Exercise as it relates to Disease/Lowering the odds of sarcopenia through physical activity in older adults?

This is a critical analysis of the article from the Aging Clinical and Experimental Research Journal, "Physical activity and sarcopenia in older adults" - Nathan F. Meier & Duck-chul Lee (2020)

What is the background of the research?
Physical activity is an essential part of being healthy, however for those that experience sarcopenia it's not as easy to engage in exercise. According to WHO, physical activity is defined as any bodily movement produced by skeletal muscles that requires energy expenditure. Regular physical activity reduces the risk of mortality from several diseases and has a beneficial effect on bone, muscle and joint health. People who experience sarcopenia have a reduction in muscle mass, strength and function as they age. This leaves them weak, frail, and more susceptible to falls, functional decline, loss of independence and mortality. This is why many sarcopenic patients are inactive and reluctant to participate in physical activity as they may fear falling during exercise. However physical activity can be used as an intervention and is extremely beneficial in reducing sarcopenia. Engaging in physical activity may slow, prevent or reverse muscle loss. Exercise training, particularly strength and resistance, is vital and should be prescribed to those that experience sarcopenia.

Where is the research from?
This article was published in the Aging Clinical and Experimental Research Journal by Springer Verlag. It offers a range of multidisciplinary research on the progressing field of gerontology and geriatrics.

The primary author of this paper, Nathan F. Meir is currently an assistant professor at the Concordia University Irvine, USA. He's published 21 articles, many of which are about physical activity reducing and preventing disease. Nathan only finished his Ph.D in 2018, and doesn't have a long history of research papers, with many of his writings only published in the past 5 years. The secondary author, Duck-chul Lee is from Iowa State University, USA. He currently has 215 publications, with his main areas of research being public health, epidemiology, and cardiology. Both authors bring knowledge and understanding of health issues to this research paper.

What kind of research was this?
This study is a cross-sectional design, which looks at the exposure of an intervention on the outcome of a disease. This study looks at the exposure of physical activity, to cause a positive outcome on older adults who experience sarcopenia. However because outcome and exposure are both measured at the same time it is difficult to establish a causal relationship. This means that any associations that are found in the study may be difficult to interpret. Cross-sectional studies can provide key information for further in-depth research studies and provide the basis for creating a hypothesis. This method was appropriate for establishing the basis of how exercise can impact on sarcopenia, but further research is needed to determine if a causal relationship exists.

What did the research involve?
Between 2015-2016, 304 adults were recruited from a mid-west university town in USA, aged 65 years and older. Individuals who had cancer or other severe conditions that make exercise difficult were excluded from the study. The individuals participated in a series of laboratory tests over 2 weeks. Previous studies on sarcopenia predominately used self-reporting data, however, using this type of measure tends to cause over-reporting and recall bias. This study aimed to limit these issues by using measurement devices to accurately capture data. These included:


 * Daily steps using an accelerometer-based pedometer - published cut-points for older adults, >2500-4999 (moderate) and >5000 (high)
 * Muscular strength tests using a one repetition maximum chest and leg press.
 * Full body scan using DXA model to approximate muscle mass in sarcopenia patients.
 * 400m walk test for cardiorespiratory fitness.
 * Handgrip strength using a digital dynamometer.

This methodology wasn't the best approach. Physical activity is a very broad topic requiring multiple variables to understand the whole picture. This method shows that cardiorespiratory fitness, strength, and speed all need to be analysed, which makes it hard to determine cause and effect, and even more difficult with no control group in the study.

What were the basic results?
The results presented in this study had significant outcomes. The prevalence of the outcomes was recorded using an odd ratio (OR):


 * OR=1 Exposure does not affect odds of outcome
 * OR> Exposure associated with higher odds of outcome
 * OR<1 Exposure associated with lower odds of outcome

It was shown that participants with a high step count had lower odds (0.58) of sarcopenia. Cardiorespiratory fitness lowered the odds across all three categories, and was significantly (0.001) associated with lower prevalence of sarcopenia and higher muscle strength. Strength was associated with lower odds of sarcopenia, low muscle mass, and low handgrip strength. Having greater strength was significantly (<0.001) associated with higher muscle mass, and lower prevalence of sarcopenia.



What conclusions can we take from this research?
Muscle strength is extremely important for elderly people, especially those experiencing sarcopenia, as it is a critical component of being able to achieve daily tasks e.g.walking. This study has shown that an association exists between older adults who participate in physical activity, including cardiorespiratory fitness and strength, and lower odds of experiencing sarcopenia. Studies by Hyuntae Park et al, and Michal Steff et al, both show similar results that physical activity increases muscle mass and reduces the odds of experiencing sarcopenia.

Although there was a large research sample, the majority were relatively healthy which may have caused a healthy responder bias. There was also no consideration for ethnic diversity, making the sample hard to generalize to the population. As mentioned previously, physical activity can't be assessed through a single variable, multiple variables are required to understand physical activity as a whole. This means causal links cannot be made from this research, instead only associations and potential relationships that may exist. Further research is required to determine a relationship between the variables.

Practical Advice
Results from this study and several others suggest that older adults should participate in some form of physical activity each day to minimise the risk factors that are associated with sarcopenia. It is advised that the physical activity should include activities that increase strength, cardiorespiratory fitness, and light aerobic activities (e.g walking). It's shown that older adults who engage in physical activity lower their odds of experiencing sarcopenia. However because older adults are at greater risk of falls and other health issues during exercise, it is recommended to seek medical advice before undertaking any form of exercise. Exercise should be prescribed by an allied health professional, and it is advised that informed consent and an ESSA Adult pre screening is undertaken before any physical activity is conducted, to protect both the patient and the practitioner.

Further information/resources
If you would like to know or learn more about this topic, below are some additional resources:


 * Finding a Exercise Professional: https://www.essa.org.au/Public/find-aep.aspx
 * Fact sheet: https://aimss.org.au/wp-content/uploads/2018/07/Sarcopenia-Day-factsheet-for-Patients.pdf
 * Basic Exercises for Sarcopenia: https://www.iowaclinic.com/physical-therapy/how-to-combat-sarcopenia/