Gait plasticity impairment as an early frailty biomarker

Reserved gait capacity and mortality among patients undergoing hemodialysis

BACKGROUND

Patients undergoing hemodialysis (HD) have difficulty increasing their gait speed in daily life. The extent of the increase from the usual gait speed (UGS) to the maximum gait speed (MGS) is considered the reserved gait capacity (RGC). Little is known regarding the implications of RGC. This study aimed to investigate the association between RGC and all-cause mortality in patients undergoing HD.

METHODS

In this retrospective study, we assessed the usual and maximum 10-m walking speed of outpatients who underwent HD between October 2002 and August 2021. RGC was defined as the ratio of MGS to UGS. Patients were divided into three groups according to the tertiles of RGC (low, moderate and high). A Cox proportional hazards regression model was used to examine the association between RGC and all-cause mortality.

RESULTS

Of the 496 (median age 66.0 years; men 59%) participants, 186 patients died during the follow-up (incident ratio of 62.0 per 1000 person-years). The patients with moderate [hazard ratio (HR) 0.66, 95% confidence interval (CI) 0.46-0.94] and high (HR 0.44, 95% CI 0.30-0.65) RGC had a lower risk of mortality than the low RGC group. Furthermore, even when restricted to a population with only UGS <1.0 m/s, the group with high RGC still had a lower risk of mortality than those with low RGC (HR 0.55, 95% CI 0.33-0.94).

CONCLUSIONS

Lower RGC was independently associated with an increased risk of all-cause mortality among patients on HD; high RGC had a survival advantage even with a slow UGS.

Gait speed is a biomarker of cancer-associated cachexia decline and recovery

Background

Progressive functional decline is a key element of cancer-associated cachexia. No therapies have successfully translated to the clinic due to an inability to measure and improve physical function in cachectic patients. Major barriers to translating pre-clinical therapies to the clinic include lack of cancer models that accurately mimic functional decline and use of non-specific outcome measures of function, like grip strength. New approaches are needed to investigate cachexia-related function at both the basic and clinical science levels.

Methods

Survival extension studies were performed by testing multiple cell lines, dilutions, and vehicle-types in orthotopic implantation of K-ras LSL.G12D/+ ; Trp53 R172H/+ ; Pdx-1-Cre (KPC) derived cells. 128 animals in this new model were then assessed for muscle wasting, inflammation, and functional decline using a battery of biochemical, physiologic, and behavioral techniques. In parallel, we analyzed a 156-subject cohort of cancer patients with a range of cachexia severity, and who required rehabilitation, to determine the relationship between gait speed via six-minute walk test (6MWT), grip strength (hGS), and functional independence measures (FIM). Cachectic patients were identified using the Weight Loss Grading Scale (WLGS), Fearon consensus criteria, and the Prognostic Nutritional Index (PNI).

Results

Using a 100-cell dose of DT10022 KPC cells, we extended the survival of the KPC orthotopic model to 8-9 weeks post-implantation compared to higher doses used (p<0.001). In this Low-dose Orthotopic (LO) model, both progressive skeletal and cardiac muscle wasting were detected in parallel to systemic inflammation; skeletal muscle atrophy at the fiber level was detected as early as 3 weeks post-implantation compared to controls (p<0.001). Gait speed in LO animals declined as early 2 week post-implantation whereas grip strength change was a late event and related to end of life. Principle component analysis (PCA) revealed distinct cachectic and non-cachectic animal populations, which we leveraged to show that gait speed decline was specific to cachexia (p<0.01) while grip strength decline was not (p=0.19). These data paralleled our observations in cancer patients with cachexia who required rehabilitation. In cachectic patients (identified by WLGS, Fearon criteria, or PNI, change in 6MWT correlated with motor FIM score changes while hGS did not (r 2 =0.18, p<0.001). This relationship between 6MWT and FIM in cachectic patients was further confirmed through multivariate regression (r 2 =0.30, p<0.001) controlling for age and cancer burden.

Conclusion

Outcome measures linked to gait are better associated with cachexia related function and preferred for future pre-clinical and clinical cachexia studies.

Agility training to integratively promote neuromuscular, cardiorespiratory and cognitive function in healthy older adults: a one-year randomized-controlled trial

BACKGROUND

Exercise training recommendations for seniors include the targeted training of strength, balance, endurance and flexibility domains. Agility training (AT) is conceptualized as a multi-component and time-efficient training framework for older adults to improve physical, functional and cognitive health domains that are relevant for maintaining activities of daily living. The aim of this one-year trial was to comparatively evaluate the effects of agility training on physical and cognitive function.

METHODS

Seventy-nine healthy older adults (AT: 61.5% female, 70.8 ± 4.8 years, 27.7 ± 4.2 kg/m2; CG: 60.5% female, 69.6 ± 4.7 years, 27.5 ± 4.4 kg/m2) took part in this one-year randomized controlled intervention and were either assigned to the agility training group (AT) with two weekly 60 min AT sessions or to the control group (CG), receiving no treatment. Participants were assessed pre, intermediate and post intervention for strength and power, balance, gait speed under multi-task conditions, aerobic capacity as well as cognitive performance. Linear mixed effects models were used to analyze the effect of treatment over time.

RESULTS

Fifty-four participants (AG: 25, CG: 29) were analyzed, most drop-outs attributed to COVID-19 (17/30 dropouts). Adherence was good (75%) of 90 offered sessions. Notable effects in favor of AT were found for gait parameters in single (d = 0.355, Δ = 4.3%), dual (d = 0.375, Δ = 6.1%) and triple (d = 0.376, Δ = 6.4%) task conditions, counter movement jump performance (strength and power) (d = 0.203, Δ = 6.9%), static one leg balance (d = 0.256, Δ = 12.33%) and n-back reaction time (cognitive performance) (d = 0.204, Δ = 3.8%). No effects were found for the remaining outcomes (d < 0.175).

CONCLUSION

AT might serve as an integrative training approach for older adults particularly improving gait and lower limb power parameters. It seems suitable to improve a broad range of seniors' health domains and should replace isolated training of these domains. However, individual variation and progression of exercises should be considered when programming agility training providing adequate challenges throughout a long-term intervention for all participants.

TRIAL REGISTRATION

DRKS, DRKS00017469 . Registered 19 June 2019-Retrospectively registered.

Recent developments in frailty identification, management, risk factors and prevention: A narrative review of leading journals in geriatrics and gerontology

Frailty is an age-related clinical condition characterised by an increased susceptibility to stressors and an elevated risk of adverse outcomes such as mortality. In the light of global population ageing, the prevalence of frailty is expected to soar in coming decades. This narrative review provides critical insights into recent developments and emerging practices in frailty research regarding identification, management, risk factors, and prevention. We searched journals in the top two quartiles of geriatrics and gerontology (from Clarivate Journal Citation Reports) for articles published between 01 January 2018 and 20 December 2022. Several recent developments were identified, including new biomarkers and biomarker panels for frailty screening and diagnosis, using artificial intelligence to identify frailty, and investigating the altered response to medications by older adults with frailty. Other areas with novel developments included exercise (including technology-based exercise), multidimensional interventions, person-centred and integrated care, assistive technologies, analysis of frailty transitions, risk-factors, clinical guidelines, COVID-19, and potential future treatments. This review identified a strong need for the implementation and evaluation of cost-effective, community-based interventions to manage and prevent frailty. Our findings highlight the need to better identify and support older adults with frailty and involve those with frailty in shared decision-making regarding their care.

Decrease in maximum paced walking speed predicts hospitalization in community-dwelling older people with disabilities

PURPOSE

Walking speed is a useful predictor of hospitalization for community-dwelling older people. However, whether it is an effective predictor for disabled older people has not been clarified. This study aimed to investigate the association of walking speed with unexpected hospitalizations in community-dwelling, disabled, older people.

METHODS

The participants were ambulatory, community-dwelling older adults aged ≥ 65 years with disabilities. Comfortable and maximum walking speeds were measured at two timepoints, baseline and 3 months later. Furthermore, the change over time at 3 months in walking speed was also calculated. If the change in walking speed decreased more than 0.1 m/s, it was defined as walking speed decreased. The primary outcome was unexpected hospitalization during 4-year follow-up. The associations among baseline walking speed, walking speed decline, and hospitalization were analyzed using Cox regression analysis adjusted for potential confounding factors.

RESULTS

A total of 93 people (age 81.8 ± 7.0 years, 64 female) were included, and unexpected hospitalization occurred in 47 people during 4-year follow-up. On Cox regression analysis adjusted for potential confounding factors, only the maximum walking speed decrease was significantly associated with hospitalization (hazard ratio = 2.53, 95% confidence interval: 1.23-5.21), not baseline walking speed and comfortable walking speed decrease.

CONCLUSION

As for the assessment of walking speed for the prediction of unexpected hospitalization in disabled people, measurement at a single timepoint is not useful, whereas change over time is. Monitoring of change over time in maximum walking speed appears to be one of the indicators for the health management of disabled people.

Usefulness of measuring maximal gait speed in conjunction with usual gait speed for risk stratification in patients with cardiovascular disease

BACKGROUND

Usual gait speed is a prognostic factor in cardiovascular disease (CVD) patients; however, given the aging population, there has been an increase in patients with CVD with slow usual gait speed. Even among patients with slow usual gait speed, some can walk with sufficient speed during maximal gait, while others cannot. This study aimed to investigate the relationship between maximal gait speed and prognosis, and the utility of evaluating maximal gait speed in conjunction with usual gait speed in risk stratification of prognosis in patients with CVD.

METHODS

We included 2953 CVD patients who underwent evaluation of both usual and maximal gait speeds. They were classified into the usual (+) group [usual gait speed ≥1.0 m/s], usual (-) and maximal (+) group [usual gait speed <1.0 m/s and maximal gait speed ≥1.0 m/s], and usual (-) and maximal (-) group [usual gait speed <1.0 m/s and maximal gait speed <1.0 m/s].

RESULTS

Slower maximal gait speed was significantly associated with higher mortality in CVD patients. This association was consistent across various subgroups, including older patients, patients with slow usual gait speed, and patients with heart failure. Maximal gait speed provided additional prognostic information to that of pre-existing prognostic factors and usual gait speed (p = 0.049). The usual (-) and maximal (-) group showed higher mortality (hazard ratio: 1.63; 95% confidence interval: 1.17-2.26; p = 0.003) than the usual (-) and maximal (+) group. There was no significant difference in mortality between the usual (+) group and the usual (-) and maximal (+) group.

CONCLUSIONS

Maximal gait speed was an independent prognostic predictor for CVD patients. Evaluating maximal gait speed in conjunction with usual gait speed was useful for further risk stratification of prognosis in CVD patients.

Kinematic characteristics during gait in frail older women identified by principal component analysis

Frailty is associated with gait variability in several quantitative parameters, including high stride time variability. However, the associations between joint kinematics during walking and increased gait variability with frailty remain unclear. In the current study, principal component analysis was used to identify the key joint kinematics characteristics of gait related to frailty. We analyzed whole kinematic waveforms during the entire gait cycle obtained from the pelvis and lower limb joint angle in 30 older women (frail/prefrail: 15 participants; non-frail: 15 participants). Principal component analysis was conducted using a 60 × 1224 input matrix constructed from participants’ time-normalized pelvic and lower-limb-joint angles along three axes (each leg of 30 participants, 51 time points, four angles, three axes, and two variables). Statistical analyses revealed that only principal component vectors 6 and 9 were related to frailty. Recombining the joint kinematics corresponding to these principal component vectors revealed that frail older women tended to exhibit greater variability of knee- and ankle-joint angles in the sagittal plane while walking compared with non-frail older women. We concluded that greater variability of knee- and ankle-joint angles in the sagittal plane are joint kinematic characteristics of gait related to frailty.

Faster or longer steps: Maintaining fast walking in older adults at risk for mobility disability

BACKGROUND

The ability to walk at various speeds is essential to independence for older adults. Maintaining fast walking requires changes in spatial-temporal measures, increasing step length and/or decreasing step time. It is unknown how mobility affects the parameters that change between preferred and fast walking.

RESEARCH QUESTION

How does preferred walking performance and measures of strength and mobility relate to the approach (decreasing step time or increasing step length) older adults at risk for mobility disability use to maintain fast walking speeds?.

METHODS

Peak isokinetic dynamometry of knee and ankle and several mobility evaluations, including the Timed Up-and-Go, Short Physical Performance Battery, and Dynamic Gait Index, assessed mobility and strength in 57 participants, aged 65-80. Biomechanical gait analysis was used to analyze step length, step time, gait speed at preferred and fast gait speeds and ground reaction force during preferred walking. A score combining the differences between step length and time at fast and preferred speeds (Length-Time Difference) separated participants into two groups: (1) Length, representing a predominant increase in step length to walk fast and (2) Time, a predominant decrease in step time.

RESULTS

Those who decreased step time to produce increased speed performed worse during repeated chair stands (p = .006) with no difference in isokinetic strength (p ≥ .15). During preferred walking, the Time group displayed increased propulsive impulse compared to the Length group (p = .007), despite no differences in preferred speed, step length, or time (p ≥ .50).

SIGNIFICANCE

While kinetics of preferred walking differed between groups separated by Length-Time Difference, basic spatial-temporals of preferred walking did not in this homogenous population. Length-Time Difference relates to a common mobility assessment and could be easily calculated by clinicians to provide a quantitative and more sensitive measure of ambulatory performance.

Comparison of Gait Speed Reserve, Usual Gait Speed, and Maximum Gait Speed of Adults Aged 50+ in Ireland Using Explainable Machine Learning

Gait speed is a measure of general fitness. Changing from usual (UGS) to maximum (MGS) gait speed requires coordinated action of many body systems. Gait speed reserve (GSR) is defined as MGS-UGS. From a shortlist of 88 features across five categories including sociodemographic, cognitive, and physiological, we aimed to find and compare the sets of predictors that best describe UGS, MGS, and GSR. For this, we leveraged data from 3,925 adults aged 50+ from Wave 3 of The Irish Longitudinal Study on Ageing (TILDA). Features were selected by a histogram gradient boosting regression-based stepwise feature selection pipeline. Each model's feature importance and input-output relationships were explored using TreeExplainer from the Shapely Additive Explanations explainable machine learning package. The mean R a d j 2 (SD) from fivefold cross-validation on training data and the R a d j 2   score on test data were 0.38 (0.04) and 0.41 for UGS, 0.45 (0.04) and 0.46 for MGS, and 0.19 (0.02) and 0.21 for GSR. Each model selected features across all categories. Features common to all models were age, grip strength, chair stands time, mean motor reaction time, and height. Exclusive to UGS and MGS were educational attainment, fear of falling, Montreal cognitive assessment errors, and orthostatic intolerance. Exclusive to MGS and GSR were body mass index (BMI), and number of medications. No features were selected exclusively for UGS and GSR. Features unique to UGS were resting-state pulse interval, Center for Epidemiologic Studies Depression Scale (CESD) depression, sit-to-stand difference in diastolic blood pressure, and left visual acuity. Unique to MGS were standard deviation in sustained attention to response task times, resting-state heart rate, smoking status, total heartbeat power during paced breathing, and visual acuity. Unique to GSR were accuracy proportion in a sound-induced flash illusion test, Mini-mental State Examination errors, and number of cardiovascular conditions. No interactions were present in the GSR model. The four features that overall gave the most impactful interactions in the UGS and MGS models were age, chair stands time, grip strength, and BMI. These findings may help provide new insights into the multisystem predictors of gait speed and gait speed reserve in older adults and support a network physiology approach to their study.