Healthy Muscle Aging Research Analysis

Q: Which other factors affect healthy muscle aging?

Obesity,[15] a low BMI,[16] smoking,[16] insufficient or excessive sleep,[17] and lower blood vitamin D levels[18] have all been associated with an increased risk of sarcopenia. Therefore, maintaining a healthy body weight, sleeping 6–8 hours per night, not smoking (or working toward quitting), and getting enough vitamin D in the diet and regular sunlight exposure are all important for supporting healthy muscle aging.

Q: What changes in muscle contribute to a loss of function with aging?

A progressive loss of muscle mass and function generally begins around the fourth to fifth decade of life, and the rate of decline increases with advancing age.[19] The rate of the age-related decline in muscle strength (about 1%–3% per year) and power (about 3%–4% per year) exceeds that of muscle loss (about 0.5%–1.5% per year).[19] What mechanisms explain this comparatively accelerated loss of muscle strength and power (i.e., muscle function)? Total muscle mass and muscle strength are strongly correlated,[20][21] so one might expect that the rate of decline for muscle mass and muscle strength would be more similar than they are. The primary reason for this discrepancy seems to be the type of muscle atrophy occurring. Muscle fibers come in different types based on their speed of contraction and metabolism, and they are generally categorized as slow-twitch (type I) and fast-twitch (type II). Type I muscle fibers contract relatively slowly and are more resistant to fatigue, whereas type II muscle fibers contract with more velocity and produce significantly more power but are quick to fatigue. Older adults predominantly experience a reduction in the size of type II muscle fibers, while type I muscle fiber size (and perhaps even their potential for hypertrophy) is preserved.[19] Furthermore, there’s evidence to suggest that type II muscle fibers in older adults are less sensitive to calcium,[22][23][24] which is detrimental for force production, as calcium triggers muscle contraction. Other factors thought to contribute to the decline in muscle function with aging are a progressive increase in myosteatosis (i.e., fat infiltration within skeletal muscle),[25] satellite cell loss and dysfunction,[26][27] and mitochondrial dysfunction.[28]

Q: How should resistance exercise be structured to support healthy muscle aging?

Resistance exercise using relatively heavy loads (≥70% of 1-repetition maximum) is undeniably effective for increasing muscle mass and strength and improving physical performance.[29][7][8] However, some individuals are apprehensive about lifting heavy loads due to the risk of injury — particularly when performed without oversight from a personal trainer — while others don’t have access to a gym. Fortunately, emerging evidence suggests that lifting relatively light loads (approximately 35%–50% of 1-repetition maximum) exerts similar benefits,[30][9] particularly when each set is performed to volitional fatigue. This suggests that meaningful improvements in muscle mass, strength, and physical performance can be achieved by performing resistance exercise using one’s own body weight or with minimal equipment (e.g., ankle weights, elastic bands), as long as the individual is exerting a high degree of effort during their workouts. It’s recommended that from midlife on, adults interested in healthy muscle aging perform resistance exercise at least twice per week.[30] The program should be progressive in nature (i.e., there is an increase in the number of repetitions performed or the amount of load lifted over time) and each workout should comprise a full-body approach with multiple sets (about 2–4) performed per exercise.[7]

Q: Do nutritional supplements enhance the benefits of resistance exercise for healthy muscle aging?

Supplementing with creatine enhances resistance-exercise-induced gains in lean mass and upper- and lower-body strength.[31] Some evidence suggests that supplementing with whey protein and/or vitamin D can enhance certain measures of muscle strength and physical performance.[32][33][34] Also, supplementing with omega-3 fatty acids may enhance improvements in performance on the TUG test.[35] In longitudinal trials, supplementing with leucine has not been found to enhance resistance-exercise-induced gains in muscle mass, muscle strength, or physical performance.[36][37] However, supplementing a suboptimal dose of protein (10–20 grams) with leucine has been shown to enhance rates of muscle protein synthesis,[38][39][40][41] so leucine may augment the benefits of resistance exercise in the context of a diet with suboptimal protein content, but further research is needed.

Mike Murray

Healthy Muscle Aging

•Last Updated: July 21, 2023

Healthy muscle aging is a goal that focuses on mitigating age-related reductions in muscle mass and function with the objective of preserving independence, quality of life, and general physical function.

Examine Database

Healthy Muscle Aging falls under theHealthy Aging & Longevitycategory.

Mike Murray, RDN, CSCS, CISSN

Nick Milazzo, MSc, MPH

•

Natalka Roshak, AB

Last Updated:July 21, 2023

Examine Database
Frequently asked questions
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References

What is healthy muscle aging?

The natural process of aging leads to a loss of muscle mass and strength.^[1]^[2] In severe cases, this manifests as sarcopenia, which can result in impaired physical function, a loss of independence, and lower quality of life.^[3] Healthy muscle aging is concerned with mitigating unfavorable changes in muscle quantity and quality and preserving physical performance to maintain a satisfactory quality of life.

What changes in muscle contribute to a loss of function with aging?

How is healthy muscle aging measured?

The main way to assess healthy muscle aging is through tests of muscle strength and physical performance. Some common tests include grip strength, gait speed, the chair stand test, and the timed-up-and-go (TUG) test. Secondarily, body composition may be assessed using tools such as dual-energy X-ray absorptiometry (DXA) or bioelectrical impedance analysis (BIA).

How does physical activity affect healthy muscle aging?

Staying physically active is pivotal to healthy muscle aging. Lifelong performance of regular exercise is associated with an improved preservation of muscle mass and strength,^[4]^[5] and physical inactivity is associated with an increased risk of sarcopenia.^[6]

The type of exercise performed is also profoundly important. High-quality evidence indicates that resistance exercise is the most potent intervention for improving muscle mass, muscle strength, and physical performance in older adults.^[7]^[8]^[9] Even in older adults who perform at least 150 minutes of moderate-to-vigorous aerobic exercise per week, a lower risk of sarcopenia, more muscle mass, and better physical performance was found in those who performed resistance exercise twice per week.^[10]

How should resistance exercise be structured to support healthy muscle aging?

Have any supplements been studied for healthy muscle aging?

A variety of supplements have been studied for healthy muscle aging, often in combination with a resistance exercise intervention. Some of the most notable are creatine, protein (such as whey protein, soy protein, or casein), essential amino acids, leucine, hydroxymethylbutyrate (HMB), omega-3 fatty acids, and vitamin D.

Do nutritional supplements enhance the benefits of resistance exercise for healthy muscle aging?

How can diet affect healthy muscle aging?

Largely consistent evidence from observational studies indicates that higher adherence to a Mediterranean diet is associated with better physical performance and a lower risk of sarcopenia,^[11] and the same goes for higher intakes of fruits and vegetables in general.^[12] In contrast, higher adherence to a Western diet is generally associated with impaired physical performance.^[11]

Among the macronutrients, protein is the most notable due to its role in stimulating muscle protein synthesis and thus preserving muscle mass. Moreover, older adults display an impaired anabolic response to protein ingestion,^[13] so it’s critical to get the details of protein intake right to maximize its benefits. The available evidence indicates that older adults should consume 1.2–2.0 grams of protein per kilogram of body weight (g/kg) per day, evenly distributed across multiple meals containing ≥ 0.4 g/kg, to support healthy muscle aging.^[14]

Which other factors affect healthy muscle aging?

Obesity,^[15] a low BMI,^[16] smoking,^[16] insufficient or excessive sleep,^[17] and lower blood vitamin D levels^[18] have all been associated with an increased risk of sarcopenia. Therefore, maintaining a healthy body weight, sleeping 6–8 hours per night, not smoking (or working toward quitting), and getting enough vitamin D in the diet and regular sunlight exposure are all important for supporting healthy muscle aging.