Is Structured Exercise Performed with Supplemental Oxygen a Promising Method of Personalized Medicine in the Therapy of Chronic Diseases?

The Impact of Exercise Training and Supplemental Oxygen on Peripheral Muscles in Chronic Obstructive Pulmonary Disease: A Randomized Controlled Trial

OBJECTIVE

Exercise training is a cornerstone of the treatment of chronic obstructive pulmonary disease, whereas the related interindividual heterogeneity in skeletal muscle dysfunction and adaptations are not yet fully understood. We set out to investigate the effects of exercise training and supplemental oxygen on functional and structural peripheral muscle adaptation.

METHODS

In this prospective, randomized, controlled, double-blind study, 28 patients with nonhypoxemic chronic obstructive pulmonary disease (forced expiratory volume in 1 second, 45.92% ± 9.06%) performed 6 wk of combined endurance and strength training, three times a week while breathing either supplemental oxygen or medical air. The impact on exercise capacity, muscle strength, and quadriceps femoris muscle cross-sectional area (CSA) was assessed by maximal cardiopulmonary exercise testing, 10-repetition maximum strength test of knee extension, and magnetic resonance imaging, respectively.

RESULTS

After exercise training, patients demonstrated a significant increase in functional capacity, aerobic capacity, exercise tolerance, quadriceps muscle strength, and bilateral CSA. Supplemental oxygen affected significantly the training impact on peak work rate when compared with medical air (+0.20 ± 0.03 vs +0.12 ± 0.03 W·kg -1 , P = 0.047); a significant increase in CSA (+3.9 ± 1.3 cm 2 , P = 0.013) was only observed in the training group using oxygen. Supplemental oxygen and exercise-induced peripheral desaturation were identified as significant opposing determinants of muscle gain during this exercise training intervention, which led to different adaptations of CSA between the respective subgroups.

CONCLUSIONS

The heterogenous functional and structural muscle adaptations seem determined by supplemental oxygen and exercise-induced hypoxia. Indeed, supplemental oxygen may facilitate muscular training adaptations, particularly in limb muscle dysfunction, thereby contributing to the enhanced training responses on maximal aerobic and functional capacity.

Pulmonary rehabilitation and physical interventions

Pulmonary rehabilitation has established a status of evidence-based therapy for patients with symptomatic COPD in the stable phase and after acute exacerbations. Rehabilitation should have the possibility of including different disciplines and be offered in several formats and lines of healthcare. This review focusses on the cornerstone intervention, exercise training, and how training interventions can be adapted to the limitations of patients. These adaptations may lead to altered cardiovascular or muscular training effects and/or may improve movement efficiency. Optimising pharmacotherapy (not the focus of this review) and oxygen supplements, whole-body low- and high-intensity training or interval training, and resistance (or neuromuscular electrical stimulation) training are important training modalities for these patients in order to accommodate cardiovascular and ventilatory impairments. Inspiratory muscle training and whole-body vibration may also be worthwhile interventions in selected patients. Patients with stable but symptomatic COPD, those who have suffered exacerbations and patients waiting for or who have received lung volume reduction or lung transplantation are good candidates. The future surely holds promise to further personalise exercise training interventions and to tailor the format of rehabilitation to the individual patient's needs and preferences.

Relationship between perceived and neuromuscular fatigue in COPD patients with chronic respiratory failure with long-term oxygen therapy: a cross-sectional study

PURPOSE

To evaluate perceived fatigue (PF) and neuromuscular fatigue (NMF) in patients with COPD and chronic respiratory failure (CRF) on long-term oxygen therapy (CRF-COPD group), and the relationships between PF, NMF, patient's characteristics, comparing severe patients with COPD to patients without CRF (COPD group).

METHODS

This cross-sectional study compared 19 CRF-COPD patients with 10 COPD patients attending a rehabilitation program. PF was determined by Fatigue Severity Scale (FSS), while dyspnea by the Barthel Dyspnea Index (BDI). We assessed quadriceps NMF via electrical nerve stimulation during and following a Maximal Voluntary Contraction (MVC) detecting changes after a Constant Workload Cycling Test (CWCT) at 80% of the peak power output at exhaustion.

RESULTS

CRF-COPD patients showed higher PF (+ 1.79 of FSS score, p = 0.0052) and dyspnea (+ 21.03 of BDI score, p = 0.0023) than COPD patients. After the fatiguing task and normalization for the total work, there was a similar decrease in the MVC (CRF-COPD -1.5 ± 2.4 vs COPD -1.1 ± 1.2% baseline kJ^-1, p = 0.5819), in the potentiated resting twitch force (CRF-COPD -2.8 ± 4.7 vs COPD -2.0 ± 3.3% baseline kJ^-1, p = 0.7481) and in the maximal voluntary activation (CRF-COPD -0.1 ± 3.9 vs COPD -0.9 ± 1.2 -2.0 ± 3.3% baseline kJ^-1, p = 0.4354). FSS and BDI were closely related (R = 0.5735, p = 0.0011), while no correlation between PF and NMF was found.

CONCLUSION

Patients with CRF-COPD develop higher levels of perceived fatigue and dyspnea than patients with COPD; while neuromuscular fatigue is similar, suggesting a mismatch between symptoms and neuromuscular dysfunction.

Impact of exercise training and supplemental oxygen on submaximal exercise performance in patients with COPD

Functional impairment caused by chronic obstructive pulmonary disease (COPD) impacts on activities of daily living and quality of life. Indeed, patients' submaximal exercise capacity is of crucial importance. It was the aim of this study to investigate the effects of an exercise training intervention with and without supplemental oxygen on submaximal exercise performance. This is a secondary analysis of a randomized, controlled, double-blind, crossover trial. 29 COPD patients (63.5 ± 5.9 years; FEV₁ 46.4 ± 8.6%) completed two consecutive 6-week periods of high-intensity interval cycling and strength training, which was performed three times/week with either supplemental oxygen or medical air (10 L/min). Submaximal exercise capacity as well as the cardiocirculatory, ventilatory, and metabolic response were evaluated at isotime (point of termination in the shortest cardiopulmonary exercise test), at physical work capacity at 110 bpm of heart rate (PWC 110), at the anaerobic threshold (AT), and at the lactate-2 mmol/L threshold. After 12 weeks of exercise training, patients improved in exercise tolerance, shown by decreased cardiocirculatory (heart rate, blood pressure) and metabolic (respiratory exchange ratio, lactate) effort at isotime; ventilatory response was not affected. Submaximal exercise capacity was improved at PWC 110, AT and the lactate-2 mmol/L threshold, respectively. Although supplemental oxygen seems to affect patients' work rate at AT and the lactate-2 mmol/L threshold, no other significant effects were found. The improved submaximal exercise capacity and tolerance might counteract patients' functional impairment. Although cardiovascular and metabolic training adaptations were shown, ventilatory efficiency remained essentially unchanged. The impact of supplemental oxygen seems less important on submaximal training effects.