The Effectiveness of Exercise Interventions for the Management of Frailty: A Systematic Review

This systematic review examines the effectiveness of current exercise interventions for the management of frailty. Eight electronic databases were searched for randomized controlled trials that identified their participants as “frail” either in the title, abstract, and/or text and included exercise as an independent component of the intervention. Three of the 47 included studies utilized a validated definition of frailty to categorize participants. Emerging evidence suggests that exercise has a positive impact on some physical determinants and on all functional ability outcomes reported in this systematic review. Exercise programs that optimize the health of frail older adults seem to be different from those recommended for healthy older adults. There was a paucity of evidence to characterize the most beneficial exercise program for this population. However, multicomponent training interventions, of long duration (≥5 months), performed three times per week, for 30–45 minutes per session, generally had superior outcomes than other exercise programs. In conclusion, structured exercise training seems to have a positive impact on frail older adults and may be used for the management of frailty

Ankle plantar flexion strength in resistance and endurance trained middle-aged adults

Comparaison de la force musculaire des muscles fléchisseurs de la cheville au cours d'actions excentriques et concentriques maximales, chez des sujets hommes et femmes agés de 49 ans en moyenne, engagés dans un programme d'entrainement aérobie avec port de charge ou dans un programme de renforcement musculaire

Increased residual force enhancement in older adults is associated with a maintenance of eccentric strength.

Despite an age-related loss of voluntary isometric and concentric strength, muscle strength is well maintained during lengthening muscle actions (i.e., eccentric strength) in old age. Additionally, in younger adults during lengthening of an activated skeletal muscle, the force level observed following the stretch is greater than the isometric force at the same muscle length. This feature is termed residual force enhancement (RFE) and is believed to be a combination of active and passive components of the contractile apparatus. The purpose of this study was to provide an initial assessment of RFE in older adults and utilize aging as a muscle model to explore RFE in a system in which isometric force production is compromised, but structural mechanisms of eccentric strength are well-maintained. Therefore, we hypothesised that older adults will experience greater RFE compared with young adults. Following a reference maximal voluntary isometric contraction (MVC) of the dorsiflexors in 10 young (26.1 ± 2.7 y) and 10 old (76.0 ± 6.5 y) men, an active stretch was performed at 15°/s over a 30° ankle joint excursion ending at the same muscle length as the reference MVCs (40° of plantar flexion). Any additional torque compared with the reference MVC therefore represented RFE. In older men RFE was ~2.5 times greater compared to young. The passive component of force enhancement contributed ~37% and ~20% to total force enhancement, in old and young respectively. The positive association (R(2) = 0.57) between maintained eccentric strength in old age and RFE indicates age-related mechanisms responsible for the maintenance of eccentric strength likely contributed to the observed elevated RFE. Additionally, as indicated by the greater passive force enhancement, these mechanisms may be related to increased muscle series elastic stiffness in old age

Eccentric and concentric strength in old (open bars) and young men (closed bars) relative to isometric strength.

<p>Values are Means ± standard error.</p

Voluntary evoked neuromuscular properties of the dorsiflexors.

<p>Old men had lower maximal voluntary isometric contraction (MVC) strength and concentric strength. Voluntary activation and antagonist coactivation (MVC Co-act) was not significantly different between groups. Eccentric strength was well maintained in old men relative to young and other contraction modes (ratio of eccentric to isometric strength; Ecc:Iso, ratio of eccentric to concentric strength; Ecc:Con). Passive force enhancement (PFE) was greater in old than young. Values are means ± standard deviation. * Denotes significant age difference.</p

Electrically evoked neuromuscular properties of the dorsiflexors.

<p>Old men had lower absolute evoked peak twitch torque (P_t), twitch potentiation (%), time to peak twitch (TPT), half-relaxation time (HRT) and 50Hz_HRT compared with young men. The 10Hz peak torque, 50Hz peak torque and 10∶50Hz ratio were not different between age groups. Values are means ± standard deviation. * Denotes significant age difference.</p

Residual force enhancement (RFE).

<p>Old men reached a steady state torque profile later than young men succeeding stretch and benefited from greater force enhancement in absolute and relative terms. Values are means ± standard deviation. * Denotes significant age difference. † Denotes steady state torque level.</p