Dynapenia

Dynapenia refers to an age-associated loss of muscle strength and power that is not caused by muscle mass loss or neurologic/muscular disease. It involves some key characteristics:

Primarily affects people over age 50 as part of sarcopenia, the degenerative loss of skeletal muscle with aging.
Involves both quantitative and qualitative changes in muscle. There can be fiber atrophy as well as reductions in contractile quality and power.
Caused by motor neuron remodeling, muscle fiber shifts, neuromuscular junction instability, excitation-contraction coupling dysfunction, and other aging processes.
Contributes significantly to decreased mobility and physical functional impairment seen in the elderly. Simple everyday tasks become increasingly challenging.
Associated with risk of adverse events like falling, bone fractures, becoming bedridden/immobilized leading to rapid progression into frailty and disability.
Can occur even with no measurable loss of muscle mass if muscle weakness arises from nervous system or intrinsic muscular aging.
Assessed by measuring grip strength by handgrip dynamometry which correlates to total body strength and future morbidity/mortality.
Exercise programs focusing on power training, eccentric exercises and maintaining fast-twitch muscle fibers may help prevent, slow or reverse dynapenia.

Detecting and addressing dynapenia early on can greatly impact healthy aging, independence, and quality of life in older demographics. Maintaining mechanical muscle quality is as important as muscle mass.

Based on current research, here are some key points about the prevalence of dynapenia:

Varies substantially depending on the population studied and diagnostic criteria used to define clinically significant muscle weakness.
When defined as grip strength below 26-32kg in men and below 16-21kg in women, estimates show dynapenia affects over 10-25% of people aged 60-80yrs.
May affect over 50% of men and 30% of women by age 80 per some estimates. Other estimates are more conservative at around 6-22% prevalence in those over age 65.
Tends to be higher in settings like nursing homes, hospitals and assisted living facilities - affects 30-60% of older adults in such settings.
In community settings, a review of multiple studies shows prevalence between 13-24% of older outpatient adults when more stringent weakness definitions are used.
Dynapenia rates vary by country and tend to track with ethnicity, undernutrition, baseline activity levels, socioeconomics and prevalence of comorbid diseases like diabetes.
Increased probability of dynapenia is associated with age over 60 years, obesity, sedentary lifestyles, depression, poor diet, chronic diseases, and a history of hospitalization.

Overall dynapenia is common among older adults, especially the frail and hospitalized. While robust standardized estimates are lacking, it likely affects at least 10-15% of adults globally over age 60. Addressing modifiable risk factors and exercise can help reduce incidence.

Here are some tips to help prevent dynapenia, which is the age-related loss of muscle strength:

Exercise regularly, especially strength training. Things like lifting weights, using resistance bands, bodyweight exercises, etc. can help maintain and even build muscle as you age. Aim for at least 2 strength sessions per week.
Eat adequate protein. Shoot for 0.5-0.7 grams of protein per pound of body weight daily to preserve muscle mass. Good sources include meat, fish, eggs, dairy, beans, lentils, etc.
Stay active in your daily life. Take the stairs, walk more, garden, etc. General physical activity keeps your muscles active.
Get enough sleep and manage stress. Lack of sleep and high stress can increase catabolism and muscle wasting.
Include vitamin D and antioxidant-rich foods in your diet. Vitamin D helps regulate protein synthesis and antioxidants reduce inflammatory damage.
Work on balance and mobility. Exercises that challenge your balance and mobility help tune the neural connections to your muscles.
See your doctor regularly. Check hormone, vitamin and mineral levels and rule out other treatable causes of muscle loss. Report new aches and pains.
Stay hydrated. Drink plenty of fluids, as dehydration can lead to muscle wastage over time.

The earlier you start preventative habits, the better! Consistency with the above strategies can help maintain strength.