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Introduction: The Turbine™ is a nasal dilator marketed to athletes to increase airflow, which may serve to reduce dyspnea and improve exercise performance, presumably via reductions in the work of breathing (WOB). However, the unpublished data supporting these claims were collected in individuals at rest that were exclusively nasal breathing. These data are not indicative of how the device influences breathing during exercise at higher ventilations when a larger proportion of breathing is through the mouth. Accordingly, the purpose of this study was to empirically test the efficacy of the Turbine™ during exercise. We hypothesized that the Turbine™ would modestly reduce the WOB at rest and very low exercise intensities but would have no effect on the WOB at moderate to high exercise intensities., Methods: We conducted a randomized crossover study in young, healthy individuals (7M:1F; age = 27 ± 5 yr) with normal lung function. Each participant performed two incremental cycle exercise tests to exhaustion with the Turbine™ device or under a sham control condition. For the sham control condition, participants were told they were breathing a low-density gas to reduce the WOB, but they were actually breathing room air. The WOB was determined through the integration of ensemble averaged esophageal pressure-volume loops. Standard cardiorespiratory measures were recorded using a commercially available metabolic cart. Dyspnea was assessed throughout exercise using the 0-10 Borg scale., Results: Peak V˙O2 and work rate were not different between conditions (P = 0.70 and P = 0.35, respectively). In addition, there was no interaction or main effect of condition on dyspnea, ventilation, or WOB throughout the exercise (all P > 0.05)., Conclusion: These findings suggest that the Turbine™ does not reduce the WOB and has no effect on dyspnea or exercise capacity.

Purpose: The physiological consequences of freely chosen cadence during cycling remains poorly understood. We sought to determine the effect of cadence on the respiratory and hemodynamic response to cycling exercise., Methods: Eleven cyclists (10 males, 1 female; age, 27 ± 6 yr; V˙O2max = 60.8 ± 3.7 mL·kg·min) completed four, 6-min constant-load cycling trials at 10% below their previously determined gas exchange threshold (i.e., 63% ± 5% peak power) while pedaling at 60, 90, and 120 rpm, and a freely chosen cadence (94.3 ± 6.9 rpm) in randomized order. Standard cardiorespiratory parameters were measured and an esophageal electrode balloon catheter was used to assess electromyography of the diaphragm (EMGdi) and the work of breathing (Wb). Leg blood flow index (BFI) was determined on four muscles using near-infrared spectroscopy with indocyanine green dye injections., Results: Oxygen uptake (V˙O2) increased as a function of increasing cadence (all pairwise comparisons, P < 0.05). The EMGdi and Wb were significantly greater at 120 rpm compared with all other conditions (all P < 0.01). Vastus medialis and semitendinosus BFI were significantly greater at 120 rpm compared with 60 and 90 rpm (all P < 0.05). Gastrocnemius BFI was higher at 120 rpm compared with all other cadences (all P < 0.01). No difference in BFI was found in the vastus lateralis (P = 0.06). Blood flow index was significantly correlated with the increase in V˙O2 with increasing cadence in the medial gastrocnemius (P < 0.001) and approached significance in the vastus lateralis (P = 0.09), vastus medialis (P = 0.06), and semitendinosus (P = 0.09). There was no effect of cadence on Borg 0-10 breathing or leg discomfort ratings (P > 0.05)., Conclusions: High cadence cycling at submaximal exercise intensities is metabolically inefficient and increases EMGdi, Wb, and leg muscle blood flow relative to slower cadences.

Purpose: Aerobars place a cyclist in a position where the trunk is flexed forward and the elbows are close to the midline of the body. This position is known to improve cycling aerodynamics and time trial race performance compared with upright cycling positions. However, the aggressive nature of this position may have important cardiorespiratory and metabolic consequences. The purpose of this investigation was to examine the respiratory mechanical, ventilatory, metabolic, and sensory consequences of cycling while using aerobars during laboratory-based cycling., Methods: Eleven endurance-trained male cyclists (age, 26 ± 9 yr; V˙O2peak, 55 ± 5 mL·kg·min) were recruited. Visit 1 consisted of an incremental cycling test to determine peak power output. Visit 2 consisted of 6-min bouts of constant load cycling at 70% of peak incremental power output in the aerobar position, drop position, and upright position while grasping the brake hoods. Metabolic and ventilatory responses were measured using a commercially available metabolic cart, and respiratory pressures were measured using an esophageal catheter., Results: Cycling in the aerobar position significantly increased the work of breathing (Wb), power of breathing (Pb), minute ventilation, ventilatory equivalent for oxygen and carbon dioxide, and transdiaphragmatic pressure compared with the upright position. Increases in the Wb and Pb in the aerobars relative to the upright position were strongly correlated with the degree of thoracic restriction, measured as the shoulder-to-aerobar width ratio (Wb: r = 0.80, P = 0.01; Pb: r = 0.69, P = 0.04)., Conclusions: Aerobars significantly increase the mechanical cost of breathing and leads to greater ventilatory inefficiency compared with upright cycling. Future work is needed to optimize aerobar width to minimize the respiratory mechanical consequences while optimizing aerodynamics.

Recent evidence suggests that surface electromyography of the parasternal intercostals (EMGpara) can be a non-invasive alternative to diaphragmatic EMG (EMGdi) for estimating neural respiratory drive (NRD) during cardiopulmonary exercise testing (CPET). The purpose of this study was to determine if non-respiratory muscles influence EMGpara by having subjects place their hands on (H on ) and off (H off ) the handlebars during cycling-based CPET. Ten healthy adults performed an incremental cycling test until volitional exhaustion. Participants were instrumented with an esophageal electrode catheter to measure EMGdi, and surface electrodes on the 2nd intercostal space to measure EMGpara. Subjects alternated between 30s of H on and 30s H off during each exercise stage. There were no differences in EMGdi across all exercise intensities. However, EMGpara was significantly greater during the H on vs. H off condition at all exercise intensities (p<0.05). These results suggest that EMGpara may not be an appropriate surrogate of NRD during cycle exercise testing due to co-activation of adjacent skeletal muscles., (Copyright © 2017 Elsevier B.V. All rights reserved.)