An exponential model of isometric muscular fatigue as a function of age and muscle groups.

Despite the recommendations that an important design criterion is not to exceed 15% of an operator's maximum voluntary contraction (MVC) with any muscle that must be used for a long period of time, many tasks involve the exertion of much higher forces coupled with long-term contractions. Many studies have investigated the force-time relationship of isometric muscle contractions to determine the endurance time of a given relative force. To date, however, direct studies of muscle performance throughout fatiguing tasks have not been conducted to the same degree. This research was concerned with studying the effects of different muscle groups (biceps vs quadriceps) of subjects with different age groups (20-29 vs 50-59 years of age) on long-term muscular isometric contractions at different levels of %MVC (20%, 40%, 60%, 80%, and 100% MVC), and modelling the functional data to describe the time course of strength decrement. The data revealed that the time course of strength decrement was best modelled by the function: [formula: see text] An experiment, using 20 subjects with each subject performing 10 conditions (two muscle groups x five levels of %MVC), showed that this function accounted for over 95% of the variance of strength decrement. All parameter estimates were statistically significant.

[1]  Franklin M. Henry,et al.  Prediction of World Records in Running Sixty Yards to Twenty-Six Miles , 1955 .

[2]  A. McComas,et al.  Extent of motor unit activation during effort. , 1981, Journal of applied physiology: respiratory, environmental and exercise physiology.

[3]  C. D. De Luca,et al.  Behaviour of human motor units in different muscles during linearly varying contractions , 1982, The Journal of physiology.

[4]  H P Clamann,et al.  Activity of single motor units during isometric tension , 1970, Neurology.

[5]  D B Chaffin,et al.  Ergonomics guide for the assessment of human static strength. , 1975, American Industrial Hygiene Association journal.

[6]  W. Kroll,et al.  Age, isometric knee extension strength, and fractionated resisted response time. , 1978, Experimental aging research.

[7]  V. Edgerton,et al.  Motor Unit Properties and Selective Involvement In Movement , 1975, Exercise and sport sciences reviews.

[8]  A. R. Lind,et al.  Aging, isometric strength and endurance, and cardiovascular responses to static effort. , 1975, Journal of applied physiology.

[9]  J. Hannerz,et al.  The fatigue and voluntary discharge properties of single motor units in man , 1981, The Journal of physiology.

[10]  L. Larsson.  Morphological and functional characteristics of the ageing skeletal muscle in man. A cross-sectional study. , 1978, Acta physiologica Scandinavica. Supplementum.

[11]  Louis D. Silverstein,et al.  Changes in Electromyographic Activity Associated with Occupational Stress and Poor Performance in the Workplace , 1987, Human factors.

[12]  D. Chaffin.  Localized muscle fatigue--definiton and measurement. , 1973, Journal of occupational medicine. : official publication of the Industrial Medical Association.

[13]  R. Stein,et al.  Changes in firing rate of human motor units during linearly changing voluntary contractions , 1973, The Journal of physiology.

[14]  A. R. Lind,et al.  The duration of sustained contractions of the human forearm at different muscle temperatures , 1958, The Journal of physiology.

[15]  Relation between force and fatigability of red and pale skeletal muscles in man. , 1979 .

[16]  Histochemical and Ultrastructural Changes in Senile Human Skeletal Muscle , 1977, Journal of the American Geriatrics Society.

[17]  D. Chaffin,et al.  A proposed standard procedure for static muscle strength testing. , 1974, American Industrial Hygiene Association journal.

[18]  L Sperling,et al.  Muscle function in old age. , 1978, Scandinavian journal of rehabilitation medicine. Supplement.

[19]  H. Monod,et al.  Capacité de travail statique d'un groupe musculaire synergique chez l'homme. , 1957 .

[20]  J Rutenfranz,et al.  Occupational health studies on airport transport workers , 1980, International archives of occupational and environmental health.

[21]  J. Bergstrom.  MUSCLE ELECTROLYTES IN MAN DETERMINED BY NEUTRON ACTIVATION ANALYSIS ON NEEDLE BIOPSY SPECIMENS , 1962 .

[22]  L. Larsson,et al.  Isometric and dynamic endurance as a function of age and skeletal muscle characteristics. , 1978, Acta physiologica Scandinavica.

[23]  W. W. Tuttle,et al.  Relation of maximum grip strength to grip strength endurance. , 1950, Journal of applied physiology.

[24]  R B Stein,et al.  The orderly recruitment of human motor units during voluntary isometric contractions , 1973, The Journal of physiology.

[25]  A Thorstensson,et al.  Relationship between isometric endurance and fibre types in human leg muscles. , 1975, Acta physiologica Scandinavica.

[26]  A. R. Lind,et al.  Muscle fatigue and recovery from fatigue induced by sustained contractions , 1959, The Journal of physiology.

[27]  L. Larsson,et al.  Muscle strength and speed of movement in relation to age and muscle morphology. , 1979, Journal of applied physiology: respiratory, environmental and exercise physiology.

[28]  C. Drury,et al.  A methodology for muscular isometric endurance and fatigue research , 1990 .

[29]  Michael J. O'Donovan,et al.  Motor unit organization of human medial gastrocnemius. , 1979, The Journal of physiology.

[30]  E Jansson,et al.  Metabolic characteristics of fibre types in human skeletal muscle. , 1975, Acta physiologica Scandinavica.

[31]  L S Caldwell.  Decrement and Recovery with Repetitive Maximal Muscular Exertions , 1970, Human factors.

[32]  A. Thorstensson,et al.  Force-velocity relations and fiber composition in human knee extensor muscles. , 1976, Journal of applied physiology.

[33]  Time to Maximal Voluntary Isometric Contraction (MVC) For Five Different Muscle Groups in College Adults , 1983 .

[34]  Alastair Heron,et al.  Age and function , 1967 .

[35]  I Petersén,et al.  Muscular reaction to welding work: an electromyographic investigation. , 1976, Ergonomics.

[36]  V. Edgerton,et al.  Histochemical, biochemical, and contractile properties of red, white, and intermediate fibers. , 1971, The American journal of physiology.

[37]  M. Johnson,et al.  Data on the distribution of fibre types in thirty-six human muscles. An autopsy study. , 1973, Journal of the neurological sciences.

[38]  P D Gollnick,et al.  Selective glycogen depletion in skeletal muscle fibres of man following sustained contractions , 1974, The Journal of physiology.

[39]  A. Monster,et al.  Activity patterns of human skeletal muscles: relation to muscle fiber type composition. , 1978, Science.

[40]  C G Drury,et al.  Handle positions in a holding task as a function of task height. , 1985, Ergonomics.

[41]  J. Royce.  Isometric Fatigue Curves in Human Muscle with Normal and Occluded Circulation , 1958 .

[42]  J. Hannerz,et al.  Firing rate and recruitment order of toe extensor motor units in different modes of voluntary conraction. , 1977, The Journal of physiology.

[43]  V. Edgerton,et al.  THE INTERMEDIATE MUSCLE FIBER OF RATS AND GUINEA PIGS , 1969, The journal of histochemistry and cytochemistry : official journal of the Histochemistry Society.

[44]  W. W. Tuttle.  Effect of physical training on capacity to do work as measured by the bicycle ergometer. , 1950 .