Quadriceps muscle strength, contractile properties, and motor unit firing rates in young and old men

Roos, Martin R.; Rice, Charles L.; Connelly, Denise M.; Vandervoort, Anthony A.

doi:10.1002/(sici)1097-4598(199908)22:8<1094::aid-mus14>3.3.co;2-7

Cited by 42 publications

(58 citation statements)

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“…The selected atrophy of type II fibres is further supported by the evidence that in the older muscle there is a relative increase in slow myosin heavy chain (MHC) content (Klitgaard et al 1990). In agreement with the results of this study is also the slowing in the contractile properties, which has been demonstrated in various muscles of the lower limbs (Vandervoort and McComas 1986;Roos et al 1999) and in the adductor pollicis muscle ) by measuring the duration of twitch contraction. At the microscopic level of muscle analysis, this has been ascribed to a reduction in sarcoplasmic reticulum activity (Kiltgaard et al 1989;Delbono et al 1997;Hunter et al 1999) and actin sliding speed on myosin (Ho¨o¨k et al 2001).…”

Section: Discussionsupporting

confidence: 92%

Comparison between young and older women in explosive power output and its determinants during a single leg-press action after optimisation of load

Macaluso

Vito

2003

Eur J Appl Physiol

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Lower limb explosive power, which is more predictive of functional difficulties than strength per se with women being more at risk than men for disability, has been previously compared between young and older women using systems with fixed inertia. Individuals may have been obliged to use a percentage of their maximum strength that is not ideal for performing the movement at the optimum speed for maximum power output. This study was designed to compare explosive power output and its two determinants, optimal force and optimal speed, during a leg-press action between young and older women after optimising the load for maximum power production. The experiments were carried out on 20 women in good physical condition: 10 older, aged between 65 and 74 years and 10 young, aged between 18 and 30. Explosive power output was measured by setting the initial load at different percentages of maximum isometric strength and measuring the corresponding speed of movement during a leg-press action of the dominant leg. Maximum peak power, which was obtained at 60% of maximum isometric strength in both young and older women, was 61% lower in the older women ( P<0.0001). This was due to a 52% lower optimal force ( P<0.0001) and 21% lower optimal speed ( P<0.01). The ratio of peak power to maximum isometric strength was 22.1% lower in the older women ( P<0.01). After optimising the load, both lower speed of movement and lower strength determine the lower levels of power in older women. Power is more affected by ageing than isometric strength.

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Section: Discussionsupporting

confidence: 92%

Comparison between young and older women in explosive power output and its determinants during a single leg-press action after optimisation of load

Macaluso

Vito

2003

Eur J Appl Physiol

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“…The older muscle is not only atrophied, but is also slower (Vandervoort and McComas 1986;Narici et al 1991;Roos et al 1999), tetanizes at lower fusion frequencies Kamen et al 1995;Connelly et al 1999;Roos et al 1999), and is more resistant to isometric fatigue than the young muscle Bilodeau et al 2001a). Slowing in the contractile properties has been demonstrated in various muscles of the lower limbs (Vandervoort and McComas 1986;Roos et al 1999), and in the adductor pollicis muscle , by measuring the duration of twitch contraction.…”

Section: Muscle Size and Morphologymentioning

confidence: 99%

“…Slowing in the contractile properties has been demonstrated in various muscles of the lower limbs (Vandervoort and McComas 1986;Roos et al 1999), and in the adductor pollicis muscle , by measuring the duration of twitch contraction. Tibialis anterior, tibialis posterior (Vandervoort and McComas 1986) and vastus medialis ) are slower in individuals over 73 than in young people in their twenties, as demonstrated by the longer time taken not only to reach the peak of tension but also to relax after the twitch.…”

Section: Muscle Size and Morphologymentioning

confidence: 99%

“…As a result of slowing of relaxation and probably of type II fibre atrophy, it has been shown that muscles of older individuals demonstrate tetanic fusion, i.e. a maximum maintained contraction in response to repetitive stimulation, at lower frequencies of stimulation than is required for young adults, thus enabling the individual MUs to use lower firing frequencies to achieve a full contraction Kamen et al 1995;Connelly et al 1999;Roos et al 1999). Slowing of relaxation and type II atrophy may also explain why older people demonstrated more resistance to isometric fatigue that young individuals , a process which is referred to as the ''fatigue-paradox'' (Narici 1999).…”

Section: Muscle Size and Morphologymentioning

confidence: 99%

“…Scaglioni et al (2002) concluded that the impaired functionality of the reflex pathway with ageing, in addition to the lack of changes following resistance training as will be mentioned later in this review, suggests that the H max /M max ratio may be related to degenerative phenomena rather than physical deconditioning. At higher levels of the central nervous system, there are still conflicting results on the possibility of a reduction in the descending drive from supraspinal centres to the motoneurons during maximum voluntary contractions in older individuals, which would be a further explanation for the loss of muscle strength with ageing (Phillips et al 1992;De Serres and Enoka 1998;Connelly et al 1999;Harridge et al 1999b;Kent-Braun and Ng 1999;Roos et al 1999;Yue et al 1999;Bilodeau et al 2001a;Jakobi and Rice 2002;Scaglioni et al 2002). Some experimenters showed by a twitch interpolation technique, a method based on delivering one or a brief series of electrical stimuli to the motor axons of muscles during maximum voluntary contraction, that older adults were not able to maximally activate a muscle or muscle group (Harridge et al 1999b;Yue et al 1999;Bilodeau et al 2001a).…”

Section: Muscle Size and Morphologymentioning

confidence: 99%

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

2003

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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.

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Reduced plantarflexor specific torque in the elderly is associated with a lower activation capacity

Morse

Thom

Davis

et al. 2004

European Journal of Applied Physiology

149

137

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Previous studies have reported a decrease in muscle torque per cross-sectional area in old age. This investigation aimed at determining the influence of agonists muscle activation and antagonists co-activation on the specific torque of the plantarflexors (PF) in recreationally active elderly males (EM) and, for comparison, in young men (YM). Twenty-one EM, aged 70-82 years, and 14 YM, aged 19-35 years, performed isometric maximum voluntary contractions (MVC). Activation was assessed by comparing the amplitude of interpolated supramaximal twitch doublets at MVC, with post-tetanic doublet peak torque. Co-activation of the tibialis anterior (TA) was evaluated as the ratio of TA-integrated EMG (IEMG) activity during PF MVC compared to TA IEMG during maximal voluntary dorsiflexion. Triceps surae muscle volume (VOL) was assessed using magnetic resonance imaging (MRI), and PF peak torque was normalised to VOL (PT/VOL) since the later approximates physiological cross-sectional area (CSA) more closely than anatomical CSA. Also, physical activity level, assessed by accelerometry, was significantly lower (21%) in the elderly males. In comparison to the YM group, a greater difference in PT (39%) than VOL (19%) was found in the EM group. PT/VOL and activation capacity were respectively lower by 25% and 21% in EM compared to YM, whereas co-activation was not significantly different. In EM PT/VOL correlated with activation (R(2)=0.31, P<0.01). In conclusion, a reduction in activation capacity may contribute significantly to the decline in specific torque in the plantar flexors of elderly males. The hypothesis is put forward that reduced physical activity is partialy responsible for the reduced activation capacity in the elderly.

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Quadriceps muscle strength, contractile properties, and motor unit firing rates in young and old men

Cited by 42 publications

References 0 publications

Comparison between young and older women in explosive power output and its determinants during a single leg-press action after optimisation of load

Comparison between young and older women in explosive power output and its determinants during a single leg-press action after optimisation of load

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

Reduced plantarflexor specific torque in the elderly is associated with a lower activation capacity

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