Effects of inspiratory muscle training versus high intensity interval training on the recovery capacity after a maximal dynamic apnoea in breath-hold divers. A randomised crossover trial.
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ABSTRACT: Introduction
After a maximal apnoea, breath-hold divers must restore O2 levels and clear CO2 and lactic acid produced. High intensity interval training (HIIT) and inspiratory muscle training (IMT) could be employed with the aim of increasing recovery capacity. This study aimed to evaluate the relative effects of IMT versus HIIT on recovery of peripheral oxygen saturation (SpO2), and also on pulmonary function, inspiratory muscle strength, lactate and heart rate recovery after a maximal dynamic apnoea in breath-hold divers.Methods
Fifteen breath-hold divers performed two training interventions (IMT and HIIT) for 20 min, three days per week over four weeks in randomised order with a two week washout period.Results
IMT produced a > 3 s reduction in SpO2 recovery time compared to HIIT. The forced expiratory volume in the first second (FEV1) and maximum inspiratory pressure (MIP) were significantly increased in the IMT group compared to HIIT. The magnitude of these differences in favour of IMT was large in both cases. Neither training intervention was superior to the other for heart rate recovery time, nor in peak- and recovery- lactate.Conclusions
IMT produced a reduction in SpO2 recovery time compared to HIIT after maximal dynamic apnoea. Even a 3 s improvement in recovery could be important in scenarios like underwater hockey where repetitive apnoeas during high levels of exercise are separated by only seconds. IMT also improved FEV1 and MIP, but no differences in lactate and heart rate recovery were found post-apnoea between HIIT and IMT.
SUBMITTER: de Asis-Fernandez F
PROVIDER: S-EPMC8026223 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:BackgroundThe physiological and pathophysiological mechanisms that govern diving, both self-contained underwater breathing apparatus (SCUBA) and breath-hold diving (BH-diving), are in large part well known, even if there are still many unknown aspects, in particular about cell metabolism during BH-diving. The scope of this study was to investigate changes in glycemia, insulinemia, and the catecholamine response to BH-diving, to better understand if the insulin-stimulated glucose uptake mechanism is involved in cellular metabolism in this sport.MethodsTwenty male experienced healthy breath-hold divers were studied. Anthropometric information was obtained. Glycemia, insulinemia, and catecholamine response were investigated before and after the series of BH-diving.ResultsWe found a statistically significant decrease in the blood glucose levels between before and after dives (mean 94.3?±?11.6 vs. 83.5?±?12.5 mg/dl) P?=?0.001 and a statistically significant increase in blood insulin value (median 4.5 range 3.4/6.4 vs. 7.0 range 4.2/10.2 mcgU/ml) P?<?0.0001. Also, we found a statistically significant increase of catecholamine production (median 14.0 range 8/18 vs. 15.5 range 10.0/21.0 ?g) P?<?0.0001.ConclusionsThe increase in blood insulin during BH-diving associated with the decrease of blood glucose levels could indicate that the upregulating cellular uptake is not caused by activation of the specific glucose transporters. Particular diving-related conditions such as the diving reflex, the intermittent hypoxia/hyperoxia, and the particular environmental condition could play an important role in the mechanism involved in glycemia decrease in BH-diving. Our data confirm that the adaptations to BH-diving are caused by complex mechanisms and involve many peculiar responses still in large part unknown.
| S-EPMC5871611 | biostudies-literature
Project description:Background:Three hours per week of vigorous physical activity is found to be associated with reduced odds of sleep-disordered breathing. Aim:To investigate whether 12 weeks of high-intensity interval training (HIIT) reduced the apnoea-hypopnea index (AHI) in obese subjects with moderate-to-severe obstructive sleep apnoea. Methods:In a prospective randomised controlled exercise study, 30 (body mass index 37±6?kg/m2, age 51±9?years) patients with sleep apnoea (AHI 41.5±25.3 events/hour) were randomised 1:1 to control or 12 weeks of supervised HIIT (4×4?min of treadmill running or walking at 90%-95% of maximal heart rate two times per week). Results:In the HIIT group, the AHI was reduced by 7.5±11.6 events/hour (within-group p<0.05), self-reported sleepiness (Epworth scale) improved from 10.0±3.6 to 7.3±3.7 (between-group p<0.05) and maximal oxygen uptake improved from 28.2±7.4 to 30.2±7.7?mL/kg/min (between-group p<0.05) from baseline to 12 weeks. The AHI, self-reported sleepiness and VO2maxwere unchanged from baseline to 12 weeks in controls (baseline AHI 50.3±25.5?events/hour, Epworth score 5.9±4.3, maximal oxygen uptake 27.0±6.8?mL/kg/min). Body weight remained unchanged in both groups. Conclusion:Twelve weeks of HIIT improved the AHI and self-reported daytime sleepiness in subjects with obese sleep apnoea without any change in the desaturation index and body weight.
| S-EPMC5875631 | biostudies-literature
Project description:Breath-hold divers (BHD) experience repeated bouts of severe hypoxia and hypercapnia with large increases in blood pressure. However, the impact of long-term breath-hold diving on cerebrovascular control remains poorly understood. The ability of cerebral blood vessels to respond rapidly to changes in blood pressure represents the property of dynamic autoregulation. The current investigation tested the hypothesis that breath-hold diving impairs dynamic autoregulation to a transient hypotensive stimulus. Seventeen BHD (3 women, 11?±?9 yr of diving) and 15 healthy controls (2 women) completed two or three repeated sit-to-stand trials during spontaneous breathing and poikilocapnic conditions. Heart rate (HR), finger arterial blood pressure (BP), and cerebral blood flow velocity (BFV) from the right middle cerebral artery were measured continuously with three-lead electrocardiography, finger photoplethysmography, and transcranial Doppler ultrasonography, respectively. End-tidal carbon dioxide partial pressure was measured with a gas analyzer. Offline, an index of cerebrovascular resistance (CVRi) was calculated as the quotient of mean BP and BFV. The rate of the drop in CVRi relative to the change in BP provided the rate of regulation [RoR; (?CVRi/?T)/?BP]. The BHD demonstrated slower RoR than controls (P ? 0.001, d?=?1.4). Underlying the reduced RoR in BHD was a longer time to reach nadir CVRi compared with controls (P = 0.004, d?=?1.1). In concert with the longer CVRi response, the time to reach peak BFV following standing was longer in BHD than controls (P = 0.01, d?=?0.9). The data suggest impaired dynamic autoregulatory mechanisms to hypotension in BHD. NEW & NOTEWORTHY Impairments in dynamic cerebral autoregulation to hypotension are associated with breath-hold diving. Although weakened autoregulation was observed acutely in this group during apneic stress, we are the first to report on chronic adaptations in cerebral autoregulation. Impaired vasomotor responses underlie the reduced rate of regulation, wherein breath-hold divers demonstrate a prolonged dilatory response to transient hypotension. The slower cerebral vasodilation produces a longer perturbation in cerebral blood flow velocity, increasing the risk of cerebral ischemia.
| S-EPMC6620660 | biostudies-literature
Project description:IntroductionElite breath-hold divers (BHD) possess several oxygen conserving adaptations to endure long dives similar to diving mammals. During dives, Bottlenose Dolphins may increase the alveolar ventilation (VA) to perfusion (Q) ratio to increase alveolar oxygen delivery. We hypothesized that BHD possess similar adaptive mechanisms during apnea.Methods and resultsPulmonary blood volume (PBV) was determined by echocardiography, 15O-H2O PET/CT, and cardiac MRi, (n = 6) during and after maximum apneas. Pulmonary function was determined by body box spirometry and compared to matched controls. After 2 min of apnea, the PBV determined by echocardiography and 15O-H2O-PET/CT decreased by 26% and 41%, respectively. After 4 min of apnea, the PBV assessed by echocardiography and cardiac MRi decreased by 48% and 67%, respectively (n = 6). Fractional saturation (F)O2Hb determined by arterial blood-gas-analyses collected after warm-up and a 5-minute pool-apnea (n = 9) decreased by 43%. Compared to matched controls (n = 8), spirometry revealed a higher total and alveolar-lung-capacity in BHD (n = 9), but a lower diffusion-constant.ConclusionOur results contrast with previous studies, that demonstrated similar lung gas transfer in BHD and matched controls. We conclude that elite BHD 1) have a lower diffusion constant than matched controls, and 2) gradually decrease PBV during apnea and in turn increase VA/Q to increase alveolar oxygen delivery during maximum apnea. We suggest that BHD possess pulmonary adaptations similar to diving mammals to tolerate decreasing tissue oxygenation.New and noteworthyThis manuscript addresses novel knowledge on tolerance to hypoxia during diving, which is shared by elite breath-hold divers and adult diving mammals: Our study indicates that elite breath-hold divers gradually decrease pulmonary blood volume and in turn increase VA/Q, to increase alveolar oxygen delivery during maximum apnea to tolerate decreasing oxygen levels similar to the Bottlenose Dolphin.
| S-EPMC11318387 | biostudies-literature
Project description:BACKGROUND:The performance of elite breath hold divers (BHD) includes static breath hold for more than 11 minutes, swimming as far as 300 m, or going below 250 m in depth, all on a single breath of air. Diving mammals are adapted to sustain oxidative metabolism in hypoxic conditions through several metabolic adaptations, including improved capacity for oxygen transport and mitochondrial oxidative phosphorylation in skeletal muscle. It was hypothesized that similar adaptations characterized human BHD. Hence, the purpose of this study was to examine the capacity for oxidative metabolism in skeletal muscle of BHD compared to matched controls. METHODS:Biopsies were obtained from the lateral vastus of the femoral muscle from 8 Danish BHD and 8 non-diving controls (Judo athletes) matched for morphometry and whole body VO2max. High resolution respirometry was used to determine mitochondrial respiratory capacity and leak respiration with simultaneous measurement of mitochondrial H2O2 emission. Maximal citrate synthase (CS) and 3-hydroxyacyl CoA dehydrogenase (HAD) activity were measured in muscle tissue homogenates. Western Blotting was used to determine protein contents of respiratory complex I-V subunits and myoglobin in muscle tissue lysates. RESULTS:Muscle biopsies of BHD revealed lower mitochondrial leak respiration and electron transfer system (ETS) capacity and higher H2O2 emission during leak respiration than controls, with no differences in enzyme activities (CS and HAD) or protein content of mitochondrial complex subunits myoglobin, myosin heavy chain isoforms, markers of glucose metabolism and antioxidant enzymes. CONCLUSION:We demonstrated for the first time in humans, that the skeletal muscles of BHD are characterized by lower mitochondrial oxygen consumption both during low leak and high (ETS) respiration than matched controls. This supports previous observations of diving mammals demonstrating a lower aerobic mitochondrial capacity of the skeletal muscles as an oxygen conserving adaptation during prolonged dives.
| S-EPMC6145504 | biostudies-literature
Project description:Introduction: The cardiac electrical conduction system is very sensitive to hypoglycemia and hypoxia, and the consequence may be brady-arrythmias. Weddell seals endure brady-arrythmias during their dives when desaturating to 3.2 kPa and elite breath-hold-divers (BHD), who share metabolic and cardiovascular adaptions including bradycardia with diving mammals, endure similar desaturation during maximum apnea. We hypothesized that hypoxia causes brady-arrythmias during maximum apnea in elite BHD. Hence, this study aimed to define the arterial blood glucose (Glu), peripheral saturation (SAT), heart rhythm (HR), and mean arterial blood pressure (MAP) of elite BHD during maximum apneas. Methods: HR was monitored with Direct-Current-Pads/ECG-lead-II and MAP and Glu from a radial arterial-catheter in nine BHD performing an immersed and head-down maximal static pool apnea after three warm-up apneas. SAT was monitored with a sensor on the neck of the subjects. On a separate day, a 12-lead-ECG-monitored maximum static apnea was repeated dry (n = 6). Results: During pool apnea of maximum duration (385 ± 70 s), SAT decreased from 99.6 ± 0.5 to 58.5 ± 5.5% (∼PaO2 4.8 ± 1.5 kPa, P < 0.001), while Glu increased from 5.8 ± 0.2 to 6.2 ± 0.2 mmol/l (P = 0.009). MAP increased from 103 ± 4 to 155 ± 6 mm Hg (P < 0.005). HR decreased to 46 ± 10 from 86 ± 14 beats/minute (P < 0.001). HR and MAP were unchanged after 3-4 min of apnea. During dry apnea (378 ± 31 s), HR decreased from 55 ± 4 to 40 ± 3 beats/minute (P = 0.031). Atrioventricular dissociation and junctional rhythm were observed both during pool and dry apneas. Conclusion: Our findings contrast with previous studies concluding that Glu decreases during apnea diving. We conclude during maximum apnea in elite BHD that (1) the diving reflex is maximized after 3-4 min, (2) increasing Glu may indicate lactate metabolism in accordance with our previous results, and (3) extreme hypoxia rather than hypoglycemia causes brady-arrythmias in elite BHD similar to diving mammals.
| S-EPMC8678416 | biostudies-literature
Project description:BackgroundHigh-intensity interval training (HIIT) induces similar or even superior adaptations compared to continuous endurance training. Indeed, just 6 HIIT sessions over 2 weeks significantly improves maximal oxygen uptake (VO2max), submaximal exercise fat oxidation, and endurance performance. Whether even faster adaptations can be achieved with HIIT is not known. Thus, we aimed to determine whether 2 sessions of HIIT per day, separated by 3 h, every other day for 5 days (double HIIT (HIIT-D), n = 15) could increase VO2max, submaximal exercise fat oxidation, and endurance capacity as effectively as 6 sessions of HIIT over 2 weeks (single HIIT (HIIT-S), n = 13).MethodsEach training session consisted of 10 × 60 s of cycling at 100% of VO2max interspersed with 75 s of low-intensity cycling at 60 watt (W). Pre- and post-training assessments included VO2max, time to exhaustion at ∼80% of VO2max, and 60-min cycling trials at ∼67% of VO2max.ResultsSimilar increases (p < 0.05) in VO2max (HIIT-D: 7.7% vs. HIIT-S: 6.0%, p > 0.05) and endurance capacity (HIIT-D: 80.1% vs. HIIT-S: 79.2%, p > 0.05) were observed. Submaximal exercise carbohydrate oxidation was reduced in the 2 groups after exercise training (HIIT-D: 9.2%, p = 0.014 vs. HIIT-S: 18.8%, p = 0.012) while submaximal exercise fat oxidation was significantly increased in HIIT-D (15.5%, p = 0.048) but not in HIIT-S (9.3%, p = 0.290).ConclusionSix HIIT sessions over 5 days was as effective in increasing VO2max and endurance capacity and was more effective in improving submaximal exercise fat oxidation than 6 HIIT sessions over 2 weeks.
| S-EPMC8343121 | biostudies-literature
Project description:There is increasing evidence that autonomic dysfunction in adults with homozygous sickle cell (haemoglobin SS) disease is associated with enhanced autonomic nervous system-mediated control of microvascular perfusion. However, it is unclear whether such differences are detectable in children with SS disease. We studied 65 children with SS disease [38 boys; median age 7.2 (interquartile range 5.1-10.6) years] and 20 control children without symptoms of SS disease [8 boys; 8.7 (5.5-10.8) years] and recorded mean arterial blood pressure (ABP) and daytime haemoglobin oxygen saturation (S(pO(2))). Cutaneous blood flux at rest (RBF) and during the sympathetically activated vasoconstrictor response to inspiratory breath hold (IBH) were measured in the finger pulp of the non-dominant hand using laser Doppler fluximetry. Local factors mediating flow motion were assessed by power spectral density analysis of the oscillatory components of the laser Doppler signal. The RBF measured across the two study groups was negatively associated with age (r = -0.25, P < 0.0001), ABP (r = -0.27, P = 0.02) and daytime S(pO(2)) (r = -0.30, P = 0.005). Children with SS disease had a higher RBF (P = 0.005) and enhanced vasoconstrictor response to IBH (P = 0.002) compared with control children. In children with SS disease, higher RBF was associated with an increase in the sympathetic interval (r = -0.28, P = 0.022). The SS disease status, daytime S(pO(2)) and age explained 22% of the variance in vasoconstrictor response to IBH (P < 0.0001). Our findings suggest that blood flow and blood flow responses in the skin of young African children with SS disease differ from those of healthy control children, with increased resting peripheral blood flow and increased sympathetic stimulation from a young age in SS disease. They further suggest that the laser Doppler flowmetry technique with inspiratory breath hold manoeuvre appears to be robust for use in young children with SS disease, to explore interactions between S(pO(2)), ABP and autonomic function with clinical complications, e.g. skin ulceration.
| S-EPMC4463767 | biostudies-literature
Project description:Skeletal muscle tissue is a highly adaptable tissue, responding to the specific demands it is subjected to. High-intensity interval training (HIIT) has been shown to generate similar, or even greater, molecular changes in skeletal muscle as that of constant load longer-lasting endurance-type training at moderate intensities. Despite shorter exposure times, the higher intensity provided by HIIT training leads to greater metabolic perturbations and thereby larger improvements in mitochondrial content and maximal oxygen uptake. During a period of regular exercise training, the performance improvements follow a non-linear pattern with a relatively faster pace initially and a gradual ‘plateauing-off’ after weeks and months. It is believed that this ‘plateau effect’ is due to a blunting of the molecular responses to acute exercise with exercise training. In the present study we utilised an explorative global transcriptomic approach to investigate the phenomenon of transcriptional-level blunting of the acute exercise response in human skeletal muscle over the course of a three-week HIIT intervention. We hypothesize that the blunting of transcription at this time-point is specific to certain pathways, including metabolic regulation and that these genes have communal transcriptional regulation.
2021-09-01 | GSE163356 | GEO
Project description:INTRODUCTION:Aerobic exercise generates increased cardiorespiratory fitness, which results in a protective factor for cardiovascular disease. High-intensity interval training (HIIT) might produce higher increases on cardiorespiratory fitness in comparison with moderate-intensity continuous training (MICT); however, current evidence is not conclusive. OBJECTIVE:To compare the effects of a low-volume HIIT and a MICT on maximal oxygen consumption (VO2max), systolic blood pressure, and diastolic blood pressure during eight weeks in healthy men between 18 and 44 years of age. MATERIALS AND METHODS:We conducted a randomized controlled trial. Forty-four volunteers were randomized to HIIT (n=22) or MICT (n=22). Both groups performed 24 sessions on a treadmill. The HIIT group completed 15 bouts of 30 seconds (90-95%, maximal heart rate, HRmax), while the MICT group completed 40 minutes of continuous exercise (65-75% HRmax). Results: Intra-group analysis showed an increase in VO2max of 3.5 ml/kg/min [95% confidence interval (CI) 2.02 to 4.93; p=0.0001] in HIIT and 1.9 ml/kg/min (95% CI -0.98 to 4.82; p=0.18) in MICT. However, the difference between the two groups was not statistically significant (1.01 ml/kg/min. 95% CI -2.16 to 4.18, p=0.52). MICT generated a greater reduction in systolic blood pressure compared to HIIT (median 8 mm Hg; p<0.001). No statistically significant differences were found between the groups for DBP. CONCLUSIONS:Results indicated no significant change in VO2max with a low-volume HIIT protocol versus MICT after 24 sessions. In contrast, MICT provided a greater reduction in systolic blood pressure compared to HIIT. The study is registered as a clinical trial via clinicaltrials.gov with identifier number: NCT02288403.
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