ECSS Paris 2023: OP-PN25
INTRODUCTION: Differences in cardiopulmonary hemodynamics of high-altitude and acclimatized sea-level natives might augment exercise performance at altitude and decrease pulmonary artery systolic pressure (PASP) by increased blood flow through intrapulmonary arteriovenous anastomoses (Q̇IPAVA) (1). Although one study reported lower PASP in Tibetans in hypoxia at rest and during exercise (2), most studies have found no differences between populations at rest (3,4), and limited data exist during exercise. We hypothesized that Tibetans would have better exercise capacity at sea level (SL) and 5000 m altitude (ALT) and more favorable cardiopulmonary physiology, such as normal right and left heart function, lower PASP at rest, and greater Q̇IPAVA during exercise. METHODS: 10 Tibetans and 10 Han Chinese without intracardiac shunts (PFO-negative) cycled stationary from 70 W with stepwise increases of 30 W every 3 min to exhaustion (Wpeak), in a hypo/hyperbaric chamber at SL and ALT. At the end of each step, respiratory variables were averaged over 30 s, and stroke volume (SV) and PASP were determined by ultrasound. Transthoracic saline contrast echocardiography (TTSCE) was used to determine Q̇IPAVA using a bubble scoring system (5). Cardiac output (Q̇T) was calculated as HR x SV and total pulmonary resistance (TPR) as TPR = PASP/Q̇T. Unpaired t-tests compared cardiorespiratory measures at peak workload. Mann-Whitney test compared bubble scores. Significance was set to p < 0.05 a priori, and effect sizes are presented as r2, with r2 > 0.1 indicating small, > 0.25 medium, and > 0.37 large effects. RESULTS: Resting cardiac structure and function was not different between groups. Tibetans achieved a higher WPEAK at SL (p = 0.026, r2 = 0.243) and at ALT (p = 0.024, r2 = 0.280), and higher V̇O2PEAK at ALT (p = 0.042, r2 = 0.2340), but not at SL (p = 0.207, r2 = 0.087). No differences were observed in HR, SV, or Q̇T. Q̇IPAVA was only lower in Tibetans during 100 W exercise at ALT (p = 0.039), while the increases in PASP and TPR at ALT were similar between the groups. CONCLUSION: Lower Q̇IPAVA in Tibetans during exercise at ALT might support higher WPEAK and V̇O2PEAK. However, no differences were observed in PASP and TPR. Our data suggest that the Tibetans superior aerobic exercise capacity over Han Chinese may be independent of cardiopulmonary features and possibly linked to differences in local muscular oxygen extraction, as previously hypothesized in Sherpas (7). 1 Stickland et al. (2004). DOI: 10.1113/jphysiol.2004.069302 2 Groves et al. (1993). DOI: 10.1152/jappl.1993.74.1.312 3 Foster et al. (2014). DOI: 10.1113/jphysiol.2013.266593 4 Faoro et al. (2014). DOI: 10.1152/japplphysiol.00236.2013 5 Elliot et al. (2011). DOI: 10.1152/japplphysiol.00145.2010 6 Kayser et al. (1991). DOI: 10.1152/jappl.1991.70.5.1938
Read CV Fabian MöllerECSS Paris 2023: OP-PN25
INTRODUCTION: Running sports often lead to lower limb mechanical injuries. Unloaded training, such as indoor cycling (IC), are often advised during recovery, to limit cardio-pulmonary capacity deconditioning with limited mechanical stress(1). Deep water running (DWR) is an alternative training method to reduce low-limb overload, improve muscle strength(2) and balance(3), with greater muscular forces than in air(4). While validated DWR training protocols still need to be established, we compared the cardio-pulmonary response during exercise sessions of DWR vs IC. It also remains unclear if sessions need to be calibrated on heart rate (HR) or oxygen consumption (VO2). METHODS: 15 healthy active subjects were enrolled in the study; 22±3 yo, 53% women, 43±7 ml/min/kg maximal VO2 measured during cyclo-ergometric cardio-pulmonary exercise test (CPET) which also allowed determination of HR and VO2 at the first ventilatory threshold (VT1). All subjects performed randomly one IC and DWR continuous exercise session calibrated on HR at VT1 (respectively IC(HR) and DWR(HR)) consisting of: 5-minutes warm-up at 80% of heart rate (HR) at the first ventilatory threshold (VT1), followed by 2 sets of 10 minutes at 100% HR@VT1 separated by 2 minutes rest. A subgroup of 7 subjects performed an additional DWR session calibrated by VO2 at VT1 (DWR(VO2)). HR, ventilation (VE) and gas exchange were measured continuously during CPET and DWR/IC sessions, with blood lactate levels measured 30s after exercise. When comparing DWR(HR) with DWR(VO2) values are given as med [Q1; Q3]. RESULTS: At identical exercise HR, VO2 was higher during DWR(HR) (38±9 ml/min/kg; 88% of VO2max) as compared to IC(HR) training (31±6 ml/min/kg; 72% of VO2max, p<0.0001) as well as VE (DWR(HR) : 74±2 L/min, 60% of VEmax vs IC(HR) : 54±6 L/min, 36% of VEmax, p<0.0001) with no difference in lactate concentrations (DWR(HR) : 3.9±1.7 mmol/L, vs IC(HR) : 3.6±2 mmol/L). Higher VE (p=0,047) (DWRHR : 80 [57; 84] L/min, DWR(VO2): 50 [44; 55] L/min) and higher HR (p=0,047) (DWRHR : 143 [138; 157] bpm, DWR(VO2) : 113 [99; 158] bpm) were observed during DWR(HR) compared to DWR(VO2), with a greater respiratory exchange ratio (RER) for DWR(HR) (p=0,03) (0.92 [0.86; 0.96] vs. 0.81 [0.75; 0.88]) but with no difference in lactate concentrations (DWR(VO2) : 2.7 [1.1; 2.9] mmol/L). CONCLUSION: DWR(HR) reaches higher exercise intensity, as measures by VO2 and VE levels, compared to IC(HR), but with identical lactate production. This is likely attributed to the chronotropic response of hydrostatic pressure inherent in DWR, which enhances venous return and stroke volume. The validation of this hypothesis through DWR(VO2) underscores the necessity of acquiring detailed knowledge regarding the physiological effects of each exercise modality. It seems therefore important to consider accurately adapting DWR training programs to meet specific performance objectives and optimize training/rehabilitation outcomes. 1 Glass, 2 Foley, 3 Simmons, 4 Miyoshu
Read CV Marine CarpentierECSS Paris 2023: OP-PN25
INTRODUCTION: Previous studies have reported an elevation in carotid-femoral pulse wave velocity (cfPWV), considered an index of arterial stiffness, during upright posture compared to the supine position. This suggests that the upright position acutely induces arterial stiffening. However, evidence supporting this assertion has not been presented. This study aims to investigate aortic impedance, a more rigorous index of arterial stiffness evaluated from the dynamic blood flow-pressure relationship, to determine whether cfPWV accurately reflects arterial stiffness in the seated position. METHODS: Twenty young, healthy subjects (14 males and 6 females) underwent arterial stiffness measurements in both supine and seated positions to validate the credibility of alterations in cfPWV specifically. Arterial stiffness in both positions was evaluated using aortic impedance measured with applanation tonometry and ultrasonography, as well as cfPWV using applanation tonometry. RESULTS: Similar to a previous study, cfPWV values significantly increased in the seated position compared to the supine position (supine vs seated; 5.41±0.62 vs 6.19±0.77 cm/s, P < 0.001). However, there were no significant differences in aortic impedance between the two positions (333±94 vs. 363±134 dyne-s/cm3, P = 0.259). CONCLUSION: The findings of the present study suggest that changes in body position may not lead to immediate changes in arterial stiffness. This implies that measuring cfPWV during the supine position is crucial for accurately identifying arterial stiffness.
Read CV Shigehiko OgohECSS Paris 2023: OP-PN25