Читать книгу Pathy's Principles and Practice of Geriatric Medicine - Группа авторов - Страница 190

Preserving muscle power output is critical to counteract the age‐related decline of functional capacity and also the earlier and more precipitous decline in muscle power and its associated disability relative to muscle strength in older men and (particularly) women. Muscle power output and rate of force development are strongly associated with the capacity to perform daily living activities in elderly populations.^92‐94 Indeed, strong associations between functional capacity test performance and muscle power output or rate of force development have been previously shown in the healthy elderly.^92‐94 More recently, it has been found that muscle power and explosiveness are also associated with functional capacity and incidence of falls in the oldest old populations, including the frail, institutionalised oldest old.^93‐95 Muscle power training should be prescribed in both healthy and frail elderly individuals, in combination with traditional slow concentric velocity resistance training, because this type of training optimises functional ability gains, reduces the incidence of falls, improves muscle strength and power output, and stimulates muscle hypertrophy.⁶

Optimal training regimens for maximising muscle power should be performed with the concentric phase as fast as possible, followed by a controlled slower eccentric phase, and emphasised in lower limbs.^96,97 The sets using explosive muscle actions can be performed alone^17,98 or combined with traditional resistance training during the same session, but always avoiding concentric failure.^96,99,100 Power is maximised at 30–45% loads for the upper extremity and 60–80% of peak force capacity (one repetition maximum or 1 RM) for the lower extremity extensors.^53,101 In a dose‐response study,¹⁰¹ it was shown that peak muscle power was improved similarly using light (20%), moderate (50%), or heavy (80%) resistances, whereas there was a dose‐response relationship between training intensity and muscle strength and endurance changes favouring high‐intensity training.¹⁰² Therefore, using heavy loads during explosive resistance training may be the most effective strategy to achieve simultaneous improvements in muscle strength, power, and endurance in older adults. In addition, power training at low loads (during which velocity is much faster) poses a risk of meniscus or tendon injuries if undiagnosed degenerative changes are present, as is common in older adults.^103,104

Several studies have used standard free weights and weight machines for power training,^17,96,105 but some studies used pneumatic resistance machines designed specifically for this type of resistance training,^106,107 resulting in similar neuromuscular and functional improvements.¹⁰⁸ As it is not possible to overcome resistance with momentum on such machines (as can be done by ‘swinging’ a free weight), they offer a theoretical and practical advantage. In the absence of such machines for power training, plyometric training (e.g., jumping up onto platforms/boxes) has traditionally been used in children and athletes for this purpose. However, arthritis and balance impairment preclude plyometrics in many frailer adults most in need of such muscle power improvements. As an alternative, the use of body weight as resistance (e.g., rising quickly from a chair) may be substituted as an initial strategy. It could start with slower execution and another person’s assistance but progress until the person can perform it alone and as fast as possible. This strategy may be easily performed in hospital rooms, at home, or in aged care residences. However, once body weight is no longer a sufficient overload of the capacity of lower extremity muscles, additional resistance provided by machines or free weights is needed to ensure progression.