Muscle strength, power and adaptations to resistance training in older people

Abstract

Muscle strength and, to a greater extent, power inexorably decline with ageing. Quantitative loss of muscle mass, referred to as "sarcopenia", is the most important factor underlying this phenomenon. However, qualitative changes of muscle fibres and tendons, such as selective atrophy of fast-twitch fibres and reduced tendon stiffness, and neural changes, such as lower activation of the agonist muscles and higher coactivation of the antagonist muscles, also account for the age-related decline in muscle function. The selective atrophy of fast-twitch fibres has been ascribed to the progressive loss of motoneurons in the spinal cord with initial denervation of fast-twitch fibres, which is often accompanied by reinnervation of these fibres by axonal sprouting from adjacent slow-twitch motor units (MUs). In addition, single fibres of older muscles containing myosin heavy chains of both type I and II show lower tension and shortening velocity with respect to the fibres of young muscles. Changes in central activation capacity are still controversial. At the peripheral level, the rate of decline in parameters of the surface-electromyogram power spectrum and in the action-potential conduction velocity has been shown to be lower in older muscle. Therefore, the older muscle seems to be more resistant to isometric fatigue (fatigue-paradox), which can be ascribed to the selective atrophy of fast-twitch fibres, slowing in the contractile properties and lower MU firing rates. Finally, specific training programmes can dramatically improve the muscle strength, power and functional abilities of older individuals, which will be examined in the second part of this review.

Comprehensive proteome analysis of human skeletal muscle in cachexia and sarcopenia: a pilot study

“…In elderly people, several of these conditions may co‐exist, and the cause of muscle wasting could not easily be allocated to a single condition. Hence, a molecular description of these different groups may hold the key to unequivocally differentiate between normal age‐related muscle loss and chronic disease‐related muscle wasting 5, 6, 7. Weight loss and muscle wasting as a result of chronic disease such as cancer, heart failure, renal failure, or chronic obstructive pulmonary disease is termed cachexia 8.…”

Muscle strength but not functional capacity is associated with plasma interleukin-6 levels of community-dwelling elderly women

“…Sarcopenia, which is defined as the loss of muscle mass related to old age, contributes to the loss of functional mobility and independence (4)(5)(6)(7). Due to the feminization of aging (i.e., more elderly women than men), sarcopenia occurs mainly among women (5).…”

Assessment of post-competition peak blood lactate in male and female master swimmers aged 40–79 years and its relationship with swimming performance

“…Ageing causes modifications in body composition that alter the muscle structure and reduce the ability to perform exercises requiring strength and power (Macaluso and De Vito 2004). Fat and connective tissue infiltrates the muscle and the muscle fibre composition changes with a decrease in the number of both type I and II fibres, coupled with the selective atrophy of type II fibres (Macaluso and De Vito 2004;Taylor et al 2004;Vandervoort 2002).…”

“…Fat and connective tissue infiltrates the muscle and the muscle fibre composition changes with a decrease in the number of both type I and II fibres, coupled with the selective atrophy of type II fibres (Macaluso and De Vito 2004;Taylor et al 2004;Vandervoort 2002). All these factors may have a role in the altered production and removal of lactate observed in the elderly.…”

“…swimming times: Donato et al 2003;Tanaka and Seals 1997). In addition, the information regarding the differences between sexes in master athletes is insufficient (Donato et al 2003) although this may represent an important topic of investigation considering that, compared to men, older women have a reduced capacity for strength and power generation and therefore a potential decrease in the ability to perform specific daily tasks (Macaluso and De Vito 2004;Skelton et al 1994). The measurement of post-competition [La] b in the master athletes of both genders could be a useful tool to further investigate the effects of ageing on muscle metabolism, especially when taking into consideration also the greater loss of muscular capacity and function present in women with respect to men.…”