Comparison of maximal muscle strength of elbow flexors and knee extensors between younger and older men with the same level of daily activity

Felipe Romano Damas Nogueira,¹ Cleiton Augusto Libardi,^1,2 Felipe Cassaro Vechin,^1,2 Manoel Emílio Lixandrão,¹ Ricardo Paes de Barros Berton,¹ Thiago Mattos Frota de Souza,¹ Miguel Soares Conceição,¹ Claudia Regina Cavaglieri,¹ Mara Patricia Traina Chacon-Mikahil<sup>1

1</sup>School of Physical Education, State University of Campinas, ²School of Physical Education and Sport, University of São Paulo, São Paulo, Brazil

Background: Aging promotes neuromuscular loss, significantly reducing muscle strength. The magnitude of loss of strength seems to be different between the limbs, probably because of differences in activities of daily living (ADL). Therefore, the present study compared the muscle strength of the elbow flexors and knee extensors in younger (n = 7, mean age 23.3 ± 1.2 years) and older (n = 5, mean age 61.8 ± 2.6 years) men matched by ADL level.
Methods: The study participants performed maximal concentric, isometric, and eccentric contractions of the elbow flexors and knee extensors using an isokinetic dynamometer following a crossover study design. Changes in the dependent variables were compared using mixed model analysis (limb versus age).
Results: The main results demonstrated that concentric, eccentric, and mean contraction torques for knee extensors were significantly (P < 0.05) higher for younger men than for elderly men. On the other hand, no statistically significant difference (P > 0.05) was found in concentric, isometric, eccentric, and mean torques for elbow flexors between younger and older individuals.
Conclusion: These results show that elbow flexors maintain better strength than knee extensors through aging, even when comparing individuals with similar ADL levels.

Keywords: aging, sarcopenia, concentric contraction, isometric contraction, eccentric contraction