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Two-button computer mouse users may exhibit sustained, static finger lifting behaviours to prevent inadvertent activations by avoiding finger pressure on the buttons, which leads to prolonged, static finger extensor muscle loading. One hundred graduate students were observed during normal computer work ill a university computer facility to qualify and quantify the prevalence of lifted finger behaviours and extended finger postures, as well as wrist/forearm and grip behaviour, during specific mouse activities. The highest prevalences observed were 48% of the students lifted their middle finger during mouse drag activities, and 23% extended their middle finger while moving the mouse. In addition, 98%, of the students rested their wrist and forearm (77%) or wrist only (21%) on the workstation surface, and 97% had an extended wrist posture (15[degrees]-30[degrees]) when using the mouse. Potential applications of these findings include future computer input device designs to reduce finger lifting behaviour and exposures to risk factors of hand/forearm musculoskeletal pain. Keywords: Finger behaviour; Computer mouse use; Finger lifting prevalence

The human hand is inherently complex and versatile. Its use in everyday activities requires its careful positioning relative to the arm and fine adjustments of the fingers to secure the [...]

While professional musicians are generally considered to possess better control of finger movements than nonmusicians, relatively few reports have experimentally addressed the nature of this discrepancy in fine motor skills. For example, it is unknown whether musicians perform with greater skill than control subjects in all aspects of different types of fine motor activities. More specifically, it is not known whether musicians perform better than control subjects on a fine motor task that is similar, but not identical, to the playing of their primary instrument. The purpose of this study was to examine the accuracy of finger placement and accuracy of timing in professional musicians and nonmusicians using a simple, rhythmical, bilateral fingering pattern and the technology that allowed separate assessment of these two parameters. Professional musicians (other than pianists) and nonmusicians were given identical, detailed and explicit instructions but not allowed physically to practice the finger pattern. After verbally repeating the correct pattern for the investigator, subjects performed he task on an electric keyboard with both hands simultaneously. Each subject's performance was then converted to a numerical score. While musicians clearly demonstrated better accuracy in timing, no significant difference was found between the groups in their finger placement scores. These findings were not correlated with subjects' age, sex, limb dominance, or primary instrument (for the professional musicians). This study indicates that professional musicians perform better in timing accuracy but not spatial accuracy while executing a simple, novel, bimanual motor sequence.

Byline: R. Barkmann (1), W. Rohrschneider (2), M. Vierling (2), J. Troger (2), F. de Terlizzi (3), R. Cadossi (3), M. Heller (1), C.-C. Gluer (1) Keywords: Key words:Bone -- Children -- Growth -- Ultrasound Abstract: Quantitative ultrasound (QUS) of the finger phalanges is a useful tool in the assessment of disease- or age-related deterioration of bone. For studying the impact of juvenile diseases or growth disorders affecting the skeleton, a reference database for QUS parameters is needed. The aim of this study was to establish a calibrated reference database of parameters of transverse ultrasound transmission through juvenile finger phalanges. A total of 1328 children (650 females, 678 males ages 3--17 years) were measured in Heidelberg and Kiel in order to establish a German reference database. Highly significant gender-specific correlations (p&lt 0.0001) were found between the QUS parameters amplitude-dependent speed of sound (AD-SoS) and bone transmission time (BTT) versus age, body height and body mass index (BMI). For AD-SoS the correlation coefficients were R .sup.2= 0.64 against age in males and R .sup.2= 0.73 in females, R .sup.2= 0.60 against body height in males and R .sup.2= 0.68 in females, and R .sup.2= 0.19 against BMI in males and R .sup.2= 0.23 in females. For BTT the correlation coefficients were R .sup.2= 0.74 against age in males and R .sup.2= 0.79 in females, R .sup.2= 0.75 against body height in males and R .sup.2= 0.77 in females, and R .sup.2= 0.32 against BMI in males and R .sup.2= 0.35 in females. Age and height were the strongest determinants of QUS results. Gender-specific differences were observed in AD-SoS (significant for ages 11--14 years and for 150--170 cm body height) and in BTT (significant for ages 7 and 11--17 years and for 160--170 cm body height). Tables of QUS parameters versus age and height can serve as a basis for the evaluation of the impact of skeletal diseases or growth disorders on phalangeal QUS. Depending on the type of disease or growth disorder, measurement results can be compared with age- or height- specific reference data. In this way a simple and radiation-free assessment of juvenile skeletal disorders using quantitative ultrasound might be possible in the future. Author Affiliation: (1) Medizinische Physik, Klinik fur Diagnostische Radiologie, Universitatsklinikum Kiel, Kiel, DE (2) Padiatrische Klinik der Universitat Heidelberg, Heidelberg, Germany , DE (3) IGEA Biophysics Laboratory, Carpi, Italy, IT Article note: Received: 9 February 2001 / Accepted: 1 August 2001

In ergonomics, handgrip has been perceived as one of the most important hand functions; however, other types of functions of the hand are also important to the ergonomist, such as finger and manual dexterity, on which few ergonomic studies have been done. This experiment involved 60 male and female college students whose performance (number of pegs placed into a board in 30 sec.) of finger dexterity were statistically significantly different between the right and left hands and between women and men. The interaction of hand and sex was significant.

The present study was designed to examine the retention of relative force in the scaling of a serial force pattern in a finger-tapping sequence using an attenuated tap. On practice trials, i2 undergraduate students tapped a force plate connected to strain gauges that gave them feedback about the force. On test trials, participants recalled the force pattern (200 gm--200 gm-200 gm-100 gm) and the intertap interval (400 msec.) practiced during the practice period without the feedback (recalled task). Then, they adaptively produced a halved (halved task) or doubled force profile (doubled task) at the fixed intertap interval. Analyses showed that mean peak forces at the first three tap positions of the tapping sequence undershot the expected forces across all tasks. Hence, the ratios of the forces in Serial Positions 1:4, 2:4, and 3:4 were considerably lower than 2.0. This is a contextual effect suggesting that the last attenuated tap affected the first three taps of the tapping sequence. Thus, because the relative force of movements appears to be a weaker invariant feature than sequencing and relative timing for generalized motor program theory of Schmidt and Lee, this finding does not support the relative force for a generalized motor program.