Normal values for maximal respiratory pressures in children and adolescents: A systematic review with meta-analysis.

BACKGROUND: The non-invasive assessment of maximal respiratory pressures (MRP) reflects the strength of the respiratory muscles. OBJECTIVE: To evaluate the studies which have established normative values for MRP in healthy children and adolescents and to synthesize these values through a meta-analysis. METHODS: The searches were conducted until October 2023 in the following databases: ScienceDirect, MEDLINE, CINAHL, SciELO, and Web of Science. Articles that determined normative values and/or reference equations for maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) in children and adolescents published in English, Portuguese, or Spanish regardless of the year of publication were included. Two reviewers selected titles and abstracts, in case of conflict, a third reviewer was consulted. Articles that presented sufficient data were included to conduct the meta-analysis. RESULTS: Initially, 252 studies were identified, 28 studies were included in the systematic review and 19 in the meta-analysis. The sample consisted of 5798 individuals, and the MIP and MEP values were stratified by sex and age groups of 4-11 and 12-19 years. Values from females 4-11 years were: 65.8 cmH2O for MIP and 72.8 cmH2O for MEP, and for males, 75.4 cmH2O for MIP and 84.0 cmH2O for MEP. In the 12-19 age group, values for females were 82.1 cmH2O for MIP and 90.0 cmH2O for MEP, and for males, they were 95.0 cmH2O for MIP and 105.7 cmH2O for MEP. CONCLUSIONS: This meta-analysis suggests normative values for MIP and MEP in children and adolescents based on 19 studies.

Eccentric versus conventional cycle training to improve muscle strength in advanced COPD: A randomized clinical trial.

OBJECTIVES: To compare eccentric (ECC) and conventional concentric (CON) cycle training on quadriceps muscle strength in advanced COPD. Secondary objective was to assess functional capacity. METHODS: A parallel-group, assessor-blind, randomized trial was conducted. Severe COPD patients were randomized to either an ECC (n = 13) or CON (n = 11) cycling program for 30-min, 3 times/week for 10 weeks. ECC group trained at ∼4-fold higher power than the CON group at similar relative heart rate intensity. RESULTS: Isometric and isokinetic quadriceps peak torque improved after ECC but not CON; between group difference was significant for isometric peak muscle force (p < 0.05). Peak cycling power and endurance time increased in both groups (p < 0.05). Dyspnea at peak cycling power improved only after ECC training (p < 0.05). Sensory intensity ratings of dyspnea and leg fatigue were significantly lower (p < 0.05) during ECC compared with CON at equivalent relative heart rate intensities. CONCLUSIONS: ECC could be an effective alternative and/or adjunct modality to pulmonary rehabilitation in severely ventilatory limited COPD patients.

Eccentric cycle exercise in severe COPD: feasibility of application.

Eccentric cycling may present an interesting alternative to traditional exercise rehabilitation for patients with advanced COPD, because of the low ventilatory cost associated with lengthening muscle actions. However, due to muscle damage and soreness typically associated with eccentric exercise, there has been reluctance in using this modality in clinical populations. This study assessed the feasibility of applying an eccentric cycling protocol, based on progressive muscle overload, in six severe COPD patients with the aim of minimizing side effects and maximizing compliance. Over 5 weeks, eccentric cycling power was progressively increased in all patients from a minimal 10-Watt workload to a target intensity of 60% peak oxygen consumption (attained in a concentric modality). By 5 weeks, patients were able to cycle on average at a 7-fold higher power output relative to baseline, with heart rate being maintained at ∼85% of peak. All patients complied with the protocol and presented tolerable dyspnea and leg fatigue throughout the study; muscle soreness was minimal and did not compromise increases in power; creatine kinase remained within normal range or was slightly elevated; and most patients showed a breathing reserve > 15 L.min(-1). At the target intensity, ventilation and breathing frequency during eccentric cycling were similar to concentric cycling while power was approximately five times higher (p = 0.02). This study showed that an eccentric cycling protocol based on progressive increases in workload is feasible in severe COPD, with no side effects and high compliance, thus warranting further study into its efficacy as a training intervention.