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Costalat G, Lemaitre F, Ramos S, Renshaw GMC. Intermittent normobaric hypoxia alters substrate partitioning and muscle oxygenation in individuals with obesity: implications for fat burning. Am J Physiol Regul Integr Comp Physiol 2024; 326:R147-R159. [PMID: 38047315 DOI: 10.1152/ajpregu.00153.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 11/28/2023] [Accepted: 11/29/2023] [Indexed: 12/05/2023]
Abstract
This single-blind, crossover study aimed to measure and evaluate the short-term metabolic responses to continuous and intermittent hypoxic patterns in individuals with obesity. Indirect calorimetry was used to quantify changes in resting metabolic rate (RMR), carbohydrate (CHOox, %CHO), and fat oxidation (FATox, %FAT) in nine individuals with obesity pre and post: 1) breathing normoxic air [normoxic sham control (NS-control)], 2) breathing continuous hypoxia (CH), or 3) breathing intermittent hypoxia (IH). A mean peripheral oxygen saturation ([Formula: see text]) of 80-85% was achieved over a total of 45 min of hypoxia. Throughout each intervention, pulmonary gas exchanges, oxygen consumption (V̇o2) carbon dioxide production (V̇co2), and deoxyhemoglobin concentration (Δ[HHb]) in the vastus lateralis were measured. Both RMR and CHOox measured pre- and postinterventions were unchanged following each treatment: NS-control, CH, or IH (all P > 0.05). Conversely, a significant increase in FATox was evident between pre- and post-IH (+44%, P = 0.048). Although the mean Δ[HHb] values significantly increased during both IH and CH (P < 0.05), the greatest zenith of Δ[HHb] was achieved in IH compared with CH (P = 0.002). Furthermore, there was a positive correlation between Δ[HHb] and the shift in FATox measured pre- and postintervention. It is suggested that during IH, the increased bouts of muscle hypoxia, revealed by elevated Δ[HHb], coupled with cyclic periods of excess posthypoxia oxygen consumption (EPHOC, inherent to the intermittent pattern) played a significant role in driving the increase in FATox post-IH.
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Affiliation(s)
- Guillaume Costalat
- Adaptations Physiologiques à l'Exercice et Réadaptation à l'Effort Laboratory, Faculty of Sport Sciences, University of Picardie Jules Verne, Amiens, France
| | - Frederic Lemaitre
- Centre d'Etude des Transformations des Activités Physiques et Sportives Laboratory, Faculty of Sport Sciences, Normandy University, Rouen, France
- Centre de Recherche Insulaire et Observatoire de l'Environnement, Centre National de la Recherche Scientifique-Ecole Pratique des Hautes Etudes-Université de Perpignan Via Domitia, Moorea, French Polynesia
| | - Sandra Ramos
- School of Medicine and Dentistry, Griffith University, Gold Coast, Queensland, Australia
| | - Gillian M C Renshaw
- Hypoxia and Ischemia Research Unit, School of Health Sciences and Social Work, Griffith University, Gold Coast, Queensland, Australia
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Exercise capacity remains supernormal, though mildly reduced in middle-aged military personnel with Moderate to Severe Obstructive Sleep Apnea. Sleep Breath 2023; 27:137-144. [PMID: 35217932 DOI: 10.1007/s11325-022-02587-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 02/15/2022] [Accepted: 02/18/2022] [Indexed: 10/19/2022]
Abstract
INTRODUCTION The relationship between moderate to severe OSA and exercise capacity remains unclear. Prior studies showing a reduction in VO2 max in this population have mostly involved middle-aged, overweight patients. We aimed to study this relationship in a similarly aged population of military personnel with previously undiagnosed moderate to severe OSA. METHODS We studied late-career male military personnel who underwent CPET and polysomnography (PSG). Patients were categorized either into an OSA group (apnea-hypopnea index (AHI) ≥ 15 events/h) or a control group (AHI < 15 events/h). VO2 max was compared between groups. RESULTS 170 male military personnel met criteria for the study. Mean AHI was 29.0/h in the OSA group (n = 58) versus 7.4/h in the controls (n = 112) while SpO2 nadir was slightly lower (86.0% vs. 89.0%). Patients were of similar age (53.1 vs. 53.7 years), and BMI was slightly higher in the OSA group (27.5 kg/m2 vs. 26.3 kg/m2). Percent-predicted VO2 max was supernormal in both groups, though it was comparatively lower in the OSA group (117% vs. 125%; p < 0.001). CONCLUSIONS Military personnel with moderate to severe OSA were able to achieve supernormal VO2 max values, yet had an 8% decrement in exercise capacity compared to controls. These findings suggest that OSA without significant hypoxemia may not significantly influence exercise capacity. It remains likely that the effects of untreated OSA on exercise capacity are complex and are affected by several variables including BMI, degree of associated hypoxemia, and regularity of exercise. Statistically lower VO2 max noted in this study may suggest that untreated OSA in less fit populations may lead to significant decrements in exercise capacity.
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Zhang P, Shi X, Downey HF. Two-week normobaric intermittent-hypoxic exposures stabilize cerebral perfusion during hypocapnia and hypercapnia. Exp Biol Med (Maywood) 2014; 240:961-8. [PMID: 25504012 DOI: 10.1177/1535370214562339] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Accepted: 10/14/2014] [Indexed: 11/15/2022] Open
Abstract
The effect of moderately extended, intermittent-hypoxia (IH) on cerebral perfusion during changes in CO2 was unknown. Thus, we assessed the changes in cerebral vascular conductance (CVC) and cerebral tissue oxygenation (ScO2) during experimental hypocapnia and hypercapnia following 14-day normobaric exposures to IH (10% O2). CVC was estimated from the ratio of mean middle cerebral arterial blood flow velocity (transcranial Doppler sonography) to mean arterial pressure (tonometry), and ScO2 in the prefrontal cortex was monitored by near-infrared spectroscopy. Changes in CVC and ScO2 during changes in partial pressure of end-tidal CO2 (PETCO2, mass spectrometry) induced by 30-s paced-hyperventilation (hypocapnia) and during 6-min CO2 rebreathing (hypercapnia) were compared before and after 14-day IH exposures in eight young nonsmokers. Repetitive IH exposures reduced the ratio of %ΔCVC/ΔPETCO2 during hypocapnia (1.00 ± 0.13 vs 1.94 ± 0.35 vs %/mmHg, P = 0.026) and the slope of ΔCVC/ΔPETCO2 during hypercapnia (1.79 ± 0.37 vs 2.97 ± 0.64 %/mmHg, P = 0.021), but had no significant effect on ΔScO2/ΔPETCO2. The ventilatory response to hypercapnia during CO2 rebreathing was significantly diminished following 14-day IH exposures (0.83 ± 0.07 vs 1.14 ± 0.09 L/min/mmHg, P = 0.009). We conclude that repetitive normobaric IH exposures significantly diminish variations of cerebral perfusion in response to hypercapnia and hypocapnia without compromising cerebral tissue oxygenation. This IH-induced blunting of cerebral vasoreactivity during CO2 variations helps buffer excessive oscillations of cerebral underperfusion and overperfusion while sustaining cerebral O2 homeostasis.
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Affiliation(s)
- Peizhen Zhang
- Department of Integrative Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX 76107, USA Beijing Sport University, Beijing 100084, China
| | - Xiangrong Shi
- Department of Integrative Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX 76107, USA Cardiovascular Research Institute, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - H Fred Downey
- Department of Integrative Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX 76107, USA Cardiovascular Research Institute, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
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Chen H, Tan X, Zhang J, Lu Q, Ou X, Ruo Y, Chen S. An electrogenerated chemiluminescent biosensor based on a g-C3N4–hemin nanocomposite and hollow gold nanoparticles for the detection of lactate. RSC Adv 2014. [DOI: 10.1039/c4ra09616a] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Rizzi CF, Cintra F, Mello-Fujita L, Rios LF, Mendonca ET, Feres MC, Tufik S, Poyares D. Does obstructive sleep apnea impair the cardiopulmonary response to exercise? Sleep 2013; 36:547-53. [PMID: 23565000 DOI: 10.5665/sleep.2542] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
STUDY OBJECTIVES The aim of this study was to evaluate cardiopulmonary exercise performance in lean and obese patients with obstructive sleep apnea (OSA) compared with controls. DESIGN Case-control study. SETTING The study was carried out in Sao Paulo Sleep Institute, Sao Paulo, Brazil. PATIENTS AND PARTICIPANTS INDIVIDUALS WITH SIMILAR AGES WERE ALLOCATED INTO GROUPS: 22 to the lean OSA group, 36 to the lean control group, 31 to the obese OSA group, and 26 to the obese control group. INTERVENTIONS The participants underwent a clinical evaluation, polysomnography, a maximum limited symptom cardiopulmonary exercise test, two-dimensional transthoracic echocardiography, and spirometry. MEASUREMENTS AND RESULTS The apnea-hypopnea index, arousal index, lowest arterial oxygen saturation (SaO2) and time of SaO2 < 90% were different among the groups. There were differences in functional capacity based on the following variables: maximal oxygen uptake (VO2max), P < 0.01 and maximal carbon dioxide production (VCO2max), P < 0.01. The obese patients with OSA and obese controls presented significantly lower VO2max and VCO2max values. However, the respiratory exchange ratio (RER) and anaerobic threshold (AT) did not differ between groups. Peak diastolic blood pressure (BP) was higher among the obese patients with OSA but was not accompanied by changes in peak systolic BP and heart rate (HR). When multiple regression was performed, body mass index (P < 0.001) and male sex in conjunction with diabetes (P < 0.001) independently predicted VO2max (mL/kg/min). CONCLUSIONS The results of this study suggest that obesity alone and sex, when associated with diabetes but not OSA, influenced exercise cardiorespiratory function.
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Affiliation(s)
- Camila F Rizzi
- Sleep Medicine and Biology Discipline, Psychobiology Department, Universidade Federal de São Paulo, São Paulo, Brazil
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Labroo P, Cui Y. Flexible graphene bio-nanosensor for lactate. Biosens Bioelectron 2013; 41:852-6. [DOI: 10.1016/j.bios.2012.08.024] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2012] [Revised: 08/09/2012] [Accepted: 08/09/2012] [Indexed: 01/08/2023]
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Workman C, Basset FA. Post-metabolic response to passive normobaric hypoxic exposure in sedendary overweight males: a pilot study. Nutr Metab (Lond) 2012; 9:103. [PMID: 23157699 PMCID: PMC3546003 DOI: 10.1186/1743-7075-9-103] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2012] [Accepted: 11/03/2012] [Indexed: 12/11/2022] Open
Abstract
UNLABELLED BACKGROUND The present pilot study was designed to test the impact of passive acute normobaric hypoxic exposure (PAH) and passive short-term normobaric hypoxic exposure (PSH) conditions on energy expenditure (EE) and substrates utilisation (glucose and lipid oxidation). METHODS Eleven participants have completed the PAH session while the control group (CG) underwent a simulated experimental condition in normobaric normoxic condition. A subset of 6 participants underwent an additional six 3-hour sessions on consecutive days. Metabolic rates were obtained pre- and post-treatments on the morning following an overnight (12 hours) fast in PAH, PSH, and CG groups. RESULTS The statistical outcomes showed a significant increase in EE for PAH, control, and PSH while a shift in substrate utilization towards lipid sources was only detected for PAH and PSH, respectively. CONCLUSION This pilot study showed that passive acute normobaric hypoxic exposure did affect EE and fuel utilization in sedentary overweight males and that further passive normobaric hypoxic exposures (PSH) magnified these metabolic adjustments. These outcomes provide valuable information for further research in the area of hypoxia as a new therapeutic strategy to improve the management of weight loss.
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Affiliation(s)
- Chad Workman
- School of Human Kinetics and Recreation, Memorial University of Newfoundland, St, John's, NL, A1C 5S7, Canada.
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Desplan M, Brun JF, Pillard F, Fedou C, Prefaut C, Mercier J, Dauvilliers Y, Avignon A. Decreased fat oxidation during exercise in severe obstructive sleep apnoea syndrome. DIABETES & METABOLISM 2012; 38:236-42. [PMID: 22633476 DOI: 10.1016/j.diabet.2011.12.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Revised: 12/31/2011] [Accepted: 12/31/2011] [Indexed: 11/19/2022]
Abstract
AIM To assess whether the severity of obstructive sleep apnoea syndrome (OSAS) is associated with altered fat oxidation (FO) during physical exercise in men with type 2 diabetes (T2DM) and/or the metabolic syndrome (MetS). METHODS A total of 105 consecutive overweight or/and T2DM male patients were hospitalized for metabolic check-ups including bioimpedancemetry to measure lean body mass (LBM), standardized exercise calorimetry to assess FO, maximum fat oxidation (MFO) and carbohydrate oxidation (CHO), and OSAS screening using respiratory polygraphy. Twenty patients were classified as having severe OSAS, according to the apnoea/hypopnoea index (AHI), with greater than 30 events/h (mean AHI: 45.2±14.3 events/h). They were group-matched for age, BMI, and the presence of T2DM and/or MetS with two other OSAS groups: mild (AHI<15 events/h [n=20]; mean AHI: 8.8±4.5 events/h); and moderate (AHI>15 events/h and<30 events/h [n=20]; mean AHI: 23.7±4.2 events/h). RESULTS MFO adjusted for LBM was severely decreased in the severe OSAS group (1.6±1.0 mg.min(-1).kgLM(-1)) compared with the moderate (2.5±0.9 mg.min(-1).kgLM(-1); P=0.008) and mild (2.9±0.8 mg.min(-1).kgLM(-1); P=0.003) groups. All exercise-intensity levels (20%, 30%, 40% and 60% of the theoretical maximum aerobic power) showed reduced FO levels between the severe and mild-to-moderate OSAS groups. However, no differences in CHO were seen at any level of exercise between groups. Pearson's correlation analysis showed that AHI and the oxygen desaturation index were negatively associated with MFO corrected for LBM (r=0.41 and r=0.37, respectively; P<0.005). CONCLUSION OSAS severity is associated with altered FO during exercise.
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Affiliation(s)
- M Desplan
- Service Central de Physiologie Clinique (CERAMM), University Montpellier 1 and INSERM, U 1046 Physiology and Experimental Medicine of Heart and Muscle, 34295 Montpellier, France.
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Blunted heart rate recovery is improved following exercise training in overweight adults with obstructive sleep apnea. Int J Cardiol 2012; 167:1610-5. [PMID: 22572632 DOI: 10.1016/j.ijcard.2012.04.108] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2012] [Revised: 03/21/2012] [Accepted: 04/16/2012] [Indexed: 11/23/2022]
Abstract
BACKGROUND Obstructive sleep apnea (OSA) predisposes individuals to cardiovascular morbidity, and cardiopulmonary exercise test (CPET) markers prognostic for cardiovascular disease have been found to be abnormal in adults with OSA. Due to the persistence of OSA and its cardiovascular consequences, whether the cardiovascular adaptations normally conferred by exercise are blunted in adults not utilizing established OSA treatment is unknown. The aims of this study were to document whether OSA participants have abnormal CPET responses and determine whether exercise modifies these CPET markers in individuals with OSA. METHODS The CPET responses of 43 sedentary, overweight adults (body mass index [BMI]>25) with untreated OSA (apnea-hypopnea index [AHI]≥ 15) were compared against matched non-OSA controls (n=9). OSA participants were then randomized to a 12-week exercise training (n=27) or stretching control treatment (n=16), followed by a post-intervention CPET. Measures of resting, exercise, and post-exercise recovery heart rate (HRR), blood pressure, and ventilation, as well as peak oxygen consumption (VO(2peak)), were obtained. RESULTS OSA participants had blunted HRR compared to non-OSA controls at 1 (P=.03), 3 (P=.02), and 5-min post-exercise (P=.03). For OSA participants, exercise training improved VO2 peak (P=.04) and HRR at 1 (P=.03), 3 (P<.01), and 5-min post-exercise (P<.001) compared to control. AHI change was associated with change in HRR at 5-min post-exercise (r=-.30, P<.05), but no other CPET markers. CONCLUSIONS These results suggest that individuals with OSA have autonomic dysfunction, and that exercise training, by increasing HRR and VO2 peak, may attenuate autonomic imbalance and improve functional capacity independent of OSA severity reduction.
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Fenik VB, Singletary T, Branconi JL, Davies RO, Kubin L. Glucoregulatory consequences and cardiorespiratory parameters in rats exposed to chronic-intermittent hypoxia: effects of the duration of exposure and losartan. Front Neurol 2012; 3:51. [PMID: 22509173 PMCID: PMC3321439 DOI: 10.3389/fneur.2012.00051] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Accepted: 03/20/2012] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND Obstructive sleep apnea (OSA) is associated with glucose intolerance. Both chronic sleep disruption and recurrent blood oxygen desaturations (chronic-intermittent hypoxia, CIH) may cause, or exacerbate, metabolic derangements. METHODS To assess the impact of CIH alone, without accompanying upper airway obstructions, on the counter-regulatory response to glucose load and cardiorespiratory parameters, we exposed adult male Sprague-Dawley rats to CIH or sham room air exchanges for 10 h/day for 7, 21, or 35 days and then, 1 day after conclusion of CIH exposure, conducted intravenous glucose-tolerance tests (ivgtt) under urethane anesthesia. Additional rats underwent 35 days of CIH followed by 35 days of regular housing, or had 35 day-long CIH exposure combined with daily administration of the type 1 angiotensin II receptor antagonist, losartan (15 mg/kg, p.o.), and then were also subjected to ivgtt. RESULTS Compared with the corresponding control groups, CIH rats had progressively reduced glucose-stimulated insulin release and impaired glucose clearance, only mildly elevated heart rate and/or arterial blood pressure and slightly reduced respiratory rate. The differences in insulin release between the CIH and sham-treated rats disappeared in the rats normally housed for 35 days after 35 days of CIH/sham exposure. The losartan-treated rats had improved insulin sensitivity, with no evidence of suppressed insulin release in the CIH group. CONCLUSION In adult rats, the glucose-stimulated insulin release is gradually suppressed with the duration of exposure to CIH, but the effect is reversible. Elimination of the detrimental effect of CIH on insulin release by losartan suggests that CIH disrupts glucoregulation through angiotensin/catecholaminergic pathways. Accordingly, treatment with continuous positive airway pressure may ameliorate pre-diabetic conditions in OSA patients, in part, by reducing sympathoexcitatory effects of recurrent nocturnal hypoxia.
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Affiliation(s)
- Victor B Fenik
- Department of Animal Biology 209E/VET, School of Veterinary Medicine, University of Pennsylvania Philadelphia, PA, USA
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