Efficacy of 12 weeks oral beta-alanine supplementation in patients with chronic obstructive pulmonary disease: a double-blind, randomized, placebo-controlled trial.

BACKGROUND: Beta-alanine (BA) supplementation increases muscle carnosine, an abundant endogenous antioxidant and pH buffer in skeletal muscle. Carnosine loading promotes exercise capacity in healthy older adults. As patients with chronic obstructive pulmonary disease (COPD) suffer from elevated exercise-induced muscle oxidative/carbonyl stress and acidosis, and from reduced muscle carnosine stores, it was investigated whether BA supplementation augments muscle carnosine and induces beneficial changes in exercise capacity, quadriceps function, and muscle oxidative/carbonyl stress in patients with COPD. METHODS: In this double-blind, randomized, placebo (PL)-controlled trial (clinicaltrials.gov identifier: NCT02770417), 40 patients (75% male) with COPD (mean ± standard deviation: age 65 ± 6 years; FEV1 % predicted 55 ± 14%) were assigned to 12 weeks oral BA or PL supplementation (3.2 g/day). The primary outcome, i.e. muscle carnosine, was quantified from m. vastus lateralis biopsies obtained before and after intervention. Co-primary outcomes, i.e. incremental and constant work rate cycle capacity, were also assessed. Linear mixed model analyses were performed. Compliance with and side effects of supplement intake and secondary outcomes (quadriceps strength and endurance, and muscle oxidative/carbonyl stress) were also assessed. RESULTS: Beta-alanine supplementation increased muscle carnosine in comparison with PL in patients with COPD (mean difference [95% confidence interval]; +2.82 [1.49-4.14] mmol/kg wet weight; P < 0.001). Maximal incremental cycling capacity (VO2 peak: +0.5 [-0.7 to 1.7] mL/kg/min; P = 0.384, Wpeak: +5 [-1 to 11] W; P = 0.103) and time to exhaustion on the constant work rate cycle test (+28 [-179 to 236] s; P = 0.782) did not change significantly. Compliance with supplement intake was similar in BA (median (quartile 1-quartile 3); 100 (98-100)%) and PL (98 (96-100)%) (P = 0.294) groups, and patients did not report side effects possibly related to supplement intake. No change was observed in secondary outcomes. CONCLUSIONS: Beta-alanine supplementation is efficacious in augmenting muscle carnosine (+54% from mean baseline value) without side effects in patients with COPD in comparison with PL. However, accompanied beneficial changes in exercise capacity, quadriceps function, and muscle oxidative/carbonyl stress were not observed.

Effects of low and high resistance training intensities on clinical outcomes in patients with COPD - a randomized trial.

AIM: To compare the effects of two different intensities of combined resistance and aerobic training on physical-functional aspects and perceptual aspects of health status in patients with Chronic Obstructive Pulmonary Disease (COPD). DESIGN: This was a randomized parallel group trial. METHODS: Thirty-one patients were assessed regarding: symptoms (COPD Assessment Test - CAT), quality of life (Saint George's Respiratory Questionnaire - SGRQ); exercise capacity (six-minute walk test and constant-workload resistance test - CWRT); and muscle strength (one-repetition maximum test and isometric muscle strength for knee extensors - Kext and elbow flexors - EFlex). Patients were randomized in two groups to perform a combined training: 1) LL/HR = Low-load/high-repetition resistance training (n = 16; 68 ± 9.3 years; FEV1 = 50.0 ± 15.7%pred); and 2) HL/LR = High-load/low-repetition resistance training (n = 15; 70 ± 6.5 years; FEV1 = 46.8 ± 14.5%pred), and underwent 36 sessions. RESULTS: Symptoms, quality of life and exercise capacity presented significant improvement (p < .05) in both groups. Both intensities of resistance training improved symptoms (∆CAT: LL/HR = -3.9; HL/LR = -2.8) and exercise capacity (∆ tolerance time in CWRT: LL/HR = +450.9s; HL/LR = +583.4s) above minimal clinically important difference value. Nevertheless, improvement in quality of life (∆SGRQ: LL/HR = -3.8; HL/LR = -10) and in isometric muscle strength (∆KExt: LL/HR = +15.8 N; HL/LR = +37.7 N and (∆EFlex: LL/HR = +9.5 N; HL/LR = +29.9 N) was observed only in the HL/LR group, which also presented a larger number of responders considering isometric muscle strength. CONCLUSION: High-intensity resistance training in a combined training was more effective in ameliorating several aspects of patients with COPD, responding more and better to physical-functional aspects and perceptual aspects of health status.

Do London Chest Activity of Daily Living Scale and St George's Respiratory Questionnaire Reflect Limitations During Activities of Daily Living in Patients With COPD?

PURPOSE: It is unclear whether activities of daily living (ADL) and quality-of-life scales reflect real ADL limitations. The aim of the study was to assess the limitation during ADL simulation and to identify whether the London Chest Activity of Daily Living (LCADL) Scale and St George's Respiratory Questionnaire (SGRQ) are able to reflect the patient's real limitations during ADL simulation. METHODS: Forty-eight patients with chronic obstructive pulmonary disease (age = 69 ± 8 y; forced expiratory volume in the first second of expiration [FEV1] = 1.37 ± 0.49 L) were assessed by SGRQ and LCADL Scale. Activities of daily living simulations were performed: showering (ADL1); lifting and lowering containers above the shoulder girdle (ADL2); and raising and lowering pots below the pelvic girdle (ADL3). RESULTS: SpO2 and ΔSpO2 in ADL2 were statistically lower than in ADL3. Ventilatory demand was statistically higher in ADL2 and ADL3 than in ADL1. Metabolic equivalent values were similar between the ADLs with values above 3.6. Oxygen desaturation was present in 41.7% (ADL1) and 33.3% (ADL2) of the patients. The LCADL% showed a moderate positive correlation with dyspnea in ADL3 and metabolic demand in ADL1. The SGRQ score presented a moderate positive correlation with dyspnea in all ADL simulations and metabolic demand in ADL1 and ADL3. Dyspnea in ADL3 and metabolic demand in ADL1 explained 33% of the variability in LCADL%. The dyspnea and metabolic demand in ADL3 explained 67% of the variability in SGRQ. CONCLUSION: Activities of daily living lead to oxygen desaturation and high ventilatory demand. London Chest Activity of Daily Living Scale reflected 33% and SGRQ reflected 67% of the functional limitation during ADL simulation, such as dyspnea and the metabolic demand during ADL.