High Density Surface Electromyography Activity of the Lumbar Erector Spinae Muscles and Comfort/Discomfort Assessment in Piano Players: Comparison of Two Chairs

Introduction: At a professional level, pianists have a high prevalence of playing-related musculoskeletal disorders. This exploratory crossover study was carried out to assess and compare quantitatively [using high density surface electromyography (HDsEMG)], and qualitatively (using musculoskeletal questionnaires) the activity of the lumbar erector spinae muscles (ESM) and the comfort/discomfort in 16 pianists sitting on a standard piano stool (SS) and on an alternative chair (A-chair) with lumbar support and a trunk-thigh angle between 105° and 135°.Materials and Methods: The subjects played for 55 min and HDsEMG was recorded for 20 s every 5 min. For the quantitative assessment of the muscle activity, the spatial mean of the root mean square (RMSROA) and the centroid of the region of activity (ROA) of the ESM were compared between the two chairs. For the qualitative assessment, musculoskeletal questionnaire-based scales were used: General Comfort Rating (GCR); Helander and Zhang’s comfort (HZc) and discomfort (HZd); and Body Part Discomfort (BPD).Results: When using the A-chair, 14 out of 16 pianists (87.5%) showed a significantly lower RMSROA on the left and right side (p < 0.05). The mixed effects model revealed that both chairs (F = 28.21, p < 0.001) and sides (F = 204.01, p < 0.001) contributed to the mean RMSROA variation by subject (Z = 2.64, p = 0.004). GCR comfort indicated that participants found the A-Chair to be “quite comfortable,” and the SS to be “uncomfortable.” GCR discomfort indicated that the SS caused more numbness than the A-Chair (p = 0.05) and indicated the A-Chair to cause more feeling of cramps (p = 0.034). No difference was found on HZc (p = 0.091) or HZd (p = 0.31) between chairs. Female participants (n = 9) reported greater comfort when using the A-Chair than the SS (F = 7.09, p = 0.01) with respect to males. No differences between chairs were indicated by the BPD assessment.Conclusion: It is concluded that using a chair with lumbar support, such as the A-chair, will provide greater comfort, less exertion of the ESM and less discomfort than the standard piano stool.

Health View to Decrease Negative Effect of High Heels Wearing: A Systemic Review

Effective recommendations about how to decrease adverse effects of high heels (HH) need to be provided, since wearing HH is inevitable for most women in their daily life, regardless of their negative impacts on the foot morphology. The main purpose of this systematic review was to summarize studies which have provided specific information about how to effectively offset the negative effects of wearing HH, in the case of women, by means of examining heel height, insole, and heel base support (HBS). Some evidence indicate the following: (i) the range of appropriate heel height for HH shoes is 3.76 cm to 4.47 cm; (ii) compared to small HBS, the larger ones effectively increase gait stability, reduce risk of ankle injury, and improve comfort rating during HH walking; and (iii) the use of a total contact insert (TCI) significantly decreases plantar pressure and the impact on the foot, resulting in higher perceived comfort. It must be noted that these results are based on short-term research; therefore, any conclusions with regard to effects in the long term should be taken with a grain of salt. Nevertheless, future studies should be aimed at combining numerical and experimental methods, in order to provide personal recommendations for HH shoes by considering heel height and HBS size, based on the individual characters (weight, height, and age).

A study of hand-movement gestures to substitute for mouse-cursor placement using an inertial sensor

This paper examines the new study of hand orientation as a substitute for computer-mouse movement and is evaluated based on ISO/TS 9241 part 411: Ergonomics of human–system interaction-evaluation methods for the design of physical input devices. Two pairs of hand-orientation candidates were evaluated, using, for example, pitch–roll and pitch–yaw to substitute for up–down and left–right mouse-cursor movements. The up–down cursor movement was generated from the pitch orientation, while the left–right cursor movement was generated from the roll or yaw orientation, depending on the evaluation of the proposed gesture. The research employed a standard computer mouse as a baseline comparison for the study. The empirical study was conducted to evaluate quantitative performance such as throughput and movement time. The best impression resulted when the throughput had the greatest value as well as the shortest movement time. The performance test was based on Fitts's law using a multi-directional tapping test as suggested by ISO/TS 9241-411. The test was divided into several levels of difficulty, including high, medium, low, and very low. The other assessment is qualitative and was performed using the comfort-rating scale questionnaire and rating of perceived exertion of comfortability and fatigue. The quantitative results show that pitch–yaw throughput is slightly higher than for the pitch–roll gesture, and that the movement time in pitch–yaw is slightly less than in pitch–roll, although there is no statistically significant difference between the two. We also found that pitch–yaw movements have a higher level of comfort based on the comfort-rating scale test. Since the test was divided into levels of difficulty, we identified those gestures suitable for the task with a low and very low level of difficulty based on throughput, movement time, and error-rate results. Finally, this study suggests that pitch–roll and pitch–yaw movements of the hand can be used as substitutes for the mouse, and that pitch–yaw movements are superior in regard to causing less fatigue than pitch–roll movements. Furthermore, this study provides a new suggestion for a suitable level of difficulty when using an inertial sensor as an emulator for the movement of a mouse cursor in the field of human–computer interaction.

Evaluation Method for Thermal Environment in Residential Houses Using Score on Warmth

The purpose of this study is to verify whether the score on warmth corresponds to the actual rating of subjects with regard to thermal comfort and satisfaction. Experiments were carried out in an experimental house in a climate chamber under five different thermal conditions, in which different combinations of air and floor temperatures were controlled by floor heating or air-conditioning systems. Twenty-four subjects rated their thermal sens2ation and satisfaction in each condition, and evaluated the thermal environment on a 100-point scale. The results of this experiment are as follows. It was suggested that score on warmth based on operative temperature and floor temperature more appropriately evaluates the living environment in Japan than the Predicted Mean Vote model, which assumes uniformity of the thermal environment. The score on warmth is considered a useful thermal environment index, which evaluates the comfort and satisfaction of residential houses in Japan. The score on warmth was 2.8 points when the percentage of comfort rating was more than 80%, and was 3.0 points when the percentage was more than 90%. In conclusion, these results show that it is possible to predict the risk of catching a cold in winter using the score on warmth.

In-situ Study of Seating Static Comfort in Passenger Vehicles

In today’s automotive market, comfort is huge selling point of a vehicle. Priority is given by buyers to how comfortable a seat feels during purchase decisions. The measure of comfort is harmonious mix of many aspects such as human ergonomics and physiological factors. However, a gap still exists between objective and subjective measures due to lack of emphasis by past researchers. This is particularly obvious in the lumbar support feature that has still not been able to address the health problems related to driving. This project focuses on bridging the gap by giving users the ability to define true preferred posture in realistic settings. This is done by the creation of a apparatus that allows users to individually manipulate the seat contour for optimum support in more segments than just lumbar area. The experiment is performed in 3 parts, where in each part different segments of the apparatus are manipulatable (lumbar segment, sacral & thoracic segment, and all segments). Sixty human subjects’ statistics are recorded (gender, age, BMI and height) and the subjects are palpated to locate internal joints. These joints are marked and postural angles between them are measured using a goniometer. In each seat configuration, the angles are measured and a comfort rating is taken to be compared. It was found that the posture angles are different among the 3 experiments, and there is a change in comfort felt. Some human factors have also been proven to contribute heavily to angles chosen by occupants.