Maximal Voluntary and Functional Performance Needed for Independence in Adults Aged 65 to 97 Years

Abstract

Background and Purpose. Age-related loss of muscle mass and cardiovascular endurance can lead to impairments in muscle force production and cardiac function that, in turn, limit performance in activities essential to everyday living. The purposes of this study were: (1) to identify the “breakpoint” or threshold of maximal voluntary performance and performance in ordinary daily function (2) to evaluate the predictive validity of the threshold to identify the ability independently without self-reported functional limitation. Subjects and Methods. Men and women (N=192; mean age=76 years, SD=7 were recruited from single-family community dwellings or retiremet communities with multiple levels of care. Physical function was measured with the Continuous-Scale Physical Functional Performance Test (CS-PFP). Maximal voluntary performance measures included peak oxygen consumption (V̇) and isokinetic knee extensor torque (KET). Segmented linear regression models of the CS-PFP on the physical performance measures were used to determine the threshold values and their confidence intervals. A logistic regression model was used to evaluate the ability of the CS-PFP scores to identify those living independently and to further illustrate the concepts of threshold and physical reserve. Results. Threshold values identified for V̇O2peak (20 mL·kg−1·min−1) and KET (2.5 N·m/[kgom-1]) were associated with an average of CS-PFP scoe of 57 units. The threshold accurately predicted individuals reporting functional limitations. Discussion and Conclusion. The thresholds provide a mechanism for easily estimating an individual's physical reserve, predicting dependency in living status, and providing unbiased guidance for intervention in late-life independence.

Influence of between‐limb asymmetry in muscle mass, strength, and power on functional capacity in healthy older adults

“…Thus, in terms of lower limb muscle strength and power, the present findings suggest the existence of a substantial physical reserve among healthy older individuals, whereby lower single-limb strength/power levels (and/or potential inter-limb asymmetries herein) may remain beyond any critical threshold below which it would start to negatively affect physical function. 11 Supporting the present observations, LaRoche and colleagues 14 also reported the weakest leg to not be a better predictor of functional performance than the stronger leg in community-dwelling older adults at risk of mobility limitation.…”

“…6,10 However, in well-functioning older individuals, the initial loss of muscle strength and power may not have strong impact on functional capacity, as the relationship between muscle strength/power and functional capability appears to be plateauing (ie, reach a ceiling region) at the upper end of this relationship. 11 A vast number of physical activities of daily living (ADL) involve bilateral lower limb movements (walking, chair stand, stair climbing, etc), and the ability to perform these activities will therefore be limited by bilateral lower limb muscle function. Thus, another possible determinant of functional capacity could be the degree of lower limb asymmetry in the aforementioned factors.…”

Estimating Cardiorespiratory Fitness in Well‐Functioning Older Adults: Treadmill Validation of the Long Distance Corridor Walk

“…26 The United States Social Security Administration (SSA) has identified a peak VO 2 below 18.0 mL O 2 /kg per minute as indicating disability, 27 and several empirical studies of older adults have found similar threshold values for independent living. [3][4][5]21 Substituting the study population mean value for ending SBP (174 mmHg) in the estimating equation and using the SSA criteria equates to a 400-m time of 4 minutes 57 seconds for short stride and 5 minutes 49 seconds for long stride. Applying Astrand's estimate of 12 mL O 2 /kg per minute as the minimum requirement for walking across a street 5 translates to a 400-m time ranging from 6 minutes 48 seconds to 7 minutes 40 seconds.…”

Sarcopenia: Prevalence and associated factors based on different suggested definitions in community‐dwelling older adults

“…21 Other measures of muscle strength included isokinetic knee extension torque and knee extension strength; however, these are not used as frequently (cut-off values summarized in Table 1). 40,41,48,51…”