On age-related muscle loss

readme.txt

From "Practical Programming for Strength Training" [1] by Mark
Rippetoe, one of the foremost authorities in the field:

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As humans advance beyond middle-age, some significant changes
generally occur. Sarcopenia (loss of muscle cells), increased body
fat, performance loss, and reduced flexibility are common effects of
aging. This is largely because the average adult has a greatly reduced
activity level and becomes increasingly sedentary, which leads to a
loss in muscle mass (atrophy); in the totally inactive older adult,
this loss is compounded by sarcopenia. The loss of functional muscle
causes a loss of performance. It has been demonstrated that about 15%
of performance capacity can be lost per decade with inactivity, and
even when activity is maintained at a relatively high level the loss
of performance proceeds with age. The logical extension of this
accumulating loss in performance is ultimately the loss of functional
mobility, unless steps are taken to prevent this as much as possible.

A significant aspect of the loss of muscle mass is the unfortunate
fact that the loss seems to be selective for the higher-threshold
motor units that contribute to power production. Coupled with the
changing quality of the connective tissues comprising the tendons and
ligaments, the practical result of this aging-related effect on the
program is the diminished capacity to use the clean and snatch
productively and the increased likelihood of tendon and joint injury
during any explosive or dynamic movements. Sports such as basketball,
racquetball, tennis, and soccer that active older people often enjoy
begin to pose a risk – one that is fortunately mitigated by getting
and staying stronger.

The loss of muscle also means the loss of metabolic machinery; muscles
account for most of the calories a healthy person burns daily, and
smaller muscles burn fewer calories. Most people don’t reduce the
amount of food they consume as activity diminishes, and the result is
an average increase in body fat of 2.5 to 3% per decade.

The loss of muscle mass has another insidious effect that becomes more
perceptible at an advanced age: a loss of proprioception and balance,
as well as the obvious loss of strength. The ability to process
information the body receives about its position in space is important
to performance for an athlete, and in an older adult it is crucial for
safety. And the ability to handle the weight of one’s own body mass –
keeping it in a position over the feet and handling the leverage
created between its center of mass and the balance point when its
position is changed – is an obvious function of strength. Both these
capacities are developed and maintained with exercise that requires
balance, coordination, and strength, and barbell training fits this
description perfectly.

In fact, barbell training is the best prescription for the prevention
of all of these age-related problems. Staying in (or getting into) the
gym slows the decay in muscle mass and pushes the onset of
pathological atrophy back for decades. Even in the 60- to 90-year-old
range, training reduces the loss of muscle mass to less than 5% per
decade. Several studies have shown that 80-year-olds who were inactive
but began training with weights actually gained muscle mass and
improved their strength, proprioception, and balance. This effect was
directly related to the amount of leg work included in the program and
the resulting improvements in leg strength. Leg strength was also
responsible for improving the ability to walk faster in older people.
In one study, twelve weeks of strength training was shown to increase
walking endurance by 38%, something walking by itself fails to do.

Less obvious to those unfamiliar with weight training is the fact that
lifting weights alone will improve flexibility. Moving through a
complete range of motion serves as a very effective dynamic stretch
while at the same time serving as a strength stimulus. This is most
useful for older trainees with marked loss of range of motion.
Osteoarthritis is a clinical condition caused by degenerative changes
in joints and a loss of joint function. Patients with arthritis
typically reduce their activity level to eliminate discomfort, which
actually exacerbates the condition. Several studies have shown that
increasing the strength of the musculature around an affected joint
decreases pain and improves function significantly. A number of these
studies used squats to reduce knee pain. [...]

The bottom line is that unless a person has significant pathology (is
terribly sick) or is post-geriatric (no longer living), that person
can benefit from a weight training program similar to those used with
younger populations at the same level of training advancement.

[1] https://www.goodreads.com/book/show/21400613-practical-programming-for-strength-training