Introduction for Force, Power and Balance Measurements
Muscle strength, more specifically muscle strength within the geriatric population is challenging to accurately test, due to the risk involved when completing various testing procedures. Many of the reasons for reduction in strength have been reviewed, much of the evidence points towards a loss of muscle mass. Though true, there is also evidence that suggests the force -producing capacity of muscles occurs at an earlier and a faster rate than reductions in muscle mass (Macaluso and De Vito, 2004). As atrophy continues to be a leading factor in an aging individuals’ decline in health it has become more apparent that testing muscle strength should be done with individuals regardless of age. With that said, traditional strength testing for the elderly may be deemed ineffective because of its poor application to various subgroups for those over the age of 65. The lack of data regarding strength in this area means that a maximal strength testing does very little to nothing when we are attempting to compare an individual to their age matched counterparts or those with the same functional ability. A squat of 95 pounds for a gentleman approaching 80 years of age is surely impressive but regarding the greater picture and understanding where that individual remains regarding others in his situation remains to be unknown with traditional strength testing. With that said, it should also be noted that without an extensive lab with various providers, equipment and funding, accurate and detailed strength testing among geriatric populations is very challenging.
Our goal was to find a strength testing protocol that allowed us to understand more than simple one-repetition-maximums or predicted ten-repetitions-maximums. The deep dive allowed for more information the be gathered which could then be compared with age and functional ability counterparts, thus creating a spectrum in which individuals would find themselves. This would help determine an exercise program, as well as be a predictor of where they might be heading (i.e. next level of care – AL, SNF, etc.)
The Force-Power relationship has become one of the most effective predictors of functional outcomes in older adults. The neuromuscular system has a major influence on functional ability throughout the aging process (Aagaard et al., 2010) and impaired muscle power should be considered one of the most important outcomes associated with functional limitations and disability in older adults (Byrne et al., 2016). Colleagues Izquierdo & Cadore (2014) and Reid & Fielding (2012) also stated muscle power should be recognized as a significant and strong predictor of functional ability in older people as well as its critical influence on remaining independent in later life.
Force and power output often require an extensive lab that many practitioners have very little to no access. Fortunately, with the use of VALD Heath’s Force Deck Mini we (LiveWell Health) were able to detect these exact metrics in order to have an understanding of the wellness landscape of individuals residing within independent and assisted living communities throughout southwest Florida.
Discussion
When comparing male and female cohorts among aging populations, there often exists an observable difference. Surely, there will be instances in which a male is far frailer than their female counterpart, but when viewing the entire cohort, we observed differences in all metrics (force, power and balance). Although force was the only metric that provided a statistically significant representation of both populations, we can see the observed relationship between force and power, as well as force and balance. Those who generated greater force production often generated greater power output, as well as increased balance metrics (a smaller area of ellipse). The data confirms it would be inaccurate for our team to compare the entire population. Males and females must be separated when determining needs and program strategy to improve health and well-being.
We expected a much larger variance between IL and AL residents as it relates to the force production. The variance of 5% between the two cohorts does not come as eye opening data. However, when utilizing the standard deviation to understand the lower range in which these individuals score, we may be able to understand what an accurate cutoff may be for those who are residing with IL but should really be in AL. It was found, the lower range for those within IL would generate force (583 N) or 27% less than the average IL resident. This correlates with the percentile ranks in which a score of 583 N would place an individual just beyond the 10th percentile of all IL residents, potentially signifying this individual may benefit from AL placement based on their strength parameters.
Power output was found to be accurately represented among IL residents, which would allow us to create the same recommendations for those who do not generate power output at numbers related to their peers. Recall, power output is an important metric when determining physical functioning in later life. Again, utilizing the standard deviation to understand the lower range for power output among IL residents places the power output at 156 W or within the 15th percentile (figure 3b). Based on the finding from both force production and power output, we may be able to begin making inferences about one’s need for a greater level of care based strength parameters (physical functioning).
Functional tests such as use of AD and stair climb produced promising results as we were able to note a statistically significant difference between the two, with SC and NAD users outperforming the NSC and AD users in both force production and power output. Similar to generating recommendations for greater levels of care, we can make inferences about those who may consider use of a walker or cane. When taking standard deviation into consideration, the lower range for force production of non-AD users equals 633 N or 25% less than the average NAD user, therefore those who produce force at rates less than 633 N may very well benefit from a walker, cane or exercise to improve their strength. We can make the same inferences with regard to power output. The lower range for NAD users equals 175 W, a score less than that of the 10th percentile (figure 4b), therefore those with power and force scores lower than the thresholds mentioned (633 N & 175 W) would likely benefit from use of an assistive device. Those who wish to step away from an AD must generate scores greater than the threshold. If there still exists a need for an AD then we must evaluate other variables that may be playing a role in AD usage.
The stairs often represent an area of concern for many families due to the balance deficiencies that may present themselves in later years. However, we found zero correlation with our quiet stand balance test with ability to climb stairs. A potential flaw may be the use of a self-guided questionnaire to collect data and the nature of the balance test (static) compared with stairs (dynamic). With that said, it is important to understand how force and power play a role in stair climbing as well. Many may choose to avoid the stairs because they do not believe they are possible. However, when calculating the ability of stair climbers, we come away with averages as well as lower ranges in which an individual must score in order to align with their stair climbing peers. Similar things can be said about those who have not climbed stairs in some time, those producing force and power above the lower thresholds for both may very well be able to do so. Force production of 606 N and power output of 138 W is the threshold in which individuals may be able to climb stairs provided there are no other variables that may prevent on from doing so such as immobility, cardiovascular endurance, etc.
Age is often a deterrent for many to begin exercise or to take the necessary steps to improve their health. Retirement, and even periods prior to, are often the stage in which individuals choose to ‘turn off’ their health and focus on the joy that is ahead, freedom. However, this often creates an open-door policy for muscle atrophy, chronic conditions, and poor health to begin its effect now and many years to come. When viewing the aging population, we did not expect our results to be affected by age in a statically significant manner due to the variance that can occur for individuals within the same cohort. Everyone in the senior care or healthcare industry knows there can be a 90-year-old who ‘runs circles’ around many of the 70-year-old individuals they encounter. With that said, our data revealed an interesting trend. Those in their 70s and 80s differ significantly in force and power production. However, when comparing those in their 80s with individuals in their 90s, the variance was relatively minute. This reveals the importance of those as they approach 80 years old, the decline may be very drastic unless measures are taken to prevent said decline. Considering the advances in healthcare, this potentially means an individual may live upwards of 20+ years in a state far different than how they felt, performed, and lived while they were in their 70s. This is a growing trend that we continue to see, lifespan continues to increase while healthspan remains stagnant. We must take the necessary steps to allow individuals to increase their healthspan in a linear fashion with their lifespan.
Summary
Force production and power output should be considered among the measurable factors when assessing older adults. The VALD Health ForceDecks allow for practitioners to use such technology within a clinic or on the go. The study demonstrates uses of both force and power measurements relating to older population regarding their level of care needs, as well as assistive device usage. Further testing is needed to understand how static balance plays a role in the physical functioning of older adults. We believe this to be an important step in the right direction as it relates to strength testing among older adults.
