Ryan McGrath

The Association Between Handgrip Strength and Diabetes on Activities of Daily Living Disability in Older Mexican Americans

Objective: The aim of this study is to determine the independent and joint effects of muscle weakness and diabetes on incident activities of daily living (ADL) disability in older Mexican Americans. Method: A subsample of 2,270 Mexican Americans aged at least 65 years at baseline were followed for 19 years. Handgrip strength was normalized to body weight (normalized grip strength [NGS]). Weakness was defined as NGS ≤0.46 in males and ≤0.30 in females. Diabetes and ADL disability were self-reported. Results: Compared with participants that were not weak and did not have diabetes, those that had diabetes only, were weak only, and were both weak and had diabetes experienced a 1.94 (95% confidence interval [CI] = [1.89, 1.98]), 1.17 (CI = [1.16, 1.19]), and 2.12 (CI = [2.08, 2.16]) higher rate for ADL disability, respectively. Discussion: Muscle weakness and diabetes were independently and jointly associated with higher rates for ADL disability in older Mexican Americans.

Muscle Strength Is Protective Against Osteoporosis in an Ethnically Diverse Sample of Adults

Abstract McGrath, RP, Kraemer, WJ, Vincent, BM, Hall, OT, and Peterson, MD. Muscle strength is protective against osteoporosis in an ethnically diverse sample of adults. J Strength Cond Res 31(9): 2586–2589, 2017—The odds of developing osteoporosis may be affected by modifiable and nonmodifiable factors such as muscle strength and ethnicity. This study sought to (a) determine whether increased muscle strength was associated with decreased odds of osteoporosis and (b) identify whether the odds of osteoporosis differed by ethnicity. Data from the 2013 to 2014 National Health and Nutrition Examination Survey were analyzed. Muscle strength was measured with a hand-held dynamometer, and dual-energy x-ray absorptiometry was used to assess femoral neck bone mineral density. A T-score of ⩽2.5 was used to define osteoporosis. Separate covariate-adjusted logistic regression models were performed on each sex to determine the association between muscle strength and osteoporosis. Odds ratios (ORs) were also generated to identify if the association between muscle strength and osteoporosis differed by ethnicity using non-Hispanic blacks as the reference group. There were 2,861 participants included. Muscle strength was shown to be protective against osteoporosis for men (OR: 0.94; 95% confidence interval [CI]: 0.94–0.94) and women (OR: 0.90; CI: 0.90–0.90). Although ORs varied across ethnicities, non-Hispanic Asian men (OR: 6.62; CI: 6.51–6.72) and women (OR: 6.42; CI: 6.37–6.48) were at highest odds of osteoporosis. Increased muscle strength reduced the odds of osteoporosis among both men and women in a nationally representative, ethnically diverse sample of adults. Non-Hispanic Asians had the highest odds of developing osteoporosis. Irrespective of sex or ethnicity, increased muscle strength may help protect against the odds of developing osteoporosis.

Exercise hemodynamics in hypertrophic cardiomyopathy identify risk of incident heart failure but not ventricular arrhythmias or sudden cardiac death

OBJECTIVE To determine whether abnormal blood pressure response (ABPR), with or without left ventricular outflow tract obstruction (LVOTO), is associated with adverse heart failure and arrhythmia outcomes in hypertrophic cardiomyopathy (HCM). METHODS A retrospective, single-center analysis was performed for adult HCM patients who underwent exercise stress testing. RESULTS Of 589 patients included in the study, 192 (33%) demonstrated ABPR. A similar proportion of patients with ABPR had LVOTO compared to those without ABPR (56% vs 63%, p = 0.11). Patients with ABPR demonstrated lower percent predicted VO2 and METs achieved than those with LVOTO (16.9 ± 6.8 vs 21.6 ± 7.9, p = 0.002 and 5.3 ± 2.4 vs 7.4 ± 3.1, p < 0.001). In a subgroup of 17 patients with LVOTO and ABPR who subsequently underwent successful myectomy, 5 (30%) demonstrated persistent ABPR. 23 patients (3.8%) experienced sudden cardiac death or ventricular arrhythmias, which were not associated with ABPR, regardless of age group. In multivariable analysis, syncope (p = 0.04), left ventricular hypertrophy (p = 0.02) and left atrial diameter (p = 0.006) were significantly associated with the composite outcome of sudden death or severe ventricular arrhythmia, whereas ABPR was not (p = 0.38). In contrast, ABPR was associated with subsequent heart failure hospitalization (p = 0.002), regardless of presence or absence of LVOTO (p = 0.04, p = 0.02). CONCLUSIONS ABPR is associated with reduced functional capacity in HCM regardless of the presence of LVOTO but is not associated with adverse arrhythmia outcomes. Patients with ABPR have a higher incidence of subsequent heart failure hospitalization.

Muscle weakness and functional limitations in an ethnically diverse sample of older adults

ABSTRACT Objectives: Muscle weakness is often linked to functional limitations in older adults. However, certain demographic characteristics, such as ethnicity, may differentially impact the association between weakness and functional limitations. This investigation sought to (1) identify sex- and ethnically-specific muscle weakness thresholds associated with functional limitations among older adults, and (2) determine the odds of functional limitations for each ethnicity by sex after identifying older adults below the weakness thresholds. Design: Persons aged ≥60 years from the 2011–2012 to 2013–2014 waves of the National Health and Nutrition Examination Survey identifying as non-Hispanic white, non-Hispanic black, Hispanic, or non-Hispanic Asian were included. Handgrip strength was normalized to each participants body weight (normalized grip strength (NGS)). Participants responded to 19-items asking them about their ability to perform certain activities of daily living, instrumental activities of daily living, leisure and social activities, lower extremity mobility functions, and general physical activities. Receiver operating characteristic curves identified the optimal NGS thresholds associated with functional limitations. Covariate-adjusted multiple logistic regression models were performed to determine the odds of functional limitations for weak vs. not-weak participants. Results: Of the 3,027 participants, the highest NGS thresholds for functional limitations were in non-Hispanic Asian males (0.41; p < 0.001) and Hispanic females (0.36; p < 0.001); whereas, the lowest NGS thresholds were in Hispanic males (0.25; p < 0.001) and non-Hispanic black females (0.23; p < 0.001). Weak non-Hispanic Asian males (odds ratio (OR): 10.42; 95% confidence interval (CI): 10.24, 10.61) and females (OR: 11.95; CI: 11.71, 12.19) had the highest odds for functional limitations compared to their non-weak counterparts. Conclusion: Preserving muscle strength, especially for certain older adult populations, may help reduce the odds of developing functional limitations. Interventions designed to increase muscle strength to preserve or improve function should consider the role of ethnicity when designing such interventions and identifying at risk populations.

Handgrip Strength and Health in Aging Adults

Handgrip strength (HGS) is often used as an indicator of overall muscle strength for aging adults, and low HGS is associated with a variety of poor health outcomes including chronic morbidities, functional disabilities, and all-cause mortality. As public health initiatives and programs target the preservation of muscle strength for aging adults, it is important to understand how HGS factors into the disabling process and the sequence of health events that connect low HGS with premature mortality. Such information will help to inform interventions designed to slow the disabling process and improve health outcomes for those at risk for muscle weakness. Further, unraveling the disabling process and identifying the role of weakness throughout the life course will help to facilitate the adoption of HGS measurements into clinical practice for healthcare providers and their patients. The purposes of this article were to (1) highlight evidence demonstrating the associations between HGS and clinically relevant health outcomes, (2) provide directions for future research in HGS and health, and (3) propose a sequence of health-related events that may better explain the role of muscle weakness in the disabling process.

The association between the etiology of a spinal cord injury and time to mortality in the United States: A 44-year investigation

Objective: To determine the association between spinal cord injury (SCI) etiology categories and mortality, and examine the association between etiology sub-categories and mortality. Design: Prospective cohort study. Setting: Model Systems and Shriners Hospital SCI units. Participants: Data were analyzed from 42,627 cases in the SCI Model System Collaborative Survival Study Database from 1973 to 2017. Those with SCI etiologies categorized as vehicular, violent, sports, falls, pedestrian, and medical were included. Interventions: Not applicable. Outcome Measure: Time to mortality after SCI. Results: Relative to the sports related etiology category, those with medical, pedestrian, violence, falls, and vehicular related SCIs had a 2.00 (95% confidence intervals (CIs): 1.79–2.24), 1.57 (CIs: 1.34–1.83), 1.54 (CIs: 1.41–1.68), 1.35 (CIs: 1.25–1.45), and 1.26 (CIs: 1.17–1.35) higher hazard for mortality, respectfully. Persons with SCIs from automobile crashes had a 1.38 (CIs: 1.23–1.56) higher hazard for mortality, whereas those with SCIs from motorcycle crashes had a 1.21 (CIs: 1.04–1.39) higher hazard for mortality, relative to other etiologies within the vehicular category. Those with SCIs from diving had a 1.37 (CIs: 1.18–1.59) higher hazard for mortality relative to other etiologies within the sports category. Conclusions: Injury etiology categories and certain sub-categories were associated with a higher risk for early mortality. Understanding how additional factors such as socioeconomic status, co-occurring injuries, medical co-morbidities, and environmental aspects interact with SCI etiologies may provide insights for how etiology of injury impacts survival. These findings may serve as a development for extending long-term life expectancy by informing SCI prevention programs and care post-injury.

Understanding the Nature of Measurement Error When Estimating Energy Expenditure and Physical Activity via Physical Activity Recall

BACKGROUND The National Health and Nutrition Examination Survey physical activity questionnaire (PAQ) is used to estimate activity energy expenditure (AEE) and moderate to vigorous physical activity (MVPA). Bias and variance in estimates of AEE and MVPA from the PAQ have not been described, nor the impact of measurement error when utilizing the PAQ to predict biomarkers and categorize individuals. METHODS The PAQ was administered to 385 adults to estimate AEE (AEE:PAQ) and MVPA (MVPA:PAQ), while simultaneously measuring AEE with doubly labeled water (DLW; AEE:DLW) and MVPA with an accelerometer (MVPA:A). RESULTS Although AEE:PAQ [3.4 (2.2) MJ·d-1] was not significantly different from AEE:DLW [3.6 (1.6) MJ·d-1; P > .14], MVPA:PAQ [36.2 (24.4) min·d-1] was significantly higher than MVPA:A [8.0 (10.4) min·d-1; P < .0001]. AEE:PAQ regressed on AEE:DLW and MVPA:PAQ regressed on MVPA:A yielded not only significant positive relationships but also large residual variances. The relationships between AEE and MVPA, and 10 of the 12 biomarkers were underestimated by the PAQ. When compared with accelerometers, the PAQ overestimated the number of participants who met the Physical Activity Guidelines for Americans. CONCLUSIONS Group-level bias in AEE:PAQ was small, but large for MVPA:PAQ. Poor within-participant estimates of AEE:PAQ and MVPA:PAQ lead to attenuated relationships with biomarkers and misclassifications of participants who met or who did not meet the Physical Activity Guidelines for Americans.

Data Imputation Improves Sedentary Behavior and Physical Activity Estimates in Low Wear Time Accelerometer Data: 3670 Board #117 June 3 8

Missing accelerometer data from low participant wear time underestimates sedentary behavior (SB) and physical activity (PA) measurements. Yet, it remains unclear if imputing data for low participant wear time improves SB and PA estimates. PURPOSE: To determine if a data imputation technique improves SB and PA estimates in accelerometer data with low participant wear time. METHODS: One-hundred participants wore an accelerometer at the hip for ≥22.0 hours/day, at least 4 days including 1 weekend day, to capture habitual SB, light physical activity (LPA), and moderate-to-vigorous physical activity (MVPA) levels. After removing sleep time (RAW; 15.9±3.5 hours/day), random 60-minute blocks of data were removed from the RAW data set until participants had a unique data set with wear time adherence at 10 hours/day. A minute-by-minute, mean data imputation technique was used to impute estimates of SB, LPA, and MVPA in place of the missing data for the 10-hour adherence level. A series of paired t-tests with a Bonferroni correction (alpha level=0.006) compared the estimates of SB, LPA, and MVPA to the RAW data set at the 10-hour adherence level. Similarly, imputed estimates of SB, LPA, and MVPA were compared to the RAW data set at the 10-hour adherence level. RESULTS: SB, LPA, and MVPA were underestimated by 163.7 (95% confidence intervals [CI]: 156.0, 171.5; p<0.0001), 138.4 (CI: 129.1, 147.9; p<0.0001), and 27.2 (CI: 24.3, 30.1; p<0.0001) minutes/day at 10-hours of wear compared to the RAW data set, respectively. When utilizing the data imputation technique at the 10-hour adherence level, SB and MVPA were underestimated by 16.8 (CI: 8.7, 24.9; p<0.0001) and 17.1 (CI: 14.5, 19.6; p<0.0001) minutes/day compared to the RAW data set, respectively. LPA at the 10-hour adherence level was overestimated by 33.9 (CI: 25.9, 41.9; p<0.0001) minutes/day compared to the RAW data set after utilizing the data imputation technique. CONCLUSION: A minute-by-minute, mean data imputation technique improved SB, LPA, and MVPA estimates in accelerometer data with low wear time adherence. Future studies should examine the impact of data imputation techniques on accelerometer data with low participant wear time.

Practitioner survey and measurement error in manual bicycle and pedestrian count programs

ABSTRACT Manual bicycle and pedestrian count programs that involve community volunteers can be a low-cost means to collect nonmotorized traffic data while providing opportunity for public involvement. The purposes of this study were to investigate why communities are performing manual counts and estimate the degree of measurement error associated with conducting manual counts. An online questionnaire was sent to transportation specialists across the United States. There were 92 responses received from 25 states. Eleven communities were contacted for phone interviews. Information about community volunteers, scheduling and logistics, data collection techniques, and reasons for conducting manual counts were summarized. Some of the reasons cited by the survey respondents for conducting manual counts seem unrealistic and possibly flawed. Measurement error was assessed through a controlled field experiment with 25 counters at five intersections. Lower measurement error rates were observed when using a four-movement data collection technique compared to a more complicated 12-movement technique; however, the differences were not statistically significant. The overall median absolute percent error for the 12-movement technique was 27% and 7% for bicyclists and pedestrians, respectively. The field experiment showed no consistent increases in measurement error when counters were assigned to collect additional information, such as sex of traveler or whether bicyclists wore helmets.