BACKGROUND: Evidence has shown benefits for mental health through aerobic training oriented in percentage of VO2max, indicating the importance of this variable for clinical practice. OBJECTIVE: To validate a method for estimating VO2max using a submaximal protocol in elderly patients with clinically diagnosis as major depressive disorder (MDD) and Parkinson's disease (PD). METHODS: The sample comprised 18 patients (64.22 ± 9.92 years) with MDD (n = 7) and with PD (n = 11). Three evaluations were performed: I) disease staging, II) direct measurement of VO2max and III) submaximal exercise test. Linear regression was performed to verify the accuracy of estimation in VO2max established in ergospirometry and the predicted VO2max from the submaximal test measurement. We also analyzed the correlation between the Bland-Altman procedures. RESULTS: The regression analysis showed that VO2max values estimated by submaximal protocol associated with the VO2max measured, both in absolute values (R² = 0.65; SEE = 0.26; p < 0.001) and the relative (R² = 0.56; SEE = 3.70; p < 0.001). The Bland-Altman plots for analysis of agreement of showed a good correlation between the two measures. DISCUSSION: The VO2max predicted by submaximal protocol demonstrated satisfactory criterion validity and simple execution compared to ergospirometry.
Exercise test; exercise; mood disorders; Parkinson's disease
CONTEXTO: Evidências demonstram benefícios para a saúde mental com o treinamento aeróbico orientado em percentuais do VO2max, indicando a importância dessa variável para a prática clínica. OBJETIVO: Validar um método para estimar o VO2max por meio de um protocolo submáximo em idosos com diagnóstico clínico de transtorno depressivo maior (DM) e doença de Parkinson (DP). MÉTODOS: A amostra foi composta por 18 pacientes (64,22 ± 9,92 anos; sete pacientes com DM e 11 com DP). Foram realizadas três avaliações: I) estadiamento da doença, II) mensuração direta de VO2max e III) teste de esforço submáximo. Foi realizada regressão linear para verificar a precisão de estimativa do VO2max estabelecido na ergoespirometria pelo VO2max predito no teste submáximo. Também foi analisada a concordância de Bland-Altman entre os procedimentos. RESULTADOS: A análise de regressão mostrou que os valores de VO2max estimados pelo protocolo submáximo associam-se com o VO2max medido, tanto no valor absoluto (R² = 0,65; EPE = 0,26 ; p < 0,001) quanto no relativo (R² = 0,56; EPE = 3,70; p < 0,001). A análise de concordância de Bland-Altman mostrou boa associação entre as duas medidas. CONCLUSÃO: O VO2max predito por meio do protocolo submáximo demonstrou satisfatória validade de critério e simples execução comparado à ergoespirometria.
Teste de esforço; exercício; transtornos de humor; doença de Parkinson
Assessment of cardiorespiratory fitness using submaximal protocol in older adults with mood disorder and Parkinson's disease
Natacha Alves de OliveiraI,II; Heitor Santos SilveiraI,II; Alessandro CarvalhoI,II; Christiane Gouvêa e Silva HellmuthIII; Tony Meireles SantosIV; José Vicente MartinsV; José Luiz Sá CavalcantiV; Jerson LaksI,VI; Andrea Camaz DeslandesI,II
ICenter for Alzheimer's Disease and Related Disorders, Institute of Psychiatry, Universidade Federal do Rio de Janeiro (CDA-IPUB-UFRJ), Rio de Janeiro, RJ, Brazil
IINeuroscience Exercise Laboratory (PPGCEE), Universidade Gama Filho (UGF), Rio de Janeiro, RJ, Brazil
IIIMedicine Exercise Clinic (Medsport), Rio de Janeiro, RJ, Brazil
IVLaboratory Performance (PPGCEE), UGF, Rio de Janeiro, RJ, Brazil
VInstitute of Neurology Deolindo Couto, UFRJ, Rio de Janeiro, RJ, Brazil
VICentro de Estudos e Pesquisa do Envelhecimento (CEPE), Instituto Vital Brazil, Rio de Janeiro, RJ, Brazil
BACKGROUND: Evidence has shown benefits for mental health through aerobic training oriented in percentage of VO2max, indicating the importance of this variable for clinical practice.
OBJECTIVE: To validate a method for estimating VO2max using a submaximal protocol in elderly patients with clinically diagnosis as major depressive disorder (MDD) and Parkinson's disease (PD).
METHODS: The sample comprised 18 patients (64.22 ± 9.92 years) with MDD (n = 7) and with PD (n = 11). Three evaluations were performed: I) disease staging, II) direct measurement of VO2max and III) submaximal exercise test. Linear regression was performed to verify the accuracy of estimation in VO2max established in ergospirometry and the predicted VO2max from the submaximal test measurement. We also analyzed the correlation between the Bland-Altman procedures.
RESULTS: The regression analysis showed that VO2max values estimated by submaximal protocol associated with the VO2max measured, both in absolute values (R2 = 0.65; SEE = 0.26; p < 0.001) and the relative (R2 = 0.56; SEE = 3.70; p < 0.001). The Bland-Altman plots for analysis of agreement of showed a good correlation between the two measures.
DISCUSSION: The VO2max predicted by submaximal protocol demonstrated satisfactory criterion validity and simple execution compared to ergospirometry.
Keywords: Exercise test, exercise, mood disorders, Parkinson's disease.
Major depressive disorder (MDD) and Parkinson's disease (PD) are highly prevalent disorders representing about 7% and 1%-2% of the elderly population, respectively1,2. In addition to the specific symptoms, there is also comorbidity with cardiovascular and metabolic diseases which compromise the quality of life and increase the risk of death3. MDD is associated with hypothalamic-pituitary-adrenal (HPA) axis hyperactivity, elevated cortisol levels and increased renin-angiotensin-aldosterone activation4,5. These physiological changes in depressive individuals contribute to an increased risk of cardiovascular diseases, such as hypertension6. Moreover, the cholinergic system hyperactivity and the autonomic nervous system impairment observed in patients with PD and depression may be associated with increased risk of cardiovascular disease7,8.
Low cardiorespiratory fitness9,10 is one of the factors contributing to the all cause risk of death including cardiovascular disease. Maximum values of metabolic equivalent (MET) above 6 MET for women and 8 MET for men are associated with a 15% reduced risk of death9. With aging, it is expected to occur a decrease of the maximum volume of oxygen uptake (VO2max): 10%11 and 5%12 per decade in sedentary and active individuals, respectively. On the other hand, aerobic exercise contributes to the reduction of the decline of VO2max13. In addition to the favorable responses in cardiovascular health, there is also a decrease in depressive symptoms and functional decline, as well as improvement in cognitive functions, which are potentially efficient in the treatment of mental illness14. However, the prescription of aerobic exercise intensity is essential to the efficiency and safety of the training program, especially considering the high prevalence of cardiovascular disease in this population.
To determine VO2max, ergospirometry is a direct method considered the "gold standard", also enabling the identification of ventilation thresholds. This measure has high reliability of VO2max in Alzheimer's disease patients (r = 0.94, p < 0.001)15 and PD (r = 0.90)16, being used for diagnosis, prognosis and therapeutics, especially for prescribing aerobic training. However, its applicability in rehabilitation and physical activity centers becomes difficult due to their high financial and operational cost.
Besides the low cardiorespiratory fitness resulting from the physical inactivity and specific symptoms of MDD and PD diseases, behavioral and motor changes also difficult the maximal tests implementation in these patients. Loss of pleasure and energy are depressive symptoms common in MDD and can difficult the performance of a maximal exercise test. On the other hand, some PD symptoms, such as tremor, rigidity, bradykinesia and postural instability may difficult the implementation of the test due to problems in motor skills. Moreover, in more advanced stages of MD and PD diseases these symptoms may worsen. Because of that, the target intensity in maximum tests is rarely reached by these patients. Thus, sometimes it is necessary and recommended the use of metabolic equations suggested by the American College of Sports Medicine (ACSM) for the oxygen uptake estimation, including VO2max17.
Predictive methods of VO2max through submaximal protocols have good reliability18 and may be a simple and low cost alternative in clinical interventions for exercise prescription. Recently, Santos et al.18 found good reproducibility of a submaximal treadmill protocol for obtaining the predicted VO2max (r = 0.89) for both maximum heart rate (HRmax) estimated by age (220-age)19 and the frequency peak heart (HRpeak) (r = 0.83). Further to the advantages of submaximal protocol, the method allows the individualization of the increments by stage, being able to adapt the initial loads and intensity settings during the procedure, as the speed and inclination to reach the steady state in the intensity at 70% of heart rate reserve (HRres). However, it is not yet established the validity of this procedure, particularly in elderly patients with mental disorders.
This study is meant to bridge the gap to obtain reliable parameters for the prescription of aerobic training in elderly diagnosed with MDD and PD. Moreover, there are not predictive protocols designed for this population. The aim of this study is to establish the criterion validity of a protocol of VO2max prediction based on HRres to be used in MDD and PD patients.
This study is part of a larger project regarding the effect of exercise training on the mental health of seniors and obtained approval from the research ethics committee of the Institute of Psychiatry, Universidade Federal do Rio de Janeiro (nº 70Liv2-09). MDD patients were diagnosed according to Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) criteria and the study performed at the Center for Alzheimer's Disease and Related Disorders, Institute of Psychiatry, Universidade Federal do Rio de Janeiro (CDA-IPUB-UFRJ). Screening of patients with PD was performed at the Institute of Neurology Deolindo Couto (INDC/UFRJ).
Inclusion criteria for MDD were age between 60 and 80 years and mild to moderate depressive symptoms assessed by the Hamilton Depression Scale (HAM-D) validated for Portuguese20. Inclusion criteria for PD were age between 45 and 70 years, diagnosis of idiopathic Parkinson's disease, stage 1 to 3 in Hoehn-Yahr21. Exclusion criteria common to all patients were illiteracy, stroke, associated neurodegenerative diseases, Parkinsonism, mental comorbidities, use of other treatments such as electroconvulsive therapy, psychotherapy, and clinical decompensate diseases. Other exclusion criteria were cardiac history of acute myocardial infarction and ischemia, symptoms of coronary artery disease (angina), ventricular extrasystole, patients who were taking beta-blocker medications. Of the 31 patients enrolled, 13 were excluded (nine showed no eligibility criteria for the study and four did not attend all visits). The sample consisted of 18 patients who read and signed an Informed Consent Form.
The patients made three visits in the morning with an interval of up to two weeks between assessments. For PD patients it was taken into consideration the "on-off" and "wearing-off" phenomena, which are fluctuations of motor skills due to the use of levodopa. To avoid impairment of motor skills, patients were assessed during "on" period. Patients were submitted to a cognitive evaluation and motor skills assessment (for PD). Both disorders were staged using the Hamilton Depression Scale (HAM-D)20, the Hoehn-Yahr21 and the motor domain of the Unified Scale for Assessment of Parkinson's disease (UPDRS III), all validated for the Portuguese.
Next, the volunteers underwent direct measurement of VO2max through the maximum test protocol (ergospirometry) supervised by a cardiologist. On the third visit VO2max was estimated using the submaximal protocol18,22. Patients were instructed to eat light meals, drink water, did not ingest alcohol and did not smoke on the test day. Furthermore, they were instructed not to perform intense effort over the past 48 hours before assessments. Before starting the test, patients were instructed on the scale of perceived exertion [Borg Scale (6-20)]23, and the safety procedures to the test on a treadmill. Weight and height were measured using a mechanical platform scale (Welmy 110, Welmy Industry and Commerce Ltda.®, SP, Brazil).
Maximal exercise test with gas analysis: The direct measurement through the maximal test with gas analysis was performed at the Medicine Exercise Clinic (MEDSPORT), in a room with a temperature of 23oC and relative humidity of 55%. Heart rate was monitored through derivation D2 on electrocardiograph (ECG Digital Elite, Micromed Biotechnology Ltda.®, DF, Brazil) and blood pressure was measured by a mercury sphygmomanometer (DiagnostixTM, American Diagnostic Corporation®, USA).
The Treadmill Ramp Test Protocol24 (ATL Millennium Super, Ltda Inbramed®, RS, Brazil) was chosen because it considers the biological individuality of patients. This protocol consisted of continuous and gradual increased stages according to the adaptation to the treadmill each patient. Tests used exclusively walking, in which the doctor set the speed and inclination to be achieved by the patient and the computerized system (VO2000, Medical Graphics®, 13® PC Ergo software version 3.3, RS, Brazil) calculated the rate at which the power was increased during testing. The cardiorespiratory variables VO2, respiratory exchange ratio (R), carbon dioxide production (VCO2) and pulmonary ventilation (VE) were measured using a gas analyzer coupled to the computerized system, with samples every 10 seconds.
Systems analysis of O2 and CO2 were calibrated according to manufacturer's specification before each test. The peak oxygen consumption (VO2 peak) was considered as highest value obtained at the end of the effort. To consider this test as maximum effort some criteria were observed, such as to reach a plateau in oxygen uptake, perceived exertion above 17 (Borg scale 6-20) and mainly, volitional fatigue. Furthermore, the evaluators were alerted to the criteria for interruption with diagnostic purposes suggested by ACSM17.
Submaximal protocol: The testing was performed at the Institute of Neurology Deolindo Couto. Vital signs were measured after 10 min rest in the supine position in a quiet and refrigerated room. During the tests we monitored and recorded heart rate by frequency meters every 20 s (model FS3TM, Polar®, Finland), the subjective feeling of exertion by the Borg scale (6-20)23 and blood pressure was measured and recorded every 2 min through the device (DuraShock, Welch Allyn, Tycos®, SC, Brazil).
To determine the HRres we used the equation (HRmax HRres) x intensity + HRres, in which HRmax = maximum heart rate estimated by equation (220 age)19, HRres = resting heart rate measured after 10 min of rest the patient in the supine position and intensity = intensity that the patient should reach during the test (65% of HRres,) and keep the steady-state (70% of HRres).
The submaximal protocol consisted of an initial 3-min warm-up on treadmill (JOG model 500, Technogym The Wellness Company®, Italy), in which the initial rate varied according to the adaptation to the treadmill between patients. The increased metabolic ratio for each stage was equivalent to 1 MET and provided by manipulating the speed and inclination on the treadmill. The objective was to reach the intensity corresponding to approximately 65% of HRres. Once achieved, this exercise intensity was maintained for six minutes featuring a steady-state25. By the end of this phase, it was expected that the HR was stabilized at approximately 70% of HRres. The criteria for interruption of both tests followed the recommendations of ACSM17.
The VO2 was obtained by equation: VO2 = [0.1 (speed) + 1.8 (speed) (inclination/100) + 3.5], in which the speed is given in m/min. Finally, VO2max was predicted by the equation: VO2max = [(VO2 3.5) / 3.5% HRres + 3.5], in which the VO2max is expressed in mL.kg-1.min-117.
We applied the Shapiro-Wilk and Levene tests to test the distribution and data variance, respectively. A linear regression was performed to verify the accuracy of the estimate in VO2max established in cardiopulmonary exercise testing by VO2max predicted in submaximal test. The accuracy of prediction was established by the coefficient of determination and adjusted by the standard error of the estimate (SEE). Moreover, to verify the correlation between measured VO2max and estimated VO2max it was used the reliability analysis Bland-Altman.
The software used for data analysis was the Statistical Package for the Social Sciences version 19 (SPSS® Inc., Chicago, IL, USA) and a value p ≤ 0.05 was accepted as indicating statistical significance.
The sample consisted of 18 patients, 11 with PD and seven with MDD. Patients had a mean age of 64.2 (SD = 9.92) years and mean schooling of 9.5 (SD = 4.13) years. The average weight and height of all patients was 67 (62.5 to 72.3) kg and 1.63 (SD = 0.09) meters, respectively. Among the patients, 11 were taking antiparkinsonian medications (61.1%), seven were taking selective serotonin reuptake inhibitors (38.9%) and eight were taking antihypertensive medications (44.4%). There was a normal distribution and homogeneity for age, education, mini mental state examination (MMSE), height, body mass index, number of medications, HAM-D score and UPDRS. Regarding symptoms of the disease, depressive patients had mild symptoms of depression assessed by HAM-D (11 ± 6). PD patients had a median score of 2.5 (2.0-3.0) on Hoehn Yahr Scale and 31.8 (SD = 10.5) points in the evaluation of motor symptoms by UPDRS III. All patients had adequate adaptation in both protocols investigated and no complications were observed.
All patients showed mean absolute VO2max of 1.6 ± 0.4 L.min-1 (measured directly) and 1.9 ± 0.4 L.min-1 (indirect measure). The VO2max values were made relative to the body mass of 23.8 ± 3.8 mL.kg-1.min-1 (direct measure) 27.5 ± 5.5 mL.kg-1.min-1 (indirect measurement). Regression analysis showed that the VO2max values estimated by submaximal protocol are associated with VO2max measured both in absolute value (R2 = 0.65, F (1,16) = 29.78; SEE = 0.26; p < 0.001) and the relative (R2 = 0.56, F (1,16) = 20.76, SEE = 3.70, p < 0.001). The Bland-Altman concordance analysis presented BIAS -3.70 ± 3.63 (mean, SD) (95% CI, -10.82, 3.41) for the relative VO2max and BIAS -0.25 ± 0.25 (95% CI, -0.74, 0.25) for the absolute VO2max, showing a good agreement between the two methods (Figure 1).
This study aimed to investigate the use of an indirect method for predicting VO2max based on HRres and VO2res through a submaximal protocol in patients with highly prevalent mental and neurodegenerative diseases in the elderly population, specifically the MDD and PD. The results showed good correlation between directly VO2max measured and VO2max provided by the proposed submaximal protocol, with standard error of the estimate of 0.26 L.min-1 and 3.70 mL.kg-1.min-1. All patients were able to perform the tests without any adverse response or impairment during or after the evaluations, highlighting the ease of application and safety of the protocol.
According to Bland-Altman analysis, we observed a difference between direct and indirect measurement, assuming that there is a slight overestimation in indirect measurement. However, the values of SEE were similar to those found in the literature22. Through the mean VO2max obtained by direct measurement (23.7 mL.kg-1.min-1) and the indirect measurement (27.4 mL.kg-1.min-1), it was possible to calculate the mean METs (6.8 to 7.8 METs, respectively). It is believed that individuals with maximal aerobic capacity of 7.9 METs or more have lower mortality rates and less cardiovascular disease9. These data indicate the suitability of the method to cardiorespiratory evaluation in MDD and PD patients, since they are at greater risk for cardiac events3,6. In addition, psychiatric disorders are prevalent in cardiac patients who participate in a supervised exercise program, even without functional impairment and multiple comorbidities26.
For greater safety, we recommend consideration of the standard error of estimate reported and demonstrated by the present study. Our data corroborate a previous data in a study which used a cycle ergometer through a submaximal protocol ramp with sedentary individuals which found high reproducibility (r = 0.85, p < 0.001) and validity (r = 0.75, p < 0.001)27. The development of these methods or indirect tests aims at helping the cardiovascular evaluation and direction for the prescription of exercise training.
The adhesion to exercise program and training effectiveness also depends on factors related to prescription, such as the intensity of the effort. Too light or too high intensity seems to be associated with a worse affective response and possibly lower adherence to an exercise program, especially in sedentary individuals28. Furthermore, studies have shown an ideal intensity for a better benefit on motor, cognitive, and behavioral skills. According to the "inverted U" theory29, moderate intensities promote the best response, requiring strict control of this variable in patients with mental disorders30.
According to ACSM guidelines for elderly population31, it is recommended to practice 150 minutes per week of physical activity, and the frequency with aerobic activity at least three times per week, intensity at 40 to 60% of HRres, 11-13 in Borg scale, lasting at least 20 min. Studies that have investigated the effect of aerobic exercise in the treatment of MDD in elderly have used VO2max relative for the prescription of training intensity32,33. It has already been demonstrated that aerobic exercise performed two to three times a week during 30 min, with 60% VO2max (12 to 14 on the Borg scale) were effective for the additional treatment in MDD32,33. Such evidence supports the importance of determining VO2max to prescribe aerobic training.
This study presents some limitations which should be considered, for example, the small number of patients and medication used by the PD patients, since they reduce the HR. In particular, this aspect may explain the slight overestimation of VO2max observed. Future studies are needed to replicate these analyzes separately for each population taking into consideration the type of medication used. Furthermore, it is suggested that future studies compare the prediction equations HRmax proposed by Fox et al.19 and Tanaka et al.34. Although the present study used only MDD and PD patients, it is expected that the method for predicting VO2max from a submaximal protocol can be used by patients with other mental disorders. Thus, future research should replicate this method with specific populations.
VO2max predicted by submaximal protocol demonstrated satisfactory validity criterion and simple implementation when compared to ergospirometry. Exercise prescription for older adults with MDD and PD can be adequately performed based on physiological variables obtained by this protocol, which should consider the accuracy reported by this study. This recommendation suggests safer and more effective aerobic training.
The authors acknowledge support from the National Council for Scientific and Technological Development (CNPq, Brazil) and the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), Rio de Janeiro, Brazil.
Jerson Laks is partially supported by the National Council for Scientific and Technological Development (CNPq) nº 300411/2009-0 and Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ) nº E-26/112631/2012.
The authors acknowledge the assistance of the researchers Helena Sales de Moraes, Raphael Marques Gomes, Dannyel Duarte Barbirato, Ingrid Storck Guimarães and Monique Nunes Carvalhaes Pinheiro during the collections and Medicine Exercise Clinic (MEDSPORT) for performing maximal tests without cost.
Institution which the study should be attributed: Institute of Psychiatry, Universidade Federal do Rio de Janeiro (UFRJ).
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Address correspondence to:
Andrea Camaz Deslandes. Universidade Federal do Rio de Janeiro, Institute of Psychiatry, Laboratory of Geriatric Neuropsychiatry.Av. Venceslau Brás, Botafogo 22290-140 Rio de Janeiro, RJ, Brazil.E-mail:
Publication in this collection
02 July 2013
Date of issue
10 Sept 2012
20 Dec 2012