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Evaluating the ventilatory effect of transnasal humidified rapid insufflation ventilatory exchange in apnoeic small children with two different oxygen flow rates: a randomised controlled trial.
Riva, T, Préel, N, Theiler, L, Greif, R, Bütikofer, L, Ulmer, F, Seiler, S, Nabecker, S
Anaesthesia. 2021;(7):924-932
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Abstract
Transnasal humidified rapid insufflation ventilatory exchange prolongs safe apnoeic oxygenation time in children. In adults, transnasal humidified rapid insufflation ventilatory exchange is reported to have a ventilatory effect with PaCO2 levels increasing less rapidly than without it. This ventilatory effect has yet to be reproduced in children. In this non-inferiority study, we tested the hypothesis that children weighing 10-15 kg exhibit no difference in carbon dioxide clearance when comparing two different high-flow nasal therapy flow rates during a 10-min apnoea period. Following standardised induction of anaesthesia including neuromuscular blockade, patients were randomly allocated to high-flow nasal therapy of 100% oxygen at 2 or 4 l.kg-1 .min-1 . Airway patency was ensured by continuous jaw thrust. The study intervention was terminated for safety reasons when SpO2 values dropped < 95%, or transcutaneous carbon dioxide levels rose > 9.3 kPa, or near-infrared spectroscopy values dropped > 20% from their baseline values, or after an apnoeic period of 10 min. Fifteen patients were included in each group. In the 2 l.kg-1 .min-1 group, mean (SD) transcutaneous carbon dioxide increase was 0.46 (0.11) kPa.min-1 , while in the 4 l.kg-1 .min-1 group it was 0.46 (0.12) kPa.min-1 . The upper limit of a one-sided 95%CI for the difference between groups was 0.07 kPa.min-1 , lower than the predefined non-inferiority margin of 0.147 kPa.min-1 (p = 0.001). The lower flow rate of 2 l.kg-1 .min-1 was non-inferior to 4 l.kg-1 .min-1 relative to the transcutaneous carbon dioxide increase. In conclusion, an additional ventilatory effect of either 2 or 4 l.kg-1 .min-1 high-flow nasal therapy in apnoeic children weighing 10-15 kg appears to be absent.
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Caffeine Increases Exercise Performance, Maximal Oxygen Uptake, and Oxygen Deficit in Elite Male Endurance Athletes.
Stadheim, HK, Stensrud, T, Brage, S, Jensen, J
Medicine and science in sports and exercise. 2021;(11):2264-2273
Abstract
PURPOSE The aims of the present study were to test the hypothesis that caffeine increases maximal oxygen uptake (V˙O2max) and to characterize the physiological mechanisms underpinning improved high-intensity endurance capacity. METHODS Twenty-three elite endurance-trained male athletes were tested twice with and twice without caffeine (four tests) in a randomized, double-blinded, and placebo-controlled study with crossover design. Caffeine (4.5 mg·kg-1) or placebo was consumed 45 min before standardized warm-up. Time to exhaustion during an incremental test (running 10.5° incline, start speed 10.0 km·h-1, and 0.5 km·h-1 increase in speed every 30 s) determined performance. Oxygen uptake was measured continuously to determine V˙O2max and O2 deficit was calculated. RESULTS Caffeine increased time to exhaustion from 355 ± 41 to 375 ± 41 s (Δ19.4 ± 16.5 s; P < 0.001). Importantly, caffeine increased V˙O2max from 75.8 ± 5.6 to 76.7 ± 6.0 mL·kg-1·min-1 (Δ 0.9 ± 1.7 mL·kg-1·min-1; P < 0.003). Caffeine increased maximal heart rate (HRpeak) and ventilation (VEpeak). Caffeine increased O2 deficit from 63.1 ± 18.2 to 69.5 ± 17.5 mL·kg-1 (P < 0.02) and blood lactate compared with placebo. The increase in time to exhaustion after caffeine ingestion was reduced to 11.7 s after adjustment for the increase in V˙O2max. Caffeine did not significantly increase V˙O2max after adjustment for VEpeak and HRpeak. Adjustment for O2 deficit and lactate explained 6.2 s of the caffeine-induced increase in time to exhaustion. The increase in V˙O2max, VE, HR, O2 deficit, and lactate explained 63% of the increased performance after caffeine intake. CONCLUSION Caffeine increased V˙O2max in elite athletes, which contributed to improvement in high-intensity endurance performance. Increases in O2 deficit and lactate also contributed to the caffeine-induced improvement in endurance performance.
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"Train-High Sleep-Low" Dietary Periodization Does Not Alter Ventilatory Strategies During Cycling Exercise.
Paris, HL, Fulton, TJ, Wilhite, DP, Baranauskas, MN, Chapman, RF, Mickleborough, TD
Journal of the American College of Nutrition. 2020;(4):325-332
Abstract
Objective: The purpose of this study was to investigate the effects of "train-high sleep-low" (THSL) dietary periodization on ventilatory strategies during cycling exercise at submaximal and maximal intensities.Method: In a randomized crossover design, 8 trained men [age (mean ± SEM) = 28 ± 1 y; peak oxygen uptake = 56.8 ± 2.4 mL kg-1 min-1] completed two glycogen-depleting protocols on a cycle ergometer on separate days, with the cycling followed by a low carbohydrate (CHO) meal and beverages containing either no additional CHO (THSL) or beverages containing 1.2 g kg-1 CHO [traditional CHO replacement (TRAD)]. The following morning, participants completed 4 minutes of cycling below (Stage 1), at (Stage 2), and above (Stage 3) gas exchange threshold, followed by a 5-km time trial.Results: Timetrial performance was significantly faster in TRAD compared to THSL (8.7 ± 0.3 minutes and 9.0 ± 0.3 minutes, respectively; p = 0.02). No differences in ventilation, tidal volume, or carbon dioxide production occurred between conditions at any exercise intensity (p > 0.05). During Stage 1, oxygen uptake was 37.9 ± 1.5 mL kg-1 min-1 in the TRAD condition and 39.6 ± 1.8 mL kg-1 min-1 in THSL (p = 0.05). During Stage 2, VO2 was 44.6 ± 1.7 mL kg-1 min-1 in the TRAD condition and 47.0 ± 1.9 mL kg-1 min-1 in THSL (p = 0.07). No change in operating lung volume was detected between dietary conditions (p > 0.05).Conclusions: THSL impairs performance following the dietary intervention, but this occurs with no alteration of ventilatory measures.
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Effect of Creatine Supplementation on the Airways of Youth Elite Soccer Players.
Simpson, AJ, Horne, S, Sharp, P, Sharps, R, Kippelen, P
Medicine and science in sports and exercise. 2019;(8):1582-1590
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Abstract
INTRODUCTION Owing to its well-established ergogenic potential, creatine is a highly popular food supplement in sports. As an oral supplement, creatine is considered safe and ethical. However, no data exist on the safety of creatine on lung function in athletes. The aim of this project was to evaluate the effects of a standard course of creatine on the airways of youth elite athletes. METHODS Nineteen elite soccer players, 16-21 yr old, completed a stratified, randomized, double-blind, placebo-controlled, parallel-group trial. The creatine group (n = 9) ingested 0.3 g·kg⋅d of creatine monohydrate (CM) for 1 wk (loading phase) and 5 g·d for 7 wk (maintenance phase), and the placebo group (n = 10) received the same dosages of maltodextrin. Airway inflammation (assessed by exhaled nitric oxide, FENO) and airway responsiveness (to dry air hyperpnoea) were measured pre- and postsupplementation. RESULTS Mild, unfavorable changes in FENO were noticed by trend over the supplementation period in the CM group only (P = 0.056 for interaction, η = 0.199), with a mean group change of 9 ± 13 ppb in the CM group versus -5 ± 16 ppb in the placebo group (P = 0.056, d = 0.695). Further, the maximum fall in forced expiratory volume in 1 s after dry air hyperpnoea was larger by trend postsupplementation in the CM group compared with the placebo group: 9.7% ± 7.5% vs 4.4% ± 1.4%, respectively (P = 0.070, d = 0.975). These adverse effects were more pronounced when atopic players only (n = 15) were considered. CONCLUSION On the basis of the observed trends and medium to large effect sizes, we cannot exclude that creatine supplementation has an adverse effect on the airways of elite athletes, particularly in those with allergic sensitization. Further safety profiling of the ergogenic food supplement is warranted.
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The effect of chronic progressive-dose sodium bicarbonate ingestion on CrossFit-like performance: A double-blind, randomized cross-over trial.
Durkalec-Michalski, K, Zawieja, EE, Podgórski, T, Łoniewski, I, Zawieja, BE, Warzybok, M, Jeszka, J
PloS one. 2018;(5):e0197480
Abstract
BACKGROUND Sodium bicarbonate (SB) has been proposed as an ergogenic aid, as it improves high-intensity and resistance exercise performance. However, no studies have yet investigated SB application in CrossFit. This study examined the effects of chronic, progressive-dose SB ingestion on CrossFit-like performance and aerobic capacity. METHODS In a randomized, double-blind, cross-over trial, 21 CrossFit-trained participants were randomly allocated to 2 groups and underwent 2 trials separated by a 14-day washout period. Participants ingested either up to 150 mg∙kg-1 of SB in a progressive-dose regimen or placebo for 10 days. Before and after each trial, Fight Gone Bad (FGB) and incremental cycling (ICT) tests were performed. In order to examine biochemical responses, blood samples were obtained prior to and 3 min after completing each exercise test. RESULTS No gastrointestinal (GI) side effects were reported during the entire protocol. The overall FGB performance improved under SB by ~6.1% (p<0.001) and it was ~3.1% higher compared to post placebo (PLApost) (p = 0.040). The number of repetitions completed in each round also improved under SB (mean from baseline: +5.8% to +6.4%). Moreover, in ICT, the time to ventilatory threshold (VT) (~8:25 min SBpost vs. ~8:00 min PLApost, p = 0.020), workload at VT (~218 W SBpost vs. ~208 W PLApost, p = 0.037) and heart rate at VT (~165 bpm SBpost vs. ~161 bpm PLApost, p = 0.030) showed higher SBpost than PLApost. Furthermore, the maximum carbon dioxide production increased under SB by ~4.8% (from ~3604 mL∙min-1 to ~3776 mL∙min-1, p = 0.049). Pyruvate concentration and creatine kinase activity before ICT showed higher SBpost than PLApost (~0.32 mmol∙L-1 vs. ~0.26 mmol∙L-1, p = 0.001; ~275 U∙L-1 vs. ~250 U∙L-1, p = 0.010, respectively). However, the small sample size limits the wide-application of our results. CONCLUSIONS Progressive-dose SB ingestion regimen eliminated GI side effects and improved CrossFit-like performance, as well as delayed ventilatory threshold occurrence.
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Cardiorespiratory responses to the 30-15 intermittent ice test.
Besson, C, Buchheit, M, Praz, M, Dériaz, O, Millet, GP
International journal of sports physiology and performance. 2013;(2):173-80
Abstract
PURPOSE In this study, the authors compared the cardiorespiratory responses between the 30-15 Intermittent Ice Test (30-15(IIT)) and the 30-15 Intermittent Fitness Test (30-15(IFT)) in semiprofessional hockey players. METHODS Ten players (age 24 ± 6 y) from a Swiss League B team performed the 30-15(IIT) and 30-15(IFT) in random order (13 ± 4 d between trials). Cardiorespiratory variables were measured with a portable gas analyzer. Ventilatory threshold (VT), respiratory-compensation point (RCP), and maximal speeds were measured for both tests. Peak blood lactate ([La(peak)]) was measured at 1 min postexercise. RESULTS Compared with 30-15(IFT), 30-15(IIT) peak heart rate (HR(peak); mean ± SD 185 ± 7 vs 189 ± 10 beats/min, P = .02) and peak oxygen consumption (VO(2peak)); 60 ± 7 vs 62.7 ± 4 mL/min/kg, P = .02) were lower, whereas [La(peak)] was higher (10.9 ± 1 vs 8.6 ± 2 mmol/L, P < .01) for the 30-15(IIT). VT and RCP values during the 30-15(IIT) and 30-15(IFT) were similar for %HR(peak) (76.3% ± 5% vs 75.5% ± 3%, P = .53, and 90.6% ± 3% vs. 89.8% ± 3%, P = .45) and % VO(2peak) (62.3% ± 5% vs 64.2% ± 6%, P = .46, and 85.9% ± 5% vs 84.0% ± 7%, P = .33). VO(2peak ))(r = .93, P < .001), HR(peak) (r = .86, P = .001), and final velocities (r = .69, P = .029) were all largely to almost perfectly correlated. CONCLUSIONS Despite slightly lower maximal cardiorespiratory responses than in the field-running version of the test, the on-ice 30-15(IIT) is of practical interest since it is a specific maximal test with a higher anaerobic component.
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VO2max and ventilatory threshold of trained cyclists are not affected by 28-day L-arginine supplementation.
Sunderland, KL, Greer, F, Morales, J
Journal of strength and conditioning research. 2011;(3):833-7
Abstract
The ergogenic effect of L-arginine on an endurance-trained population is not well studied. The few studies that have investigated L-arginine on this population have not been conducted in a laboratory setting or measured aerobic variables. The purpose of the current study is to determine if 28 days of L-arginine supplementation in trained male cyclists affects VO2max and ventilatory threshold (VT). Eighteen (18) endurance-trained male cyclists (mean ± SD, age: 36.3 ± 7.9 years; height: 182.4 ± 4.6 cm; and body mass: 79.5 ± 4.7 kg) performed a graded exercise test (GXT; 50 W + 25 W·min) before and after 28 days of supplementation with L-arginine (ARG; 2 × 6 g·d) or placebo (PLA; cornstarch). The GXT was conducted on the subject's own bicycle using the RacerMate CompuTrainer (Seattle, WA, USA). VO2 was continuously recorded using the ParvoMedics TrueOne 2400 metabolic cart (Salt Lake City, UT, USA) and VT was established by plotting the ventilatory equivalent for O2 (VE/VO2) and the ventilatory equivalent for CO2 (VE/VCO2) and identifying the point at which VE/VO2 increases with no substantial changes in VE/VCO2. L-arginine supplementation had no effect from initial VO2max (PL, 58.7 ± 7.1 ml·kg·min; ARG, 63.5 ± 7.3 ml·kg·min) to postsupplement VO2max (PL, 58.9 ± 6.0 ml·kg·min; ARG, 63.2 ± 7.2 ml·kg·min). Also, no effect was seen from initial VT (PL, 75.7 ± 4.6% VO2max; ARG, 76.0 ± 5.3% VO2max) to postsupplement VT (PL, 74.3 ± 8.1% VO2max; ARG, 74.2 ± 6.4% VO2max). These results indicate that L-arginine does not impact VO2max or VT in trained male cyclists.
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Translation of submaximal exercise test responses to exercise prescription using the Talk Test.
Foster, C, Porcari, JP, Gibson, M, Wright, G, Greany, J, Talati, N, Recalde, P
Journal of strength and conditioning research. 2009;(9):2425-9
Abstract
The exercise intensity at the Talk Test (TT) has been shown to be highly correlated with objective physiological markers, a useful outcome marker in patients with heart disease, a useful tool for avoiding exertional ischemia, and responsive to both positive and negative changes in exercise capacity. This randomized observational study evaluated the ability of the intensity at the TT during exercise testing to define absolute training workloads. Sedentary adults (n = 14) performed an incremental Balke type exercise test (3.0-3.5 mph at 0% grade, +2% grade every 2 minutes). Heart rate (HR), rating of perceived exertion (RPE), and TT were evaluated at each stage. Subsequently, the subjects performed 3 x 20-minute exercise bouts with the workload over the last 10 minutes of each bout equal to the absolute intensity at the stage preceding the LP (LP-1), at the last positive stage of the TT (LP), and at the first equivocal stage of the TT (EQ). During LP-1, LP, and EQ, HR was 140 +/- 23, 151 +/- 20, and 160 +/- 21 bpm, or 73 +/- 11, 79 +/- 9, and 82 +/- 9 % HRmax; RPE (CR scale) was 3.6 +/- 1.5, 4.4 +/- 1.8, and 6.3 +/- 2.2. The TT Score-ranked as 1 = comfortable speech, 2 = slightly uncomfortable speech, and 3 = speech not comfortable-was 1.4 +/- 0.5, 1.8 +/- 0.4, and 2.6 +/- 0.5 LP-1, LP, and at EQ, LP, respectively. The results suggest that to prescribe absolute training intensity from the TT and to get appropriate HR, RPE, and TT responses in sedentary individuals during training, the workload needs to be based on the intensity approximately 1 stage (approximately 1.0-1.2 metabolic equivalents) below the LP stage observed during an incremental test.
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Estimated times to exhaustion at the PWC V O2, PWC HRT, and VT.
Mielke, M, Housh, TJ, Malek, MH, Beck, TW, Hendrix, CR, Schmidt, RJ, Johnson, GO
Journal of strength and conditioning research. 2008;(6):2003-10
Abstract
The purpose of this study was to validate the Physical Working Capacity at the Heart Rate Threshold (PWC HRT) and Physical Working Capacity at the Oxygen Consumption Threshold (PWC V O2) tests by 1) using individual power vs. duration relationships to estimate the times to exhaustion (ETTE) at the PWC HRT and PWC V O2, and 2) comparing the power outputs and ETTE values of the PWC HRT and PWC V O2 with those of the ventilatory threshold (VT). Ten adults (mean age +/- SD = 23 +/- 1 years) performed an incremental test to exhaustion on a cycle ergometer for the determination of V O2 peak and VT. The subjects also performed four randomly ordered workbouts to exhaustion at different power outputs (ranging from 98 to 246 W) to determine the PWC V O2, PWC HRT, and power vs. duration relationship. Power curve analyses (y = ax b) were used to define the hyperbolic power vs. duration relationship for each subject and to determine the ETTE at the PWC V O2, PWC HRT, and VT. Two separate one-way repeated-measures analyses of variance indicated that there were significant differences among the fatigue thresholds (PWC V O2 > PWC HRT) and ETTE values (PWC HRT > PWC V O2): PWC V O2 (mean +/- SD = 147 +/- 43 W; ETTE = 21 +/- 3 minutes), PWCHRT (136 +/- 37 W; ETTE = 29 +/- 6 minutes), and VT (143 +/- 44 W; ETTE = 27 +/- 11 minutes). These findings were consistent with previous studies that indicated that the PWC HRT occurred at a lower power output than the PWC V O2. Furthermore, the PWC HRT was maintained for a mean of 29 minutes, whereas the PWC V O2 and VT were maintained for 21 and 27 minutes, respectively. These findings indicate that the ETTE values for the PWC V O2 and PWC HRT were substantially less than those suggested in previous studies.
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Caffeine stimulates ventilation in athletes with exercise-induced hypoxemia.
Chapman, RF, Stager, JM
Medicine and science in sports and exercise. 2008;(6):1080-6
Abstract
INTRODUCTION/PURPOSE Many athletes with exercise-induced hypoxemia (EIH) show an insufficient ventilatory response to exercise and low resting ventilatory responsiveness. The purpose of this project was to determine whether a moderate dosage of caffeine, a common ventilatory stimulant, could augment resting ventilatory responsiveness, exercise ventilation (V E), end-tidal O2 partial pressure (PetO2), and arterial oxyhemoglobin saturation (HbSaO2) in athletes with EIH. METHODS Eight highly trained males (V[spacing dot above]O2max, 69.2 +/- 4.0 mL.[kg.min]) who demonstrated EIH at V[spacing dot above]O2max (HbSaO2, 88.0 +/- 1.7%), ingested in a randomized design a placebo or caffeine (CAF, 8 mg.kg body wt) 1 h before testing. Ventilatory responsiveness at rest was assessed via the isocapnic hypoxic and hyperoxic hypercapnic ventilatory responses (HVR and HCVR, respectively). Dependent measures of metabolic variables, ventilation, and saturation were determined during progressive treadmill exercise to exhaustion. RESULTS V E was higher at 75%, 80%, and 100% of V[spacing dot above]O2max with CAF (P < 0.05). V E/V O2, PetO2, and HbSaO2 were increased at 75%, 80%, and 90% of [formula: see text] with CAF but were not different at V[spacing dot above]O2max despite an increase in V e. No change in V[spacing dot above]O2max was observed between treatments. HVR and HCVR were not different between the two conditions, indicating that the increased V E likely came from central stimulation or secondary effects of CAF. CONCLUSION The failure of HbSaO2 to increase at [formula: see text] despite an increase in V E suggests that mechanisms influencing HbSaO2 other than an inadequate hyperventilatory response may operate to different degrees across individuals as V[spacing dot above]O2max is approached.