Soft tissue radiodensity parameters mediate the relationship between self-reported physical activity and lower extremity function in AGES-Reykjavík participants

AbstractAlthough previous studies have highlighted the association between physical activity and lower extremity function (LEF) in elderly individuals, the mechanisms underlying this relationship remain debated. Our recent work has recognized the utility of nonlinear trimodal regression analysis (NTRA) parameters in characterizing changes in soft tissue radiodensity as a quantitative construct for sarcopenia in the longitudinal, population-based cohort of the AGES-Reykjavík study. For the present work, we assembled a series of prospective multivariate regression models to interrogate whether NTRA parameters mediate the 5-year longitudinal relationship between physical activity and LEF in AGES-Reykjavík participants. Healthy elderly volunteers from the AGES-Reykjavík cohort underwent mid-thigh X-ray CT scans along with a four-part battery of LEF tasks: normal gait speed, fastest-comfortable gait speed, isometric leg strength, and timed up-and-go. These data were recorded at two study timepoints which were separated by approximately 5 years: AGES-I (n = 3157) and AGES-II (n = 3098). Participants in AGES-I were likewise administered a survey to approximate their weekly frequency of engaging in moderate-to-vigorous physical activity (PAAGES-I). Using a multivariate mediation analysis framework, linear regression models were assembled to test whether NTRA parameters mediated the longitudinal relationship between PAAGES-I and LEFAGES-II; all models were covariate-adjusted for age, sex, BMI, and baseline LEF, and results were corrected for multiple statistical comparisons. Our first series of models confirmed that all four LEF tasks were significantly related to PAAGES-I; next, modelling the relationship between PAAGES-I and NTRAAGES-II identified muscle amplitude (Nm) and location (μm) as potential mediators of LEF to test. Finally, adding these two parameters into our PAAGES-I → LEFAGES-II models attenuated the prior effect of PAAGES-I; bootstrapping confirmed Nm and μm as significant partial mediators of the PAAGES-I → LEFAGES-II relationship, with the strongest effect found in isometric leg strength. This work describes a novel approach toward clarifying the mechanisms that underly the relationship between physical activity and LEF in aging individuals. Identifying Nm and μm as significant partial mediators of this relationship provides strong evidence that physical activity protects aging mobility through the preservation of both lean tissue quantity and quality.

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Mediating effects of lower extremity function on the relationship between night sleep duration and cardiovascular disease risk: a cross-sectional study in elderly Chinese without cardiovascular diseases

BMJ Open ◽

10.1136/bmjopen-2020-046015 ◽

2021 ◽

Vol 11 (7) ◽

pp. e046015

Author(s):

Hui Zhang ◽

Xiaoyu Chen ◽

Peipei Han ◽

Weibo Ma ◽

Yuanyuan Zhang ◽

...

Keyword(s):

Lower Extremity ◽

Sleep Duration ◽

Physical Performance ◽

Indirect Effect ◽

Night Sleep ◽

Lower Extremity Function ◽

Cvd Risk ◽

Extremity Function ◽

Elderly Chinese ◽

The Relationship

ObjectiveThe purpose of this study is to investigate the mediating effect of physical performance on the relationship between night sleep duration and risk of cardiovascular disease (CVD) in elderly Chinese without CVD.Methods782 participants without CVD over 65 years (average: 70.82±3.86 years, 448 women) were included in this study. CVD risk was calculated by the Framingham Risk Score and participants were divided into four groups of night sleep duration (in hours): <7 hours, ≥7–8 hours, >8–9 hours and >9 hours. Upper extremity function was measured by grip strength and lower extremity function was measured by the Short Physical Performance Battery (SPPB), consisting of balance, 4 m walk and chair stands tests.ResultsAfter adjusting for covariates, long night sleep duration (>9 hours) and CVD risk were significantly positively associated compared with moderate night sleep duration (≥7–8 hours) (β=1.152; 95% CI 0.05 to 2.25). SPPB total score (indirect effect ab=−0.122; 95% CI −0.291 to –0.0008) rather than grip strength partially mediated the relationship between long night sleep duration and CVD risk, in which chair stands played a major mediating role (indirect effect ab=−0.171; 95% CI −0.040 to –0.0006), while balance (indirect effect ab=−0.016; 95% CI −0.100 to 0.063) and 4 m walk (indirect effect ab=0.048; 95% CI −0.066 to 0.201) did not.ConclusionsLower extremity function, especially lower limb muscle strength, partially mediates a positive association between long night sleep duration and CVD risk in the elderly without CVD. Suitable interventions for physical performance and sleep may minimise the risk of subsequent CVD.

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The relationship between lower limb muscle strength and lower extremity function in HIV disease

South African Journal of Physiotherapy ◽

10.4102/sajp.v73i1.360 ◽

2017 ◽

Vol 73 (1) ◽

Cited By ~ 1

Author(s):

Peter C. Mhariwa ◽

Hellen Myezwa ◽

Mary L. Galantino ◽

Douglas Maleka

Keyword(s):

Muscle Strength ◽

Lower Extremity ◽

Lower Limb ◽

Lower Limb Muscle ◽

Limb Muscle ◽

Plantar Flexors ◽

Lower Extremity Function ◽

Extremity Function ◽

The Relationship ◽

Hiv Negative

Background: Human immunodeficiency virus (HIV) negatively impacts muscle strength and function. This study aimed to establish the relationship between lower limb muscle strength and lower extremity function in HIV disease.Method: A cross-sectional study was undertaken with a sample of 113 HIV-positive participants. Lower limb muscle strength and self-reported function were established using dynamometry and the Lower Extremity Functional Scale (LEFS), respectively. Muscle strength and functional status were established in a subset of 30 HIV-negative participants to determine normative values.Results: Muscle strength for participants with HIV ranged from an ankle dorsiflexion mean of 9.33 kg/m2 to 15.79 kg/m2 in hip extensors. In the HIV-negative group, ankle dorsiflexors recorded 11.17 kg/m2, whereas hip extensors were the strongest, generating 17.68 kg/m2. In the HIV-positive group, linear regression showed a positive relationship between lower limb muscle strength and lower extremity function (r = 0.71, p = 0.00). Fifty per cent of the changes in lower extremity function were attributable to lower limb muscle strength. A simple linear regression model showed that lower limb ankle plantar flexors contributed the most to lower extremity function in this cohort, contrary to the literature which states that hip and trunk muscles are the most active in lower limb functional activities.Conclusion: Lower extremity strength impacts perceived function in individuals stabilised on antiretroviral therapy for HIV disease. These findings demonstrate that ankle plantar flexors produce more force over hip flexors. Careful attention should be paid to the implications for strength training in this population.

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The Relationship Between Cognitive Decline and Sedentary Time

Innovation in Aging ◽

10.1093/geroni/igaa057.618 ◽

2020 ◽

Vol 4 (Supplement_1) ◽

pp. 191-191

Author(s):

Lorraine Phillips ◽

Mary Bowen

Keyword(s):

Physical Activity ◽

Older Adults ◽

Cognitive Function ◽

Lower Extremity ◽

Sedentary Time ◽

Community Dwelling ◽

Physical Activity Intensity ◽

Lower Extremity Function ◽

Activity Intensity ◽

Extremity Function

Abstract Early identification of functional decline in older adults with mild cognitive impairment (MCI) provides the opportunity to initiate behavioral interventions to slow decline. More frequent breaks in sedentary time has been associated with greater lower extremity function. This longitudinal study examined the effect of 6-month change in cognitive function on monthly sedentary time, controlling for lower extremity function, among community-dwelling older adults with MCI. Twenty adults with Montreal Cognitive Assessment Score (MoCA) between 19-25, who were age ≥ 60 years old, and ambulatory, wore an actigraph for 6 months and participated in monthly in-person assessments. Measures included MoCA change (baseline to month 6), Short Physical Performance Battery (SPPB; baseline, months 3 and 6); sedentary time and physical activity intensity; and falls (monthly). The sample was 70% female, 60% non-Hispanic white, with a mean age of 77 years. Sixteen participants provided complete data for mixed-model analysis. Over 6 months, 11 falls occurred among 7 participants. The mean MoCA score declined from 22.7 to 21.9 while SPPB remained stable. Overall time spent in sedentary behavior was high (71%) and physical activity intensity was low (light and moderate combined= 26.1%). Results of multi-level analysis with sedentary time as a continuous Level-1 variable and MoCA change scores, SPPB scores, and age in Level-2 showed that negative change in MoCA (β=-0.11; p≤0.05) was associated with increased sedentary time. Given sedentary time increases as cognitive function declines, older adults with MCI could benefit from interventions designed to interrupt sedentary time as well as increase physical activity.

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