José Alberto Neder

A step test to assess exercise-related oxygen desaturation in interstitial lung disease

A 6-min step test (6MST) may constitute a practical method for routinely assessing effort tolerance and exercise-related oxyhaemoglobin desaturation (ERD) in the primary care of patients with interstitial lung disease. In total, 31 patients (19 males) with idiopathic pulmonary fibrosis (n = 25) and chronic hypersensitivity pneumonia were submitted, on different days, to two 6MSTs. Physiological responses were compared with those found on maximal and submaximal cycle ergometer tests at the same oxygen uptake (V′O2). Chronic breathlessness was also determined, as measured by the baseline dyspnoea index (BDI). Responses to 6MST were highly reproducible: 1.3±2.0 steps·min-1, ±5 beats·min-1 (cardiac frequency), ±50 mL·min-1 (V′O2), ±7 L·min-1 (minute ventilation) and ±2% (arterial oxygen saturation measured by pulse oximetry (Sp,O2)). The number of steps climbed in 6 min was correlated to peak V′O2 and the BDI. There were significant associations among the tests in relation to presence (change in Sp,O2 between rest and exercise ≥4%) and severity (Sp,O2 <88%) of ERD. Four patients, however, presented ERD only in response to 6MST. Resting diffusing capacity of the lung for carbon monoxide and alveolar–arterial oxygen tension difference were the independent predictors of the number of steps climbed. A single-stage, self-paced 6-min step test provided reliable and reproducible estimates of exercise capacity and exercise-related oxyhaemoglobin desaturation in interstitial lung disease patients.

The pattern and timing of breathing during incremental exercise: a normative study.

Clinical evaluation of the pattern and timing of breathing during submaximal exercise can be valuable for the identification of the mechanical ventilatory consequences of different disease processes and for assessing the efficacy of certain interventions. Sedentary individuals (60 male/60 female, aged 20–80 yrs) were randomly selected from >8,000 subjects and submitted to ramp incremental cycle ergometry. Tidal volume (VT)/ resting inspiratory capacity, respiratory frequency, total respiratory time (Ttot), inspiratory time (TI), expiratory time (TE), duty cycle (TI/Ttot) and mean inspiratory flow (VT/TI) were analysed at selected submaximal ventilatory intensities. Senescence and female sex were associated with a more tachypnoeic breathing pattern during isoventilation. The decline in Ttot was proportional to the TI and TE reductions, i.e. TI/Ttot was remarkably constant across age strata, independent of sex. The pattern, but not timing, of breathing was also influenced by weight and height; a set of demographically and anthropometrically based prediction equations are therefore presented. These data provide a frame of reference for assessing the normality of some clinically useful indices of the pattern and timing of breathing during incremental cycle ergometry in sedentary males and females aged 20–80 yrs.

Neuromuscular electrical stimulation improves exercise tolerance in chronic obstructive pulmonary disease patients with better preserved fat-free mass

BACKGROUND: High-frequency neuromuscular electrical stimulation increases exercise tolerance in patients with advanced chronic obstructive pulmonary disease (COPD patients). However, it is conceivable that its benefits are more prominent in patients with better-preserved peripheral muscle function and structure. OBJECTIVE: To investigate the effects of high-frequency neuromuscular electrical stimulation in COPD patients with better-preserved peripheral muscle function. Design: Prospective and cross-over study. METHODS: Thirty COPD patients were randomly assigned to either home-based, high-frequency neuromuscular electrical stimulation or sham stimulation for six weeks. The training intensity was adjusted according to each subjects tolerance. Fat-free mass, isometric strength, six-minute walking distance and time to exercise intolerance (Tlim) were assessed. RESULTS: Thirteen (46.4%) patients responded to high-frequency neuromuscular electrical stimulation; that is, they had a post/pre ΔTlim >10% after stimulation (unimproved after sham stimulation). Responders had a higher baseline fat-free mass and six-minute walking distance than their seventeen (53.6%) non-responding counterparts. Responders trained at higher stimulation intensities; their mean amplitude of stimulation during training was significantly related to their fat-free mass (r  =  0.65; p<0.01). Logistic regression revealed that fat-free mass was the single independent predictor of Tlim improvement (odds ratio [95% CI]  =  1.15 [1.04-1.26]; p<0.05). CONCLUSIONS: We conclude that high-frequency neuromuscular electrical stimulation improved the exercise capacity of COPD patients with better-preserved fat-free mass because they tolerated higher training stimulus levels. These data suggest that early training with high-frequency neuromuscular electrical stimulation before tissue wasting begins might enhance exercise tolerance in patients with less advanced COPD.

Clinical value of anthropometric estimates of leg lean volume in nutritionally depleted and non-depleted patients with chronic obstructive pulmonary disease

This study aimed to investigate the clinical usefulness of an anthropometrically based method for estimating leg lean volume (LLV) in patients with chronic obstructive pulmonary disease (COPD) who presented or not with nutritional depletion. We prospectively evaluated a group of forty-eight patients (thirty-eight males) with moderate to severe COPD (Global Initiative for Chronic Obstructive Lung disease stages II-IV) who underwent a 6 min walking test and knee isokinetic dynamometry. Leg lean mass (muscle mass plus bone) was determined by dual-energy X-ray absorptiometry (DEXA) with derivation of its respective volume: these values were compared with those obtained by the truncated cones method first described by Jones and Pearson in 1969. As expected, depleted patients (n 19) had reduced exercise capacity and impaired muscle performance as compared to non-depleted subjects (P < 0.01). The mean bias of the LLV differences between anthropometry and DEXA were 0.40 litre (95 % CI - 0.59, 1.39) and 0.50 litre (95 % CI - 1.08, 2.08) for depleted and non-depleted patients, respectively. Anthropometrically and DEXA-based estimates correlated similarly with muscle functional attributes. A ROC curve analysis revealed that leg height-corrected LLV values had acceptable sensitivity and specificity to identify depleted patients (area under the curve 0.93 (range 0.86-1.00); P < 0.001). Moreover, patients with LLV <or= 9.2 litres/m (the best cut-off value according to the ROC curve) had significantly lower exercise capacity and muscle performance than their counterparts (P < 0.05). In conclusion, an anthropometrically based method of estimating LLV (Jones and Pearson method) was shown to present with clinically acceptable accuracy and external validity in depleted and non-depleted patients with stable COPD.

Efeito do exercício aeróbico durante as sessões de hemodiálise na variabilidade da frequência cardíaca e na função ventricular esquerda em pacientes com doença renal crônica

INTRODUCAO: Pacientes com doenca renal cronica (DRC) sob tratamento hemodialitico apresentam diminuicao da variabilidade da frequencia cardiaca (VFC) que representa um fator de risco independente para a mortalidade cardiaca, especialmente a morte subita. OBJETIVO: Avaliar o efeito do exercicio aerobico, realizado durante as sessoes de hemodialise, na VFC e na funcao ventricular esquerda de pacientes portadores de DRC. METODOS: Foram avaliados 22 pacientes randomizados em dois grupos: exercicio (n = 11; 49,6 ± 10,6 anos; 4 homens) e controle (n = 11; 43,5 ± 12,8; 4 homens). Os pacientes do grupoexercicio foram submetidos a tres sessoes semanais de exercicio aerobico, realizado nas duas horas iniciais da hemodialise, durante 12 semanas. Para a analise da VFC e da funcao ventricular esquerda, todos os pacientes foram submetidos aos exames de Holter de 24 horas e ecocardiograma, respectivamente. RESULTADOS: Apos 12 semanas de protocolo, nao foi observada diferenca significante em nenhum dos parametros da VFC nos dominios do tempo e da frequencia em ambos os grupos. A fracao de ejecao aumentou de modo nao significante nos pacientes do grupo-exercicio (67,5 ± 12,6% vs. 70,4 ± 12%) e diminuiu nao significantemente nos pacientes do grupo-controle (73,6 ± 8,4% vs. 71,4 ± 7,6%). CONCLUSAO: A realizacao de 12 semanas de exercicio aerobico, durante as sessoes de hemodialise, nao modificou a VFC e nao promoveu melhora significante na funcao ventricular esquerda.

Efeitos sistêmicos da hipoxemia noturna em pacientes com doença pulmonar obstrutiva crônica sem síndrome da apnéia obstrutiva do sono

OBJETIVO: Estudar os efeitos da hipoxemia noturna em pacientes com doenca pulmonar obstrutiva cronica sem sindrome da apneia obstrutiva do sono. METODOS: Estudamos 21 pacientes-10 dessaturadores e 11 nao-dessaturadores-submetidos a gasometria arterial, polissonografia, espirometria, teste de exercicio cardiopulmonar (cicloergometro), dinamometria manual e medidas de pressao inspiratoria maxima, pressao expiratoria maxima e proteina C reativa (PCR). Incluiram-se os pacientes com pressao parcial arterial de oxigenio > 60 mmHg; excluiram-se os com indice de apneia-hipopneia > 5 eventos/hora de sono. Foram medidos consumo maximo de oxigenio, potencia maxima, pressao arterial sistolica, pressao arterial diastolica (PAD) e frequencia cardiaca maxima durante exercicio, visando detectar alteracoes hemodinâmicas. A PCR foi considerada positiva quando acima de 3 mg/L. RESULTADOS: A saturacao periferica de oxigenio minima durante o sono foi significativamente maior nos nao-dessaturadores (p = 0,03). Mais dessaturadores apresentaram PCR > 3 mg/L (p < 0,05). Nao houve diferenca quanto a capacidade de exercicio e demais variaveis. No entanto, PAD (p < 0,001) e pressao inspiratoria maxima (p = 0,001) correlacionaram-se com saturacao periferica de oxigenio media durante o sono. CONCLUSOES: A hipoxemia noturna nao reduz a capacidade de exercicio e a forca de preensao manual em pacientes com DPOC leve/moderada, mas o ajuste da PAD durante o exercicio maximo parece depender do grau de hipoxemia. Alem disso, ha uma relacao positiva entre pressao inspiratoria maxima e saturacao periferica de oxigenio media durante o sono, bem como indicios de ativacao inflamatoria diferenciada em pacientes com hipoxemia noturna.

Differences between remaining ability and loss of capacity in maximum aerobic impairment.

In the evaluation of exercise intolerance of patients with respiratory diseases the American Medical Association (AMA) and the American Thoracic Society (ATS) have proposed similar classification for rating aerobic impairment using maximum oxygen uptake (VO2max) normalized for total body weight (ml min-1 kg-1). However, subjects with the same VO2max weight-corrected values may have considerably different losses of aerobic performance (VO2max expressed as % predicted). We have proposed a new, specific method for rating loss of aerobic capacity (VO2max, % predicted) and we have compared the two classifications in a prospective study involving 75 silicotic claimants. Logistic regression analysis showed that the disagreement between rating systems (higher dysfunction by the AMA/ATS classification) was associated with age > 50 years (P < 0.005) and overweight (P = 0.04). Interestingly, clinical (dyspnea score) and spirometric (FEV1) normality were only associated with the VO2max, % predicted, normal values (P < 0.01); therefore, in older and obese subjects the AMA/ATS classification tended to overestimate the aerobic dysfunction. We conclude that in the evaluation of aerobic impairment in patients with respiratory diseases, the loss of aerobic capacity (VO2max, % predicted) should be used instead of the traditional method (remaining aerobic ability, VO2max, in ml min-1 kg-1).

Comportamento da hiperinsuflação dinâmica em teste em esteira rolante em pacientes com DPOC moderada a grave

OBJECTIVE: To characterize the presence, extent, and patterns of dynamic hyperinflation (DH) during treadmill exercise testing in patients with moderate to severe COPD. METHODS: This was a cross-sectional study involving 30 non-hypoxemic patients (FEV1= 43 ± 14% of predicted) who were submitted to a cardiopulmonary exercise test on a treadmill at a constant speed (70-80% of maximum speed) to the tolerance limit (Tlim). Serial inspiratory capacity (IC) maneuvers were used in order to assess DH. RESULTS: Of the 30 patients studied, 19 (63.3%) presented with DH (DH+ group), having greater pulmonary function impairment at rest than did those without DH (DH- group). None of the variables studied correlated with exercise tolerance in the DH- group, whereas Tlim, IC, and perception of dyspnea during exercise did so correlate in the DH+ group (p < 0.05). In the DH+ group, 7 and 12 patients, respectively, presented with a progressive and a stable pattern of DH (ΔICTlim,2min = -0.28 ± 0.11 L vs. 0.04 ± 0.10 L; p < 0.01). Patients with a progressive pattern of DH presented with higher perception of dyspnea/Tlim rate and lower exercise tolerance than did those with a stable pattern (354 ± 118 s and 465 ± 178 s, respectively; p < 0.05). CONCLUSIONS: The presence of DH is not a universal phenomenon during walking in COPD patients, even in those with moderate to severe airflow limitation. In the patients who presented DH, a progressive pattern of DH had a greater impact on exercise tolerance than did a stable pattern of DH.

Relationship between peripheral muscle structure and function in patients with chronic obstructive pulmonary disease with different nutritional status.

Malaguti, C, Napolis, LM, Villaça, D, Neder, JA, Nery, LE, and Dal Corso, S. Relationship between peripheral muscle structure and function in patients with chronic obstructive pulmonary disease with different nutritional status. J Strength Cond Res 25(7): 1795-1803, 2011—The purpose of this study was to investigate the relationships between peripheral muscle structure (mass) and function (strength, endurance, and maximal aerobic capacity) in patients with chronic obstructive pulmonary disease (COPD) with different nutritional states. Thirty-nine patients (31 male) with moderate-severe COPD (63.5 ± 7.3 [SD] years) and 17 controls (14 male; 64.7 ± 5.5 [SD] years) underwent isokinetic (peak torque [PT]), isometric (isometric torque [IT]), and endurance strength (total work [TW]) measurements of the knee extensor muscles and a maximal cardiopulmonary exercise test to evaluate the maximal aerobic capacity (peak oxygen uptake [&OV0312;O2] peak). Muscle mass (MM) was determined using dual-energy x-ray absorptiometry. Patients with COPD presented with reduced muscle function as compared with the healthy controls: PT (105.9 ± 33.9 vs. 134.3 ± 30.9, N·m−1, respectively, p < 0.05), TW (1,446.3 ± 550.8 vs. 1,792.9 ± 469.1 kJ, respectively, p < 0.05), and &OV0312;O2peak (68.1 ± 15.1 vs. 93.7 ± 14.5, % pred, respectively, p < 0.05). Significant relationships were found between muscle structure and function (strength and endurance) in the patient subgroup with preserved MM and in the control group: PT·MM−1(r2 = 0.36; p = 0.01 vs. r2= 0.32; p = 0.01, respectively) and TW·MM−1 (r2 = 0.32; p = 0.01 vs. r2 = 0.22; p = 0.05, respectively). Strength corrected for mass normalized this function in both patient subgroups, whereas endurance was normalized only in the patient subgroup without muscle depletion. Maximal aerobic capacity remained reduced, despite the correction, in both patient subgroups (depleted or nondepleted) compared with the healthy controls (&OV0312;O2peak.MM−1: 9.1 ± 3.7 vs. 21.8 ± 4.9 vs. 28.5 ± 4.2 ml·min·kg−1, respectively, with p < 0.01 among groups). Muscle atrophy seems to be the main determinant of strength reduction among patients with moderate-severe COPD, whereas endurance reduction seems to be more related to imbalance between oxygen delivery and consumption than to the local muscle structure itself. Peripheral MM did not constitute a good predictor for maximal aerobic capacity in this population. The main practical application of this study is to point out a crucial role for the strategies able to ameliorate cardiorespiratory and muscular fitness in patients with COPD, even in those patients with preserved MM.

Novas terapias ergogênicas no tratamento da doença pulmonar obstrutiva crônica

Chronic obstructive pulmonary disease is currently considered a systemic disease, presenting structural and metabolic alterations that can lead to skeletal muscle dysfunction. This negatively affects the performance of respiratory and peripheral muscles, functional capacity, health-related quality of life and even survival. The decision to prescribe ergogenic aids for patients with chronic obstructive pulmonary disease is based on the fact that these drugs can avert or minimize catabolism and stimulate protein synthesis, thereby reducing the loss of muscle mass and increasing exercise tolerance. This review summarizes the available data regarding the use of anabolic steroids, creatine, L-carnitine, branched-chain amino acids and growth hormones in patients with chronic obstructive pulmonary disease. The advantage of using these ergogenic aids appears to lie in increasing lean muscle mass and inducing bioenergetic modifications. Within this context, most of the data collected deals with anabolic steroids. However, to date, the clinical benefits in terms of increased exercise tolerance and muscle strength, as well as in terms of the effect on morbidity and mortality, have not been consistently demonstrated. Dietary supplementation with substances of ergogenic potential might prove to be a valid adjuvant therapy for treating patients with advanced chronic obstructive pulmonary disease, especially those presenting loss of muscle mass or peripheral muscle weakness.