In vivo physiological cross-sectional area and specific force are reduced in the gastrocnemius of elderly men.

Sarcopenia and muscle weakness are well-known consequences of aging. The aim of the present study was to ascertain whether a decrease in fascicle force (Ff) could be accounted for entirely by muscle atrophy. In vivo physiological cross-sectional area (PCSA) and specific force (Ff/PCSA) of the lateral head of the gastrocnemius (GL) muscle were assessed in a group of elderly men [EM, aged 73.8 yr (SD 3.5), height 173.4 cm (SD 4.4), weight 78.4 kg (SD 8.3); means (SD)] and for comparison in a group of young men [YM, aged 25.3 yr (SD 4.4), height 176.4 cm (SD 7.7), weight 79.1 kg (SD 11.9)]. GL muscle volume (Vol) and Achilles tendon moment arm length were evaluated using magnetic resonance imaging. Pennation angle and fiber fascicle length (Lf) were measured using B-mode ultrasonography during isometric maximum voluntary contraction of the plantar flexors. PCSA was estimated as Vol/Lf. GL Ff was calculated by dividing Achilles tendon force by the cosine of theta, during the interpolation of a supramaximal doublet, and accounting for antagonist activation level (assessed using EMG), Achilles tendon moment arm length, and the relative PCSA of the GL within the plantar flexor group. Voluntary activation of the plantar flexors was lower in the EM than in the YM (86 vs. 98%, respectively, P < 0.05). Compared with the YM, plantar flexor maximal voluntary contraction torque and Ff of the EM were lower by 47 and 40%, respectively (P < 0.01). Both Vol and PCSA were smaller in the EM by 28% (P < 0.01) and 16% (P < 0.05), respectively. Also, pennation angle was 12% smaller in the EM, whereas there was no significant difference in Lf between the YM and EM. After accounting for differences in agonists and antagonists activation, the Ff/PCSA of the EM was 30% lower than that of the YM (P < 0.01). These findings demonstrate that the loss of muscle strength with aging may be explained not only by a reduction in voluntary drive to the muscle, but mostly by a decrease in intrinsic muscle force. This phenomenon may possibly be due to a reduction in single-fiber specific tension.

[1]  H. Fujino,et al.  Formation of uniform nanoscale Si islands on a Si(111)-7×7 substrate , 1999 .

[2]  M Stokes,et al.  The size and strength of the quadriceps muscles of old and young men. , 1985, Clinical physiology.

[3]  W. Frontera,et al.  Skeletal muscle fiber quality in older men and women. , 2000, American journal of physiology. Cell physiology.

[4]  J. Lexell,et al.  Variability in muscle fibre areas in whole human quadriceps muscle: effects of increasing age. , 1991, Journal of anatomy.

[5]  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.

[6]  J. Kent‐Braun,et al.  Skeletal muscle contractile and noncontractile components in young and older women and men. , 2000, Journal of applied physiology.

[7]  M. Brown,et al.  Age-related changes in contractile properties of single skeletal fibers from the soleus muscle. , 1999, Journal of applied physiology.

[8]  P A Tesch,et al.  Changes in lower limb muscle cross-sectional area and tissue fluid volume after transition from standing to supine. , 1993, Acta physiologica Scandinavica.

[9]  M. Urbanchek,et al.  A specific force deficit exists in skeletal muscle after partial denervation , 2002, Muscle & nerve.

[10]  D. D. Thomas,et al.  Electron paramagnetic resonance reveals age-related myosin structural changes in rat skeletal muscle fibers. , 2001, American journal of physiology. Cell physiology.

[11]  P Capodaglio,et al.  Strength and power changes of the human plantar flexors and knee extensors in response to resistance training in old age. , 2003, Acta physiologica Scandinavica.

[12]  C. Maganaris,et al.  Effect of resistance training on skeletal muscle-specific force in elderly humans. , 2004, Journal of applied physiology.

[13]  G R Hunter,et al.  Evaluation of the strength-size relationship in vivo using various muscle size indices. , 2000, Medicine and science in sports and exercise.

[14]  P A Tesch,et al.  Effects of lower limb unloading on skeletal muscle mass and function in humans. , 1991, Journal of applied physiology.

[15]  G. Goldspink,et al.  Longitudinal growth of striated muscle fibres. , 1971, Journal of cell science.

[16]  S. Hunter,et al.  Human skeletal sarcoplasmic reticulum Ca2+ uptake and muscle function with aging and strength training. , 1999, Journal of applied physiology.

[17]  R. Gregor,et al.  In vivo moment arm calculations at the ankle using magnetic resonance imaging (MRI). , 1990, Journal of biomechanics.

[18]  A. Minetti,et al.  Assessment of human knee extensor muscles stress from in vivo physiological cross-sectional area and strength measurements , 2004, European Journal of Applied Physiology and Occupational Physiology.

[19]  A. Macaluso,et al.  Contractile muscle volume and agonist‐antagonist coactivation account for differences in torque between young and older women , 2002, Muscle & nerve.

[20]  C. Maganaris,et al.  Effect of aging on human muscle architecture. , 2003, Journal of applied physiology.

[21]  J. Kent‐Braun,et al.  Specific strength and voluntary muscle activation in young and elderly women and men. , 1999, Journal of applied physiology.

[22]  M. Urbanchek,et al.  Specific force deficit in skeletal muscles of old rats is partially explained by the existence of denervated muscle fibers. , 2001, The journals of gerontology. Series A, Biological sciences and medical sciences.

[23]  Matthew Harber,et al.  Single Muscle Fibre Contractile Properties in Young and Old Men and Women , 2003, The Journal of physiology.

[24]  C. Rice,et al.  Normalized force, activation, and coactivation in the arm muscles of young and old men. , 2001, Journal of applied physiology.

[25]  R. Lieber,et al.  Relationship between muscle fiber types and sizes and muscle architectural properties in the mouse hindlimb , 1994, Journal of morphology.

[26]  R. Woledge,et al.  Effect of age on voluntary force and cross-sectional area of human adductor pollicis muscle. , 1989, Quarterly journal of experimental physiology.

[27]  T. Fukunaga,et al.  Muscle architectural characteristics in women aged 20-79 years. , 2003, Medicine and science in sports and exercise.

[28]  P. Cerretelli,et al.  In vivo human gastrocnemius architecture with changing joint angle at rest and during graded isometric contraction. , 1996, The Journal of physiology.

[29]  Marco V. Narici,et al.  Reduced plantarflexor specific torque in the elderly is associated with a lower activation capacity , 2004, European Journal of Applied Physiology.

[30]  B. Saltin,et al.  The effect of ageing and immobilization on structure and function of human skeletal muscle fibres. , 2003, The Journal of physiology.

[31]  A A Vandervoort,et al.  Contractile changes in opposing muscles of the human ankle joint with aging. , 1986, Journal of applied physiology.

[32]  A J Sargeant,et al.  Differences in human antagonistic ankle dorsiflexor coactivation between legs; can they explain the moment deficit in the weaker plantarflexor leg? , 1998, Experimental physiology.

[33]  C. Maganaris.  Force‐length characteristics of the in vivo human gastrocnemius muscle , 2003, Clinical anatomy.

[34]  M. Narici,et al.  Tendon elongation influences the amplitude of interpolated doublets in the assessment of activation in elderly men. , 2005, Journal of applied physiology.

[35]  M. Narici,et al.  Changes in triceps surae muscle architecture with sarcopenia. , 2005, Acta physiologica Scandinavica.

[36]  T. Fukunaga,et al.  Muscle volume is a major determinant of joint torque in humans. , 2001, Acta physiologica Scandinavica.

[37]  O. Delbono,et al.  Excitation‐Ca2+ release‐contraction coupling in single aged human skeletal muscle fiber , 1997, Muscle & nerve. Supplement.

[38]  V R Edgerton,et al.  Specific tension of human plantar flexors and dorsiflexors. , 1996, Journal of applied physiology.

[39]  W. Frontera,et al.  Effects of aging on shortening velocity and myosin isoform composition in single human skeletal muscle cells. , 1997, The American journal of physiology.

[40]  C. Davies,et al.  Mechanical properties of young and elderly human muscle. , 2009, Acta medica Scandinavica. Supplementum.

[41]  F. Felici,et al.  Electromyogram changes during sustained contraction after resistance training in women in their 3rd and 8th decades , 2000, European Journal of Applied Physiology.

[42]  P. Esselman,et al.  Decline in isokinetic force with age: muscle cross-sectional area and specific force , 1997, Pflügers Archiv.

[43]  C. Maganaris,et al.  In vivo specific tension of human skeletal muscle. , 2001, Journal of applied physiology.

[44]  L. Tamil,et al.  An inverse‐scattering model for an all‐optical logic gate , 1991 .

[45]  J A Faulkner,et al.  Skeletal muscle weakness in old age: underlying mechanisms. , 1994, Medicine and science in sports and exercise.

[46]  M. Fujishima,et al.  Membrane currents evoked by histamine in rabbit basilar artery. , 1997, The American journal of physiology.

[47]  V. Edgerton,et al.  Muscle architecture of the human lower limb. , 1983, Clinical orthopaedics and related research.