Chronic Effects of a Training Program Using a Nasal Inspiratory Restriction Device on Elite Cyclists

International Journal of Environmental Research and Public Health Article Chronic Effects of a Training Program Using a Nasal Inspiratory Restriction Device on Elite Cyclists Jose L. Gonzalez-Montesinos 1, Jorge R. Fernandez-Santos 2,3,* , Carmen Vaz-Pardal 4, Ruben Aragon-Martin 3,5, Aurelio Arnedillo-Muñoz 6, Jose Reina-Novo 7, Eva Orantes-Gonzalez 8, Jose Heredia-Jimenez 8and Jesus G. Ponce-Gonzalez 3,5   Citation: Gonzalez-Montesinos, J.L.; Fernandez-Santos, J.R.; Vaz-Pardal, C.; Aragon-Martin, R.; Arnedillo-Muñoz, A.; Reina-Novo, J.; Orantes-Gonzalez, E.; Heredia-Jimenez, J.; Ponce-Gonzalez, J.G. Chronic Effects of a Training Program Using a Nasal Inspiratory Restriction Device on Elite Cyclists. Int. J. Environ. Res. Public Health 2021, 18, 777. https://doi.org/10.3390/ ijerph18020777 Received: 4 December 2020 Accepted: 15 January 2021 Published: 18 January 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). 1Department of Physical Education, Faculty of Education Sciences, University of Cádiz, Puerto Real, 11003 Cádiz, Spain; [email protected] 2Galeno Research Group, Department of Physical Education, Faculty of Education Sciences, University of Cádiz, 11003 Cádiz, Spain 3Biomedical Research and Innovation Institute of Cádiz (INiBICA) Research Unit, Puerta del Mar University Hospital University of Cádiz, 11009 Cádiz, Spain; [email protected] (R.A.-M.); [email protected] (J.G.P.-G.) 4Bahía Sur Andalusian Center for Sports Medicine, 11100 Cádiz, Spain; [email protected] 5MOVE-IT Research Group, Department of Physical Education, Faculty of Education Sciences, University of Cádiz, 11003 Cádiz, Spain 6Allergy and Thoracic Surgery Department, University Hospital Puerta del Mar. Pneumology, 11009 Cádiz, Spain; [email protected] 7National Cycling Coach, IES, Stadium Path 2504, Hong Kong; [email protected] 8Department of Physical Education & Sports, University of Granada, 18010 Granada, Spain; [email protected] (E.O.-G.); [email protected] (J.H.-J.) *Correspondence: jorgedelr[email protected]; Tel.: +34-679052107 Abstract: This study compared the response of a 9-week cycling training on ventilatory efficiency under two conditions: (i) Combined with respiratory muscle training (RMT) using a new nasal restriction device (FeelBreathe) (FB group) and (ii) without RMT (Control group). Eighteen healthy elite cyclists were randomly separated into the FB group (n= 10) or Control group (n= 8). Gas exchange was measured breath by breath to measure ventilatory efficiency during an incremental test on a cycloergometer before (Pre) and after (Post) the nine weeks of training. The FB group showed higher peak power ( ∆ (95%HDI) (0.82 W/kg (0.49, 1.17)), VO 2 max (5.27 mL/kg/min ( 0.69, 10.83 )) and VT 1 (29.3 W ( 1.8, 56.7 )) compared to Control at Post FINAL . The FB group showed lower values from Pre to Post PRE in minute ventilation (VE) ( − 21.0 L/min ( − 29.7, − 11.5)), Breathing frequency (BF) ( − 5.1 breaths/min ( − 9.4, − 0.9)), carbon dioxide output (VCO 2 ) ( − 0.5 L/min ( −0.7, −0.2 )), respiratory equivalents for oxygen (EqO 2 ) ( − 0.8 L/min ( − 2.4, 0.8)), heart rate (HR) ( − 5.9 beats/min ( −9.2, −2.5 )), respiratory exchange ratio (RER) ( − 0.1 ( − 0.1, − 0.0) and a higher value in inspiratory time (Tin) (0.05 s (0.00, 0.10)), expiratory time (Tex) (0.11 s (0.05, 0.17)) and end-tidal partial pressure of CO 2 (PETCO 2 ) (0.3 mmHg (0.1, 0.6)). In conclusion, RMT using FB seems to be a new and easy alternative ergogenic tool which can be used at the same time as day-to-day training for performance enhancement. Keywords: respiratory muscle training; cyclists; cardiopulmonary exercise testing 1. Introduction Respiratory muscle training (RMT) has been considered as an effective method to improve the inspiratory muscle strength and performance of athletes of endurance sports [1–5] . Indeed, several studies performed specifically with cyclists have shown that RMT causes physiological adaptations with improvements in the respiratory system, the peak power developed and the time trial performance, both in elite and amateur cyclists [6–10]. However, the RMTs performed in these previous studies have been in static position at rest. Int. J. Environ. Res. Public Health 2021,18, 777. https://doi.org/10.3390/ijerph18020777 https://www.mdpi.com/journal/ijerph Int. J. Environ. Res. Public Health 2021,18, 777 2 of 13 Thus, it has not been possible to address the possible additive effect of RMT and exercise at the same time in these previous studies. Functional RMT while cycling has been investigated previously using 3 different devices: (i) Power Breathe Kinetic KH1 [ 11 ]; (ii) Training Mask v2.0 [ 12 ]; and (iii) FeelBreathe nasal strips [ 13 ]. Using the Power Breathe Kinetic KH1 to RMT while performing stationary cycling increased the electromyography activity in the diaphragm [ 6 ]. Despite these results, it should be noted that participants in this study with Power Breathe performed a “static” exercise and, therefore, not a specific cycling training exercise. The use of Training Mask v2.0 while performing 6 weeks of high-intensity cycle ergometer training resulted in improvements in ventilatory threshold, power output at ventilatory threshold, respiratory compensation threshold, and power output at the intensity of respiratory compensation threshold [ 12 ]. However, the training mask should be used only part-time during the training season as it could cause inadequate hyperventilation and psychological discomfort [14]. Recently, a new nasal ventilatory flow restriction and filtering device, called FeelBreathe (FB), has been designed, developed and patented to increase nasal airflow resistance [ 15 ]. A previous study with elite cyclists has shown that FB used for 10 min on cycle ergometer at 50% of VO 2peak causes acute effects in lung ventilation, gas exchange and heart rate during exercise, with improvements on ventilatory efficiency, which could be a target of RMT in sport performance. However, the chronic effect of FB combined with aerobic training in cyclists is unknown [13]. Therefore, the aim of this study was to analyze the additive effect of RMT using FB while performing a specific cycling training plan on different cardiorespiratory variables. We hypothesized, based on the previous results, that the FB group will obtain higher benefits in terms of ventilatory efficiency and peak power developed compared to exercise group without FB without changes on VO2uptake after the period of training. 2. Materials and Methods 2.1. Subjects Twenty healthy elite cyclists from two sport clubs in Chiclana de la Frontera (Cádiz, Spain) voluntary participated in this study (mean ± SD, age: 36 ± 10, weight: 71.7 ±6.7 kg , height: 1.75 ± 0.06 m). All the cyclists had participated in regional and national championships during the last 5 years at least. One of them dropped out the training plan due to illness and another one due to disagreements with the club’s coach, which led to a final sample of eighteen completing the study. All of the participants were informed of the aims of the study and requirements during the first experimental session. In addition, they signed a written informed consent in accordance with the Declaration of Helsinki. The study protocol and design were approved by the Ethics Committee University Hospital Puerta del Mar (Date: 22 December 2015). 2.2. Training Program The training plan of this study was directed and controlled by a national cycling coach daily. The training intervention lasted 9 weeks, and one group combined the exercise with RMT at the same time as using the FB device (FB group), and another group trained without any airflow restriction (CG group). The training was carried out at the Moreno Periñan velodrome (Chiclana, Cádiz, Spain) and on the road. The distances and slopes of the roads were controlled for the preparation of the training. Physiological evaluations were before (Pre) and after (Post) the training program to evaluate breathing efficiency through gas exchange. FB was manufactured for the present study in three models, 4, 5 and 6 mm of ventilatory flow restriction, which produce different levels of air restriction and inspiratory effort. FB has been authorized by the Spanish Agency for Medicines and Health Products (AEMPS No. Exp: 521/15/EC, Spain) (Figure 1). The use of this device during exercise has been used in previous investigations, both in athletes [13] and in patients with COPD [16,17]. Int. J. Environ. Res. Public Health 2021,18, 777 3 of 13 Int. J. Environ. Res. Public Health 2021, 18, x 3 of 13 (AEMPS No. Exp: 521/15/EC, Spain) (Figure 1). The use of this device during exercise has been used in previous investigations, both in athletes [13] and in patients with COPD [16,17]. Figure 1. FeelBreathe (FB) devices of 4, 5 and 6 mm arranged in sheets of 10 units. FB placement mode under the nostrils. Participants were randomly assigned to either the cycling training combined with FB (FB, n = 10) or control group without FB (Control, n = 8). Both groups were matched by age and VO 2 max. All participants were instructed to avoid changes in their diet or physical activity while they were following the training plan. The training intensity was set based on the heart rate corresponding to the lactate threshold (HRlactate): (i) Regenerative (<75% HRlactate); A0 (75–90% HRlactate); A1 (90–95% HRlactate); A2 (95–100% HRlactate); A3 (100–105% HRlactate); A4 (105% HRlactate—HRpeak). Both groups completed a volume of 144 h of training during the 9 weeks of intervention, with similar intensity and duration adapted to each athlete (Regenerative: ~42/43% of total training time, A0: ~36/38%, A1: ~8/9%, A2: ~8%, A3: ~3%, A4: ~1%). The participants of the FB group were instructed on how to place the FB device correctly. During the first 2 weeks, all the participants used the 4 mm FB device model, increasing the width of the device to the 5 mm FB model for the next 4 weeks and to 6 mm FB during the last 3 weeks of training. 2.3. Measurements At the Andalusian Center for Sports Medicine (Bahía Sur, San Fernando, Spain), pre and post training tests were performed on all participants. During the testing day, resting tests were done with measurement of weight and height, blood pressure, cardiopulmonary auscultation, baseline spirometry (Cardinal Health Spirometer, D-97204 Hoechberg, Germany) and a twelve-lead resting electrocardiogram (Mortara R-SCRIBETM 5, Milwaukee, USA). Moreover, maximal inspiratory pressure (MIP) (Micro RPM of Micro Medical, Chatham, Kent, UK) was measured according to American Thoracic Society (ATS) protocol, choosing the highest value of the 3 efforts with a lower than 5% difference [18]. After that, all participants completed an incremental test on a cycle ergometer (Cardgirus Bikemarc SL, Barcelona, Spain). This test consisted of a stepwise protocol of 30 watt increments every minute with constant revolutions per minute of 80–85 rpm, as used previously [19,20]. The incremental test continued until exhaustion or until the cadence was not maintained. Gas exchange and ventilatory variables were recorded during the incremental test using a gas analyzer (Jaeger-CareFusion modelo MasterScreen CPX). The oxygen consumption (VO 2 ), carbon dioxide output (VCO 2 ), Breathing frequency (BF), Figure 1. FeelBreathe (FB) devices of 4, 5 and 6 mm arranged in sheets of 10 units. FB placement mode under the nostrils. Participants were randomly assigned to either the cycling training combined with FB (FB, n= 10) or control group without FB (Control, n= 8). Both groups were matched by age and VO 2 max. All participants were instructed to avoid changes in their diet or physical activity while they were following the training plan. The training intensity was set based on the heart rate corresponding to the lactate threshold (HRlactate): (i) Regenerative (<75% HRlactate); A0 (75–90% HRlactate); A1 (90–95% HRlactate); A2 (95–100% HRlactate); A3 (100–105% HRlactate); A4 (105% HRlactate—HRpeak). Both groups completed a volume of 144 h of training during the 9 weeks of intervention, with similar intensity and duration adapted to each athlete (Regenerative: ~42/43% of total training time, A0: ~36/38%, A1: ~8/9%, A2: ~8%, A3: ~3%, A4: ~1%). The participants of the FB group were instructed on how to place the FB device correctly. During the first 2 weeks, all the participants used the 4 mm FB device model, increasing the width of the device to the 5 mm FB model for the next 4 weeks and to 6 mm FB during the last 3 weeks of training. 2.3. Measurements At the Andalusian Center for Sports Medicine (Bahía Sur, San Fernando, Spain), pre and post training tests were performed on all participants. During the testing day, resting tests were done with measurement of weight and height, blood pressure, cardiopulmonary auscultation, baseline spirometry (Cardinal Health Spirometer, D-97204 Hoechberg, Germany) and a twelve-lead resting electrocardiogram (Mortara R-SCRIBETM 5, Milwaukee, USA). Moreover, maximal inspiratory pressure (MIP) (Micro RPM of Micro Medical, Chatham, Kent, UK) was measured according to American Thoracic Society (ATS) protocol, choosing the highest value of the 3 efforts with a lower than 5% difference [18]. After that, all participants completed an incremental test on a cycle ergometer (Cardgirus Bikemarc SL, Barcelona, Spain). This test consisted of a stepwise protocol of 30 watt increments every minute with constant revolutions per minute of 80–85 rpm, as used previously [ 19 , 20 ]. The incremental test continued until exhaustion or until the cadence was not maintained. Gas exchange and ventilatory variables were recorded during the incremental test using a gas analyzer (Jaeger-CareFusion modelo MasterScreen CPX). The oxygen consumption (VO 2 ), carbon dioxide output (VCO 2 ), Breathing frequency (BF), tidal volume (Vt), inspiratory tidal volume (VTin), expiratory tidal volume (VTex), inspiratory time (Tin), expiratory time (Tex), duty cycle (TiTot), minute ventilation (VE), respiratory equivalents for oxygen (EqO 2 ) and carbon dioxide (EqCO 2 ), end-tidal partial pressure of O 2 (PETO 2 ) and CO 2 (PETCO 2 ), and respiratory exchange ratio (RER) were registered in a breath-by-breath manner and averaged by 10 s. Moreover, two dependent evaluators Int. J. Environ. Res. Public Health 2021,18, 777 4 of 13 assessed VT 1 from visual inspection of (1) the first disproportionate increase in VE; (2) an increase in VE/VO 2 with no increase in VE/VCO 2 (i.e., the ventilatory equivalents); (3) an increase in PETO 2 with no consequent fall in PETCO 2 , and (4) V-slope plot. VT 2 was determined from visual inspection of (1) the second disproportionate increase in VE, (2) the first systematic decrease in PETCO 2 , and (3) the first systematic increase in VE/VCO 2 . Rating of Perceived Exertion (RPE) was detected using the Borg Scale CR 0–10 [ 21 ]. One minute after the end of exercise, MIP were repeated post-exercise. After the 9-week training program, all post-tests were performed in the same order and conditions of the pre-test. The evaluators who performed the tests were blind to which individual they were evaluating since they did not participate in the training sessions. 3. Statistical Analysis Values are reported as mean ± standard deviation. For cardiorespiratory variables analyses, three values were obtained corresponding to three different temporal points in the incremental test: The maximum value recorded at the pre-training test (Pre), the value obtained at the post-training test at the same time as the maximum value at the pre-training test (Post PRE ) was obtained, and the maximum value recorded at the post-training test (PostFINAL) (Figure 2). Int. J. Environ. Res. Public Health 2021, 18, x 4 of 13 tidal volume (Vt), inspiratory tidal volume (VTin), expiratory tidal volume (VTex), inspiratory time (Tin), expiratory time (Tex), duty cycle (TiTot), minute ventilation (VE), respiratory equivalents for oxygen (EqO2) and carbon dioxide (EqCO2), end-tidal partial pressure of O2 (PETO2) and CO2 (PETCO2), and respiratory exchange ratio (RER) were registered in a breath-by-breath manner and averaged by 10 s. Moreover, two dependent evaluators assessed VT1 from visual inspection of (1) the first disproportionate increase in VE; (2) an increase in VE/VO2 with no increase in VE/VCO2 (i.e., the ventilatory equivalents); (3) an increase in PETO2 with no consequent fall in PETCO2, and (4) V-slope plot. VT2 was determined from visual inspection of (1) the second disproportionate increase in VE, (2) the first systematic decrease in PETCO2, and (3) the first systematic increase in VE/VCO2. Rating of Perceived Exertion (RPE) was detected using the Borg Scale CR 0–10 [21]. One minute after the end of exercise, MIP were repeated post-exercise. After the 9-week training program, all post-tests were performed in the same order and conditions of the pre-test. The evaluators who performed the tests were blind to which individual they were evaluating since they did not participate in the training sessions. 3. Statistical Analysis Values are reported as mean ± standard deviation. For cardiorespiratory variables analyses, three values were obtained corresponding to three different temporal points in the incremental test: The maximum value recorded at the pre-training test (Pre), the value obtained at the post-training test at the same time as the maximum value at the pre-training test (PostPRE) was obtained, and the maximum value recorded at the post-training test (PostFINAL) (Figure 2). Figure 2. Graphical representation of temporal points selected for statistical analyses. Withinand between-group differences were assessed using a Bayesian hierarchical regression model. All hyperparameters in the model followed a weakly informative prior distribution (i.e., a prior distribution that encoded enough information to restrict the plausible range of values of the parameter space but still left a wide range of values to be covered) [22]. Inference was performed based on the 95% highest density interval (95%HDI), which contains a range of values where we can be 95% certain that the true value lies Figure 2. Graphical representation of temporal points selected for statistical analyses. Withinand between-group differences were assessed using a Bayesian hierarchical regression model. All hyperparameters in the model followed a weakly informative prior distribution (i.e., a prior distribution that encoded enough information to restrict the plausible range of values of the parameter space but still left a wide range of values to be covered) [ 22 ]. Inference was performed based on the 95% highest density interval (95%HDI), which contains a range of values where we can be 95% certain that the true value lies given the data at hand and the model fitted. The null value in our analysis is 0, so if this number is not inside the 95%HDI then we can reject that value for practical purposes [ 23 ]. Bayesian estimation of the parameters was obtained by using the package brms for the R programming language [ 24 ]. All parameters estimated showed a good convergence with values of ˆ R = 1 and number of effective sample size > 1000. Further details about the analysis can be found in the supplemental file S1, while the code and the dataset to replicate it are stored in https://github.com/JorgeDelro/cyclists_PE. Int. J. Environ. Res. Public Health 2021,18, 777 5 of 13 4. Results No significant differences were found between FB and CG groups at the baseline (Table 1). Table 1. Participant’s baseline characteristics by group. Variable FB (n= 10) CG (n= 8) FB vs. CG Age (years) 35.3 ±9.4 38.1 ±11.7 −1.4 (−6.2, 3.9) Weight (kg) 71.2 ±4.0 72.2 ±9.4 −0.5 (−3.7, 2.9) Height (cm) 176.8 ±7.1 172.5 ±4.9 2.0 (−1.1, 5.0) BMI (kg/m2)22.7 ±2.0 24.3 ±2.9 −0.7 (−1.8, 0.6) VO2max (mL/kg/min) 55.8 ±4.7 51.1 ±5.4 2.3 (−0.2, 4.6) MIP (cmH2O) 155.5 ±36.2 167.6 ±51.7 −5.4 (−27.7, 14.8) FB, Feelbreathe group; CG, control group. Values are expressed as mean ± standard deviation. Differences are expressed as mean (95% HDI). Regarding within-group differences, the FB group (Table 2) obtained a lower value from Pre to Post PRE in VE ( ∆ (95%HDI) = − 21.0 L/min ( − 29.7, − 11.5)), BF ( − 5.1 breaths/min ( −9.4, −0.9 )), VCO 2 ( − 0.5L/min( − 0.7, − 0.2)), EqO 2 ( − 0.8L/min( − 2.4, 0.8)), HR ( − 5.9beats/min( −9.2, −2.5 )) and RER ( − 0.1 ( − 0.1, − 0.0) and a higher value in Tin (0.05 s ( 0.00, 0.10 )), Tex (0.11 s (0.05, 0.17)) and PETCO 2 (0.3 mmHg (0.1, 0.6)). Additionally, the FB group (Table 2) increased the peak power from Pre to Post FINAL (0.7 W/kg (0.5, 0.9)), VT 1 (21.0 W (9.6, 32.4)) and VT 2 (17.7 W (0.7, 36.2)). The Control group (Table 3) reached a lower value from Pre to Post PRE in VCO 2 ( − 0.2 L/min ( − 0.5, − 0.0)) and HR ( − 4.6 beats/min ( −7.7, −1.1 )) and a higher value in VT 2 (21.0 W (9.6, 32.4)). Between-group differences for breathing conditions (Table 4) showed a difference in VT 2 (7.69 mL/kg/min (1.86, 13.27)) at Pre; in BF ( − 10.73 breath/min ( − 19.7, − 2.13)), tin (0.10 s ( − 0.00, − 0.20)), tex (0.19 s (0.09, 0.30)) and PETCO 2 (0.56 mmHg (0.15, 0.97)) at Post PRE ; in Peak power (0.82 W/kg (0.49, 1.17)), VO 2 max (5.27 mL(kg/min (0.69, 10.83)) and VT 1 (29.3 W (1.8, 56.7)) at Post FINAL ; in VCO 2 ( − 371.7 L/min ( − 732.9, − 10.2)), tex (0.14 s (0.01, 0.27)), titot ( − 2.49% ( − 4.10, − 0.85)) and PETO 2 ( − 0.51 mmHg ( − 0.99, − 0.03)) of ∆ at Post PRE ; in Peak power (0.58 W/kg (0.23, 0.92)) and HR (5.0 beats/min (3.5, 9.6)) of ∆at PostFINAL. Int. J. Environ. Res. Public Health 2021,18, 777 6 of 13 Table 2. Average of the maximum value obtained by the Feelbreathe group (FB) in each variable at the pre-training test (Pre-Value), value obtained in the post-training test at the same moment that the maximum in the pre-training test was obtained (Post PRE -Value), and maximum obtained at the post-training test (Post FINAL -Value). Percentage of change (% Change ), increment (∆), and 95% HDI are reported from Pre to PostPRE and from Pre to PostFINAL. FB (n= 10) Pre PostPRE PostFINAL Variable Value Value %Change ∆(95%CrI) Value %Change ∆(95%CrI) Power (W/kg) 4.9 ±0.3 5.0 ±0.4 3.3 0.2 (−0.1, 0.4) 5.6 ±0.4 14.3 0.7 (0.5, 0.9) VO2max (mL/min) 3981.4 ±475.8 3714.2 ±425.2 −6.7 −205.0(−416.0, 16.7) 3988.3 ±479.6 0.2 11.1 (−217.0, 225.0) VO2max (mL/kg/min) 55.8 ±4.7 53.2 ±5.8 −4.7 −2.5 (−6.1, 1.6) 56.8 ±6.6 1.8 0.8 (−3.3, 4.7) VT1(W) 159.0 ±28.5 180.0 ±33.9 13.2 21.0 (9.6, 32.4) VT1(mL/kg/min) 26.7 ±3.9 29.6 ±5.7 10.8 2.9 (0.5, 5.4) VT1(L/min) 1.9 ±0.4 2.1 ±0.5 10.5 0.2 (0.0, 0.4) VT2(W) 288.0 ±28.1 306.0 ±30.2 6.3 17.7 (0.6, 36.2) VT2(mL/kg/min) 47.1 ±8.7 46.7 ±8.0 −0.8 −0.4 (−0.4, 3.8) VT2(L/min) 3.4 ±0.4 3.3 ±0.6 −0.9 −0.0 (−0.3, 0.3) VE (L/min) 149.1 ±24.0 126.6 ±21.4 −15.1 −21.0 (−29.7, −11.5) 152.0 ±15.7 1.9 3.6 (−12.5, 18.8) BF (breaths/min) 49.4 ±10.5 43.4 ±10.0 −12.1 −5.1 (−9.4, −0.9) 51.5 ±7.2 4.3 2.9 (−3.6, 9.7) VCO2(L/min) 5.2 ±0.5 4.5 ±0.3 −13.5 −0.5 (−0.7, −0.2) 4.9 ±0.3 −5.8 −0.2 (−0.4, 0.1) EqO2(L/min) 36.2 ±4.4 33.1 ±6.3 −8.6 −3.4 (−5.8, −0.7) 37.9 ±4.9 4.7 0.8 (−2.3, 3.7) EqCO2(L/min) 27.7 ±2.4 26.9 ±3.2 −2.9 −0.8 (−2.4, 0.8) 29.7 ±3.2 7.2 2.1 (−0.3, 4.4) HR (beats/min) 181.2 ±8.9 174.9 ±9.8 −3.5 −5.9 (−9.2, −2.5) 183.3 ±7.1 1.2 2.0 (−1.0, 5.2) VTin (L) 3.1 ±0.3 2.7 ±1.0 −12.9 −1.2 (−0.3, 0.1) 3.04 ±0.25 −1.3 −0.04 (−0.22, 0.16) VTex (L) 3.1 ±0.3 2.6 ±1.0 −16.1 −0.4 (−0.9, 0.1) 2.97 ±0.20 −2.6 −0.10 (−0.32, 0.14) Tin (s) 0.61 ±0.11 0.67 ±0.14 9.8 0.05 (0.00, 0.10) 0.56 ±0.08 −8.2 −0.05 (−0.18, 0.03) Tex (s) 0.64 ±0.11 0.77 ±0.15 20.3 0.11 (0.05, 0.17) 0.62 ±0.11 −3.1 −0.03 (−0.12, 0.05) TiTot (%) 48.5 ±1.9 46.4 ±2.4 −4.3 −2.1 (−3.2, 0.9) 47.7 ±2.2 −1.6 −0.1 (−0.6, 0.4) PETO2(mmHg) 16.0 ±0.4 15.4 ±0.7 −3.8 −0.4 (−0.63, −0.15) 15.9 ±0.2 −0.6 −0.0 (−0.3, 0.2) PETCO2(mmHg) 4.8 ±0.4 5.2 ±0.5 8.3 0.3 (0.1, 0.6) 4.8 ±0.5 0.6 0.02 (−0.3, 0.3) RER 1.31 ±0.09 1.22 ±0.13 −6.9 −0.1 (−0.1, −0.0) 1.25 ±0.10 −4.6 −0.06 (−0.11, −0.01) 95% HDIs that 0 is not inside are expressed in bold. Int. J. Environ. Res. Public Health 2021,18, 777 7 of 13 Table 3. Average of the maximum value obtained by the control group (CG) in each variable at the pre-training test (Pre-Value), value obtained in the post-training test at the same moment that the maximum in the pre-training test was obtained (Post PRE -Value), and maximum obtained at the post-training test (Post FINAL -Value). Percentage of change (% Change ), increment ( ∆ ), and 95% HDI are reported from Pre to PostPRE and from Pre to PostFINAL. CG (n= 8) Pre PostPRE PostFINAL Variable Value Value %Change ∆(95%CrI) Value %Change ∆(95%CrI) Power (W/kg) 4.6 ±0.3 4.7 ±0.3 0.9 0.1 (−0.2, 0.3) 4.8 ±0.3 3.0 0.1 (−0.1, 0.4) VO2max (mL/min) 3673.0 ±451.8 3581.6 ±508.5 −2.5 −94.5(−326.0, 125.0) 3689.3 ±491.3 0.4 8.1 (−218.0, 239.0) VO2max (mL/kg/min) 51.1 ±5.4 49.4 ±3.9 −3.3 −1.6 (−5.6, 2.7) 50.9 ±4.0 −0.4 −0.1 (−4.6, 4.2) VT1(W) 144.4 ±28.8 150.6 ±27.8 4.3 6.2 (−7.1, 20.3) VT1(mL/kg/min) 23.6 ±4.8 25.9 ±3.6 9.8 2.3 (−0.5, 5.2) VT1(L/min) 1.7 ±0.4 1.9 ±0.4 9.9 0.2 (−0.0, 0.4) VT2(W) 253.8 ±52.7 286.3 ±38.1 12.8 32.5 (11.4, 53.7) VT2(mL/kg/min) 39.1 ±6.5 44.1 ±5.4 12.8 5.0 (0.6, 9.4) VT2(L/min) 2.8 ±0.6 3.2 ±0.6 13.1 0.3 (0.1, 0.7) VE (L/min) 141.9 ±17.4 139.6 ±17.9 −1.6 −1.8 (−11.9, 7.70) 140.5 ±22.3 −1.0 −1.9 (−19.0, 15.7) BF (breaths/min) 53.3 ±8.7 54.8 ±9.3 2.8 1.6 (−3.3, 6.2) 53.0 ±7.5 −0.6 0.1 (−7.0, 6.4) VCO2(L/min) 4.8 ±0.7 4.5 ±0.6 −6.3 −0.2 (−0.5, −0.0) 4.9 ±0.3 2.1 −0.1 (−0.4, 0.1) EqO2(L/min) 37.2 ±3.9 37.3 ±2.3 0.2 0.4 (−2.3, 3.2) 36.4 ±1.9 −2.2 −0.5 (−2.3, 3.7) EqCO2(L/min) 28.7 ±2.8 29.4 ±1.3 2.4 1.2 (−0.7, 2.8) 29.0 ±2.8 1.0 0.5 (−2.3, 3.0) HR (beats/min) 178.4 ±12.6 173.8 ±13.5 −2.6 −4.6 (−7.7, −1.1) 175.4 ±14.8 −1.7 −3.0 (−6.4, 0.4) VTin (L) 2.74 ±0.57 2.69 ±0.6 −1.8 −0.03(−0.29, 0.24) 2.75 ±0.56 0.4 0.01 (−0.20, 0.24) VTex (L) 2.73 ±0.60 2.62 ±0.59 −4.0 −0.1 (−0.7, 0.5) 2.70 ±0.54 −1.1 −0.02 (−0.27, 0.22) Tin (s) 0.57 ±0.11 0.56 ±0.10 −1.8 −0.01 (−0.06, 0.04) 0.57 ±0.09 0.5 0.01(−0.07, 0.09) Tex (s) 0.58 ±0.10 0.57 ±0.09 −1.7 −0.01 (−0.08, 0.05) 0.58 ±0.06 0.5 −0.01 (−0.09, 0.08) TiTot (%) 49.3 ±2.0 49.6 ±1.6 0.6 0.4 (−0.8, 1.5) 49.9 ±2.2 1.2 −0.0 (−0.3, 0.3) Vt/Ti (L/s) 4.81 ±0.56 4.70 ±0.64 −2.3 −0.1 (−0.3, 0.2) 4.72 ±0.82 −1.9 −0.1 (−0.6, 0.4) Vt (L) 2.74 ±0.61 2.62 ±0.60 −4.4 −0.1 (−0.3, 0.1) 2.69 ±0.54 −1.8 −0.0 (−0.3, 0.2) PETO2(mmHg) 16.1 ±0.3 16.1 ±0.3 −0.1 −0.1 (−0.31, 0.1) 16.0 ±0.2 −0.6 −0.1 (−0.3, 0.1) PETCO2(mmHg) 4.7 ±0.4 4.6 ±0.1 −2.1 0.1 (−0.2, 0.3) 4.8 ±0.5 2.2 0.02 (−0.21, 0.26) RER 1.30 ±0.05 1.27 ±0.10 −2.3 −0.0 (−0.1, 0.0) 1.26 ±0.09 −3.1 −0.04 (−0.09, 0.02) 95% HDIs that 0 is not inside are expressed in bold. Int. J. Environ. Res. Public Health 2021,18, 777 8 of 13 Table 4. Between-group differences for breathing conditions at the pre-training test (Pre), at the value obtained in the post-training test at the same moment that the maximum in the pre-training test was obtained (Post PRE ), at the maximum value obtained at the post-training test (Post FINAL ), and between increments at Post PRE ( ∆ Post PRE ) and Post FINAL ( ∆ Post FINAL ). Variable FB vs. Control Pre PostPRE PostFINAL ∆PostPRE ∆PostFINAL Power (W/kg) 0.26 (−0.09, 0.59) 0.39 (−0.04, 0.76) 0.82 (0.49, 1.17) 0.12 (−0.18, 0.44) 0.58 (0.23, 0.92) VO2max (mL/min) 285.0 (−131.0, 750.0) 172 (−277.0, 619.0) 280.0 (−157.0, 740.0) −110.6 (−366.0, 152.0) −5.1 (−362.9, 346.8) VO2max (mL/kg/min) 4.53 (−0.19, 9.45) 4.27 (−1.0, 9.0) 5.27 (0.69, 10.83) −0.39 (−5.12, 4.35) 1.2 (−4.5, 6.9) VT1(W) 14.5 (−12.4, 43.0) 29.3 (1.8, 56.7) 14.8 (−3.5, 32.9) VT1(mL/kg/min) 2.94 (−1.26, 7.31) 3.58 (−0.68, 7.93) 0.5 (−3.2, 4.3) VT1(L/min) 0.20 (−0.18, 0.60) 0.23 (−0.13, 0.63) 0.03 (−0.22, 0.29) VT2(W) 32.5 (−5.17, 67.5) 19.4 (−17.5, 54.7) −14.8 (−43.6, 13.9) VT2(mL/kg/min) 7.69 (1.86, 13.27) 2.61 (−2.77, 8.43) −5.4 (−11.3, 0.6) VT2(L/min) 0.51 (−0.00, 0.98) 0.13 (−0.36, 0.61) 0.2 (−0.8, 0.0) VE (L/min) 6.68 (−12.25, 26.0) −12.01 (−31.76, 6.1) 11.48 (−7.25, 30.8) −19.77 (−39.95, 0.10) 5.5 (−18.9, 30.2) BF (breaths/min) −3.90 (−11.9, 4.88) −10.73 (−19.7, −2.13) −1.51 (−10.3, 7.21) −7.20 (−17–41, 3.19) 2.8 (−6.5, 11.3) VCO2(L/min) −382.6 (−889, 82.4) −22.1 (−542, 436.0) −287.7 (−772, 223.8) −371.7 (−732.9, −10.2) −0.03 (−0.30, 0.24) EqO2(L/min) −1.03 (−4.97, 3.15) −4.36 (−8.41, 0.03) 0.51 (−3.84, 4.55) −3.51 (−8.07, 1.21) 1.3 (−3.2, 5.8) EqCO2(L/min) −0.96 (−3.57, 1.44) −2.50 (−4.97, 0.38) 0.65 (−1.87, 3.09) −1.61 (−4.87, 1.81) 1.6 (−1.8, 5.2) HR (beats/min) 2.80 (−6.91, 13.1) 1.46 (−8.96, 11.3) 7.78 (−2.58, 17.5) −1.08 (−5.47, 3.27) 5.0 (3.5, 9.6) VTin (mL) 320.7 (−177.0, 858.0) −21.3 (−530.0, 564.0) 4.1 (−536.0, 522.0) −371.0 (−1075.3, 335.0) −0.05 (−0.34, 0.24) Vtex (mL) 340.3 (−174.0, 880.0) −28.6 (−586.0, 509.0) −9.8 (−543.0, 518.0) −324.0 (−1002.6, 374.1) −0.07 (−0.41, 0.26) Tin (s) 0.03 (−0.06, 0.13) 0.10 (−0.00, −0.20) −0.01 (−0.11, 0.08) 0.06 (−0.04, 0.17) −0.05 (−0.15, 0.06) Tex (s) 0.01 (−0.04, 0.16) 0.19 (0.09, 0.30) 0.04 (−0.06, 0.14) 0.14 (0.01, 0.27) −0.02 (−0.14, 0.09) Titot (%) −0.79 (−2.85, 1.07) −3.19 (−5.25, 1.10) −2.12 (−4.07, 0.02) −2.49 (−4.10, −0.85) −0.1 (−0.5, 0.3) PETO2(mmHg) −0.17 (−0.58, 0.27) −0.65 (−1.08, 0.21) −0.06 (−0.46, 0.37) −0.51 (−0.99, −0.03) 0.0 (−0.2, 0.3) PETCO2(mmHg) 0.11 (−0.28, 0.50) 0.56 (0.15, 0.97) 0.06 (−0.36, 0.46) 0.48 (−0.02, 0.98) 0.00 (−0.28, 0.30) RER 0.01 (−0.07, 0.09) −0.05 (−0.14, 0.04) −0.00 (−0.09, 0.09) −0.06 (−0.12, 0.01) −0.02 (−0.09, 0.05) 95% HDIs that 0 is not inside are expressed in bold. Int. J. Environ. Res. Public Health 2021,18, 777 9 of 13 Within-group differences were found pre-test and pre-training vs. pre-test and posttraining in MIP for FB (30.5 cmH 2 O (18.1, 43.0)) and CG (15.4 cmH 2 O (2.6, 27.7) and in RPE post-training vs. pre-training for the control group (0.7 (0.1–1.4)) (Table 5). Table 5. Within-group preand post-test differences in MIP and RPE values. FB (n= 10) Variable Pre-Incremental Test Post-Incremental Test %Change ∆(95% HDI) Pre vs. Pre ∆POST vs. ∆PRE MIPPRE (cmH2O) 165.3 ±35.5 172.4 ±34.4 4.3 30.5 (18.1, 43.0) −7.5 (−24.7, 10.2) MIPPOST (cmH2O) 198.2 ±35.2 200.9 ±36.7 1.3 Value %Change Post vs. Pre RPEPRE 8.9 ±1.0 6.7 0.6 (−0.0 to 1.2) RPEPOST 9.5 ±0.5 CG (n= 8) Variable Pre-incremental test Postincremental test %Change ∆(95% HDI) Pre vs. Pre ∆POST vs. ∆PRE MIPPRE (cmH2O) 180.8 ±44.0 178.5 ±54.7 −1.3 15.4 (2.6, 27.7) 3.7 (−14.7, 21.9) MIPPOST (cmH2O) 195.6 ±37.1 191.6 ±33.0 −2.1 Value %Change Post vs. Pre RPEPRE 8.4 ±0.9 9.5 0.7 (0.1, 1.4) RPEPOST 9.2 ±0.7 95% HDIs that 0 is not inside are expressed in bold. MIP: maximal inspiratory pressure; RPE: rating of perceived exertion; PRE and POST subindex indicates preand post-training respectively; %Change, percentage of change; Pre vs. Pre, pre-test and pre-training MIP value vs. pre-test and post-training MIP value; ∆POST vs. ∆PRE , increase in MIP value during incremental test post-training vs. increase in MIP value during PE test pre-training; Post vs. Pre, post-training RPE value vs. pre-training RPE value. Finally, no significant between-group differences were found in the increments in MIP or RPE values (Table 6). Table 6. Between-group differences in the increments in MIP and RPE values. Variable ∆(95% HDI) Pre vs. Pre ∆POST vs. ∆PRE Post vs. Pre MIP (cmH2O) 17.0 (−1.6, 35.3) −4.5 (−22.3, 10.7) RPE −1.1 (−2.4, 0.2) Differences are expressed as FB vs. CG. MIP: maximal inspiratory pressure; RPE: rating of perceived exertion. Pre vs. Pre, pre-test and pre-training MIP value vs. pre-test and post-training MIP value; ∆POST vs. ∆PRE , increase in MIP value during incremental test post-training vs. increase in MIP value during PE test pre-training; Post vs. Pre, post-training RPE value vs. pre-training RPE value. 5. Discussion The main finding of the present study was that the ventilatory efficiency and the breathing pattern were improved after the exercise training program in the FB group at the maximum intensity reached in the Pre-test (Post PRE ) but not in the control group. FB showed improvements in the time trial and hence in the maximum peak of power developed in the maximum test but without changes in the VO 2 max compared to pretraining values, while the Control group remained unchanged. This could be explained in part by the higher VO 2 max and VT 1 in the FB compared to the Control group after the training program at maximum values (Post FINAL ). Moreover, VT 2 showed similar values between conditions after intervention despite the Control group beginning with higher values at Pre. Therefore, only the combination of cyclist training with RMT and FB optimized the breathing pattern such that it could improve performance. To our knowledge, this is the first study which has analyzed the benefits on ventilatory efficiency