Muscle fiber number in the biceps brachii muscle of young and old men

  title={Muscle fiber number in the biceps brachii muscle of young and old men},
  author={Cliff S Klein and Greg D. Marsh and Robert J. Petrella and Charles L Rice},
  journal={Muscle \& Nerve},
We have compared the number of muscle fibers in the biceps brachii muscle (BB) of six old men (82.3 ± 4.3 years) and six young men (21.2 ± 1.9 years). Muscle fiber number was estimated by dividing the maximal area of the BB, determined with magnetic resonance imaging, by the mean fiber area of the BB determined in a muscle biopsy. The percentage of type II fibers in the BB (∼60%) and the type I fiber area were not different between the groups. The BB area (−26%), type II fiber area (−24%), mean… 

Comparison of muscle mechanical and histochemical properties between young and elderly subjects.

The decrease of the specific power with age on the whole muscle would be compatible with the age-induced changes in the muscle histochemical characteristics, when data of both IIa and IIx fibers were considered.

Muscle endurance is greater for old men compared with strength-matched young men.

Findings indicate that the longer time to task failure for the old men when performing the submaximal contraction was not due the absolute target torque exerted during the contraction.

Effect of Age and Gender on Muscle Function : Analysis by Muscle Fiber Conduction Velocity

Age and gender differences must be considered when determining standard values of MFCV because of a tendency of delay in M FCV due to aging.

Functional Anatomy of Palmar Musculature

The results indicate that the PB is voluntarily activated during prehensile movements of the hand with significant changes in muscle architecture, which supports its proposed protective role as a muscular barrier to neurovasculature within the ulnar canal.

Responses of old men to repeated bouts of eccentric exercise of the elbow flexors in comparison with young men

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Difference in the magnitude of muscle damage between elbow flexors and knee extensors eccentric exercises.

The magnitude of muscle damage is greater and the recovery is slower following maximal eccentric exercise of the EF than of the KE for sedentary males and this may be because of the higher total eccentric work per muscle unit in elbow flexors.

Age independent and position-dependent alterations in motor unit activity of the biceps brachii

The results suggest that MU activity is modulated following a change in forearm position, but the response is similar in young and old adults.



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Muscle size and strength are important determinants ofCA in the humerus and forearm, and the lower CA in the ninth decade may be explained, in part, by reduced bone strains due to a smaller muscle mass.

Normalized force, activation, and coactivation in the arm muscles of young and old men.

Although the decline in PCSA explained the majority of strength loss in the old men, additional factors such as greater coactivation or reduced specific tension also may have contributed to the age-related loss of isometric strength.

Morphology of the brachial biceps muscle and elbow flexion in man.

The specific tension of the brachial biceps muscle averaged 33 N/cm2 with no demonstrable difference between subjects of widely different fibre compositions, suggesting that maximal tetanic tension is similar in fast- and slow-twitch fibres in man.

Intramuscular variation of fiber types in the brachial biceps and the lateral vastus muscles of elderly men: How representative is a small biopsy sample?

It was concluded that in the BB the site of a biopsy should be well defined, since, the incidence of fiber types varied systematically, and in the LV the biopsies should be large to permit a reliable estimate of the incidenceof fiber types.

Voluntary strength and muscle characteristics in untrained men and women and male bodybuilders.

Flexor CSA correlated negatively with the ratio of IT, PT, and W to CSA, and Muscle fiber composition failed to correlate with any measure of strength.

Histochemical and enzymatic comparison of the gastrocnemius muscle of young and elderly men and women.

Structural and biochemical changes probably contribute to the decreases in muscle mass, strength, and endurance often observed in healthy but sedentary older men and women.

Adaptations in the elbow flexors of elderly males after heavy-resistance training.

The results demonstrate that the skeletal muscles of elderly individuals can adapt to heavy-resistance exercise and do so by increases in both muscle size and strength.

Morphology and enzymatic capacity in arm and leg muscles in 78-81 year old men and women.

Correlation analysis showed that only a minor part of the reduction in body cell mass with age could be explained by a reduction in fibre areas and that a reduction with age of the number of muscle fibres of both fibre types must be assumed.

Fiber number and type composition in extensor digitorum longus, soleus, and diaphragm muscles with aging in Fisher 344 rats.

Findings bring into question published results that imply that decreasing fiber number and preferential loss of type II (a and b) fibers are typical aging phenomena.

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A follow‐up study of muscle strength, muscle morphology, and enzymatic activity in 23 men, 73–83 years of age, was performed 7 years after the first investigation and indicated a maintained metabolic capacity at high age.