Age‐related differences in twitch contractile properties of plantarflexor muscles in women

Abstract

This study compared maximal voluntary isometric strength and electrically evoked twitch characteristics of the plantarflexor muscles among the groups of women of the 3rd (n=14), 4th (n=13), 5th (n=11), 6th (n=12) and 8th (n=13) decade. A significant decrease (P < 0.05-0.001) has been found in isometric maximal voluntary contraction (MVC) force from the 5th decade and in twitch maximal force from the 6th decade. The 3rd decade group produced 72% greater MVC force and 43% greater twitch maximal force than the 8th decade group (P < 0.001). A prolongation (P < 0.01) in twitch contraction time was observed from the 5th decade. Twitch contraction time in the 3rd decade group was 16% shorter (P < 0.001) compared with the 8th decade group (P < 0.01). Twitch half-relaxation time did not differ significantly (P > 0.05) among the groups. A decrease (P < 0. 05-0.001) has been found in twitch maximal rate of force development from the 5th decade and in twitch maximal rate of relaxation from the 6th decade. The 3rd decade group produced 63% greater (P < 0. 001) twitch maximal rate of force development than the 8th decade group. It was concluded that in women a marked age-related reduction in maximal voluntary force-generating capacity of the plantarflexor muscles and speed of contraction of the electrically evoked twitch takes place after 40 years of age, while reduction in maximal force-generating capacity and speed of relaxation of the twitch occurs after 50 years of age.

Reproducibility and changes in twitch properties associated with age and resistance training in young and elderly women

“…We observed that the maximal force generating capacity of the knee extensors assessed as either MVC or PT was significantly reduced with age, which is in agreement with previous studies examining other muscle groups (Vandervoort & McComas, 1986; Doherty et al, 1993; Pääsuke et al, 2000). In our study, the reductions in MVC and PT were 29% and 26%, respectively.…”

“…All data reported were obtained following a thorough familiarization session conducted approximately 1 week before the first test session, which involved subjects performing the evoked twitch assessment and MVC protocols used during testing. The sample size employed in this study is sufficient for assessing measurement reproducibility as the number of subjects involved is highly comparable with previous studies examining evoked twitch properties and neuromuscular adaptations to resistance training (Alway et al, 1989; Rice et al, 1993; Roos et al, 1999; Pääsuke et al, 2000).…”

“…In addition to the reduction in MVC, ageing is also accompanied by changes in evoked twitch contractile properties, in which stimulated forces are often lower and the rate of contraction is slowed compared with young individuals (Roos et al, 1999). Such age changes in evoked twitch properties have been reported in a variety of muscle groups, including the ankle dorsiflexors (Vandervoort & McComas, 1986), ankle plantar flexors (Pääsuke et al, 2000), triceps surae (Klein et al, 1988), elbow flexors (Doherty et al, 1993), and gastrocnemius (Petrella et al, 1989). However, studies specifically examining age‐associated changes in evoked twitch properties of the knee extensors are limited and have not been adequately examined (Roos et al, 1999; Cannon et al, 2006).…”

Muscle strength testing: evaluation of tests of explosive force production

“…The conclusion that ''…ability to exert both isometric and dynamic peak force shares some structural and functional foundation with the ability to generate force rapidly'' (Haff et al 1997;p 269) was based on the positive relationship observed between RFD and maximum force recorded under both isometric and dynamic conditions. F max and RFD increase at a similar rate with maturation (Paasuke et al 2001), but decrease with fatigue (Zhou et al 1996) or aging (Paasuke et al 2000). Finally, the well known differences in F max observed between eccentric and isometric force production are also associated with similar differences in RFD (Pryor et al 1994).…”

Mudanças no desenvolvimento temporal da força em mulheres de diferentes faixas etárias

“…Essa redução associada ao declínio da velocidade da contração muscular são as maiores causas de debilidade funcional em idosos 2 . Adicionalmente, estudos têm demonstrado que a habilidade de gerar força rapidamente pode ser mais funcionalmente relevante do que a capacidade de gerar força máxima 3,4 , uma vez que muitas das atividades da vida diária são caracterizadas pelo limitado tempo de desenvolvimento de força (50-200ms), o qual é consideravelmente menor do que o necessário para alcançar a força máxima (≥ 300 ms) 5 .…”