Is there an association between quadriceps muscle endurance and performance on activities of daily living in individuals with COPD?

Abstract Introduction Chronic obstructive pulmonary disease (COPD) is characterized by limited airflow associated with inflammatory response and systemic manifestations, such as dyspnea, as well as physical inactivity and intolerance to exercise. The sum of these changes can lead to peripheral muscle fatigue and exert an impact on the performance of activities of daily living (ADL). Objective To investigate the possible association between peripheral muscle fatigue and performance on ADL in individuals with COPD, and to compare the results to those of healthy age-matched individuals. Methods Individuals with a diagnosis of COPD and healthy volunteers aged 60 years or older were submitted to evaluations of peripheral muscle fatigue (using surface electromyography) and performance on the Glittre-ADL test. Results Nine individuals with COPD and ten controls were evaluated. Median isometric quadriceps contraction time was 72 [38] and 56 [51] seconds, respectively. Execution time on the ADL test was 6.1 [4] and 3.6 [1.3] minutes for COPD and control group respectively, with a significant difference between groups (p < 0.05). However, no significant correlation was found between the evaluations. Conclusion No association was found between quadriceps muscle fatigue and performance on ADL in the sample studied. In the intergroup comparison, the individuals with COPD exhibited worse ADL time execution, but no significant difference was found regarding quadriceps muscle fatigue.


Introduction
Chronic obstructive pulmonary disease (COPD) is defined as limited airflow resulting from exposure to toxic gases and harmful particles associated with an inflammatory response.1 It is characterized as a common, preventable and treatable disease, but is not completely reversible, leading to lung and extrapulmonary impairment.
As COPD is a systemic inflammatory disease, extrapulmonary manifestations may contribute to the severity of the disease.O tempo de execução do teste de AVD foi de 6,18 [4,09] e 3,67 [1,3]  The tests were performed by the same evaluators, on two non-consecutive days, with an interval of 24 hours between them, so that the results of the estimates did not interfere with each other.On the first day, anamnesis, anthropometry, spirometry and quadriceps fatigue were performed; on the second day, the two ADL tests were performed.

Experimental procedure
Complete patient histories were taken, followed by the collection of anthropometric data.Height was measured using a metric tape (Wiso®) and body mass was determined in the standing position using a digital scale (FILIZOLA®).The body mass index (BMI) was then calculated using the equation: body weight (kg)/height (m 2 ). Spirometry was then performed with a portable spirometer (Easy One®, Ndd, Zurich, Switzerland) in a temperature-controlled environment (22 to 24 ºC).The If SpO 2 dropped below 85%, oxygen was offered through a nasal cannula to maintain the SpO 2 above 90%.The test would be interrupted if the volunteer reported a score higher than 6 on the Borg scale, exhibited signs of low cardiac output, reported chest pain or dizziness, or if the SpO 2 remained low even with oxygen supplementation.

Statistical analysis
The sample size was calculated based on a previous cross-sectional study

Results
Twenty volunteers were recruited (10 in the control group and 10 in the COPD group).One volunteer in the COPD group was excluded for not finishing the evaluation protocol.Thus, the final sample was composed of 19 volunteers.(used for the fatigue protocol) and tolerance limit.No significant differences were found between groups.

2
Skeletal muscle dysfunction is an apparent manifestation in the initial stages 3 and involves muscle weakness of the upper and lower limbs, muscle atrophy, reduction in muscle oxidative capacity, the prevalence of type II fibers, reduction in capillary density and reduction in aerobic enzymes.4-6 Besides weakness, some studies have reported that individuals with COPD have lower limb muscle fatigue, especially in the quadriceps, which is directly associated with the severity of the disease.7-9 All these factors together lead to a progressive reduction in the level of daily physical activity, reduction in the capacity for physical exercise, limited tolerance to exercise and poorer quality of life.This vicious circle can lead to debility and generalized immobility.5,10 The reduction in functional capacity explained by muscle weakness and fatigue, especially in the lower limbs, is well documented in the literature on COPD 7-9,11-14 and the sum of these systemic alterations can exert a negative impact on quality of life.However, a possible association between peripheral muscle fatigue, especially in the quadriceps, and an effective performance on ADL in this population is not yet well established.Therefore, the aims of the present study were to investigate the possible association between quadriceps muscle endurance and performance on ADL in individuals with COPD, and to compare the results to those of healthy age-matched individuals.Methods A cross-sectional study was conducted at the Laboratório de Avaliação Funcional Pulmonar (LARESP; Lung Function Assessment Lab) of Universidade Nove de Julho involving patients with a clinical diagnosis of COPD and healthy individuals, of both sexes, and older than 60 years of age.This study received approval from the institutional review board of the university (certificate number: 4.308.091)and all volunteers agreed to participate by signing a statement of informed consent.The inclusion criteria were age 60 years or older, a clinical diagnosis of COPD confirmed by postbronchodilator spirometry, clinical stability and not having undergone any lung rehabilitation program in the previous three months.The healthy individuals were recruited from the same city through personal invitation and were also 60 years of age or older.Exclusion criteria were incapacity to perform any of the tests, dropping out of the protocol and not agreeing to participate in the study (Figure 1).

8
using the correlation coefficient for muscle fatigue of the vastus medialis measured using EMG correlated to the distance travelled on the sixminute walk test, with an effect size of r = 0.77, two-tailed of α = 0.05 and 80% power.The minimum sample was determined to be ten individuals.The Shapiro-Wilk test was used to determine the normality of the data.The data were expressed as median and inter-quartile range.The paired t-test and t-test for independent samples were used for the intra-group and inter-group comparisons.Repeatedmeasures analysis of variance (ANOVA) was used to determine interactions between the EMG data, with the Bonferroni correction and Bonferroni post hoc test.Pearson's correlation test was used for the correlation analyses.The level of significance was set at 5% (p ≤ 0.05).All analyses were performed with the aid of SPSS 20.0 (IBM SPSS Statistics for Windows, Version 20.0.Armonk, NY: IBM Corp).

Figure 2
Figure 2 displays the MDF data of the quadriceps muscle determined by EMG, with the means of the rectus femoris, vastus medialis and vastus lateralis.The participants exhibited muscle fatigue at the end of the test (100%), as demonstrated by the significant reduction in MDF.No significant differences between groups were found in any of the steps or phases of the contractions.

Table 1
the control group had higher BMI values compared to the COPD group, characterizing overweight and normal weight, respectively, we do not believe they are characterized as possible biases, as these values were very close.Castellari CB et al.Fisioter Mov.2023;36:e36103 5

Table 3
displays the execution times on the first and second Glittre-ADL test.Significant differences were found between the first and second test.Moreover, the COPD group had significantly longer execution times compared to the healthy individuals.The analysis of the quadriceps muscle fatigue data and performance on the Glittre-ADL test revealed no significant correlations.

Table 1 -
General characteristics of the sample 1 = forced expiratory volume in the first second; FVC= forced vital capacity; MVV= maximum voluntary ventilation.*Inter-group comparison (p ≤ 0.05).Data are expressed in median [interquartile range].

Table 3 -
Comparison of execution times on first and second Glittre-ADL tests