Wrist strength is dependent on simultaneous power grip intensity

The effect of grip activities on wrist flexion/extension strength was examined. Twelve healthy subjects performed maximum wrist flexion/extension exertions with one of five levels of simultaneous grip effort: minimum effort; preferred effort; 30%, 60% and 100% maximum voluntary contraction. As grip force increased from the minimum to the maximum effort, average wrist flexion strength increased 34% and average wrist extension strength decreased 10%. It appears that the finger flexor tendons on the volar aspect of the wrist act agonistically in wrist flexion and act antagonistically to wrist extension. When an object gripped by the hand is fragile or uncomfortable, the reduced finger flexor activity will limit wrist flexion strength. Gripping a slippery object that requires high grip effort will result in reduced wrist extension strength. Grip force should be controlled during measurement of wrist flexion or extension strength. When analysing a task that involves both grip and wrist exertions, use of grip/wrist strength values that were measured during grip exertions only, or wrist exertions only, may incorrectly estimate the true grip/wrist strength, as grip and wrist activities significantly interact with each other as demonstrated in this paper.

[1]  Adam Siemieński,et al.  Muscular co-operation during joint stabilisation, as reflected by EMG , 2001, European Journal of Applied Physiology.

[2]  P. Helm.  Clinical mechanics of the hand , 1986 .

[3]  T. Milner,et al.  Wrist muscle activation patterns and stiffness associated with stable and unstable mechanical loads , 2004, Experimental Brain Research.

[4]  T. Milner.  Adaptation to destabilizing dynamics by means of muscle cocontraction , 2002, Experimental Brain Research.

[5]  Peter J Keir,et al.  Crosstalk in surface electromyography of the proximal forearm during gripping tasks. , 2003, Journal of electromyography and kinesiology : official journal of the International Society of Electrophysiological Kinesiology.

[6]  Scott L. Delp,et al.  A Model of the Upper Extremity for Simulating Musculoskeletal Surgery and Analyzing Neuromuscular Control , 2005, Annals of Biomedical Engineering.

[7]  S. Delp,et al.  How muscle architecture and moment arms affect wrist flexion-extension moments. , 1997, Journal of biomechanics.

[8]  J W Garrett,et al.  The Adult Human Hand: Some Anthropometric and Biomechanical Considerations , 1971, Human factors.

[9]  G. Ng,et al.  Effect of wrist positioning on the repeatability and strength of power grip. , 2001, The American journal of occupational therapy : official publication of the American Occupational Therapy Association.

[10]  T S Buchanan,et al.  Estimation of muscle forces about the wrist joint during isometric tasks using an EMG coefficient method. , 1993, Journal of biomechanics.

[11]  Robert J. Marley,et al.  Isokinetic strength characteristics in wrist flexion and extension , 2000 .

[12]  T. Armstrong,et al.  A conceptual model for work-related neck and upper-limb musculoskeletal disorders. , 1993, Scandinavian journal of work, environment & health.

[13]  Myung-Chul Jung,et al.  Maximal dynamic grip force and wrist torque: the effects of gender, exertion direction, angular velocity, and wrist angle. , 2006, Applied ergonomics.

[14]  W Rohmert,et al.  Problems in determining rest allowances Part 1: use of modern methods to evaluate stress and strain in static muscular work. , 1973, Applied ergonomics.

[15]  Effect of wrist positioning on isokinetic performance and repeatability of measurement for wrist flexors and extensors , 2000 .

[16]  S. Delp,et al.  Moment-generating capacity of upper limb muscles in healthy adults. , 2007, Journal of biomechanics.

[17]  S. Delp,et al.  Maximum isometric moments generated by the wrist muscles in flexion-extension and radial-ulnar deviation. , 1996, Journal of biomechanics.

[18]  J. Fridén,et al.  Human wrist motors: biomechanical design and application to tendon transfers. , 1996, Journal of biomechanics.

[19]  Myung-Chul Jung,et al.  The effect of wrist position, angular velocity, and exertion direction on simultaneous maximal grip force and wrist torque under the isokinetic conditions , 2002 .

[20]  P W Brand,et al.  The determination of moments for extension of the wrist generated by muscles of the forearm. , 1978, The Journal of hand surgery.

[21]  Bo Peterson,et al.  On a Model of the Upper Extremity , 1994 .

[22]  S. L. Lehman,et al.  An identified model for human wrist movements , 2004, Experimental Brain Research.

[23]  J. Cholewicki,et al.  Mechanical stability of the in vivo lumbar spine: implications for injury and chronic low back pain. , 1996, Clinical biomechanics.

[24]  A. Pénicaud,et al.  Reciprocal inhibition between wrist flexors and extensors in man: a new set of interneurones? , 1995, The Journal of physiology.

[25]  T. Milner,et al.  Inability to activate muscles maximally during cocontraction and the effect on joint stiffness , 2004, Experimental Brain Research.

[26]  M. Susan Hallbeck,et al.  The Effects of Gender, Wrist and Forearm Position on Maximum Isometric Power Grasp Force, Wrist Force, and their Interactions , 1995 .

[27]  C Fransson-Hall,et al.  Acceptability of Intermittent Handgrip Contractions Based on Physiological Response , 1994, Human factors.

[28]  T S Miles,et al.  Control of motor units in human flexor digitorum profundus under different proprioceptive conditions , 1997, The Journal of physiology.

[29]  E. Whelan,et al.  Normative study of grip and wrist flexion strength employing a BTE Work Simulator. , 1990, The Journal of hand surgery.

[30]  M. Hallbeck.  Flexion and extension forces generated by wrist-dedicated muscles over the range of motion. , 1994, Applied ergonomics.

[31]  Timothy J. Carroll,et al.  Task dependent gain regulation of spinal circuits projecting to the human flexor carpi radialis , 2005, Experimental Brain Research.

[32]  S. Kumar,et al.  Theories of musculoskeletal injury causation , 2001, Ergonomics.

[33]  V. Mathiowetz,et al.  Grip and pinch strength: normative data for adults. , 1985, Archives of physical medicine and rehabilitation.

[34]  D. Gravel,et al.  Maximal grip force in chronic stroke subjects and its relationship to global upper extremity function , 1999, Clinical rehabilitation.

[35]  W. Smith.  The Integrative Action of the Nervous System , 1907, Nature.