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Mandarins are picked by hand with the use of shears. An average mandarin picker makes at least 20,000 cuts daily. This daily workload on the upper limbs is the cause of occupational cervicobrachial disorders (OCD). In order to improve their working conditions, we devised two types of shears, one with a soft grip wrapped around the handle and another with shock reducing cushions in between the handles. The following two experiments were conducted. First we tested and compared the Borg scale and pinch meter scores of each participant by having them cut sticks as the same radius as those of mandarin stems using both the improved and conventional shears. Next, we placed two pressure sensors on each shear, where the middle finger and thumb contact the handles, to measure and compare the impact pressure within the hand. The results of the first experiment suggested that the improved shears reduces workload to the hand and fingers when comparing results to those of the conventional shears. The second experiment indicates that the shock reducing cushions reduces impact pressure to the hand from the handles when cutting.

We have developed a new armrest (NA) with adequate width supporting forearms, inclining upper surface, an area for mouse, and fixers at the edge of a shallow desk. We compared the cervicobrachial load among NA, NA with a mouse-pad (NAM) and a conventional palmrest with a mouse-pad (PRM) during word processing work. Seventeen healthy subjects operated a word processor for 1-h, alternately using 3 devices. EMG and subjective pain scores (PS) were recorded mainly from the right-side upper limb. EMG of the trapezius in PRM was significantly lower than in NAM; EMG of the anterior deltoideus (DELTa) in NA lower than in NAM; EMG of the medial deltoideus (DELTm) in NA lower than in PRM. The shoulder PS in NA/NAM was significantly lower than in PRM; the upper arm PS in NAM lower than in PRM; the forearm PS in NA/NAM lower than in PRM. These results suggest that NA reduces the cervicobrachial load than PRM.

Recently there has been an increasing incidence of occupational cervicobrachial disorders (OCD) and writer's cramp in office workers using ballpoint pens in writing operations. For the sake of workers who use ballpoint pens, it is essential to prevent such health hazards. It has been observed that a strong gripping pressure on the ballpoint pen significantly contributes to the development of these conditions. The present authors have been developing a new ballpoint pen by altering the grip area in such a way as to reduce the gripping pressure, and thus prevent OCD. The purpose of this study is to compare our ballpoint pen (new pen) with a conventional ballpoint pen (conventional pen) for the load that they exert on the upper limb during one hour of continuous writing. Electromyograms (EMG) and upper limb pain scores are used as indicators. The conventional pen used was selected from commercially available ballpoint pens widely used in offices. The grip area is cylindrical with an 8.3 mm diameter. It is manufactured of hard plastic, which can make it feel rigid and slippery to the user. The new pen has a cylindrical grip area that flares out at the bottom, near the pen-tip, and has a diameter ranging from 11.9-13.6 mm. In addition, the grip is constructed of a 2 to 3 mm-thick silicon rubber sleeve that is softer and less slippery in comparison with the conventional pen. Twelve students (5 males and 7 females) without any preexisting cervicobrachial disorders were asked to transcribe an English text for one hour, alternately using the two kinds of pens. The EMG of the flexor pollicis brevis was measured and recorded every second, while subjective pain scores were recorded every five minutes for the thumb, forefinger, middle finger, thenar, forearm extensor (forearm) and shoulder. The EMG of the flexor pollicis brevis and the pain scores for the thumb, forefinger, middle finger, forearm and shoulder were significantly lower for the new pen than for the conventional pen. These results suggest that after an hour of continuous writing, the new pen reduces the muscle load on the upper limb, and therefore mitigates fatigue in this area.

The purpose of this study is to compare a New pen (N pen) with a conventional pen (C pen) for the load on the upper limb during 1 h writing. EMG of flexor pollicis brevis and the pain scores for thumb, forefinger, middle finger, forearm and shoulder were significantly lower for N pen than for C pen.