RESUMEN

The purpose of the present study was to assess the effects of aerobic interval training on muscle and brain oxygenation to incremental ramp exercise. Eleven physically active subjects performed a 6-week interval training period, proceeded and followed by an incremental ramp exercise to exhaustion (25 W min-1). Throughout the tests pulmonary gas exchange and muscle (Vastus Lateralis) and brain (prefrontal cortex) oxygenation [concentration of deoxygenated and oxygenated hemoglobin, HHb and O2Hb, and tissue oxygenation index (TOI)] were continuously recorded. Following the training intervention V . ⁢ O 2 peak had increased with 7.8 ± 5.0% (P < 0.001). The slope of the decrease in muscle TOI had decreased (P = 0.017) 16.6 ± 6.4% and the amplitude of muscle HHb and totHb had increased (P < 0.001) 40.4 ± 15.8 and 125.3 ± 43.1%, respectively. The amplitude of brain O2Hb and totHb had increased (P < 0.05) 40.1 ± 18.7 and 26.8 ± 13.6%, respectively. The training intervention shifted breakpoints in muscle HHb, totHb and TOI, and brain O2Hb, HHb, totHb and TOI to a higher absolute work rate and V . ⁢ O 2 (P < 0.05). The relative (in %) change in V . ⁢ O 2 peak was significantly correlated to relative (in %) change slope of muscle TOI (r = 0.69, P = 0.011) and amplitude of muscle HHb (r = 0.72, P = 0.003) and totHb (r = 0.52, P = 0.021), but not to changes in brain oxygenation. These results indicate that interval training affects both muscle and brain oxygenation, coinciding with an increase in aerobic fitness (i.e., V . ⁢ O 2 peak). The relation between the change in V . ⁢ O 2 peak and muscle but not brain oxygenation suggests that brain oxygenation per se is not a primary factor limiting exercise tolerance during incremental exercise.

RESUMEN

OBJECTIVES: Stair climbing is considered the first step for functional evaluation of patients requiring anatomical lung resection who have low-predicted postoperative forced expiratory volume in the first second of expiration (FEV1) or diffusing capacity of the lungs for carbon monoxide (DLCO) values. Nevertheless, stair climbing is not performed in many centres because of structural issues or patient safety concerns. We hypothesized that comparable exercise can be obtained on an ergometric bicycle in a safer environment where any adverse event can be treated. We tried to correlate the amount of exercise performed by stair climbing and by using an ergometric bicycle in a series of patients with non-small-cell lung cancer (NSCLC) evaluated prospectively. METHODS: Thirty-four consecutive patients with NSCLC who were scheduled for lung resection were prospectively enrolled to complete two low-technology exercise tests: The first one was stair climbing, and the second was a ramp test on an ergometric bicycle. For most patients (85%), both tests were performed on the same day, separated with at least 2 h of rest. The amount of exercise on the stair-climbing test (in watts: Watt 1) was calculated per patient weight, height reached on stairs and time spent. The bicycle test was performed on a Lode Corival ergometer with automatic calculation of the total work load (Watt 2). No estimation of VO 2 max was attempted. The bicycle test was conducted in an ad-hoc room fully equipped with oxygen, cardiac and blood pressure and PO 2 monitoring and resuscitation equipment. The Bland-Altman plot was used to evaluate the agreement between both tests. A linear regression model was constructed in which the power developed on the stairs was the dependent variable and the watts generated on the bicycle and patient age were the covariates. RESULTS: All patients (median age: 65.5 years; range: 41-84), completed both tests without any adverse events. The number of watts was greater on the stairs tests (mean 227 vs 64 on the ergometric bicycle). The Bland-Altman plot showed agreement between tests in most cases (Pitman-Morgan test: 0.96). Work load was more dependent on age in the stairs tests (Pearson coefficient -0.72 on stairs; -0.52 on ergometric bicycle). The logistic model was highly predictive when the workload on the bicycle was corrected by the patient's age ( R 2 = 0.80; Wald test <0.001). CONCLUSIONS: This simple test on an ergometric bicycle shows a high correlation with the widely accepted stair-climbing test when workload results are corrected using the patient's age. It could replace the stair-climbing test and has the advantage of being conducted in an environment that is safer for the patient. Nevertheless, its reliability for risk prediction needs to be adequately evaluated.

Asunto(s)

Prueba de Esfuerzo/métodos , Pulmón/fisiopatología , Cuidados Preoperatorios/métodos , Pruebas de Función Respiratoria/métodos , Adulto , Anciano , Anciano de 80 o más Años , Carcinoma de Pulmón de Células no Pequeñas/fisiopatología , Carcinoma de Pulmón de Células no Pequeñas/cirugía , Femenino , Humanos , Pulmón/cirugía , Neoplasias Pulmonares/fisiopatología , Neoplasias Pulmonares/cirugía , Masculino , Persona de Mediana Edad , Seguridad del Paciente , Proyectos Piloto , Neumonectomía/métodos , Estudios Prospectivos

RESUMEN

The pulmonary oxygen uptake (VO2) response to incremental-ramp cycle ergometry typically demonstrates lagged-linear first-order kinetics with a slope of ~10-11 ml·min(-1)·W(-1), both above and below the lactate threshold (θL), i.e. there is no discernible VO2 slow component (or "excess" VO2) above θL. We were interested in determining whether a reverse ramp profile would yield the same response dynamics. Ten healthy males performed a maximum incremental -ramp (15-30 W·min(-1), depending on fitness). On another day, the work rate (WR) was increased abruptly to the incremental maximum and then decremented at the same rate of 15-30 W.min(-1) (step-decremental ramp). Five subjects also performed a sub-maximal ramp-decremental test from 90% of θL. VO2 was determined breath-by-breath from continuous monitoring of respired volumes (turbine) and gas concentrations (mass spectrometer). The incremental-ramp VO2-WR slope was 10.3 ± 0.7 ml·min(-1)·W(-1), whereas that of the descending limb of the decremental ramp was 14.2 ± 1.1 ml·min(-1)·W(-1) (p < 0.005). The sub-maximal decremental-ramp slope, however, was only 9. 8 ± 0.9 ml·min(-1)·W(-1): not significantly different from that of the incremental-ramp. This suggests that the VO2 response in the supra-θL domain of incremental-ramp exercise manifest not actual, but pseudo, first-order kinetics. Key pointsThe slope of the decremental-ramp response is appreciably greater than that of the incremental.The response dynamics in supra-θL domain of the incremental-ramp appear not to manifest actual first-order kinetics.The mechanisms underlying the different dynamic response behaviour for incremental and decremental ramps are presently unclear.