Chord Keyboard Richard Wells

Complaints user-keyboard interface postures movements of the fingers, wrists, shoulders forces necessary to activate keys. R.P. Wells, P.J. Keir, A.E. Moore & D.A. Ranney, Muscle Activity in the Hand and Forearm using a Traditional and a Chording Keyboard, Marconi Keyboard Conference, 1996.

Ergonomic Issues Wrist Posture Ulnar deviation Extension Finger Range of Motion Repetitiveness muscle activity - frequency joint motion/tendon travel Force static load - wrist extensors key actuation force R.P. Wells, P.J. Keir, A.E. Moore & D.A. Ranney, Muscle Activity in the Hand and Forearm using a Traditional and a Chording Keyboard, Marconi Keyboard Conference, 1996.

Solutions? Modifications remapping the key configuration to reduce finger motion,( Dvorak) physical layout of the keys have been altered (eg. Kinesis, Apple Split, Microsoft Natural) Alternatives “chording” keyboards 8-10 key simultaneous key combinations (“chords”) requires learning of “new” system R.P. Wells, P.J. Keir, A.E. Moore & D.A. Ranney, Muscle Activity in the Hand and Forearm using a Traditional and a Chording Keyboard, Marconi Keyboard Conference, 1996.

Purpose The purpose of this phenomenological study is to quantify the activity of some of the major muscles responsible for keying in computer input tasks and the influence of a chord keyboard R.P. Wells, P.J. Keir, A.E. Moore & D.A. Ranney, Muscle Activity in the Hand and Forearm using a Traditional and a Chording Keyboard, Marconi Keyboard Conference, 1996.

Chord Keyboard Accukey 8 ternary keys simultaneous key combinations (“chords”)

Methods EMG surface (5 sites) fine wire (3 sites) wrist goniometry (not reported here) 2 keyboards generic 101- key Ternary Chord keyboard (“Accukey”) n = 8 males R.P. Wells, P.J. Keir, A.E. Moore & D.A. Ranney, Muscle Activity in the Hand and Forearm using a Traditional and a Chording Keyboard, Marconi Keyboard Conference, 1996.

Electromyography 5 surface sites first dorsal interosseous (FDI) extensor carpi ulnaris (ECU) common extensor site pronator teres (PT) forearm flexor 3 bipolar fine wire sites (index finger) lumbrical (LUM) palmar interosseus (PI) flexor digitorum profundus (FDP) R.P. Wells, P.J. Keir, A.E. Moore & D.A. Ranney, Muscle Activity in the Hand and Forearm using a Traditional and a Chording Keyboard, Marconi Keyboard Conference, 1996.

EMG Processing and Analysis Linear envelope processing Normalization to MVC Amplitude Probability Distribution Function (APDF) “Static” - 10th percentile “Dynamic” - 50th percentile “Peak” - 90th percentile ANOVA (SPSS) R.P. Wells, P.J. Keir, A.E. Moore & D.A. Ranney, Muscle Activity in the Hand and Forearm using a Traditional and a Chording Keyboard, Marconi Keyboard Conference, 1996.

Lumbrical Activity:Chord vs Standard Chord Standard R.P. Wells, P.J. Keir, A.E. Moore & D.A. Ranney, Muscle Activity in the Hand and Forearm using a Traditional and a Chording Keyboard, Marconi Keyboard Conference, *p<0.1, **p<0.05, ***p<0.01

Chord vs. Standard Palmar Interosseous Activity Chord Standard R.P. Wells, P.J. Keir, A.E. Moore & D.A. Ranney, Muscle Activity in the Hand and Forearm using a Traditional and a Chording Keyboard, Marconi Keyboard Conference, *p<0.1, **p<0.05, ***p<0.01

Chord vs. Standard Extensor Activity Chord Standard R.P. Wells, P.J. Keir, A.E. Moore & D.A. Ranney, Muscle Activity in the Hand and Forearm using a Traditional and a Chording Keyboard, Marconi Keyboard Conference, *p<0.1, **p<0.05, ***p<0.01

Chord vs. Standard Extensor Carpi Ulnaris Activity Chord Standard R.P. Wells, P.J. Keir, A.E. Moore & D.A. Ranney, Muscle Activity in the Hand and Forearm using a Traditional and a Chording Keyboard, Marconi Keyboard Conference, *p<0.1, **p<0.05, ***p<0.01

Chord vs. Standard Flexor Digitorum Profundus Activity Chord Standard R.P. Wells, P.J. Keir, A.E. Moore & D.A. Ranney, Muscle Activity in the Hand and Forearm using a Traditional and a Chording Keyboard, Marconi Keyboard Conference, *p<0.1, **p<0.05, ***p<0.01

Summary Trend to lower activation on the chord keyboard Extensors/ulnar deviators lower Intrinsic muscles lower or similar activation Flexor muscles similar or higher R.P. Wells, P.J. Keir, A.E. Moore & D.A. Ranney, Muscle Activity in the Hand and Forearm using a Traditional and a Chording Keyboard, Marconi Keyboard Conference, 1996.

Conclusions The ternary chord keyboard, under the conditions tested, appears to promote lower activations in many of the muscles of the forearm and hand BUT The results of this phenomenological study may not be representative of typical use by trained “chord” typists under field conditions R.P. Wells, P.J. Keir, A.E. Moore & D.A. Ranney, Muscle Activity in the Hand and Forearm using a Traditional and a Chording Keyboard, Marconi Keyboard Conference, 1996.