A Defense Against Age-Related Slowing
The right kind of exercise can limit the biological damage created by a loss of function.
Age-related slowing of movement plays a critical role in the declining health of older adults. Slowing typically begins after age 62 with a marked decrease in gait velocity. It can lead to dysfunction, poor mental and physical health, a loss of independence and higher risk of mortality.
In older adults, fatal falls due to dysfunction more than doubled between 2000 and 2012, while nonfatal falls increased by 23%. Direct medical costs of fatal falls jumped more than 200%, while medical costs from nonfatal falls rose 58% (Burns, Stevens & Lee 2016). Clearly, age-related slowing goes beyond the risks for individuals, creating serious financial implications for the community.
As a fitness pro working with older adults, you need to understand the physiological changes that lead to age-related slowing. This knowledge will help you create effective exercise programs for older exercisers.
Exercise Recommendations for Age-Related Slowing
Optimal exercise programming can decelerate the degenerative biology of aging. First, make sure you understand the physiological changes of aging (see “Reaction Time and Brain Structural Changes” and “Neuromuscular Changes With Aging”). Then you can start focusing on motor-learning techniques to combat the physiological causes of age-related slowing. Developing motor-learning skills builds new cerebral connections, promotes development of new neural pathways and encourages the reinnervation of motor units—neurons and muscle that work together to produce motion. Power training is also very important, as function happens during quick movements, such as catching yourself when you fall.
Incorporating exercises that require the development of new motor skills leads to functional reorganization and the creation of new synaptic connections in the cerebrum (Wei et al. 2014). Moreover, exercises that emphasize skill development and movement complexity can increase function and decrease reaction times. Skill training has also been associated with increased neuromuscular drive and total neuromuscular activation, which can lead to faster, more powerful movements.
Skill development within an exercise program may be addressed separately (Islam et al. 2004) or in combination with strength and power training (Josephson & Williams 2017). Progression of skill-related exercises should be based loosely on the stability and complexity elements of Gentile’s taxonomy (Gentile 1987) (see “Arm Curl Progressions,” below). The taxonomy’s stability elements include body stability in early progressions and body transport in later progressions. Complexity elements begin with a closed, predictive environment and progress to an open, unpredictive environment.
Within these environments, tasks can have either no intertrial variability (all performed the same way) or intertrial variability (performed using multiple methods).
A loose application of Gentile’s taxonomy in a fitness setting can take several forms. Stability progressions should begin with a wide, stable base of support (BOS) and narrow as the client becomes more proficient. Unstable support apparatuses, like a rocker board or BOSU® Balance Trainer, should be added after the client masters a narrow BOS. A dynamic BOS can be added after the narrow base has been mastered.
Complexity progressions should begin with simple exercises in a predictable setting. The exercises can be progressed by adding alternating movements or intertrial variability, then adding secondary actions. Exercises can be further progressed by having the client repeat the same progressions in an open environment. The environment can be progressed by adding more unpredictable elements. This application of the overload principle creates an ongoing state of motor learning.
Give careful consideration to the timing of progressions. Motor activity without skill development creates new blood vessels but does not create new neural synapses. Therefore, ensure that the client has mastered a new skill before progressing.
The chart below provides sample progressions for a combined skill development and strength training exercise—a standing dumbbell supinated arm curl. Each category has multiple possible progressions. For example, a narrow BOS can be feet together, a heel/toe stance or a single-leg stance. Resistance level or movement velocity progressions can be intermixed with complexity/stability progressions to challenge strength and power.
The neuromuscular response to age-related slowing, which in part means a decrease in power, stems from dynapenia (Clark & Manini 2008), or a loss of fast-fatiguing/power motor units and a restructuring of muscle fiber. The literature tells us that power training is more effective than strength training in improving performance and function in older adults (Hazell, Kenno & Jakobi 2007). While one research group (Fiatarone et al. 1990) found that heavy resistance strength training increased maximum lower-extremity strength in frail, older adults three- to fourfold, increases in strength create a ceiling on rate-dependent functions (Buchner et al. 1996) such as gait speed.
High-speed, low-resistance power training is an effective way to change and maintain power motor units (Häkkinen et al. 2001) and to help older adults regain balance and function (Orr et al. 2006). Power-based programs should be performed at resistance levels less than 50% of one-repetition maximum, and they need not be performed to fatigue for functional improvement. Progressions can be based on a plateau of the number of repetitions during a timed set or on a 1-RM test every 2 weeks with resistance level adjusted accordingly.
Choose specific exercises based on the individual client’s wants and needs. Rather than dictating the exercises to be done, base your programming methods on power and skill development to better combat age-related movement slowing.
Exercise Puts the Brakes on Age-Related Slowing
Proper exercise is crucial to limiting the effects of age-related changes to human biology. Focus on exercises that require skill development, which helps the brain create new cerebral synapses. Apply the overload principle by adding complexity to movements, and subtract stability to improve muscular function.
Moreover, work on integrating high-speed, low-resistance power exercises that stimulate the use of fast-fatiguing motor units, which may initiate the re-innervation of denervated type II muscle fibers. All these efforts encourage the brain and body’s neuromuscular systems to preserve strength and slow the pace of aging.
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