Lower Limb Fatigue Research Articles

A new method to track the thigh segment which combines the advantages of two long established techniques

The objective of the present study was to investigate the effects of multi-joint muscular fatigue on biomechanics of slips. Both lower-limb fatigue and upper-limb fatigue were examined, and the fatiguing exercises involved multi-joint movements to replicate muscular fatigue in realistic scenarios. Sixty healthy young adults participated in the study, and were evenly categorized into three groups: no fatigue, lower-limb fatigue, and upper-limb fatigue. These participants were instructed to walk on a linear walkway, and slips were induced unexpectedly during walking. The results showed that multi-joint muscular fatigue affects biomechanics of slips in all three phases of slips (i.e. initiation, detection, and recovery). In particular, adaptive safer postural control strategies were adopted with the application of both lower-limb fatigue and upper-limb fatigue to maintain the likelihood of slip initiation as in the no fatigue condition. In the phases of detection and recovery, lower-limb fatigue was found to compromise biomechanics of slips while upper-limb fatigue did not show any effects. Based on these findings, minimizing exposures to lower-limb fatigue should be given higher priority compared to upper-limb fatigue when developing interventions to prevent slip-induced falls. In addition, these findings also suggest that interventions aimed at enhancing proprioceptive acuity and increasing muscular strength in the lower limb could also be effective in slip-induced fall prevention.

Investigation of Lower Limb Fatigue on Two Standing Posture

The purpose of this study was to investigate the different effect from the two standing posture on lower limb fatigue and discomfort. Sixteen subjects (eight females and eight males), aged between 23-29 years, participated in the experiment. They performed a sorting task in front of a grading table by picking and placing objects for 90 minutes in two posture (1) standing and (2) standing using a footrest. Muscle activity was recorded with surface EMG through disposable electrodes. The result shows that standing for ninety minutes developed fatigue in lower limb muscles and back muscles that lead to low back pain. Standing using a footrest result proper posture for prolonged standing period and reduce force at the back. It also results less fatigue and reduce the %MVC of EMG. So, it is recommended to attach a footrest in standing workstation to reduce the fatigue and discomfort.Keywords:fatigue, posture, standing,lower limb, EMG

Effect of short-term fatigue, induced by high-intensity exercise, on the profile of the ground reaction force during single-leg anterior drop-jumps

[Purpose] Fatigue may be an important contributing factor to non-contact anterior cruciate ligament injuries in sports. The purpose of this study was to evaluate the effects of controlled lower limb fatigue, induced by a short-term, high-intensity exercise protocol, on the profile of the ground reaction force during landings from single-leg anterior drop-jumps. [Subjects and Methods] Twelve healthy males, 18 to 24 years old, performed single-leg anterior drop-jumps, from a 20 cm height, under two conditions, ‘fatigue’ and ‘non-fatigue’. Short-term fatigue was induced by high-intensity interval cycling on an ergometer. Effects of fatigue on peak vertical ground reaction force, time-to-peak of the vertical ground reaction force, and loading rate were evaluated by paired t-test. [Results] Fatigue shortened the time-to-peak duration of the vertical ground reaction force by 10% (non-fatigue, 44.0 ± 16.8 ms; fatigue, 39.6 ± 15.8 ms). Fatigue also yielded a 3.6% lowering in peak vertical ground reaction force and 9.4% increase in loading rate, although these effects were not significant. [Conclusion] The effects of fatigue in reducing time-to-peak of the vertical ground reaction force during single-leg anterior drop-jumps may increase the risk for non-contact anterior cruciate ligament injury in males.

Reference Equation for the Incremental Shuttle Walk Test in Children and Adolescents

To determine a prediction equation for distance walked of incremental shuttle walk test (ISWT) and test its reliability in children and adolescents. Cross-sectional study, which included 108 healthy volunteers between 6 and 18 years old. Those who had an abnormal spirometry or had a history of chronic disease were excluded. Two ISWT were performed. Heart rate and peripheral capillary oxygen saturation (SpO2) were continuously measured during the test. Dyspnea and lower limb fatigue were assessed by Borg scale before and after the tests. Boys walked longer distances compared with girls (1066.4 ± 254.1 m vs 889.7 ± 159.6 m, respectively, P < .0001). Except for dyspnea, there were no significant differences in the other outcomes measured (heart rate, lower limb fatigue, SpO2, and distance walked) at the peak of the two ISWT. The variables included in the predicted equation were age, body mass index, and sex. The predicted equation is: ISWTpred = 845.559 + (sex * 193.265) + (age * 47.850) - (body mass index * 26.179). The distance walked had an excellent reliability between the two ISWT, 0.98 (95% CI 0.97-0.99). The Bland-Altman plot shows agreement between tests (range from -40 to 45 m). We established a prediction equation for ISWT. It can be used as a reference to evaluate exercise capacity for children and adolescents. ISWT has excellent repeatability and it is a maximal-effort field test for this age group.

Association among body composition, muscle performance and functional autonomy in older adults

Introduction Decrease in muscle mass and increase in body fat are important changes that occur with aging. Strength decline and worse resistance to fatigue can lead to a decreased functional autonomy of the elderly. Objective The present study aimed to verify the existence of a relationship between body composition, muscle strength, lower limbs fatigue and functional autonomy in active elderly women. Materials and methods The sample consisted of 29 elderly women with a mean age of 68.2 (± 7.3) years. Body composition was analyzed by total and segmental bioelectrical impedance. Muscle fatigue was assessed using electromyography, through the analysis of median frequency and root mean square during a 60-second sustained isometric knee extension contraction, at 50% of the maximum voluntary isometric contraction. Functional autonomy was assessed by using the Latin American Development Group for Maturity (GDLAM) protocol. Results There were significant correlations between height and strength (r = 0.49), age and lean body mass (r = -0.42), body fat percentage (BF%) and GDLAM tests (r = 0.39-0.41). The lean body mass was positively correlated with strength (r = 0.55), but not with resistance to fatigue. Conclusion The lean body mass of the analyzed sample was found to be associated with the performance on the maximum strength test, but not with the performance on the resistance to fatigue test. This shows that these two parameters (strength and fatigue) are independent of one another. Elderly women with higher BF% showed worse performance on the GDLAM tests. This evidences that individuals with high adiposity levels tend to have a more limited functional autonomy.

The Role of Inspiratory Muscle Training in the Process of Rehabilitation of Patients with Chronic Obstructive Pulmonary Disease.

Chronic obstructive pulmonary disease (COPD) adversely affects the quality of life and life expectancy of patients. Shortness of breath, cough, and fatigue in lower limbs are the main reasons limiting physical activities of patients. The lack of physical activity results in poorer muscle strength. The latest guidelines regarding breathing rehabilitation in COPD patients emphasize a significant role of inspiratory muscle exercises. The objective of the present study was to evaluate the effects of an 8-week long inspiratory muscle training, interval training on a cycle ergometer, and training combining both kinds of rehabilitation, on pulmonary function, health-related quality of life, and the tolerance to exercise in patients with COPD. The study was conducted in a group of 43 patients with diagnosed COPD stage II and III according to GOLD. They were randomly divided into four training groups: inspiratory muscle training (Group 1), cycle ergometer training (Group 2), cycle ergometer and inspiratory muscle training (Group 3), control group - patients who did not participate in any rehabilitation programs (Group 4 - control). Before the rehabilitation process and after its completion the patients were medically examined, they completed a health-related quality of life questionnaire, performed a 6-min walk test, spirometry, and a treadmill exercise test according to the modified Bruce protocol. The results demonstrate a significant improvement in the quality of life measured for Group 3 in comparison with the control group.

Cardiac, ventilatory, and metabolic adjustments in chronic obstructive pulmonary disease patients during the performance of Glittre activities of daily living test.

Functional status and quality of life are measures of the chronic obstructive pulmonary disease (COPD) patient's health status and can demonstrate the impact of the disease on the patient's ability to perform activities of daily living (ADLs). The Glittre-ADL test was developed to evaluate the functional status of COPD patients and their ability to perform activities of daily life. The objective of this study was to evaluate the cardiac, respiratory, and metabolic adjustments and reproducibility of the Glittre ADL test performed by COPD patients. Twenty-two mild to severe COPD patients (forced expiratory volume in 1 second (FEV1): 56.6 ± 19.9% predicted; mean age: 66.3 ± 9.18 years old) were enrolled in this study. Metabolic (oxygen uptake (VO2), carbon dioxide production (VCO2), pulmonary ventilation (VE)/VCO2, and VE/VO2), ventilatory (tidal volume, respiratory rate, and VE), and cardiovascular (pulse oxygen saturation, VO2/heart rate (HR), and HR) variables, lower limbs fatigue, and dyspnea (Borg score) after each lap of two Glittre ADL test were analyzed. All metabolic, ventilatory, and cardiac variables increased their values up to the third lap and remained stable (plateau) until the end of the test (five laps; multivariate analysis); there was no difference among the time spent to complete each of the five laps in each test and between tests (total time of second test: 4 minutes and 3 seconds); the second test was 17.8 seconds (6.6%) shorter than the first one (NS). All variables were highly reproducible in the two tests (NS). At the end of the test, patients reached 87.7% of the VO2 max, 81% of VE peak, and 88.5% of the HR peak obtained from an incremental maximal test on a treadmill. The Glittre ADL test is easy for COPD patients to perform and is a highly reproducible test in COPD patients with mild to severe stages of the disease. In addition, our results suggest that it is possible to demonstrate the patient's functional capacity with a single test of only three laps, making it faster and easier to apply and less stressful for some patients.

Resting and active motor thresholds versus stimulus–response curves to determine transcranial magnetic stimulation intensity in quadriceps femoris

BackgroundTranscranial magnetic stimulation (TMS) is a widely-used investigative technique in motor cortical evaluation. Recently, there has been a surge in TMS studies evaluating lower-limb fatigue. TMS intensity of 120-130% resting motor threshold (RMT) and 120% active motor threshold (AMT) and TMS intensity determined using stimulus–response curves during muscular contraction have been used in these studies. With the expansion of fatigue research in locomotion, the quadriceps femoris is increasingly of interest. It is important to select a stimulus intensity appropriate to evaluate the variables, including voluntary activation, being measured in this functionally important muscle group. This study assessed whether selected quadriceps TMS stimulus intensity determined by frequently employed methods is similar between methods and muscles.MethodsStimulus intensity in vastus lateralis, rectus femoris and vastus medialis muscles was determined by RMT, AMT (i.e. during brief voluntary contractions at 10% maximal voluntary force, MVC) and maximal motor-evoked potential (MEP) amplitude from stimulus–response curves during brief voluntary contractions at 10, 20 and 50% MVC at different stimulus intensities.ResultsStimulus intensity determined from a 10% MVC stimulus–response curve and at 120 and 130% RMT was higher than stimulus intensity at 120% AMT (lowest) and from a 50% MVC stimulus–response curve (p < 0.05). Stimulus intensity from a 20% MVC stimulus–response curve was similar to 120% RMT and 50% MVC stimulus–response curve. Mean stimulus intensity for stimulus–response curves at 10, 20 and 50% MVC corresponded to approximately 135, 115 and 100% RMT and 180, 155 and 130% AMT, respectively. Selected stimulus intensity was similar between muscles for all methods (p > 0.05).ConclusionsSimilar optimal stimulus intensity and maximal MEP amplitudes at 20 and 50% MVC and the minimal risk of residual fatigue at 20% MVC suggest that a 20% MVC stimulus–response curve is appropriate for determining TMS stimulus intensity in the quadriceps femoris. The higher selected stimulus intensities at 120-130% RMT have the potential to cause increased coactivation and discomfort and the lower stimulus intensity at 120% AMT may underestimate evoked responses. One muscle may also act as a surrogate in determining optimal quadriceps femoris stimulation intensity.

Respuesta fisiológica en el test de marcha en 6 minutos en pacientes con enfermedad pulmonar obstructiva crónica

ObjectiveTo analyze the physiological response associated to the application of the 6MWT in Chilean COPD patients. MethodIn this descriptive, cross-sectional study, 30 patients (70.97±8.89 years), with moderate ventilatory impairment (%FEV1=58.83±7.92) completed the 6MWT. Heart rate (HR), partial arterial saturation (SpO2), rating of perceived effort (RPE), and fatigue of lower limbs (LL) were measured at each minute of the test. In addition, these variables were recorded at 4minutes after completing the test. ResultsThe patients completed 106.63%±22.16 of the predicted distance. RPE and fatigue of LL increased significantly (P<.05). On average, the subjects used approximately 50% of their HR reserve without exhibiting desaturations. After 4minutes of post-test rest, HR did not reach pre-test levels. Conclusion6MWT generates significant increases in the cardiac chronotropic response, RPE and LL fatigue that remains higher, even after four minutes of post-test rest. This could reflect functional alterations that go beyond the performance measured just in terms of distance covered.

Effects of multi-joint muscular fatigue on biomechanics of slips

The objective of the present study was to investigate the effects of multi-joint muscular fatigue on biomechanics of slips. Both lower-limb fatigue and upper-limb fatigue were examined, and the fatiguing exercises involved multi-joint movements to replicate muscular fatigue in realistic scenarios. Sixty healthy young adults participated in the study, and were evenly categorized into three groups: no fatigue, lower-limb fatigue, and upper-limb fatigue. These participants were instructed to walk on a linear walkway, and slips were induced unexpectedly during walking. The results showed that multi-joint muscular fatigue affects biomechanics of slips in all three phases of slips (i.e. initiation, detection, and recovery). In particular, adaptive safer postural control strategies were adopted with the application of both lower-limb fatigue and upper-limb fatigue to maintain the likelihood of slip initiation as in the no fatigue condition. In the phases of detection and recovery, lower-limb fatigue was found to compromise biomechanics of slips while upper-limb fatigue did not show any effects. Based on these findings, minimizing exposures to lower-limb fatigue should be given higher priority compared to upper-limb fatigue when developing interventions to prevent slip-induced falls. In addition, these findings also suggest that interventions aimed at enhancing proprioceptive acuity and increasing muscular strength in the lower limb could also be effective in slip-induced fall prevention.

The Costumes and Cultures of Buge in the era of Kamakura and the End of Heian in Japan

Stand-up cycling leads to fatigue on the lower limbs because whole body weight is loaded on the leg at the stance phase. Especially changing the stance phase from one leg to the other side is involves increased knee joint moment. In this study, the feature of gait pattern characterized by extended stance phase which occupies 60% of gait cycle is applied to the design of crank drive system in order to decrease lower limb fatigue. An eccentric crank axis deviated from the chaining axis is adopted to realize slow motion at stance phase and quick return at swing phase. Design parameters of eccentric crank mechanism are defined, and kinematic simulations are performed to understand the behavior of the mechanism. The simulation results say that the increased eccentric distance (A) lead to increase the deviation angle (θ) which means stance phase occupies more time of the entire cycle. This study may contribute to develop a stand up bicycle having more portability.

Biomechanical changes at the knee after lower limb fatigue in healthy young women

BackgroundThe purpose of this study was to identify changes in knee kinematics, kinetics and stiffness that occur during gait due to lower limb neuromuscular fatigue. MethodsKinematic, kinetic and electromyographic measures of gait were collected on healthy, young women (n=20) before and after two bouts of fatigue. After baseline gait analysis, two bouts of fatiguing contractions were completed. Fatigue was induced using sets of 50 isotonic knee extensions and flexions at 50% of the peak torque during a maximum voluntary isometric contraction. Fatigue was defined as a drop in knee extension or flexion maximum voluntary isometric torques of at least 25% from baseline. Gait analyses were completed after each bout of fatigue. Dynamic knee stiffness was calculated as the change in knee flexion moment divided by the change in knee flexion angle from 3 to 15% of the gait cycle. Co-activations of the biceps femoris and rectus femoris muscles were calculated from 3 to 15% and 40 to 52% of gait. Repeated measures analyses of variance assessed differences in discrete gait measures, knee torques, and electromyography amplitudes between baseline and after each bout of fatigue. FindingsFatigue decreased peak isometric torque. Fatigue did not alter knee adduction moments, knee flexion angles, dynamic knee stiffness, or muscle co-activation. Fatigue reduced the peak knee extension moment. InterpretationWhile neuromuscular fatigue of the knee musculature alters the sagittal plane knee moment in healthy, young women during walking, high intensity fatigue is not consistent with known mechanical environments implicated in knee pathologies or injuries.

Acidentes de trabalho com mototaxistas

The use of motorcycles as a means of work has contributed to the increase in traffic accidents, in particular, mototaxi accidents. The aim of this study was to estimate and characterize the incidence of occupational accidents among the mototaxis registered in Feira de Santana, BA. This is a cross-sectional study with descriptive and census data. Of the 300 professionals registered at the Municipal Transportation Service, 267 professionals were interviewed through a structured questionnaire. Then, a descriptive analysis was conducted and the incidence of accidents was estimated based on the variables studied. Relative risks were calculated and statistical significance was determined using the chi-square test and Fisher's exact test, considering p < 0.05. Logistic regression was used in order to perform simultaneous adjustment of variables. Occupational accidents were observed in 10.5% of mototaxis. There were mainly minor injuries (48.7%), 27% of them requiring leaves of absence from work. There was an association between the days of work per week, fatigue in lower limbs and musculoskeletal complaints, and accidents. Knowledge of the working conditions and accidents involved in this activity can be of great importance for the adoption of traffic education policies, and to help prevent accidents by improving the working conditions and lives of these professionals.

Influência da fadiga unilateral de membro inferior sobre o salto vertical bilateral

Em saltos verticais é comum a verificação do déficit de força bilateral. Essa é caracterizada pela menor força gerada em contrações bilaterais, quando comparada à soma das contrações unilaterais dos mesmos músculos. Pouco se conhece sobre o efeito da fadiga unilateral sobre atividades bilaterais. O objetivo do estudo foi verificar o efeito da fadiga unilateral sobre o rendimento e o déficit bilateral durante saltos verticais bipedais. Dez adultos jovens sedentários fatigaram unilateralmente cada membro inferior e realizaram saltos verticais (bipedal e unipedal). Foram medidas a força de reação do solo vertical e a atividade mioelétrica de cada membro em cada condição (pré-fadiga, fadiga do membro dominante (FD) e não dominante (FND)). Houve diferença entre tarefas e condições apenas na pré-fadiga (p = 0,030). Verificaram-se diferenças para o salto bipedal entre a condição de pré-fadiga e FD (p = 0,005), e no salto unipedal, entre a pré-fadiga e FD (p &lt; 0,001) e FND (p &lt; 0,001). Apenas durante a condição de FD houve alteração no desempenho dos saltos bipedais, tendo maior influência no desempenho dos saltos. Observou-se tendência de diminuição do índice de assimetria para a ação muscular do membro contralateral fatigado, observado através de eletromiografia. Através dos dados sugere-se que exista um comando comum onde o sistema nervoso considere os músculos ativados simultaneamente como uma unidade, exceto em condições de fadiga unilateral.

Teste de caminhada de seis minutos: valores de referência para adultos saudáveis no Brasil

To develop regression equations for six-minute walk distance (6MWD) in healthy adults (20-80 years of age) in Brazil. We included 132 volunteers (66 males) without respiratory disease, cardiac disease, or comorbidities that affect ambulation. The volunteers completed three six-minute walk tests. Prior to and at the end of each test, we obtained SpO2 and maximal HR, as well as the Borg scale scores for sensation of dyspnea and lower limb fatigue. The data included in the final analysis were derived from the test with the greatest 6MWD. The mean 6MWD values were 566 ± 87 m and 538 ± 95 m in males and females, respectively (p = 0.08). The 6MWD was greater in taller individuals and decreased in parallel with increases in age or body index mass (BMI). The best adjusted model was the quadratic model. We derived the following equation (valid for both genders): 6MWD = 511 + stature² (cm) × 0.0066 - age² × 0.030 - BMI² × 0.068. This equation explained 55% of the variance in 6MWD. Reference values explaining a high proportion of the variance were derived by a quadratic regression model in healthy adults (of a wide range of ages) in Brazil.

Intravascular large B-cell lymphoma of the kidney: A case report

We report a 41-year-old Chinese woman with intravascular large B-cell lymphoma diagnosed by percutaneous renal biopsy. The patient was admitted to Nanfang Hospital of Southern Medical University, Guangzhou, China with complaints of high spiking fever for a month and bilateral lower limb fatigue with difficulty ambulating for the past 5 months.She had renal dysfunction with a total urinary protein of 5.61 g/dL (56.1 g/L), serum albumin of 2.89 g/dL (28.9 g/L), urea nitrogen of 2.24 mg/dL (1.6 mmol/L), and serum creatinine of 0.54 mg/dL (48 μmol/L). Bone marrow biopsy revealed myeloproliferative disorder without abnormal myeloid or lymphocytic proliferation. Positron Emission Tomography-Computed Tomography (PET-CT) showed marked bilateral swelling and enlargement of the renal parenchyma with splenic enlargement and involvement of multiple vertebrae. Percutaneous renal biopsy showed island-like accumulations of medium to large lymphoid cells in many areas of the interstitium, with round vesicular nuclei containing distinct basophilic nucleoli. Immunohistochemical analysis together with other supportive investigation confirmed the diagnosis of intravascular large B-cell lymphoma. Ten days later, she was started on chemotherapy with CHOP (cyclophosphamide, doxorubicin, leurocristime and prednisone) for a week. Palliative radiotherapy DT 40Gy/20F with other supportive treatment was provided for metastatic foci in the medullary cavity of the sternum, T1-T7. The patient regained muscle strength in both lower limbs and was able to walk again after three weeks. The patient was discharged after hepatic and renal function and proteinuria values had returned to normal. Follow-up data shows the patient to be alive nine months after discharge.

The effects of treadmill training on inspiratory muscle strength,dyspnea and lower limb fatigue in chronic obstructive pulmonary disease patients

Objective To explore the relationship between improved exercise endurance and inspiratory muscle strength,dyspnea and lower limb fatigue in chronic obstructive pulmonary disease(COPD)patients. Methods Twelve moderate-to-severe COPD patients were given lower limb exercise training for 12 weeks.Routine tests of pulmonary ventilation function,diffusion function,lung volume,maximal inspiratory pressure(MIP),expiratory flow limitation(EFL),cycle ergometer exercise capacity and constant work rate capacity were administered before and after the training program.Borg's scale(BS)was used to assess dyspnea and lower limb fatigue was measured during the exercise tests.Results After training,the average peak work rate(W Rpeak)and average MIP both had increased significantly,but no significant change was observed in routine pulmonary ventilation function,diffusion function or lung volume.The 5-point EFL score showed no significant change.hut Borg's scale dyspnea scores and lower limb fatigue decreased significantly.The changes in W Rpeak were positively correlated with the MIP changes,Borg scale scores and changes in Borg scores.All of these relationships were statistically significant. Conclusion The improved exercise endurance of moderate-to-severe COPD patients after lower limb exercise training is due to increased inspiratory muscle strength and decreases in the sensation of dyspnea and lower limb fatigue. Key words: Pulmonary disease,chronic obstructive; Pulmonary rehabilitation; Exercise training; Dyspnea

Neuromuscular fatigue after maximal exercise in patients with cystic fibrosis

The aim of this study was to determine whether patients with cystic fibrosis (CF), despite their ventilatory limitation, would develop neuromuscular fatigue of quadriceps muscles following a maximal cycling exercise. Eleven adults with CF (age = 26.8 ± 6.9 years; forced expiratory volume in 1 s = 54.1 ± 12.8% predicted) and 11 age-matched healthy subjects performed a maximal incremental cycle test with respiratory gas exchange measurements. Maximal voluntary contraction (MVC) and electromyographic (EMG) activity of the vastus medialis muscle were recorded before and after exercise. Neural and contractile properties of the quadriceps were also investigated using femoral nerve electrical stimulation. Patients had lower exercise capacity, peak oxygen uptake and MVC than controls. MVC fell significantly postexercise in both groups (CF: −20 ± 10%, controls: −19 ± 6%; p < 0.01). EMG root mean square values, M-wave amplitude and duration were unchanged in both groups. Peak twitch (−46.9 ± 13.8%), maximal rate of twitch torque development (−50.3 ± 13.8%) and relaxation (−35.2 ± 19.5%) were all reduced after exercise in CF patients. The control group followed the same pattern (−38.4 ± 14.4%, −42.1 ± 14.7% and −15 ± 20.4%) but the statistical significance was not reached for the maximal rate of twitch torque relaxation. In conclusion, CF patients demonstrated lower limb fatigue following symptom-limited cycle exercise, which was comparable to that exhibited by healthy controls. This fatigue may be due to contractile impairments and not to transmission failure. Further studies should be conducted in a larger sample to confirm these preliminary results.

Avaliação da capacidade de exercício em adolescentes asmáticos e saudáveis

To compare the physical performance and responses obtained in the six-minute walking test (6MWT) and the six-minute step test (6MST) between asthmatic and healthy adolescents; and to investigate the relationship between the responses obtained in the tests and the body mass index (BMI), physical activity level and spirometric variables. Nineteen asthmatic adolescents (AG) and 19 healthy adolescents (HG) of both sexes, aged between 11 and 15 years, were assessed by means of spirometry, the 6MWT and the 6MST, and their physical activity levels were quantified using the International Physical Activity Questionnaire (IPAQ). The AG had poorer physical performance, lower heart rate (HR) and greater lower-limb (LL) fatigue in the 6MST. In the 6MWT, the AG had positive correlations between walked distance (WD) and duration of intense activity, and between HR and BMI, whereas the HG had positive correlations between WD and HR and between WD and respiratory rate (RR). In the 6MST, the AG showed positive correlations between RR and maximum voluntary ventilation (MVV) and between duration of moderate activity and physical performance. The AG also showed negative correlations between physical performance in the 6MST and BMI, and between sensation of dyspnea and duration of walking. Also in the 6MST, the HG showed positive correlations between RR and MVV, and between BMI and LL fatigue (p < or = 0.05). The 6MST demonstrated differences in exercise capacity between the asthmatic and healthy individuals. Furthermore, the physical performance and responses obtained in the tests were correlated with the MVV, BMI and physical activity level.

Influência da massa magra corporal nas repercussões cardiopulmonares durante o teste de caminhada de seis minutos em pacientes com DPOC

Although lean body mass (LBM) has been associated with mortality in patients with COPD, its influence on functional limitation is not clear. The objective of this study was to analyze the cardiopulmonary variables in COPD patients with or without LBM depletion, prior to and after the six-minute walk test (6MWT). We evaluated COPD patients, 32 with LBM depletion and 36 without. All patients underwent clinical evaluation, spirometry, evaluation of body mass composition and 6MWT, as well as completing questionnaires related to quality of life and perception of dyspnea. No significant differences in the severity of airway obstruction, perception of dyspnea and quality of life scores were found between the groups. The distance covered on the 6MWT was similar in COPD patients with and without LBM depletion (470.3 +/- 68.5 m vs. 448.2 +/- 89.2 m). However, patients with LBM depletion presented significantly greater differences between baseline and final values in terms of heart rate and Borg scale index for lower limb fatigue. There was a significant positive correlation between distance covered on the 6MWT and FEV1 (r = 0.381, p = 0.01). In the patients studied, functional exercise tolerance and quality of life were unaffected by LBM depletion. However, the patients with LBM depletion presented more pronounced lower limb fatigue during the 6MWT, which underscores the importance of the evaluation and treatment of systemic manifestations in COPD patients.