was attached to the subject's waist. Recordings were made of a standard reading passage before work (baseline) and of spontaneous speech during work. The recording technique allowed separate analyses of the level of the background noise, and of the subjects' voice sound pressure level, mean fundamental frequency, and total phonation time. Among the results, mean background noise level for the ten DCCs was 76.1 dBA (range 73.0–78.2), which is more than 20 dB higher than what is recommended where speech communication is important (50–55 dBA). The subjects spoke on an average of 9.1 dB louder ( p < 0.0001), and with higher mean fundamental frequency (247 Hz) during work as compared to the baseline (202 Hz) ( p < 0.0001). Mean phonation time for the group was 17%, which was considered high. It was concluded that preschool teachers do have a highly vocally demanding profession. Important steps to reduce the vocal loading for this occupation would be to decrease the background noise levels and include pauses so that preschool teachers can rest their voices.

CHANGES IN MAXIMAL POWER AND FORCE OVER THE COURSE OF A COMPETITIVE COLLEGIATE FOOTBALL GAME

There is a scarcity of research examining changes in maximal power output over the course of a football game and yet such information is important to athlete and coach from both training and game strategy aspects. PURPOSE: To examine the changes in force and power production in the leg extensors over the course of a competitive collegiate football game. METHODS: Subjects were drawn from two groups. Those selected to play (players, N = 10) and ôred-shirtsö (non-players, N = 9) who participated in all activities of the team except did not play on the day of testing. In order to assess changes in lower body strength and power, the subjects were tested for jump performance immediately before the game (Pre), and after each quarter (Q1, Q2, Q3, Post). All testing session took place on the sideline of the field. Prior to the game each subject warmed up by participating in the usual program of exercises completed prior to a football game. Immediately before kickoff the subject was tested on Squat Jump (SJ) and Countermovement Jump (CMJ). Order of testing was alternated between players such that half were tested on CMJ first and half SJ first. The SJ and CMJ tests were all performed on a portable force plate and a position transducer was attached to the subject's waist to measure displacement of the trunk. A computer recorded force and displacement data with power output subsequently calculated. RESULTS: Force and power output was significantly higher in players compared to non-players at several time points with an average peak force of 2229N and 2506N and peak power of 4397W and 5089W for the non-players and players respectively. There were significant changes in force and power output over the course of the game in both groups with an average decrease from PRE to Q2 of 16–24% and 18–20% for the nonplayers and players respectively. CONCLUSION: In non-players there is a considerable decrease in maximal power which remains throughout the game most probably because the initial warm-up effect is transient. For players in the particular game studied, performance decreased most probably due to fatigue and repetitive impact over the first two quarters but as the game intensity diminished they recovered somewhat and by post-game had returned to their pre-game capacity. These results suggest that a) non-players may have to be kept in a higher state of warm-up if they are to be effective if called on to play; and b) decline in maximal performance is significant and important over the course of a collegiate football game and training and game strategy should encompass this.

Twenty-four hour ambulatory nasal pH monitoring.

The nasal delivery of drugs, both for systemic and local use, is an expanding field with many drugs being delivered by this route. It is known that changes in pH can affect drug absorption but there is no data regarding intranasal pH over time. We present the results of 24-h ambulatory nasal pH monitoring in four subjects, each of whom had monitoring on two separate occasions. The apparatus consisted of a pH monitor with two electrodes, thus enabling us to take readings from 1 and 4 cm behind the anterior end of the inferior turbinate. Measurements were recorded every 6 s by the posterior electrode and every 30 s by the anterior electrode. The recording apparatus was worn around the subjects waist. Analysis of the results showed that there was no diurnal variation and no significant differences between the subjects. The mean pH from the anterior electrode was higher than that from the posterior (7.1 versus 6.6). The pH did not fluctuate with daily activities such as eating, drinking or sleeping. The results are interesting and may be of importance with regard to the design of formulations for nasal drug delivery systems.

The use of a two-dimensional ultrasound time-of-flight system forlocation of the centre of gravity in posturography measurements

A method has been developed for objective assessment of balance usingultrasound time-of-flight (ToF) posturography measurements to accuratelylocate the centre of gravity (CoG) of a subject. Two orthogonal 40 kHzultrasound transmitters are mounted on the subject's waist at the height ofthe CoG. Anterior/posterior and lateral motions are detected independently bymeasuring variations in the ToF from the transmitters to appropriatelypositioned wall-mounted receivers. The motion of the CoG is accurately tracedduring the course of 20 second assessment periods as the subject stands on asolid surface with eyes open and eyes closed. The tests are repeated with thesubject standing on a standardized soft surface.Trials of day-to-day repeatability and repeated tests on patients prior totherapy indicate there is no significant improvement to balance measures withexperience of the system. Balance measures are significantly worse in patientssuffering vertigo symptoms following traumatic brain injury than forequivalent normal volunteers. Repeated measures post-therapy indicatesignificant improvement in balance measures following vestibular therapy inpatients with vertigo.CoG location using ultrasound ToF is a suitable method of tracking sway andthus assessing balance in normals and balance-compromised patients.

Classification of waist-acceleration signals in a continuous walking record

We attempted to distinguish walking on level ground from walking on a stairway using waist acceleration signals. A triaxial accelerometer was fixed to the subject's waist and the three acceleration signals were recorded by a portable data logger at a sampling rate of 256 Hz. Twenty healthy male subjects were asked to walk through a corridor and up and down a stairway as a single sequence, without any instruction. The data were analyzed using discrete wavelet transform. Walking patterns were classified in two stages. In the first stage, the times when the walking pattern changed were detected using the low-frequency component of the anteroposterior acceleration ( LF A) and of the vertical acceleration ( LF V). In the second stage, the three types of walking patterns were classified by comparing powers of wavelet coefficients in the vertical direction ( P WCV) and in the anteroposterior direction ( RP WCA). Changes in walking patterns could be detected by using either LF A or LF V. Walking down stairs could be distinguished from the other types of walking as it gave the largest value in P WCV, and walking up stairs could be discriminated from level walking using RP WCA. Level and stairway walking could be classified from continuous records of waist acceleration.

Night-day-night sleep-wakefulness monitoring by ambulatory integrated circuit memories.

A medium-sized portable digital recorder with fully integrated circuit (IC) memories for sleep monitoring has been developed. It has five amplifiers for EEG, EMG, EOG, ECG, and a signal of body acceleration or respiration sound, four event markers, an 8 ch A/D converter, a digital signal processor (DSP), 192 Mbytes IC flash memories, and batteries. The whole system weighs 1200 g including batteries and is put into a small bag worn on the subject's waist or carried in their hand. The sampling rate for each input channel is programmable through the DSP. This apparatus is valuable for continuously monitoring the states of sleep-wakefulness over 24 h, making a night-day-night recording possible in a hospital, home, or car.

Simultaneous palpation of the craniosacral rate at the head and feet: intrarater and interrater reliability and rate comparisons.

The main purpose of this study was to determine the interrater and intrarater reliability of measurements obtained during palpation of the craniosacral rate at the head and feet. Palpated craniosacral rates of head and feet measured simultaneously were also compared. Subjects. Twenty-eight adult subjects and 2 craniosacral examiners participated in the study. A within-subjects repeated-measures design was used. A standard cubicle privacy curtain, hung over the subject's waist, was used to prevent the examiners from seeing each other. Interrater intraclass correlation coefficients (ICCs) were .08 at the head and .19 at the feet. Intrarater ICCs ranged from .18 to .30. Craniosacral rates simultaneously palpated at the head and feet were different. The results did not support the theories that underlie craniosacral therapy or claims that craniosacral motion can be palpated reliably.

Validity of surrogates for determination of 30-1000 Hz magnetic field exposure for video display terminal users in office settings.

In studies investigating adverse reproductive outcomes associated with video display terminal (VDT) usage, amounts of time spent in front of a VDT or magnetic field (MF) levels in front of the VDT are used as surrogate measures of subject's MF exposure. However, the relevance of such surrogates to actual exposures has not been demonstrated, and the validity of the use of such measures as a surrogate for the actual MF exposure is only speculative. This study examines 1) measurements of MFs at frequencies of approximately 30-1000 Hz at a fixed distance from the VDTs, 2) reported hours of VDT use, and 3) reported distance between the VDT and the subject's waist as surrogate measures for the average MF exposure level of a VDT user during one 8 h workday. The results showed a weak correlation between the average exposure level of a VDT user and the MF 46 cm from a VDT (R = 0.52, n = 67, P < 0.001). This study showed no association between self-reported hours of VDT usage, or self-reported distance between waist and VDT, and the average MF exposures. Moreover, individuals' average MF exposures did not seem to be affected by other variables, such as position of a VDT on the desk, hours of desk use, and the VDT type (color vs. monochrome). These findings indicate that VDT exposures within office settings are complex and cannot be easily predicted by surrogates.