Effects of Desk Pedaling Work Rate on Concurrent Work Performance among Physically Inactive Adults: A Randomized Experiment.

PURPOSE: Under-desk pedaling devices could help reduce health risks associated with the global decline in work-related energy expenditure. However, the optimal pedaling work rate to facilitate concurrent work performance among physically inactive adults is unclear. We examined the effects of two light-intensity pedaling work rates on physically inactive adults' work performance. METHODS: We recruited equal numbers of older (45-65 yr) versus younger (20-44 yr), male versus female, and overweight/obese (body mass index [BMI], 25-35 kg·m -2 ) versus normal weight (BMI, 18.5-24.9 kg·m -2 ) participants. Using a Graeco-Latin square design, participants ( n = 96) completed a laboratory experiment to evaluate the effects of using an under-desk pedaling device at two seated light-intensity work rates (17 and 25 W), relative to a seated nonpedaling condition on objectively measured typing, reading, logical reasoning, and phone task performance. Ergonomic comfort under each pedaling work rate was also assessed. Equivalence tests were used to compare work performance under the pedaling versus nonpedaling conditions. RESULTS: Treatment fidelity to the 17- and 25-W pedaling work rates exceeded 95%. Mean work performance scores for each pedaling and nonpedaling condition were equivalent under alpha = 0.025. Age, sex, and BMI did not significantly moderate the effect of pedaling on work performance. Participants reported greater ergonomic comfort while completing work tasks at the 17-W relative to the 25-W work rate. CONCLUSIONS: Physically inactive adults obtained similar work performance scores under the 17- and 25-W pedaling and the nonpedaling conditions, suggesting that either pedaling work rate could help reduce health risks of sedentary work time. The 17-W work rate yielded greater ergonomic comfort and may be an appropriate starting point for introducing diverse inactive workers to under-desk pedaling.

Assessment of postural sway with a pendant-mounted wearable sensor.

BACKGROUND: Body-worn inertial measurement unit (IMU) sensors have been widely used in postural stability and balance studies because of their low cost and convenience. In most of these studies, a single IMU sensor is attached to a waist belt near the body's center of mass. Some populations such as pregnant women, however, may find a waist belt challenging in terms of fit and comfort. For this reason it may be useful to identify an alternative location for placement of an IMU and a more comfortable means for attaching the sensor to the body. Research question Does placing an IMU sensor in a pendant worn around the neck permit discrimination between conditions with varying postural stability? METHODS: Twenty-six healthy participants performed three standing tasks (double-leg, tandem, and single-leg standing) under eyes-open and eyes-closed vision conditions to preliminarily assess the ability of the pendant sensor to discriminate between balance conditions. Discrimination based upon data from a belt-mounted IMU was assessed in the same trials. Differences in standard deviation of acceleration components, sway area, and jerkiness due to trial condition and sensor were evaluated using analysis of variance followed by post hoc comparisons. These data were also incorporated into receiver-operator characteristic (ROC) curve analysis to assess the effectiveness of each sensor at discriminating between conditions. RESULTS: Stability was found to vary across conditions, but there was no interaction between stability and sensor location (all p ≥ 0.323). ROC curve analysis showed that sensors in both locations were good discriminators between conditions. Significance Placing an IMU in a pendant may be feasible for studying and monitoring postural instability. This approach may be especially valuable when considering populations for which wearing a belt is uncomfortable.

Development and evaluation of attachable anti-vibration handle.

Blueberry production has skyrocketed in the past two decades due to an exponential increase in consumer demand around the world. Hand harvesters are used, avoiding damage to the fruit and increasing harvesting efficiency multifold when compared with that of hand-picking. The downside of these hand harvesters is their high Hand Arm Vibration (HAV), which is very dangerous for the worker and can cause hand-arm vibration syndrome (HAVS). The aim of this study is to propose a spring-based anti-vibration handle that can be attached to vibrating equipment (blueberry hand harvester). Four different parameters were measured for the developed spring-based handles: hand arm vibration, wrist posture, muscle activity, and subjective discomfort rating. Results have shown that the use of a spring-based handle can reduce HAV by 61.1%, which is within the exposure limit values (ELV) defined by the European Union.

Development of an ergonomic four-finger-push manual pipette design.

The purpose of this study was to develop a new pipette design in which the pipette is operated by four fingers, taking into account the anatomy and anthropometry of the hand. The proposed new pipette designs were compared with a traditional thumb-push pipette based on muscle activity, wrist posture, subjective discomfort ratings for upper extremities, and user preference. The results of the study revealed that the four-finger, ergonomic pipette design reduced muscle exertion (25% reduction for aspiration and 35% reduction for dispensing), awkward wrist posture (33% reduction in wrist flexion, radial and ulnar deviation), and perceived discomfort in the wrist, hand and lower arm. Furthermore, most participants (9 of 10) who used a pipette in their daily work preferred the new pipette designs to a traditional thumb-push pipette design. Thus, we expect that this study will contribute to the reduction of WMSDs risk factors and pain.

Glasses-type wearable computer displays: usability considerations examined with a 3D glasses case study.

This study presents usability considerations and solutions for the design of glasses-type wearable computer displays and examines their effectiveness in a case study. Design countermeasures were investigated by a four-step design process: (1) preliminary design analysis; (2) design idea generation; (3) final design selection; and (4) virtual fitting trial. Three design interventions were devised from the design process: (1) weight balance to reduce pressure concentrated on the nose, (2) compliant temples to accommodate diverse head sizes and (3) a hanger mechanism to help spectacle users hang their wearable display on their eye glasses. To investigate their effectiveness, in the case study, the novel 3D glasses adopting the three interventions were compared with two existing 3D glasses in terms of neck muscle fatigue and subjective discomfort rating. While neck muscle fatigue was not significantly different among the three glasses (p = 0.467), the novel glasses had significantly smaller discomfort ratings (p = 0.009). Relevance to Industry: A four-step design process identified usability considerations and solutions for the design of glasses-type wearable computer displays. A novel 3D glasses was proposed through the process and its effectiveness was validated. The results identify design considerations and opportunities relevant to the emerging wearable display industry.

Investigation of index finger triggering force using a cadaver experiment: Effects of trigger grip span, contact location, and internal tendon force.

A cadaver study was conducted to investigate the effects of triggering conditions (trigger grip span, contact location, and internal tendon force) on index finger triggering force and the force efficiency of involved tendons. Eight right human cadaveric hands were employed, and a motion simulator was built to secure and control the specimens. Index finger triggering forces were investigated as a function of different internal tendon forces (flexor digitorum profundus + flexor digitorum superficialis = 40, 70, and 100 N), trigger grip spans (40, 50, and 60 mm), and contact locations between the index finger and a trigger. Triggering forces significantly increased when internal tendon forces increased from 40 to 100 N. Also, trigger grip spans and contact locations had significant effects on triggering forces; maximum triggering forces were found at a 50 mm span and the most proximal contact location. The results revealed that only 10-30% of internal tendon forces were converted to their external triggering forces.

Utilizing anthropometric data to improve the usability of desk bikes, and influence of desk bikes on reading and typing performance.

This study investigated the feasibility of using a desk bike in an office setting. Workstation measurements were introduced to accommodate 95% of the general U.S. population in using desk bikes. Reading and typing performances were compared at three different cycling conditions (no cycling, 10 and 25 W). Thirty healthy individuals (15 female and 15 male; Age mean: 23.1, σ: 4.19) were recruited based on 5/50/95th percentile stature. Participants were required to select preferred workstation settings and perform reading and typing tasks while pedaling. According to anthropometric measurements and variability from user preference, recommended adjustable ranges of workstation settings for the general U.S. population were derived. Repeated measures ANOVA showed that pedaling had no significant effect on reading comprehension (p > 0.05), but had significant effect on typing performance (p < 0.001). A preferred level of cycling intensity was determined (mean 17.3 W, σ: 3.69).

Investigation of methods for estimating hand bone dimensions using X-ray hand anthropometric data.

This study examined two conversion methods, M1 and M2, to predict finger/phalange bone lengths based on finger/phalange surface lengths. Forty-one Korean college students (25 males and 16 females) were recruited and their finger/phalange surface lengths, bone lengths and grip strengths were measured using a vernier caliper, an X-ray generator and a double-handle force measurement system, respectively. M1 and M2 were defined as formulas able to estimate finger/phalange bone lengths based on one dimension (i.e., surface hand length) and four finger dimensions (surface finger lengths), respectively. As a result of conversion, the estimation errors by M1 presented mean 1.22 mm, which was smaller than those (1.29 mm) by M2. The bone lengths estimated by M1 (mean r = 0.81) presented higher correlations with the measured bone lengths than those estimated by M2 (0.79). Thus, the M1 method was recommended in the present study, based on conversion simplicity and accuracy.

Feasibility of using a compact elliptical device to increase energy expenditure during sedentary activities.

OBJECTIVES: This study aimed to evaluate the feasibility of using a compact elliptical device to increase energy expenditure during sedentary activities. A secondary aim was to evaluate if two accelerometers attached to the elliptical device could provide reliable and valid assessments of participants' frequency and duration of elliptical device use. DESIGN: Physically inactive adults (n=32, age range=25-65) were recruited through local advertisements and selected using stratified random sampling based on sex, body mass index (BMI), and age. METHODS: Indirect calorimetry was used to assess participants' energy expenditure while seated and while using the elliptical device at a self-selected intensity level. Participants also self-reported their interest in using the elliptical device during sedentary activities. Two Actigraph GT3X accelerometers were attached to the elliptical device to record time-use patterns. RESULTS: Participants expended a median of 179.1 kilocalories per hour while using the elliptical device (range=108.2-269.0), or a median of 87.9 more kilocalories (range=19.7-178.6) than they would expend per hour of sedentary sitting. Participants reported high interest in using the elliptical device during TV watching and computer work, but relatively low interest in using the device during office meetings. Women reported greater interest in using the elliptical device than men. The two accelerometers recorded identical time-use patterns on the elliptical device and demonstrated concurrent validity with time-stamped computer records. CONCLUSIONS: Compact elliptical devices could increase energy expenditure during sedentary activities, and may provide proximal environmental cues for increasing energy expenditure across multiple life domains.

Comparison of artificial neural network (ANN) and partial least squares (PLS) regression models for predicting respiratory ventilation: an exploratory study.

The objective of this study was to assess the potential for using artificial neural networks (ANN) to predict inspired minute ventilation (V(I)) during exercise activities. Six physiological/kinematic measurements obtained from a portable ambulatory monitoring system, along with individual's anthropometric and demographic characteristics, were employed as input variables to develop and optimize the ANN configuration with respect to reference values simultaneously measured using a pneumotachograph (PT). The generalization ability of the resulting two-hidden-layer ANN model was compared with a linear predictive model developed through partial least squares (PLS) regression, as well as other V(I) predictive models proposed in the literature. Using an independent dataset recorded from nine 80-min step tests, the results showed that the ANN-estimated V(I) was highly correlated (R(2) = 0.88) with V(I) measured by the PT, with a mean difference of approximately 0.9%. In contrast, the PLS and other regression-based models resulted in larger average errors ranging from 7 to 34%. In addition, the ANN model yielded estimates of cumulative total volume that were on average within 1% of reference PT measurements. Compared with established statistical methods, the proposed ANN model demonstrates the potential to provide improved prediction of respiratory ventilation in workplace applications for which the use of traditional laboratory-based instruments is not feasible. Further research should be conducted to investigate the performance of ANNs for different types of physical activity in larger and more varied worker populations.

Laboratory evaluation of a physiologic sampling pump (PSP).

Recently, physiologic sampling pumps (PSPs), which can adjust their sampling rates in proportion to wearers' minute ventilation (V[combining dot above](E)), have been proposed to better estimate exposure to airborne contaminants in the workplace. A laboratory evaluation was conducted to compare the performance of a new PSP with a traditional sampling pump (TSP) in an exposure chamber. Fifteen subjects (aged 19-36 years) performed two replicate sessions of step-tests for correlated and uncorrelated exposure scenarios on four separate days. When exposed to a scenario in which subject V[combining dot above](E) is highly correlated with m-xylene concentration over the sampling period (r = 0.93), the PSP-measured time-weighted average (TWA) concentrations are higher than TSP-measured concentrations (average ratio of PSP to TSP = 1.18). The ratio of PSP- and TSP-measured TWA concentrations for the uncorrelated scenario (r = 0.02) is closer to one, as expected, with an average value of 0.94. The test results of the linear mixed model further indicate that the performance of the PSP is unaffected by the anthropometric and physiological characteristics of the wearer. Potential differences in exposure estimates resulting from the use of the two instruments were examined in light of various schemes which can potentially occur in the field. With the capability of estimating the total volume of air inhaled over the sampling period with improved accuracy, PSPs show promise in reducing the inherent uncertainty in current risk assessment approaches that entail constant-flow (TSP) sampling approaches.

A novel physiologic sampling pump capable of rapid response to breathing.

The merits of using physiologic sampling pumps (PSPs) instead of using constant-flow sampling pumps, i.e., "traditional sampling pumps" (TSPs), are discussed. A novel PSP that overcomes shortcomings of previous PSP designs is presented. Calibrated valves are used to obviate pump inertia that has limited the system response and accuracy of prior work. Technologies that provide minute ventilation (V[combining dot above](E)) of subjects in real time may therefore be used to the limit of their own accuracies to sample inhalation exposures. Analysis of the design and data from a prototype are presented to show how air sampling can be modulated to follow breathing.

Backpack load limit recommendation for middle school students based on physiological and psychophysical measurements.

The load of student's backpacks has raised questions over the safety and health of schoolchildren everywhere. The purpose of this study is to use electromyography (EMG), posture evaluation, heart rate, and ratings of perceived exertion and perceptions of pain to find an acceptable backpack load limit for middle school students. Twenty middle school students aged 11 to 14 (10 female and 10 male) volunteered for the study. The subjects completed two tests, standing stationary and walking on a treadmill, where they carried 5% incremental loads from 0% body mass (BM) to 20% BM. The study indicated that the Borg-CR10 ratings and trunk flexion angle for the walking trial indicated a possible load limit of 10% BM due to the non-significant difference between 0 and 10% BM and the significant difference between 10 and 15% BM.

Electromyographic assessment of apple bucket intervention designed to reduce back strain.

The authors previously developed an apple bucket that was modified by use of a hip belt to reduce muscle fatigue. The intervention of belt use was accepted by workers and shown not to interfere with productivity. However, use of this intervention did not appear to reduce muscle fatigue when measured by tests of voluntary muscle strength. The purpose of the present study was to evaluate the intervention's effect on muscle fatigue employing surface electromyographic (EMG) amplitude. Amplitude measurements on 15 muscles were taken from 10 laboratory volunteers who were carrying a full bucket of apples, once while wearing the intervention belt and once without the intervention. These measurements were taken for seven different postures (four angles of trunk flexion (0 degrees , 20 degrees , 45 degrees , 90 degrees ) and three raised-arm positions (both up, dominant up, non-dominant up)) common to apple harvest work. Participants were measured in these conditions both with the bucket carried in front and with the bucket carried to the side. Significant reductions in amplitude favouring the intervention were seen for 11 of the 15 muscles in models considering the four body flexion angles. Ten of these were of the middle and lower back. These control/intervention differences were seen with both bucket-carrying positions (front vs. side) and tended to increase with increasing flexion angle. In contrast, no significant intervention effects were observed in models considering treatment by arm-raised position. One significant main effect (upper trapezius, side bucket) showed an amplitude reduction in the treatment condition. Another main effect showing increased amplitude in the intervention condition use was observed in the dominant levator scapulae (side bucket). Thus, the use of the intervention belt reduces EMG amplitude among a number of mid- and lower-back muscles. This is suggestive of a protective effect against back strain.

Exposure assessment by physiologic sampling pump--prediction of minute ventilation using a portable respiratory inductive plethysmograph system.

A study was conducted to evaluate a portable respiratory inductive plethysmograph (RIP) as a means to estimate minute ventilation (V(E)) for use in controlling the flow rate of a physiologic sampling pump (PSP). Specific aims were to: (1) evaluate the ability of the portable RIP system to measure V(E) using a direct (individual) fixed-volume calibration method (Direct RIP model), (2) develop and evaluate the performance of indirect (group) regression models for V(E) prediction using output data from the portable RIP and subject demographic characteristics (Indirect RIP model), and (3) compare V(E) estimates from indirect and direct portable RIP calibration with indirect estimation models published previously. Nine subjects (19-44 years) were divided into calibration (n = 6) and test (n = 3) datasets and performed step-tests on three different days while wearing the portable RIP and breathing through a pneumotachometer (reference). Minute ventilation and portable RIP output including heart rate, breathing rate, and a motion index were recorded simultaneously during the 80 minute sessions. Calibration data were used to develop a regression model for V(E) prediction that was subsequently applied to the test dataset. Direct calibration of the portable RIP system produced highly variable estimates of V(E) (R2 = 0.62, average % error = 15 +/- 50) while Indirect RIP model results were highly correlated with the reference (R2 = 0.80-0.88) and estimates of total volume were within 10% of reference values on average. Although developed from a limited dataset, the Indirect RIP model provided an alternative approach to estimation of V(E) and total volume with accuracy comparable to previously published models.

Laboratory evaluation of belt usage with apple buckets.

BACKGROUND: Migrant and seasonal orchard harvest workers experience musculoskeletal strain caused by carrying heavy loads and holding awkward postures. An ergonomic hip belt designed to redistribute weight from the upper back, neck, and shoulders to the hips was evaluated. METHODS: A comparison of muscle exertion (using electromyography [EMG]) of four key back and shoulder muscles and shoulder surface pressure (using a surface pressure sensor [PS]) was made among 10 laboratory volunteers under intervention and control conditions, in two postures (standing erect [0 degrees ]) and flexed [45 degrees ]). RESULTS: All but one measure showed a significant reduction in the flexed posture with the intervention. Two of eight measures showed a significant reduction in the erect posture. Correlations with shoulder discomfort were found for deep shoulder EMG (r=0.71, P=0.021) and shoulder surface pressure (r=0.58, P=0.082). CONCLUSIONS: The hip belt intervention produces significant reductions in muscle activity while in a posture commonly assumed during orchard work.

Evaluation of hook handles in a pulling task.

To evaluate the effect of handle design characteristics on subjective ratings and pulling forces, meat-hook handles with various handle shapes, sizes, and hook positions were tested in a pulling task. Finger and phalange force data measured by force sensitive resistors and subjective ratings of discomfort were also evaluated. Generally subjects preferred 37-mm double frustum, 30-mm oval handles followed by 30-mm double frustum handles, 37-mm oval, and 45-mm double frustum handles. In the analyses of total pulling force, 37- and 45-mm double frustum handles showed less required pulling force than the others. The averages of finger force contributions to the total pulling force were 27.2, 28.1, 23.9, and 20.8% in order from index to little fingers. The average of phalange force contributions were 28.8, 33.6, and 37.6% for the distal, middle, and proximal phalanges, respectively. The findings illustrate that the pulling finger forces and subjective discomfort ratings were related to the handle shape as well as handle size.

Evaluation of handles in a maximum gripping task.

Various hook handles were tested to evaluate the effect of handle design characteristics on subjective discomfort ratings and phalange forces in a maximum gripping task. A force glove system with 12 thin force sensitive resistor (FSR) sensors was used to measure phalange forces on the hook handles. Thirty subjects (15 males and 15 females) were tested, and generally subjects preferred 30 or 37 mm (the latter for large handed males) double frustrum handles followed by 30 mm oval handles, whereas overall they showed less preference for 37 mm oval handles and 45 mm double frustrum handles. The phalange force was more related to handle shape than to handle size in this study, i.e. the individual phalange forces on oval handles were about 8% higher than those on double frustum handles. The force distributions in the maximum gripping task showed significant differences in finger and phalange forces, in the order of middle, index, ring, and little fingers and distal, middle, and proximal phalanges from the highest to the lowest forces. The findings of this study may provide guidelines for designing double frustum handles for satisfying user's preference and oval handles for obtaining high phalange forces in a maximum gripping task.

The development of risk assessment models for carpal tunnel syndrome: a case-referent study.

The present study developed risk assessment models for carpal tunnel syndrome (CTS) which can provide information of the likelihood of developing CTS for an individual having certain personal characteristics and occupational risks. A case-referent study was conducted consisting of two case groups and one referent group: (1) 22 work-related CTS patients (W-CTS), (2) 25 non-work related CTS patients (NW-CTS), and (3) 50 healthy workers (HEALTHY) having had no CTS history. The classification of CTS patients into one of the case groups was determined according to the type of insurance covering their medical costs. Personal characteristics, psychosocial stresses at work, and physical work conditions were surveyed by using a questionnaire tailor-designed to CTS (reliability of each scale > or = 0.7). By contrasting the risk information of each case group to that of the referent group, three logistic regression models were developed: W-CTS/HEALTHY, NW-CTS/HEALTHY, and C-CTS/HEALTHY (C-CTS, the combined group of W-CTS and NW-CTS). ROC analysis indicated that the models have satisfactory discriminability (d' = 1.91 to 2.51) and high classification accuracy (overall accuracy = 83-89%). Both W-CTS/HEALTHY and C-CTS/HEALTHY include personal and physical factors, while NW-CTS/HEALTHY involves only personal factors. This suggests that the injury causation of NW-CTS patients should be attributable mainly to their 'high' personal susceptibility to the disorder rather than exposure to adverse work conditions, while that of W-CTS patients be attributable to improper work conditions and CTS-prone personal characteristics in combination.