Age-related muscle loss and why it is essential to perform resistance training.

Age-related muscle loss and why it is essential to perform resistance training.

What is Sarcopenia? 

Sarcopenia is loss of muscle mass in relation to age. Sarcopenia can also be described as the involuntary loss of muscle mass which can affect muscle mass, strength, and the body’s function (Volpi et al., 2004). 

What is Dynapenia.

This is the weakness that is associated with old age (Law et al., 2016).

What causes Muscle loss?

As we age, hormonal changes occur along with a lack of physical activity, which can result in decreases in muscle mass that can lead to individuals becoming frailer, leading to metabolic disease and osteoporosis, (Yoo et al., 2018) There is a reduction in the body’s muscle cell count, the muscle’s ability to produce force, and the speed at which the muscles can contract (Volpi et al., 2004). 

Adverse effects of Muscle loss.

Alarmingly, muscle mass can decrease by 3-8% per decade after age 30, with the rate of muscle mass loss being higher after age 60 (Volpi et al., 2004). 

The muscle’s ability to store energy like ATP and creatine phosphate is depleted, having adverse effects on muscular strength and power production as well as losses in the ability to transport mitochondria, leading to around a 30% decrease in aerobic performance all whilst reducing the metabolic rate by around 10% (Volpi et al., 2004).

The loss of muscle mass, strength, and function is the leading factor in disability in the elderly population. It can be the cause of falls, frailty, and injury which can lead to dependence and disability (Volpi et al., 2004). Decreases in muscle mass are followed by a progressive increase in fat mass, changes in body composition, and metabolic diseases like insulin resistance (Volpi et al., 2004). Issues like decreases in bone density, joint stiffness, and kyphosis (an excessive curve in the spine) can all aid the increase of metabolic conditions like type 2 diabetes, obesity, heart disease, and osteoporosis (Volpi et al., 2004).  

The importance of muscle mass?

Barriers

While working in the fitness industry, I hear people say they are trying to lose muscle mass, women mistaking a temporary muscle pump for bulking to an out-of-control level, and athletes being terrified of adding too much muscle for their sport. Muscle mass has a bad rep amongst many, when muscle mass is vital for quality of life and health especially as we start to age. 

Skeletal muscle can be considered an organ, it has a vital role to play in the body by providing locomotion (movement) and support for the body. Skeletal muscle degrades because of the aging process, poor nutrition, lack of use and age-related changes in hormones (Yoo, et al., 2018).

How to treat sarcopenia

From as far back as the Ancient Greeks, weakening and loss of athleticism was acknowledged as a disease and was seen as an uncurable condition. Over time, humans have discovered that aging can be a modifiable condition acknowledging sensible eating practices and moderate exercise being solid advice that holds up with today’s science (Law et al., 2016). 

Sarcopenia is a multifactor problem, but it can be treated to a degree with behavioural change like bringing a balanced exercise routine into play (Volpi et al., 2004). A well-rounded regimen of exercise would include aerobic training and progressive resistance training (increasing the weight and the volume of resistance over time). I go into detail below:

Aerobic Training 

Aerobic exercise can provide a partial solution to sarcopenia due to the relief of mitochondria-derived issues, while resistance training helps by aiding in increasing muscle mass and function of the muscles. This would suggest a healthy training regimen would be optimal for reducing the negative effects of sarcopenia (Yoo, et al., 2018). 

Aerobic exercise will lead to an increase in ATP in mitochondria within skeletal muscle, it also helps by improving cardiovascular function and aids metabolic regulation (as mammal cells need to constantly produce energy throughout a life span to maintain cellular processes and functions). (Bradshaw, and Stahl, 2015, Yoo et al., 2018). 

Aerobic exercise also reduces the number of catabolic genes and helps increase muscle protein synthesis (the ability to build muscle).

Resistance training 

Research has shown that the older adult population can have excellent results in increasing muscle size, strength, and muscle capacity when partaking in progressive resistance training (Law et al., 2016).

One study in adults aged from 90-100 years showed excellent results. After an 8-week high-intensity resistance training intervention, they were able to increase muscle strength by an astonishing 174%, increase muscle mass around the thigh by 9% and increase walking speed by 48%. Resistance training can increase muscle size by 30% in a 16-week training program, and muscle fibre types can transition to increase fast twitch fibres along with increased muscle nuclei. These results are comparable to a younger population. (Law et al., 2016).

Training principles. 

Although people have the best intentions, the training methodologies I am presented with and have witnessed over the years are concerning! Basic but essential principles like exercise selection and progressive overload are vital for progression and injury prevention but are not taken into consideration.

Frequency: 2-4 sessions a week on alternating days.

Duration: Between 30-60 minutes session duration, rest periods anywhere from 1-3 minutes. Longer rest for higher-intensity exercises and longer rest periods do not seem to affect muscle growth so rest can be down to individual preferences.

Exercise selection: Compound or multi-joint exercises are highly recommended due to their similarities to life tasks. Beginners are recommended to use machine weights as they have less skill demand and can be safer for those with less experience. As individuals progress, free weights (barbells and dumbbells) are recommended as they add further skill challenges like balance demands. 

Sets: 1-3 sets have been shown to provide significant increases in strength. One set of an exercise can be an effective stimulus for beginner lifters. As gym goers become more advanced, more sets become vital to increase strength and muscle size. 

Intensity: This can be defined as the amount of weight lifted and is described by the percentage of maximum weight. Research has shown that higher-intensity exercises (80% + of one repetition max) are safe and tolerable in the older population. 

Repetitions: If lifting 90%, 1-4 reps are recommended as this will induce neuromuscular adaptations. If lifting 80% around 4 to 10 reps could be completed and this would induce more cellular adaptations, which would build more muscle size. 8-15 reps are recommended for muscle strength endurance and are typically performed at around 60%.   

Progression

Even short-term muscle inactivity can lead to severe losses in muscular strength and muscle mass. Resistance training is acknowledged as a vital tool in preventing muscle wastage, it prevents this by increasing muscle size and strength, and it also helps to switch the balance of muscle protein synthesis (muscle building) and degradation (muscle wastage) and encourages more protein synthesis (Yoo et al., 2018). Resistance training can have excellent effects on detrained elderly individuals. 

It is vital that the training is structured and uses relevant loading and volume to progressively overload the individual to ensure muscle strength and muscle size are maintained (Volpi, 2004). Resistance training also switches protein synthesis into the positive anabolic. 

In Conclusion

Adults lose muscle with age due to factors like hormonal changes and lifestyle factors like a lack of physical activity. Resistance and aerobic training are vital for health and are especially important as we age. Resistance and aerobic training gains can be made across the age spectrum with adults aged from 90-99 seeing an increase of 174% in neuromuscular strength, a 48% increase in walking speed, and a 9% increase in thigh muscle size which would lead to dramatic lifestyle improvements. A lack of muscle mass can lead to dire health consequences and metabolic diseases with a dramatic drop in quality of life.

References

Bradshaw, R.A. and Stahl, P.D., 2015. Encyclopedia of cell biology. Academic Press.
Volpi, E., Nazemi, R. and Fujita, S., 2004. Muscle tissue changes with aging. Current opinion in clinical nutrition and metabolic care, 7(4), p.405.

Clark, B.C., Clark, L.A. and Law, T.D., 2016. Resistance exercise to prevent and manage sarcopenia and dynapenia. Annual Review of Gerontology and Geriatrics, 36(1), pp.205-228.

Kavanaugh, A., 2007. The role of progressive overload in sports conditioning. Conditioning Foundamentals. NSCA’s Performance Training Journal, 6(1).

Piasecki, M., Ireland, A., Coulson, J., Stashuk, D.W., Hamilton‐Wright, A., Swiecicka, A., Rutter, M.K., McPhee, J.S. and Jones, D.A., 2016. Motor unit number estimates and neuromuscular transmission in the tibialis anterior of master athletes: evidence that athletic older people are not spared from age‐related motor unit remodeling. Physiological reports, 4(19), p.e12987.

Yoo, S.Z., No, M.H., Heo, J.W., Park, D.H., Kang, J.H., Kim, S.H. and Kwak, H.B., 2018. Role of exercise in age-related sarcopenia. Journal of exercise rehabilitation, 14(4), p.551.