Differences in the force/endurance relationship between young and older men

The aim of the present study was to ascertain ifin six young (23–35 years) and in six older (70–72 years)healthy men matched for comparable absolute andspecific maximal force of the dominant elbow flexors,differences in isometric endurance, myoelectrical fatigability,and shortening velocity are still recognizable. Toassess the specific force, the muscle cross sectional area(CSA) was determined from magnetic resonance imaging(MRI) scans. The performance of the elbow flexorswas studied by assessing the isometric endurance times(ET) at different percentages of maximal isometriccontraction (MVC), the average muscle fibre conductionvelocity of action potentials (CV), and the median frequency(MDF) of the surface electromyogram (sEMG)of the biceps brachii. Finally, the torque-velocity curvewas assessed by means of maximal isokinetic contractionsat six fixed angular velocities. All data wereexpressed as the mean (SD). The results showed that: (1)the ET was longer in the older subjects at the highestlevels of isometric contraction, independently from theabsolute force; (2) the modifications of muscle fibre CVduring isometric effort progressed less rapidly in theolder than the younger groups, as did those of MDF;and (3) at the same angular velocity, the older subjectsexerted less absolute force than the younger subjects.These results suggest an impairment of the neuromuscularsystem of older men, which is less powerful andless fatigable than that of young men.