Muscle care for the aging person: Life and longevity part 3

The second article within this series [“Assessing the aging person (life and longevity part 2)” Chiropractic + Naturopathic Doctor, September 2020] introduced functional assessment tools to help fill in the gaps not covered with our standard consultation/physical, which helps the Doctor to obtain a more comprehensive overview of the aging patient focusing on impairments and/or functional limitations.

One very important aspect of the aging process is that all muscles begin to weaken, more specifically in the lower body. Muscle mass and strength/power declines. This contributes to the aging person becoming more unstable, predisposing them to falls. They begin to alter their gait patterns and their stride length shortens until it becomes a shuffle. These aging changes contribute to numerous body and functional changes for the aging person.

To better appreciate some of the contributing factors, we will briefly look at their muscle activity levels, diet and exercise, which will provide insights into the progression and their impairment and how we may begin to reverse some of these impairments.

Muscle
To begin to understand muscle mass, strength and power loss, one needs to take a deep dive into the physiology of aging muscle. Muscle is made up of two main types of muscle fibers. Type I (slow twitch) and type II (fast twitch).

As people age, there is atrophy of type II muscle fibres and this contributes to reduced muscle mass. With specific exercises to target these muscle fibers, hypertrophy occurs and muscle mass will increase.(1). Aging also affects locomotion and increases fall risks. Some aspects of locomotion and fall prevention involve quick and powerful movements. In aging people, these movements are impaired by their weakened fast-twitch type II muscle fibers. Maximal strength training has a potential role in improving type II muscle fibers, thus assisting with physical function and fall prevention.(2). But muscle strength, which is necessary for all muscles, does not translate to increased muscle function and movement capabilities. The lower limbs of the aging persons need to be specifically trained for quick movements. That is training for power, which is force x velocity, or in lay terms, strength x speed. To do this, they can be trained on techniques with light to moderate weights and then have them increase their speed of contraction. This will cause hypertrophy of the type II fibers providing strength to the muscles and the ability to move quickly. This will allow the aging person to move normally and in the event of a stumble, quickly correct their step and regain normal balance.

Aging affects numerous body functions as we saw in part 1(CND June 2020). One, which may specifically affect aging muscle function is blood flow. With a sedentary lifestyle, blood flow to all organs is decreased and in skeletal muscle capillarization is reduced. This decreased capillarization will initiate metabolic functions leading to impairment in the skeletal muscle. Nutrients to the muscles will be compromised, contributing to even more metabolic function and muscle impairment. Interestingly, resistance–type exercise for strength can modify or reverse this process supporting healthy aging.(3,4)

Nutrition
This section will address a few of the basic nutritional interactions with muscle. Vitamin D is very important for the function and performance of muscles. Vitamin D can contribute to increasing muscle cell proliferation and differentiation contributing to muscle mass. One of the chief effects of Vitamin D on muscle, is that it increases the number of type II cells.(5) This of course has the ability to affect strength, function and fall prevention in the aging person. Some studies have shown that low Vitamin D levels can contribute to decreased contractile capacity. If there is decreased contractile capacity, decreased type II muscle fibers, then logically one will experience decreased muscle mass, strength and physical impairment. This will cause a reduction in physical capabilities and increase the risk of falls. With the addition of Vitamin D supplementation in the aging, muscle function and physical performance significantly improves.(6)

As people age, they eat less of the right foods and malnutrition may develop. This will affect energy and physical performance, specifically the dynamic components more so than static. The dynamic component is related to power, Type II, as compared to muscle strength.(7) This will negatively involve quick movements, so falls may be prevalent.

Protein intake significantly affects muscle mass. With aging some people may require increased amounts of dietary protein. Digestive enzymes should also be assessed, because with aging, the amount of digestive enzymes released per meal decreases. If protein intake and digestive enzyme levels are not adequate, then muscle mass declines. Exercise and dietary protein work synergistically together, when these are combined, muscle mass will increase.(8) Adequate intake of dietary protein will increase the function of all body systems, as it will provide more nutrients for better health and energy. Fruits and vegetables are also necessary for body function, as they provide minerals/vitamins and important roughage for the aging person. The vitamins and minerals supplied will help all body systems to improve. 3 portions of fruit/d and 2 portions of vegetables/d. was shown to be adequate.(9)

Key Lower Limb Muscle Weakness
As people age, they have problems with the gait cycle. Think of the gait cycle for a moment. This cycle cannot occur without proper neuromuscular and biomechanical co-ordination of the entire body, from the brain, balance, posture, sacro-iliac and pelvic joints, to the motor unit and proper foot strength and mechanics. For each person, the normal gait cycle has a certain pace, a little pelvic sway and other factors. With aging the gait cycle begins to slow down and the lateral sway becomes less pronounced. Because it feels less stable they become more guarded with their gait. Specifically, this lack of pelvic sway over time affects the integrity of adductors and abductors – the lateral stabilizers, and they atrophy, decreasing their stabilizing function. A study showed that with aging, the hip adductors and hip abductors weaken compared to other muscles in the thigh.(10) These neuromuscular changes in the hip adductors – abductors will eventually affect force development and power production for balance and stability. When the hip adductors – abductors were power trained, this training was more effective than strength training to help neuromuscular function and improve medio-lateral balance recovery.(11)

Other muscles that should be monitored to improve the speed of the gait cycle are the tibialis anterior and vastus lateralis muscles. They weaken with lack of proper use. The tibialis anterior raises the foot in the swing phase and this helps with stride length.(12) All muscles should be monitored as a slowing of the gait cycle will also shorten the hamstring, weaken the gluteus muscles and without proper push off of the foot, the intrinsic muscles of the foot, especially the forefoot become weakened, contributing to gait and balance issues.

Apart from the fact that programs need to be individualized, they should also be ethnic specific and identify at risk populations.(13) Also, some people may require more rhythmic forms of exercise compared to resistance exercises. Some may require cardiovascular – elliptical, instead of treadmill exercises.

By undertaking a comprehensive assessment of the aging person, their training program can be specifically focused on their impairments. This will help the Doctor in designing a program that addresses their specific needs, ie., power vs strength training. In addition, if certain nutritional supplements are recommended along with making sure the patient has adequate protein, fruits and vegetables, then rapid improvement will occur for the patient.

Beginning the rehabilitation process for the patient could start with basic foot exercises to enhance foot strength, placement and stability. A good first exercise would be to have the patient sit and do heel/forefoot raises. As movement becomes easier, have the patient stand, hands on the wall for support and do heel/forefoot raises. Just by strengthening the foot, this will provide the patient with a sense of achievement and more stability. Their confidence improves, they feel more capable, progress happens.

References

1. Nilwik R, et al. The decline in skeletal muscle mass with aging is mainly attributed to a reduction in type II muscle fiber size. Exp Gerontol. 2013 May; 48(5):492-8.
2. Wang E, et al. Impact of maximal strength training on work efficiency and muscle fiber type in the elderly: Implications for physical function and fall prevention. Exp Gerontol. 2017 May; 91:64-71.
3. Landers-Ramos R. The Microvasculature and Skeletal Muscle Health in Aging. Exercise Sport Sciences Reviews. 2018 July: 46(3):172–179.
4. Verdijk L, et al. Resistance Training Increases Skeletal Muscle Capillarization in Healthy Older Men. Med Sci Sports Exerc. 2016 Nov; 48(11):2157-2164.
5. Koundourakis N, et al. Muscular effects of vitamin D in young athletes and non-athletes and in the elderly. Hormones(Athens). 2016 Oct; 15(4):471-488.
6. Walrand S. Effect of Vitamin D on Skeletal Muscle. Geriatr Psychol Neuropsychiatr Vieil, June1 2016: 14 (2), 127-34.
7. Ramsey K, et al. Malnutrition is associated with dynamic physical performance. Aging Clin Exp Res. 2019 Aug 19.
8. Turżańska K. Protein and physical activity in prevention and treatment of sarcopenia. Wiad Lek. 2019; 72(9 cz 1):1660-1666.
9. García-Esquinas E. Consumption of fruit and vegetables and risk of frailty: a dose-response analysis of 3 prospective cohorts of community-dwelling older adults. Am J Clin Nutr. 2016 Jul; 104(1):132-42.
10. Daun F, et al. Different strength declines in leg primary movers versus stabilizers across age-Implications for the risk of falls in older adults? PLoS One. 2019 Mar 7;14(3). I
11. Inacio M, et al. Low-dose hip abductor-adductor power training improves neuromechanical weight-transfer control during lateral balance recovery in older adults. Clin Biomech (Bristol, Avon). 2018 Dec;60:127-133.
12. Guadagnin, et al. Correlation Between Lower Limb Isometric Strength and Muscle Structure With Normal and Challenged Gait Performance in Older Adults. Gait Posture. 2019 Sep; 73:101-107.
13. McGrath R, et al. Muscle Weakness and Functional Limitations in an Ethnically Diverse Sample of Older Adults. Ethn Health. 2020 Apr; 25(3): 342-353.

Dr. Don Fitz- Ritson is a chiropractor and a rehab specialist. He was an Assistant Professor at CMCC. He published 17 papers and 3 chapters on chiropractic.He co-invented a laser and it received 7 Health Canada Approvals. He is focused on helping the aging population live better lives.