Martijn A. Spruit

Quantifying physical activity in daily life with questionnaires and motion sensors in COPD

Accurate assessment of the amount and intensity of physical activity in daily life is considered very important due to the close relationship between physical activity level, health, disability and mortality. For this reason, assessment of physical activity in daily life has gained interest in recent years, especially in sedentary populations, such as patients with chronic obstructive pulmonary disease (COPD). The present article aims to compare and discuss the two kinds of instruments more commonly used to quantify the amount of physical activity performed by COPD patients in daily life: subjective methods (questionnaires, diaries) and motion sensors (electronic or mechanical methods). Their characteristics are summarised and evidence of their validity, reliability and sensitivity is discussed, when available. Subjective methods have practical value mainly in providing the patients view on their performance in activities of daily living and functional status. However, care must be taken when using subjective methods to accurately quantify the amount of daily physical activity performed. More accurate information is likely to be available with motion sensors rather than questionnaires. The selection of which motion sensor to use for quantification of physical activity in daily life should depend mainly on the purpose of its use.

Muscle force during an acute exacerbation in hospitalised patients with COPD and its relationship with CXCL8 and IGF-I

Background: Chronic obstructive pulmonary disease (COPD) is often associated with peripheral muscle weakness, which is caused by several factors. Acute exacerbations may contribute, but their impact on muscle force remains unclear. Correlations between peripheral muscle force and inflammatory and anabolic markers have never been studied in COPD. The effect of an acute exacerbation on quadriceps peak torque (QPT) was therefore studied in hospitalised patients, and the aforementioned correlations were examined in hospitalised and in stable patients. Methods: Lung function, respiratory and peripheral muscle force, and inflammatory and anabolic markers were assessed in hospitalised patients on days 3 and 8 of the hospital admission and 90 days later. The results on day 3 (n=34) were compared with those in clinically stable outpatients (n=13) and sedentary healthy elderly subjects (n=10). Results: Hospitalised patients had lowest mean (SD) QPT (66 (22)% predicted) and highest median (IQR) levels of systemic interleukin-8 (CXCL8, 6.1 (4.5 to 8.3) pg/ml). Insulin-like growth factor I (IGF-I) tended to be higher in healthy elderly subjects (p=0.09). QPT declined between days 3 and 8 in hospital (mean −5% predicted (95% CI −22 to 8)) and partially recovered 90 days after admission to hospital (mean 6% predicted (95% CI −1 to 23)). QPT was negatively correlated with CXCL8 and positively correlated with IGF-I and lung transfer factor in hospitalised and in stable patients. Conclusions: Peripheral muscle weakness is enhanced during an acute exacerbation of COPD. CXCL8 and IGF-I may be involved in the development of peripheral muscle weakness in hospitalised and in stable patients with COPD.

Resistance versus endurance training in patients with COPD and peripheral muscle weakness

The effects of endurance training on exercise capacity and health-related quality of life (HRQL) in chronic obstructive pulmonary disease (COPD) patients have been studied thoroughly, while resistance training has been rarely evaluated. This study investigated the effects of resistance training in comparison with endurance training in patients with moderate to severe COPD and peripheral muscle weakness (isometric knee extension peak torque <75% predicted). Forty-eight patients (age 64±8u2005yrs, forced expiratory volume in one second 38±17% pred) were randomly assigned to resistance training (RT, n=24) or endurance training (ET, n=24). The former consisted of dynamic strengthening exercises. The latter consisted of walking, cycling and arm cranking. Respiratory and peripheral muscle force, exercise capacity, and HRQL were re-evaluated in all patients who completed the 12-week rehabilitation (RT n=14, ET n=16). Statistically significant increases in knee extension peak torque (RT 20±21%, ET 42±21%), maximal knee flexion force (RT 31±39%, ET 28±37%), elbow flexion force (RT 24±19%, ET 33±25%), 6-min walking distance (6MWD) (RT 79±74u2005m, ET 95±57u2005m), maximum workload (RT 15±16 Watt, ET 14±13 Watt) and HRQL (RT 16±25 points, ET 16±15 points) were observed. No significant differences in changes in HRQL and 6MWD were seen between the two treatments. Resistance training and endurance training have similar effects on peripheral muscle force, exercise capacity and health-related quality of life in chronic obstructive pulmonary disease patients with peripheral muscle weakness.

Skeletal muscle weakness in patients with sarcoidosis and its relationship with exercise intolerance and reduced health status

Background: Skeletal muscle weakness is assumed to be present in patients with sarcoidosis but has never been reported in a consecutive group of patients. Moreover, its relationship with previously observed exercise intolerance and reduced health status has never been studied in these patients. Methods: Pulmonary function, skeletal and respiratory muscle forces, peak and functional exercise capacity, health status, and the circulating levels of inflammatory and anabolic markers were determined in 25 patients with sarcoidosis who complained of fatigue (15 men) and in 21 healthy subjects (13 men). Results: Patients with sarcoidosis had lower respiratory and skeletal muscle forces, reduced exercise capacity and health status, higher anxiety and depression scores, and higher circulating levels of tumour necrosis factor-α than healthy subjects (all p⩽0.01). Its soluble receptor p75 tended to be higher (pu200a=u200a0.04). Circulating levels of interleukin (IL)-6, IL-8, insulin-like growth factor I and its binding protein 3 were not significantly different between the two groups. Skeletal muscle weakness was related to exercise intolerance, depression, and reduced health status in patients with sarcoidosis, irrespective of age, sex, body weight and height (p⩽0.05). Quadriceps peak torque was inversely related to fatigue but not to the circulating levels of inflammatory or anabolic markers. The mean daily dose of corticosteroids received in the 6 month period before testing was related to quadriceps peak torque only in patients who received oral corticosteroids. Conclusion: Skeletal muscle weakness occurs in patients with sarcoidosis who complain of fatigue and is associated with reduced health status and exercise intolerance.

Markers of inflammation and disuse in vastus lateralis of chronic obstructive pulmonary disease patients.

Backgroundu2003 Disuse and/or local inflammation in the muscle cannot be excluded as potential influences for the decreased muscle force in patients hospitalised due to an acute chronic obstructive pulmonary disease (COPD) exacerbation. This study aims to compare expression levels of markers of disuse (insulin‐like growth factor‐1 (IGF‐I), MyoD and myogenin) and inflammation [interleukin‐6 (IL‐6), IL‐8 and tumour necrosis factor‐alpha (TNF‐α)] in the muscle of hospitalised and stable COPD patients and healthy elderly.

Exercise training during rehabilitation of patients with COPD: A current perspective

Patients with chronic obstructive pulmonary disease (COPD) suffer frequently from physiologic and psychological impairments, such as dyspnea, peripheral muscle weakness, exercise intolerance, decreased health-related quality of life (HRQOL) and emotional distress. Rehabilitation programmes have shown to result in significant changes in perceived dyspnea and fatigue, utilisation of healthcare resources, exercise performance and HRQOL. Exercise training, which consists of whole-body exercise training and local resistance training, is the cornerstone of these programmes. Regrettably, the positive effects of respiratory rehabilitation deteriorate over time, especially after short programmes. Hence, attention should be given to the aftercare of these patients to prevent them to revert again to a sedentary lifestyle. On empirical basis three possibilities seem to be clinically feasible: (1) continuous outpatient exercise training; (2) exercise training in a home-based or community-based setting; or (3) exercise training sessions in a group of asthma and COPD patients.