Browsing by Author "Arce-Alvarez, Alexis"

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    Cardiorespiratory optimal point as a submaximal evaluation tool in endurance athletes: An exploratory study
    (2023) Oyarzo-Aravena, Alexis; Arce-Alvarez, Alexis; Salazar-Ardiles, Camila; Ramirez-Campillo, Rodrigo; Alvarez, Cristian; Toledo, Camilo; Izquierdo, Mikel; Andrade, David C.
    Introduction: The cardiorespiratory optimal point (COP) represents the lowest minute ventilation to oxygen consumption ratio (VE/VO2) and can be estimated during a CPET at submaximal intensity when an exercise test until volitional fatigue is not always advisable (i.e., a conflict zone where you cannot be confident of the security because near-competition, off-season, among other). COP's physiological components have not been wholly described yet. Therefore, this study seeks to identify the determinants of COP in highly trained athletes and its influence on maximum and sub-maximum variables during CPET through principal c omponent analysis (PCA) (explains the dataset's variance).Methods: Female (n = 9; age, 17.4 +/- 3.1 y; maximal VO2 [VO2max]), 46.2 +/- 5.9 mL/kg/min) and male (n = 24; age, 19.7 +/- 4.0 y; VO2max, 56.1 +/- 7.6 mL/kg/min) athletes performed a CPET to determine the COP, ventilatory threshold 1 (VT1) and 2 (VT2), and VO2max. The PCA was used to determine the relationship between variables and COP, explaining their variance.Results: Our data revealed that females and males displayed different COP values. Indeed, males showed a significant diminished COP compared to the female group (22.6 +/- 2.9 vs. 27.2 +/- 3.4 VE/VO2, respectively); nevertheless, COP was allocated before VT1 in both groups.Discussion: PC analysis revealed that the COP variance was mainly explained (75.6%) by PC1 (expired CO2 at VO2max) and PC2 (VE at VT2), possibly influencing cardiorespiratory efficiency at VO2max and VT2. Our data suggest that COP could be used as a submaximal index to monitor and assess cardiorespiratory system efficiency in endurance athletes. The COP could be particularly useful during the offseason and competitive periods and the return to the sports continuum.
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    Effect of chronic exogenous oxytocin administration on exercise performance and cardiovagal control in hypobaric hypoxia in rats
    (2024) Salazar-Ardiles, Camila; Cornejo, Carlos; Paz, Cristobal; Vasquez-Muñoz, Manuel; Arce-Alvarez, Alexis; Rodríguez Fernández, María; Millet, Gregoire P.; Izquierdo Redín, Mikel; Andrade, David C.
    Background Outstanding exercise performance has been associated with an exacerbated vagal outflow. Nevertheless, during high-altitude hypobaric-hypoxia (HH), there is a baroreflex-dependent parasympathetic withdrawal and exercise performance deterioration. Notably, vagal control is pivotal in exercise performance, and exogenous oxytocin (OXY) administration has been shown to enhance parasympathetic drive; however, no evidence shows their role in exercise performance during HH. Then, this study aimed to examine the effect of prolonged exogenous oxytocin (OXY) administration on exercise performance during hypobaric hypoxia (HH) in rats. Results A vehicle group (n = 6) and an OXY group (n = 6) performed incremental exercise and baroreflex tests during both normobaric normoxia (NN) and HH (PO2: 100 mmHg, simulated 3,500 m) prior (pre-) and after (post-) 14 days of administration. The results showed that at pre-, there were no significant differences in exercise performance between the two groups, while at post-, the OXY group exhibited similar performance between NN and HH, while the Vehicle group maintained a significant decline in performance at HH compared to NN. At post-, the Vehicle group also demonstrated a reset in the baroreflex and a worse bradycardic response in HH, which was reversed in the OXY group, while the hypoxic ventilatory response was similar in both groups. Conclusion The findings suggest prolonged OXY administration prevents impaired exercise performance and vagal control during short-term HH.
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    Hypoxic Respiratory Chemoreflex Control in Young Trained Swimmers
    (2021) Arce-Alvarez, Alexis; Veliz, Carlos; Vazquez-Munoz, Manuel; von Igel, Magdalena; Alvares, Cristian; Ramirez-Campillo, Rodrigo; Izquierdo, Mikel; Millet, Gregoire P.; Del Rio, Rodrigo; Andrade, David C.
    During an apnea, changes in PaO2 activate peripheral chemoreceptors to increase respiratory drive. Athletes with continuous apnea, such as breath-hold divers, have shown a decrease in hypoxic ventilatory response (HVR), which could explain the long apnea times; however, this has not been studied in swimmers. We hypothesize that the long periods of voluntary apnea in swimmers is related to a decreased HVR. Therefore, we sought to determine the HVR and cardiovascular adjustments during a maximum voluntary apnea in young-trained swimmers. In fifteen trained swimmers and twenty-seven controls we studied minute ventilation (V-E), arterial saturation (SpO(2)), heart rate (HR), and autonomic response [through heart rate variability (HRV) analysis], during acute chemoreflex activation (five inhalations of pure N-2) and maximum voluntary apnea test. In apnea tests, the maximum voluntary apnea time and the end-apnea HR were higher in swimmers than in controls (p < 0.05), as well as a higher low frequency component of HRV (p < 0.05), than controls. Swimmers showed lower HVR than controls (p < 0.01) without differences in cardiac hypoxic response (CHR). We conclude that swimmers had a reduced HVR response and greater maximal voluntary apnea duration, probably due to decreased HVR.
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    Oscillatory pattern of glycemic control in patients with diabetes mellitus
    (2021) Vasquez-Munoz, Manuel; Arce-Alvarez, Alexis; von Igel, Magdalena; Veliz, Carlos; Ruiz-Esquide, Gonzalo; Ramirez-Campillo, Rodrigo; Alvarez, Cristian; Ramirez-Velez, Robinson; Crespo, Fernando A.; Izquierdo, Mikel; Del Rio, Rodrigo; Andrade, David C.
    Daily glucose variability is higher in diabetic mellitus (DM) patients which has been related to the severity of the disease. However, it is unclear whether glycemic variability displays a specific pattern oscillation or if it is completely random. Thus, to determine glycemic variability pattern, we measured and analyzed continuous glucose monitoring (CGM) data, in control subjects and patients with DM type-1 (T1D). CGM data was assessed for 6 days (day: 08:00-20:00-h; and night: 20:00-08:00-h). Participants (n =172; age =18-80 years) were assigned to T1D (n =144, females = 65) and Control (i.e., healthy; n = 28, females = 22) groups. Anthropometry, pharmacologic treatments, glycosylated hemoglobin (HbA1c) and years of evolution were determined. T1D females displayed a higher glycemia at 10:00-14:00-h vs. T1D males and Control females. DM patients displays mainly stationary oscillations (deterministic), with circadian rhythm characteristics. The glycemia oscillated between 2 and 6 days. The predictive model of glycemia showed that it is possible to predict hyper and hypoglycemia (R-2 =0.94 and 0.98, respectively) in DM patients independent of their etiology. Our data showed that glycemic variability had a specific oscillation pattern with circadian characteristics, with episodes of hypoglycemia and hyperglycemia at day phases, which could help therapeutic action for this population.
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    Topical Application of Connexin43 Hemichannel Blocker Reduces Carotid Body-Mediated Chemoreflex Drive in Rats
    (2018) Andrade Andrade, David Cristóbal; Iturriaga Agüera, Rodrigo; Toledo, Camilo; Lucero, Claudia M.; Diaz, Hugo S.; Arce-Alvarez, Alexis; Retamal, Mauricio A.; Marcus, Noah J.; Alcayaga Urbina, Julio Andrés; Del Rio, Rodrigo