The physical performance test predicts aerobic capacity sufficient for independence in early-stage Alzheimer disease

Establishing Reference Cardiorespiratory Fitness Parameters in Alzheimer's Disease

Evidence is growing for aerobic exercise training as a viable means to attenuate cognitive losses associated with Alzheimer's disease. The mechanism of action for aerobic exercise's cognitive benefits is likely enhanced cardiorespiratory fitness and its response to incremental aerobic exercise have been incompletely evaluated in Alzheimer's disease. The aim of this analysis was to establish cardiorespiratory fitness reference values in older adults with mild to moderate Alzheimer's disease using a cardiopulmonary graded exercise testing. Ninety-seven community-dwelling older adults with mild to moderate Alzheimer's disease underwent a symptom limited cardiopulmonary graded exercise test on a cycle ergometer. Differences between sexes and between Alzheimer's disease participants with and without diagnosis of cardiovascular diseases were assessed by independent T-tests. Peak oxygen consumption was 10-20% lower than those achieved by similar clinical populations on treadmill tests. As expected, males produced significantly higher peak oxygen consumption compared to females (p =0 .02). However, the presence of concurrent cardiovascular disease did not result in statistically significant lower peak oxygen consumption compared to those without cardiovascular disease. These data provide a frame of reference for metabolic, cardiovascular, and ventilatory function during cardiopulmonary graded exercise testing performed on cycle ergometer in older adults with mild to moderate Alzheimer's disease.

AEROBIC CAPACITY OF CHILEAN ADULTS AND ELDERLY: PROPOSAL OF CLASSIFICATION BY REGIONAL PERCENTILES

ABSTRACT Introduction Aerobic fitness is an important predictor that contributes to the preservation of functional independence during the aging process. Its measurement represents a fundamental tool in the identification of multiple health problems. Objective To compare the aerobic capacity of adults and elderly subjects through international studies and to develop percentiles by age group using the LMS method. Methods A cross-sectional descriptive study was conducted with 1146 subjects (437 men and 709 women). The age group of the sample ranged from 50 to 84 years. The subjects evaluated came from the physical activity programs offered by the National Sports Institute (IND) and by the city council of Talca (Chile). Body mass, stature, oxygen saturation (SatO2), six-minute walk test, and systolic and diastolic blood pressure were assessed. Body Mass Index (BMI) was calculated for both sexes. The LMS method was used to propose the percent distribution. Results Aerobic capacity decreases with age (28.5% for men and 29.9% for women). There was a negative relationship between age and the six-minute walk test (men r = -0.13 and women r = -0.39). There was a discrepancy between the elderly subjects in the current study and those from international studies. The normative data for the classification of aerobic fitness were expressed in percentiles (p3, p5, p10, p15, p25, p50, p75, p85, p90, p95 and p97). Conclusion The aerobic performance of elderly subjects diminishes as they age; in addition, the current results differ from international studies, which motivated the development of percentiles to classify aerobic fitness in everyday situations, especially in places with few resources and particularly where field tests are considered a priority for large-scale physical evaluation. Level of evidence II; Diagnostic studies – investigation of diagnostic test.

Change in Fitness and the Relation to Change in Cognition and Neuropsychiatric Symptoms After Aerobic Exercise in Patients with Mild Alzheimer's Disease

BACKGROUND

Physical activity has the potential to improve physical function in patients with Alzheimer's disease (AD) and may contribute to modify disease processes and cognitive function.

OBJECTIVE

The aim of this study was to investigate 1) the effect of moderate-high-intensity aerobic exercise on cardiorespiratory fitness, i.e., peak oxygen uptake (VO2peak) determined by direct breath-by-breath cardiopulmonary exercise test, and 2) the association between changes in VO2peak and changes in cognition and neuropsychiatric symptoms in patients with mild AD.

METHODS

The study is based on secondary outcome analyses from the large single-blinded multi-center study ADEX (Preserving Cognition, Quality of Life, Physical Health and Functional Ability in Alzheimer's Disease: The Effect of Physical Exercise). A preselected sub-group of 55 participants (age 52-83 years), 29 from the intervention group (IG) and 26 from the control group (CG), was included. IG performed 16 weeks of supervised moderate-to-high intensity aerobic exercise. Assessments of VO2peak, mental speed and attention (Symbol Digit Modalities Test, SDMT), and neuropsychiatric symptoms (Neuropsychiatric Inventory, NPI) were performed at baseline and at 16 weeks.

RESULT

VO2peak increased 13% in the IG and a between-group difference in mean change (3.92 ml/kg/min, 95% CI 6.34-1.51, p = 0.003) was present in favor of the IG. Combined data from IG and CG showed positive associations between changes in VO2peak and changes in NPI (Rho = - 0.41, p = 0.042) and changes in SDMT (Rho = 0.36, p = 0.010), respectively.

CONCLUSION

Aerobic exercise improves VO2peak in community-dwelling patients with mild AD. Furthermore, changes in VO2peak appear to be associated to changes in cognition and neuropsychiatric symptoms.

Determination of Aerobic Capacity via Cycle Ergometer Exercise Testing in Alzheimer's Disease

BACKGROUND

Older adults with Alzheimer's disease (AD) may be unable to perform treadmill testing due to balance issues. We investigated whether older adults with AD could successfully complete a peak cycle ergometer test.

METHODS

Peak oxygen consumption (peak [Formula: see text]) assessed via a cycle ergometer test in 44 participants with AD (age 78.4 ± 6.8). Physical function was assessed via the incremental shuttle walk, 6-minute walk, and the Short Physical Performance Battery (SPPB).

RESULTS

All participants completed the cycle ergometer test successfully. Peak [Formula: see text] was correlated with SPPB ( r = .35, P = .023), shuttle walk ( r = .35, P = .024), 6-minute walk ( r = .31, P = .05), and inversely with age ( r = -.4, P = .009). There was no correlation between peak [Formula: see text] and cognition.

CONCLUSION

Older adults with AD are able to safely complete a peak cycle ergometer exercise testing protocol. We provide an individualized cycle ergometer test for determining aerobic capacity in older adults with AD who may be unable to perform treadmill testing due to balance or gait issues.

Use of a Nonexercise Estimate for Prestroke Peak Vo2 During the Acute Stroke Hospital Stay

PURPOSE

For individuals with acute stroke, it is difficult to conduct an exercise test to assess peak oxygen consumption (peak Vo₂). Therefore, the purpose of this study was to use a clinically feasible tool for assessing prestroke peak Vo₂ using a nonexercise estimation equation to test whether estimated prestroke peak Vo₂ was related to the functional outcome measures at discharge from the hospital in individuals after an acute stroke. We hypothesized that the estimated prestroke peak Vo₂ would be significantly related to discharge Physical Performance Test (PPT), 6-minute walk test (6MWT), and lower extremity Fugl-Meyer (LEFM) assessment.

METHODS

Estimated prestroke peak Vo₂ was calculated using a previously validated prediction equation using the following variables: body mass index, age, sex, resting heart rate, and a self-reported measure of physical activity. Outcome measures were assessed 4 days after enrollment or immediately before discharge (whichever occurred first).

RESULTS

Thirty-four participants (mean age = 56.0, SD = 12.6 years; 20 men) with acute stroke were enrolled within 48 hours of admission. For all individuals, mean estimated prestroke peak Vo₂ was 27.3 (SD = 7.4) mL·kg^-1·min^-1 and had a weak, nonsignificant relationship with the PPT (r = 0.19; P = .28), 6MWT (r = 0.10; P = .56), and LEFM (r = 0.32; P = .06). However, when considering sex, women, but not men, had a significant relationship with LEFM (r = 0.73; P = .005) and moderate but nonsignificant relationship with PPT (r = 0.53; P = .06) and 6MWT (r = 0.47; P = .10).

CONCLUSIONS

Within 48 hours of stroke admission, we were able to administer a nonexercise equation to estimate prestroke peak Vo₂. For the entire sample, functional measures conducted at discharge were not related to estimated prestroke peak Vo₂. However, when considering sex, the relationship between prestroke Vo₂ and the functional measures was strengthened.

Alzheimer disease alters the relationship of cardiorespiratory fitness with brain activity during the stroop task

BACKGROUND

Despite mounting evidence that physical activity has positive benefits for brain and cognitive health, there has been little characterization of the relationship between cardiorespiratory (CR) fitness and cognition-associated brain activity as measured by functional magnetic resonance imaging (fMRI). The lack of evidence is particularly glaring for diseases such as Alzheimer disease (AD) that degrade cognitive and functional performance.

OBJECTIVE

The aim of this study was to describe the relationship between regional brain activity during cognitive tasks and CR fitness level in people with and without AD.

DESIGN

A case-control, single-observation study design was used.

METHODS

Thirty-four individuals (18 without dementia and 16 in the earliest stages of AD) completed maximal exercise testing and performed a Stroop task during fMRI.

RESULTS

Cardiorespiratory fitness was inversely associated with anterior cingulate activity in the participants without dementia (r=-.48, P=.05) and unassociated with activation in those with AD (P>.7). Weak associations of CR fitness and middle frontal cortex were noted.

LIMITATIONS

The wide age range and the use of a single task in fMRI rather than multiple tasks challenging different cognitive capacities were limitations of the study.

CONCLUSIONS

The results offer further support of the relationship between CR fitness and regional brain activity. However, this relationship may be attenuated by disease. Future work in this area may provide clinicians and researchers with interpretable and dependable regional fMRI biomarker signatures responsive to exercise intervention. It also may shed light on mechanisms by which exercise can support cognitive function.

Validity of the step test for exercise prescription: no extension to a larger age range

The purpose of this study was to determine the validity of a submaximal exercise test, the Step Test Exercise Prescription (STEP), in a broad age range and in individuals in the earliest stages of Alzheimer's disease (AD). Individuals (n = 102) underwent treadmill-based maximal exercise testing and a STEP. The STEP failed to predict peak oxygen consumption (VO2peak), and was a biased estimate of VO2peak (p < .0001). Only 43% of subjects' STEP results were within 3.5 ml · kg-1 · min-1 of VO2peak. When categorized into fitness levels these 2 measures demonstrated moderate agreement (kappa = .59). The validity of the STEP was not supported in our participants, including those with AD. The STEP may not be appropriate in the clinic as a basis for exercise recommendations in these groups, although it may continue to have utility in classifying fitness in research or community health screenings.