Assessing Additional Characteristics of Muscle Function With Digital Handgrip Dynamometry and Accelerometry: Framework for a Novel Handgrip Strength Protocol

Explaining the influence of practice on the grooved pegboard times of older adults: role of force steadiness

The purpose was to identify the variables that can explain the variance in the grooved pegboard times of older adults categorized as either fast or slow performers. Participants (n = 28; 60-83 years) completed two experimental sessions, before and after 6 practice sessions of the grooved pegboard test. The 2 groups were identified based on average pegboard times during the practice sessions. Average pegboard time during practice was 73 ± 11 s for the fast group and 85 ± 13 s for the slow group. Explanatory variables for the pegboard times before and after practice were the durations of 4 peg-manipulation phases and 12 measures of force steadiness (coefficient of variation [CV] for force) during isometric contractions with the index finger abductor and wrist extensor muscles. Time to complete the grooved pegboard test after practice decreased by 25 ± 11% for the fast group and by 28 ± 10% for the slow group. Multiple regression models explained more of the variance in the pegboard times for the fast group before practice (Adjusted R2 = 0.85) than after practice (R2 = 0.51), whereas the variance explained for the slow group was similar before (Adjusted R2 = 0.67) and after (Adjusted R2 = 0.64) practice. The explanatory variables differed between before and after practice for the fast group but only slightly for the slow group. These findings indicate that performance-based stratification of older adults can identify unique adjustments in motor function that are independent of chronological age.

Hand Grip Force-Time Curve Indicators Evaluated by Dynamometer: A Systematic Review

BACKGROUND

Handgrip strength (HGS) is an indicator of muscular strength, used in the diagnosis of sarcopenia, undernutrition, and physical frailty as well as recovery. Typically, the maximum HGS value is used; however, recent evidence suggests the exploration of new indicators provided based on the force-time curve to achieve a more comprehensive assessment of muscle function. Therefore, the objective was to identify indicators of the HGS profile beyond maximum HGS, based on force-time curves, and to systematize knowledge about their applications to various types of samples, health issues, and physical performance.

METHODS

A systematic review was performed including studies whose participants' HGS was assessed with a digital or adapted dynamometer. The outcome measures were HGS profile indicators calculated from the force-time curve.

RESULTS

a total of 15 studies were included, and the following indicators were identified: grip fatigue, fatigability index, fatigue rate, fatigue resistance, time to 80% maximal voluntary contraction, plateau coefficient of variability, time to maximum value, T-90%, release rate, power factor, grip work, average integrated area, endurance, cycle duration, time between cycles, maximum and minimum force-velocity, rate of grip force, final force, inflection point, integrated area, submaximal control, and response time.

CONCLUSIONS

Various indicators based on the force-time curve can be assessed through digital or adapted dynamometers. Future research should analyze these indicators to understand their implications for muscle function assessment, to standardize evaluation procedures, to identify clinically relevant measures, and to clarify their implications in clinical practice.

Impact of professional experience on clinical judgment and muscular response in various neuromuscular tests

Muscle testing is an integral component in assessing musculoskeletal function and tailoring rehabilitation efforts. This study aimed i. to identify an objective evaluation system sensitive to analyze changes in different muscular conditions in different neuromuscular tests across a spectrum of professional experience levels; and ii. to analyze differences in objective parameters and clinical judgment between participants of different levels of expertise in different muscular conditions in different neuromuscular tests. Participants included 60 subjects with Level I to III expertise who performed blinded neuromuscular tests on the middle deltoid and rectus femoris muscles of 40 volunteer subjects. The methodology centered on standardizing test protocols to minimize variability, employing EMG to quantify muscle activity, thermography to capture thermographic muscular response, and digital dynamometry to measure muscular resistance. The findings revealed that while traditional methods like thermography and electromyography provide valuable insights, digital dynamometry stands out for its sensitivity in detecting muscle condition changes in neuromuscular test. Moreover, the data underscored the pivotal role of advanced training and expertise in enhancing the precision and accuracy of neuromuscular diagnostics, since there were significant differences in objective parameters and clinical judgment between participants of different levels of expertise in the different muscular conditions in Middle deltoid and Rectus femoris neuromuscular tests analyzed, presenting higher expertise participant clinical judgment like objective validated instrument.

Association of handgrip strength asymmetry and weakness with functional disability among middle-aged and older adults in China

Background

Little is known about the association of handgrip strength (HGS) asymmetry with functional disability in China. We aimed to examine the individual and combined association of HGS asymmetry and weakness with functional disability among middle-aged and older Chinese adults.

Methods

We included participants aged ≥45 years from two waves of the China Health and Retirement Longitudinal Study (2011 and 2015). HGS weakness was defined as the maximal HGS<28 kg for men and <18 kg for women. HGS asymmetry was measured by dividing the maximal nondominant HGS (kg) by the maximal dominant HGS (kg), with the value <0.90 or >1.10 considered as asymmetry. Functional disability was assessed by activities of daily living (ADL) and instrumental activities of daily living (IADL) and was defined as encountering difficulty in completing one or more ADL/IADL tasks. The logistic regression models were used to explore the association between HGS measures and functional disability.

Results

11 950 (mean age 59.2 ± 9.6 years, 47.9% males) and 7540 (mean age 57.5 ± 8.6 years, 50.1% males) participants were included in the cross-sectional and prospective study, respectively. HGS asymmetry and weakness, individually or simultaneously, were associated with an increased prevalence of functional disability. During the four-year follow-up, 1822 (24.2%) participants had incident functional disability. The separate exposure to HGS asymmetry (odds ratio (OR) = 1.18; 95% confidence interval (CI) = 1.05-1.32) or weakness (OR = 1.59; 95% CI = 1.30-1.95) was independently associated with functional disability. For combined associations, those with both weakness and asymmetry showed the greatest risk of new-onset functional disability (OR = 1.91; 95% CI = 1.45-2.52).

Conclusions

HGS asymmetry and weakness were associated with a higher risk of functional disability. Assessing HGS asymmetry together with weakness may help to better identify those at risk of functional disability to enable early interventions.

The Role of Different Weakness Cut-Points for Future Cognitive Impairment in Older Americans

OBJECTIVES

New absolute and normalized handgrip strength (HGS) cut-points may not yield similar predictive value for cognitive performance. We sought to determine the associations of (1) each absolute and normalized weakness cut-point, and (2) compounding weakness on future cognitive impairment in older Americans.

DESIGN

Longitudinal panel.

SETTING AND PARTICIPANTS

The analytic sample included 11,116 participants aged ≥65 years from the 2006 to 2018 waves of the Health and Retirement Study. Participants from the Health and Retirement Study completed detailed interviews that included physical measures and core interviews.

METHODS

The modified Telephone Interview of Cognitive Status assessed cognitive function and persons scoring <11 were classified as having a cognitive impairment. A handgrip dynamometer measured HGS. Men were considered weak if their HGS was <35.5 kg (absolute), <0.45 kg/kg (body mass normalized), or <1.05 kg (body mass index normalized), whereas women were classified as weak if their HGS was <20.0 kg, <0.337 kg/kg, or <0.79 kg. Compounding weakness included those below 1, 2, or all 3 cut-points. Generalized estimating equations quantified the associations.

RESULTS

Persons considered weak under the absolute cut-point had 1.62 (95% CI 1.34-1.96) greater odds for future cognitive impairment, but no significant associations were observed for those classified as weak under the body mass [odds ratio (OR) 1.12, CI 0.91-1.36] and body mass index normalized (OR 1.17, CI 0.95-1.43) cut-points. Older Americans below all 3 weakness cut-points had 1.47 (CI 1.15-1.88) greater odds for future cognitive impairment, but no significant associations were found for persons classified as weak under 1 (OR 1.08, CI 0.83-1.42) or 2 (OR 1.19, CI 0.91-1.55) cut-points.

CONCLUSIONS AND IMPLICATIONS

Our findings suggest that each weakness cut-point has differential prognostic value for future cognitive impairment, and aggregating weakness cut-points may improve their predictive utility. Consideration should be given to how weakness categories are uniquely linked to cognitive function.

The relationship between low handgrip strength with or without asymmetry and fall risk among middle-aged and older males in China: evidence from the China Health and Retirement Longitudinal Study

PURPOSE

This study sought to explore the potential correlation between low handgrip strength (HGS) with or without asymmetry and fall risk in middle-aged and older Chinese adults.

METHODS

Baseline characteristic data from participants 45+ years of age and data regarding fall events collected from two rounds (2011-2013) of the China Health and Retirement Longitudinal Study were utilized for the present analyses. HGS and HGS asymmetry was defined according to the updated American Society of Hand Therapist. Fall events were identified through self- or proxy-reported details. Logistic regression analyses were employed to gauge the potential relationship between abnormal HGS and fall risk.

RESULTS

In total, 10 563 participants were enrolled in this analysis, of whom 47.49% (5016/10 563) were male. The proportions of low HGS alone, HGS asymmetry alone, and low HGS with asymmetry were 22.23%, 18.34%, and 22.75%, respectively, in males, but just 3.64%, 35.12%, and 6.62% in females. A total of 693 and 1019 fall events were recorded for male (13.82%) and female (18.37%) participants over the 2-year follow-up period, respectively. Significant differences in fall event incidence among different HGS groups were only observed among males. An adjusted logistic regression analysis model confirmed that low HGS with dominant asymmetry was closely related to fall risk among middle-aged and older males [P = 0.014, odds ratio = 1.332, 95% confidence interval: 1.059-1.676).

CONCLUSION

These results demonstrated that low HGS with dominant asymmetry is a risk factor linked to increased fall risk among middle-aged and older Chinese males. What is already known on this topic Low HGS or HGS asymmetry is been reported to be linked to an increased risk of falls in middle-aged and older adults; however, little is known about the association between fall risk and low HGS and/or HGS asymmetry. Main messages The prevalence of low HGS alone and low HGS asymmetry in men was significantly higher than in women, while HGS alone asymmetry was more common in women than men. The risk factor for the increased risk of falls in Chinese middle-aged and older men is low and asymmetric HGS, rather than low or asymmetric HGS alone. Low HGS with dominant asymmetry rather than nondominant asymmetry is associated with future fall risk among middle-aged and older Chinese males. Current research questions What is the mechanism for the significant difference in the proportion of abnormal HGS components between the sexes? If female subjects with low HGS and asymmetric HGS were added, would an association be observed between low HGS and asymmetric HGS falls? Is there an association between the severity of asymmetric HGS with weakness and falls?

Examining the role of different weakness categories for mobility and future falls in older Americans

BACKGROUND

Recently developed absolute and body size normalized handgrip strength (HGS) cut-points could be used individually and collectively to predict mobility problems and falls.

AIMS

We examined the associations of (1) each absolute and normalized weakness cut-point, (2) collective weakness categories, and (3) changes in weakness status on future falls in older Americans.

METHODS

The analytic sample included 11,675 participants from the 2006-2018 waves of the Health and Retirement Study. Falls were self-reported. Men were classified as weak if their HGS was < 35.5-kg (absolute), < 0.45 kg/kg (body mass normalized), or < 1.05 kg/kg/m2 (body mass index normalized). While, women were considered weak if their HGS was < 20.0-kg, < 0.337 kg/kg, or < 0.79 kg/kg/m2. Collective weakness categorized those below 1, 2, or all 3 cut-points. The collective weakness categories were also used to observe changes in weakness status over time.

RESULTS

Older Americans below each absolute and normalized cut-point had greater odds for future falls: 1.23 (95% confidence interval (CI): 1.15-1.32) for absolute weakness, 1.20 (CI 1.11-1.29) for body mass index normalized weakness, and 1.26 (CI 1.17-1.34) for body mass normalized weakness. Persons below 1, 2, or all 3 weakness cut-points had 1.17 (CI 1.07-1.27), 1.29 (CI 1.18-1.40), and 1.36 (CI 1.24-1.48) greater odds for future falls, respectively. Those in some changing weakness categories had greater odds for future falls: 1.26 (CI 1.08-1.48) for persistent and 1.31 (CI 1.11-1.55) for progressive.

DISCUSSION

Collectively using these weakness cut-points may improve their predictive value.

CONCLUSION

We recommend HGS be evaluated in mobility and fall risk assessments.

Minimal short-term decline in functional performance and quality of life predicts better long-term outcomes for both in older Taiwanese adults after hip fracture surgery: a prospective study

BACKGROUND

Hip fracture can lead to long-term loss of mobility and self-care ability in older adults. Despite initial decreases in functional performance after hip fracture surgery, patients tend to gradually recover. However, recovery can vary, with some regaining their abilities quickly while others becoming functionally dependent. In this study, we investigated whether the level of short-term postoperative decline in activity of daily living (ADL) performance and quality of life (QoL) can predict the 1-year outcomes for both following hip fracture surgery in older Taiwanese adults.

METHODS

This prospective cohort study included 427 older adults (≥ 60 years) who underwent hip fracture surgery at a single tertiary medical center in Taiwan between November 2017 and March 2021. We collected pre-fracture data, including the patients' demographics, Charlson comorbidity index (CCI) scores, and responses to a questionnaire (Short Portable Mental State Questionnaire [SPMSQ]) for dementia screening. Moreover, their scores on the EuroQol-5D questionnaire (for evaluating QoL) and the Barthel Index (for assessing ADL performance) were collected at pre-fracture status and at 3- and 12-months following surgery. Changes in ADL and QoL three months post-surgery compared to pre-fracture status were evaluated, and the associations of these parameters (and other potential factors) with 1-year outcomes for ADL and QoL were investigated.

RESULTS

We analyzed the data of 318 patients with hip fracture and complete follow-up data regarding ADL performance and QoL at 3- and 12-months post-surgery. After adjusting for covariates, multivariate linear regression revealed that changes in ADL and QoL at 3 months post-surgery from pre-fracture status were positively and significantly associated with 1-year outcomes for both (p < .001 for both). Furthermore, pre-fracture CCI and SPMSQ scores were independent predictive factors associated with 1-year ADL outcomes (p = .042 and < .001, respectively).

CONCLUSIONS

Patients who exhibit a smaller decline in functional performance and quality of life three months after hip fracture surgery from pre-fracture status are likely to have improved long-term ADL and QoL.

TRIAL REGISTRATION

TMU-JIRB N201709053.

Using Electronic Handgrip Dynamometry and Accelerometry to Examine Multiple Aspects of Handgrip Function in Master Endurance Athletes: A Pilot Study

ABSTRACT

Klawitter, LA, Hackney, KJ, Christensen, BK, Hamm, JM, Hanson, M, and McGrath, R. Using electronic handgrip dynamometry and accelerometry to examine multiple aspects of handgrip function in master endurance athletes: A Pilot Study. J Strength Cond Res 37(9): 1777-1782, 2023-Electronic handgrip dynamometry and accelerometry may provide novel opportunities to comprehensively measure muscle function for human performance, especially for master athletes. This investigation sought to determine the multivariate relationships between maximal strength, asymmetry, rate of force development, fatigability, submaximal force control, bimanual coordination, and neuromuscular steadiness to derive one or more handgrip principal components in master-aged endurance athletes. We included n = 31 cyclists and triathletes aged 35-70 years. Maximal strength, asymmetry, rate of force development, fatigability, submaximal force control, bimanual coordination, and neuromuscular steadiness were measured twice on each hand using electronic handgrip dynamometry and accelerometry. The highest performing measures were included in the analyses. A principal component analysis was conducted to derive a new collection of uncorrelated variables from the collected handgrip measurements. Principal components with eigenvalues >1.0 were kept, and individual measures with a factor loading of |>0.40| were retained in each principal component. There were 3 principal components retained with eigenvalues of 2.46, 1.31, and 1.17. The first principal component, "robust strength," contained maximal strength, rate of force development, submaximal force control, and neuromuscular steadiness. The second principal component, "bilateral synergy," contained asymmetry and bimanual coordination, whereas the third principal component, "muscle conditioning," contained fatigability. Principal components 1, 2, and 3 explained 44.0, 31.6, and 24.4% of the variance, respectively. Different dimensions of muscle function emerged from our findings, suggesting the potential of a muscle function battery. Further research examining how these measures are associated with appropriate human performance metrics and lower extremity correlates is warranted.

Prevalence and Trends of Handgrip Strength Asymmetry in the United States

Background

Strength asymmetries are a type of muscle function impairment that is associated with several health conditions. However, the prevalence of these asymmetries among adults from the United States remains unknown. We sought to estimate the prevalence and trends of handgrip strength (HGS) asymmetry in American adults.

Methods

The unweighted analytic sample included 23,056 persons aged at least 50-years with information on HGS for both hands from the 2006-2016 waves of the Health and Retirement Study. A handgrip dynamometer measured HGS, with the highest recorded values for each hand used to calculate asymmetry. Persons were categorized into the following asymmetry severity categories: (1) >10%, (2) >20.0%, and (3) >30.0%. Survey weights were used to generate nationally-representative asymmetry estimates.

Results

Overall, there were no statistically significant trends in HGS asymmetry categories over time. The prevalence of HGS asymmetry in the 2014-2016 wave was 53.4% (CI: 52.2-54.4), 26.0% (CI: 25.0-26.9), and 11.7% (CI: 10.9-12.3) for asymmetry at >10%, >20%, and >30%, respectively. HGS asymmetry was generally higher in older Americans compared to middle-aged adults at each wave. In the 2014-2016 wave, >30% asymmetry prevalence was 13.7% (CI: 12.7-14.6) in females and 9.3% (CI: 8.4-10.2) in males. Some differences in asymmetry prevalence by race and ethnicity were observed.

Conclusions

The prevalence of asymmetry was generally high, especially in women and older adults. Ongoing surveillance of strength asymmetry will help monitor trends in muscle dysfunction, guide screening for disablement, identify subpopulations at risk for asymmetry, and inform relevant interventions.

Use of a physiological profile to document upper limb motor impairment in ageing and in neurological conditions

Profiling performance in the physiological domains underpinning upper limb function (such as strength, sensation, coordination) provides insight into an individual's specific impairments. This compliments the traditional medical 'diagnosis' model that is currently used in contemporary medicine. From an initial battery of 13 tests in which data were collected across the adult lifespan (n = 367, 20-95 years) and in those with neurological conditions (specifically, multiple sclerosis (n = 40), Parkinson's disease (n = 34), and stroke (n = 50)), six tests were selected to comprise a core upper limb physiological profile assessment (PPA). This comprised measures of handgrip strength, simple reaction time, finger dexterity, tactile sensation, bimanual coordination, and a functional task. Individual performance in each of these tests can be compared to a reference population score (devised from our database of healthy individuals aged under 60 years), informing the researcher or clinician how to best direct an intervention or treatment for the individual based on their specific impairment(s). Lastly, a composite score calculated from the average performance across the six tests provides a broad overview of an individual's overall upper limb function. Collectively, the upper limb PPA highlights specific impairments that are prevalent within distinct pathologies and reveals the magnitude of upper limb motor impairment specific to each condition.

Development of a Novel Diagnostic Support Tool for Degenerative Cervical Myelopathy Combining 10-s Grip and Release Test and Grip Strength: A Pilot Study

Early diagnosis of degenerative cervical myelopathy (DCM) is desirable, as delayed treatment can cause irreversible spinal cord injury and subsequent activity of daily living (ADL) impairment. We attempted to develop a straightforward and accurate diagnostic tool for DCM by combining the grip and release test (GRT) and grip strength. As a pilot study, we measured the GRT and grip strength of patients with DCM (n = 247) and a control group (n = 721). Receiver operating characteristic analysis was performed using the lower left and right. The Youden index was used to set cutoff values by sex and age group. The diagnostic performance of each test varied by sex and age, and a diagnostic support tool was created to determine any abnormal results in a test. The calculated M/F cutoff values for GRT were as follows: 40–59 years, 21/18; 60–69 years, 17/17; 70–79 years, 15/15; and 80–89 years, 11/12. The calculated M/F cutoff values for grip strength 32/20, 29/13, 21/15, and 19/10. When either GRT or grip strength was judged as positive, the overall sensitivity was 88.2%, specificity was 78.1%, positive likelihood ratio was 4.03, and the negative likelihood ratio was 0.15. This novel diagnostic support tool was superior to using GRT and grip strength alone in the early DCM diagnosis. Future research to obtain age- and sex-specific data is necessary to validate and further improve the tool.

Undiagnosed Dementia Is Associated with Poor Physical Function in Older Adults

BACKGROUND

Older adults with a cognitive impairment, including those not yet diagnosed, may have deficits in their physical function.

OBJECTIVE

We sought to determine the associations of cognitive impairment consistent with dementia (CICD) diagnosis status on handgrip strength, gait speed, and functional disability in older adults.

METHODS

The analytical sample included 8,383 adults aged ≥65-years without history of stroke, cancers, neurological conditions, or brain damage who participated in at least one-wave of the 2010-2016 waves of the Health and Retirement Study. A handgrip dynamometer measured handgrip strength. Men with handgrip strength <26 kg and women <16 kg were weak. Gait speed was timed across a 2.5-m course and those with slowness had gait speed <0.8 m/s. Participants with difficulty or an inability in completing any basic activities of daily living had a functional disability. The adapted Telephone Interview of Cognitive Status evaluated cognitive function. Persons with scores <7 had a CICD. Healthcare provider dementia-related diagnosis was self-reported. Undiagnosed CICD was defined as no reported dementia-related diagnosis but had CICD, while diagnosed CICD was classified as reporting a dementia-related diagnosis. Covariate-adjusted logistic models were used for the analyses.

RESULTS

Persons with undiagnosed CICD had 1.37 (95% confidence interval (CI): 1.04-1.80) greater odds for weakness and 2.02 (CI: 1.39-2.94) greater odds for slow gait speed. Older adults with diagnosed CICD had 2.29 (CI: 1.32-3.97) greater odds for slowness and 1.85 (CI: 1.19-2.90) greater odds for functional disability.

CONCLUSION

Screening for CICD could be recommended when defects in physical function are observed in older adults.

Older American Women May Especially Benefit from Distributing and Consuming Protein for Decreasing Odds of Functional Limitations

OBJECTIVES

Protein is a key macronutrient for preserving physical function, but the role of protein intake on functional status may differ in men and women. We sought to examine the associations of daily protein intake and distribution on functional limitations in older American men and women.

DESIGN

Cross-sectional.

SETTING

Population-based survey.

PARTICIPANTS

The analytic sample included 3,976 men and 4,081 women aged ≥60-years from the 2007-2016 waves of the National Health and Nutrition Examination Survey.

MEASUREMENTS

Participants reported their ability to perform basic activities of daily living, instrumental activities of daily living, leisure and social activities, lower extremity mobility activities, and general physical tasks. Those reporting difficulty or an inability in completing such functional tasks were considered as having a functional limitation. Protein intake was determined with dietary recalls and participants revealed functional limitations. Protein recommendations of ≥0.80, ≥1.00, and ≥1.50 g/kg/day were used. Based on these cut-points, we also investigated distribution of protein across 4 eating occasions at ≥0.20, ≥0.25, and ≥0.38 g/kg/meal, respectively.

RESULTS

Older women meeting each recommendation had decreased odds for functional limitations: 0.55 (95% confidence interval (CI): 0.40-0.75) for ≥0.80 g/kg/day, 0.75 (CI: 0.58-0.97) for ≥1.00 g/kg/day, and 0.72 (CI: 0.55-0.94) for ≥1.5 g/kg/day. No significant associations were observed in older men. Further, older women with protein consumption ≥0.20 g/kg/meal had decreased odds for functional limitations: 0.24 (CI: 0.10-0.61) for 1 occasion, 0.20 (CI: 0.08-0.49) for 2 occasions, 0.16 (CI: 0.07-0.40) for 3 occasions, and 0.12 (CI: 0.04-0.32) for 4 occasions. A similar trend was observed for intake ≥0.25 g/kg/meal: 0.31 (CI: 0.16-0.62) for 2 occasions, 0.30 (CI: 0.14-0.61) for 3 occasions, and 0.31 (CI: 0.12-0.78) for 4 occasions. Women with 1 and 2 eating occasions at ≥0.38 g/kg/meal of protein had 0.66 (CI: 0.48-0.91) and 0.54 (CI: 0.37-0.79) decreased odds for functional limitations, respectively.

CONCLUSION

Trials that are powered to detect the effects of protein on functional status in women will help to establish causality.

Handgrip Strength Asymmetry and Weakness Are Associated With Future Morbidity Accumulation in Americans

ABSTRACT

Klawitter, L, Vincent, BM, Choi, BJ, Smith, J, Hammer, KD, Jurivich, DA, Dahl, LJ, and McGrath, R. Handgrip strength asymmetry and weakness are associated with future morbidity accumulation in americans. J Strength Cond Res 36(1): 106-112, 2022-Identifying strength asymmetries in physically deconditioned populations may help in screening and treating persons at risk for morbidities linked to muscle dysfunction. Our investigation sought to examine the associations between handgrip strength (HGS) asymmetry and weakness on accumulating morbidities in aging Americans. The analytic sample included 18,506 Americans aged ≥50 years from the 2006-2016 Health and Retirement Study. Handgrip strength was measured on each hand with a handgrip dynamometer, and persons with an imbalance in strength >10% between hands had HGS asymmetry. Men with HGS <26 kg and women with HGS <16 kg were considered as weak. Subjects reported the presence of healthcare provider-diagnosed morbidities: hypertension, diabetes, cancer, chronic lung disease, cardiovascular disease, stroke, arthritis, and psychiatric problems. Covariate-adjusted ordinal generalized estimating equations analyzed the associations for each HGS asymmetry and weakness group on future accumulating morbidities. Of those included in our study, subjects at baseline were aged 65.0 ± 10.2 years, 9,570 (51.7%) had asymmetric HGS, and 996 (5.4%) were weak. Asymmetry alone and weakness alone were associated with 1.09 (95% confidence interval [CI]: 1.04-1.14) and 1.27 (CI: 1.11-1.45) greater odds for future accumulating morbidities, respectively. Having both HGS asymmetry and weakness was associated with 1.46 (CI: 1.29-1.65) greater odds for future accumulating morbidities. Handgrip-strength asymmetry, as another potential indicator of impaired muscle function, is associated with future morbidity status during aging. Exercise professionals and related practitioners should consider examining asymmetry and weakness with handgrip dynamometers as a simple and noninvasive screening method for helping to determine muscle dysfunction and future chronic disease risk.

The Associations between Asymmetric Handgrip Strength and Chronic Disease Status in American Adults: Results from the National Health and Nutrition Examination Survey

This study examined the associations between asymmetric handgrip strength (HGS) and multimorbidity in American adults. Secondary analyses of data from persons aged at least 40 years from the 2011-2012 and 2013-2014 waves of the National Health and Nutrition Examination Survey were conducted. A handheld dynamometer collected HGS on each hand and persons with a strength imbalance >10% between hands were classified as having asymmetric HGS. Adults with the presence of ≥2 of the following conditions had multimorbidity: cardiovascular disease, chronic obstructive pulmonary disease, chronic kidney disease, asthma, arthritis, cancer, obesity, stroke, hypertension, high cholesterol, and diabetes. Of the n = 3483 participants included, n = 2700 (77.5%) had multimorbidity. A greater proportion of adults with multimorbidity had HGS asymmetry (n = 1234 (45.7%)), compared to persons living without multimorbidity (n = 314 (40.1%); p < 0.05). Relative to individuals without asymmetry, adults with asymmetric HGS had 1.31 (95% confidence interval (CI): 1.03-1.67) greater odds for multimorbidity. Moreover, persons with HGS asymmetry had 1.22 (CI: 1.04-1.44) greater odds for accumulating morbidities. Asymmetric strength, as another indicator of diminished muscle function, is linked to chronic morbidity status. Healthcare providers should recommend healthy behaviors for reducing asymmetries to improve muscle function and mitigate morbidity risk after completing asymmetry screenings.