This study investigated the relationships between thumb muscle activity and thumb operating tasks on a smartphone touch screen with one-hand posture. Six muscles in the right thumb and forearm were targeted in this study, namely adductor pollicis, flexor pollicis brevis, abductor pollicis brevis (APB), abductor pollicis longus, first dorsal interosseous (FDI) and extensor digitorum. The performance measures showed that the thumb developed fatigue rapidly when tapping on smaller buttons (diameter: 9 mm compared with 3 mm), and moved more slowly in flexion-extension than in adduction-abduction orientation. Meanwhile, the electromyography and perceived exertion values of FDI significantly increased in small button and flexion-extension tasks, while those of APB were greater in the adduction-abduction task. This study reveals that muscle effort among thumb muscles on a touch screen smartphone varies according to the task, and suggests that the use of small touch buttons should be minimised for better thumb performance.

Objective: To examine whether the psychological bene®ts of sports activity di er between tetraplegics and paraplegics with spinal cord injury, and investigate the e ect of frequency and modes of sports activity on the psychological bene®ts. Methods: The Self-rating Depression Scale (SDS), State-Trait Anxiety Inventory (STAI) and Pro®les of Mood States (POMS) were administered to 169 male individuals with spinal cord injury (mean age=42.7 years) including 53 tetraplegics and 116 paraplegics. The subjects were divided into four groups according to their frequencies of sports activity; High-active (more than three times a week; n=32), Middle-active (once or twice a week, n=41), Low-active (once to three times a month, n=32), and Inactive (no sports participation, n=64). Results: Analysis of variance revealed signi®cant di erences in depression for SDS, trait anxiety for STAI and depression and vigor for POMS among the groups. High-active group showed the lowest scores of depression and trait anxiety and the highest score of vigor among the four groups. In contrast, no signi®cant di erence was found for any psychological measurements between tetraplegics and paraplegics. In addition, there was no signi®cant di erence for any psychological measurements among modes (wheelchair basketball, wheelchair racing, wheelchair tennis and minor modes). Conclusions: These ®ndings demonstrated that sports activity can improve the psychological status, irrespective of tetraplegics and paraplegics, and that the psychological bene®ts are emphasized by sports activity at high frequency. Spinal Cord (2000) 38, 309 ± 314

This study quantified the interaction of electromyography (EMG) obtained from the vastus lateralis and metabolic energy cost of running (C r ; mL · [massϩ load] Ϫ1 · meter Ϫ1), an index of running economy, during submaximal treadmill running. Experiments were conducted with and without load on the back on a motor-driven treadmill on the downhill, level and uphill slopes. The obtained EMG was full-wave rectified and integrated (iEMG). The iEMG was divided into eccentric (ECC) and concentric (CON) phases with a foot sensor and a knee-joint goniometer. The ratio of ECC to CON (ECC/CON ratio) was regarded as the muscle elastic capacity during running on each slope. The C r was determined as the ratio of the 2-min steady-state VO 2 to the running speed. We found a significant decrease in the C r when carrying the load at all slopes. The ECC/CON ratio was significantly higher in the load condition at the downhill and level slopes, but not at the uphill slope. A significant gradient difference was observed in the C r (downϽlevelϽup) and ECC/CON ratio (downϭlevelϾuphill). Thus, an alteration of Cr by the gradient and load was almost consistent with that of the ECC/CON ratio. The ECC/CON ratio, but not the rotative torque (T ) functioning around the center of body mass, significantly correlated with C r (rϭϪ0.41, pϽ0.05). These results indicated that the ECC/CON ratio, rather than T, contributed to one of the energy-saving mechanisms during running with load.

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