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European Journal of Sport Science Jun 2024This study investigates whether exercise as a strategy for improving physical fitness at sea level also offers comparable benefits in the unique context of high... (Randomized Controlled Trial)
Randomized Controlled Trial
This study investigates whether exercise as a strategy for improving physical fitness at sea level also offers comparable benefits in the unique context of high altitudes (HA), considering the physiological challenges of hypoxic conditions. Overall, 121 lowlanders who had lived on the Tibetan Plateau for >2 years and were still living at HA during the measurements were randomly classified into four groups. Each individual of the low-intensity (LI), moderate-intensity (MI), and high-intensity (HI) groups performed 20 sessions of aerobic exercise at HA (3680 m) over 4 weeks, while the control group (CG) did not undergo any intervention. Physiological responses before and after the intervention were observed. The LI and MI groups experienced significant improvement in cardiopulmonary fitness (0.27 and 0.35 L/min increases in peak oxygen uptake [ O], both p < 0.05) after exercise intervention, while the hematocrit (HCT) remained unchanged (p > 0.05). However, HI exercise was less efficient for cardiopulmonary fitness of lowlanders (0.02 L/min decrease in O, p > 0.05), whereas both the HCT (1.74 %, p < 0.001) and glomerular filtration rate (18.41 mL/min, p < 0.001) increased with HI intervention. Therefore, LI and MI aerobic exercise, rather than HI, can help lowlanders in Tibet become more acclimated to the HA by increasing cardiopulmonary function and counteracting erythrocytosis.
Topics: Humans; Tibet; Exercise; Altitude; Male; Adult; Acclimatization; Oxygen Consumption; Cardiorespiratory Fitness; Female; Hematocrit; Young Adult; Glomerular Filtration Rate; Physical Fitness; Heart Rate
PubMed: 38874991
DOI: 10.1002/ejsc.12110 -
European Journal of Sport Science Jun 2024We aimed to assess the effects of muscle disuse on muscle strength (MS), muscle mass (MM) and cardiovascular fitness. Databases were scrutinized to identify human... (Meta-Analysis)
Meta-Analysis Review
We aimed to assess the effects of muscle disuse on muscle strength (MS), muscle mass (MM) and cardiovascular fitness. Databases were scrutinized to identify human studies assessing the effects of muscle disuse on both (1) MM and (2) maximal oxygen uptake (VO) and/or MS. Random-effects meta-analysis and meta-regression with initial physical fitness and length of the protocol as a priori determined moderators were performed. We quantitatively analyzed 51 different studies, and the level of significance was set at p < 0.05. Data from the participants in 14 studies showed a decline in both VO (SMD: -0.93; 95% CI: -1.27 to -0.58) and MM (SMD: -0.34; 95% CI: -0.57 to -0.10). Data from 47 studies showed a decline in strength (-0.88; 95% CI: -1.04 to -0.73) and mass (SMD: -0.47; 95% CI: -0.58 to -0.36). MS loss was twice as high as MM loss, but differences existed between anatomical regions. Notably, meta-regression analysis revealed that initial MS was inversely associated with MS decline. VO and MS decline to a higher extent than MM during muscle disuse. We reported a more profound strength loss in subjects with high muscular strength. This is physiologically relevant for athletes because their required muscular strength can profoundly decline during a period of muscle disuse. It should however be noted that a period of muscle disuse can have devastating consequences in old subjects with low muscular strength.
Topics: Humans; Muscle, Skeletal; Muscle Strength; Oxygen Consumption; Cardiorespiratory Fitness
PubMed: 38874988
DOI: 10.1002/ejsc.12093 -
European Journal of Sport Science Jun 2024Blood flow restriction (BFR) is increasingly being used to enhance aerobic performance in endurance athletes. This study examined physiological responses to BFR applied... (Randomized Controlled Trial)
Randomized Controlled Trial
Blood flow restriction (BFR) is increasingly being used to enhance aerobic performance in endurance athletes. This study examined physiological responses to BFR applied in recovery phases within a high-intensity interval training (HIIT) session in trained cyclists. Eleven competitive road cyclists (mean ± SD, age: 28 ± 7 years, body mass: 69 ± 6 kg, peak oxygen uptake: 65 ± 9 mL · kg · min) completed two randomised crossover conditions: HIIT with (BFR) and without (CON) BFR applied during recovery phases. HIIT consisted of six 30-s cycling bouts at an intensity equivalent to 85% of maximal 30-s power (523 ± 93 W), interspersed with 4.5-min recovery. BFR (200 mmHg, 12 cm cuff width) was applied for 2-min in the early recovery phase between each interval. Pulmonary gas exchange (V̇O, V̇CO, and V̇E), tissue oxygen saturation index (TSI), heart rate (HR), and serum vascular endothelial growth factor concentration (VEGF) were measured. Compared to CON, BFR increased V̇CO and V̇E during work bouts (both p < 0.05, dz < 0.5), but there was no effect on V̇O, TSI, or HR (p > 0.05). In early recovery, BFR decreased TSI, V̇O, V̇CO, and V̇E (all p < 0.05, dz > 0.8) versus CON, with no change in HR (p > 0.05). In late recovery, when BFR was released, V̇O, V̇CO, V̇E, and HR increased, but TSI decreased versus CON (all p < 0.05, dz > 0.8). There was a greater increase in VEGF at 3-h post-exercise in BFR compared to CON (p < 0.05, dz > 0.8). Incorporating BFR into HIIT recovery phases altered physiological responses compared to exercise alone.
Topics: Humans; Bicycling; High-Intensity Interval Training; Adult; Heart Rate; Oxygen Consumption; Cross-Over Studies; Male; Young Adult; Pulmonary Gas Exchange; Vascular Endothelial Growth Factor A; Regional Blood Flow; Athletic Performance; Oxygen Saturation
PubMed: 38874956
DOI: 10.1002/ejsc.12107 -
European Journal of Sport Science Jun 2024This study examined the impact of continuous blood flow restriction (BFR) during repeated-sprint exercise (RSE) on acute performance, peripheral, systemic physiological,... (Randomized Controlled Trial)
Randomized Controlled Trial
This study examined the impact of continuous blood flow restriction (BFR) during repeated-sprint exercise (RSE) on acute performance, peripheral, systemic physiological, and perceptual responses. In a randomized crossover design, 26 adult male semi-professional and amateur team-sport players completed two RSE sessions (3 sets of 5 × 5-s sprints with 25 s of passive recovery and 3 min of rest) with continuous BFR (45% arterial occlusion; excluding during between-set rest periods) or without (non-BFR). Mean and peak power output were significantly lower (p < 0.001) during BFR compared to non-BFR (d = 0.85 and 0.77, respectively). Minimum tissue saturation index during the sprints and rest periods was significantly reduced (p < 0.001) for BFR (d = 1.26 and 1.21, respectively). Electromyography root mean square was significantly decreased (p < 0.01) for biceps femoris and lateral gastrocnemius muscles during BFR (d = 0.35 and 0.79, respectively), but remained unchanged for the vastus lateralis muscle in both conditions. Oxygen consumption and minute ventilation were significantly reduced (both p < 0.01) for BFR (d = 1.46 and 0.43, respectively). Perceived limb discomfort was significantly higher (p < 0.001) for BFR (d = 0.78). No differences (p > 0.05) in blood lactate concentration or rating of perceived exertion were observed between conditions. Blood flow-restricted RSE reduced performance and likely increased the physiological and perceptual stimulus for the periphery with greater reliance on anaerobic glycolysis, despite comparable or decreased systemic demands.
Topics: Humans; Male; Cross-Over Studies; Oxygen Consumption; Young Adult; Adult; Muscle, Skeletal; Regional Blood Flow; Electromyography; Running; Athletic Performance; Perception
PubMed: 38874946
DOI: 10.1002/ejsc.12106 -
Journal of Medical Economics 2024Patients with obstructive hypertrophic cardiomyopathy (oHCM) experience significant clinical burden which is associated with a high economic burden. Peak oxygen uptake... (Review)
Review
AIMS
Patients with obstructive hypertrophic cardiomyopathy (oHCM) experience significant clinical burden which is associated with a high economic burden. Peak oxygen uptake (pVO2), measured by cardiopulmonary exercise testing, is used to quantify functional capacity, and has been studied as a primary endpoint in recent clinical trials. This study aimed to gather evidence to consolidate the prognostic value of pVO2 in oHCM and to assess whether it is feasible to predict health outcomes in an economic model based on changes in pVO2.
METHODS
A targeted literature review was conducted in MEDLINE ( PubMed) and Embase databases to identify evidence on the prognostic value of pVO2 as a surrogate health outcome to support future oHCM economic model development. Following screening, study characteristics, population characteristics, and pVO2 prognostic association data were extracted.
RESULTS
A total of 4,687 studies were identified. In total, 3,531 and 538 studies underwent title/abstract and full-text screening, respectively, of which 151 were included and nine of these were in hypertrophic cardiomyopathy (HCM); only three studies focused on oHCM. The nine HCM studies consisted of one systematic literature review and eight primary studies reporting on 27 potentially predictive relationships from a pVO2-based metric with clinical outcomes including all-cause mortality, cardiovascular mortality, sudden cardiac death, transplant, paroxysmal, and permanent atrial fibrillation. pVO2 was described as a predictor of single and composite endpoints, in three and six studies, respectively, with one study reporting on both.
LIMITATIONS
This study primarily uses systemic literature review methods but does not qualify as one due to not entailing parallel reviewers during title-abstract and full-text stages of review.
CONCLUSION
The findings of this study suggest pVO2 is predictive of multiple health outcomes, providing a rationale to use pVO2 in the development of an economic model.
Topics: Humans; Cardiomyopathy, Hypertrophic; Exercise Test; Models, Economic; Oxygen Consumption; Prognosis
PubMed: 38868944
DOI: 10.1080/13696998.2024.2367920 -
Current Developments in Nutrition Jun 2024Iron supplementation, especially in female athletes, is 1 of the influential factors in aerobic capacity, and its deficiency can lead to significant problems related to...
BACKGROUND
Iron supplementation, especially in female athletes, is 1 of the influential factors in aerobic capacity, and its deficiency can lead to significant problems related to reduced aerobic capacity.
OBJECTIVES
This study aimed to investigate the effect of 3 wk of iron supplementation on the aerobic capacity of female handball players.
METHODS
In this randomized double-blinded, and placebo control trial, 14 elite handball players (age: 21.6 ± 5.68 y; height: 169.5 ± 4.9 cm; weight: 62.2 ± 9.25 kg; body mass index (in kg/m): 21.5 ± 2.9) randomly divided into 2 supplement groups (receiving a 100 mg/d of poly-maltose tri hydroxide iron complex in the form of tablets) and the placebo group (receiving a tablet containing 100 mg/d starch which is the same color and shape as iron tablets). The supplementation protocol was performed for 3 wk during the off-season. Maximal oxygen consumption (VO), amounts of carbon dioxide at the first ventilatory threshold, amounts of carbon dioxide at the second ventilatory threshold, time to exhaustion (TTE), pulmonary ventilation (VE), ventilatory equivalents for oxygen, amounts of oxygen at the first ventilatory threshold, amounts of oxygen at the second ventilatory threshold, time to reach first ventilatory threshold, end-tidal partial pressure of oxygen at the first ventilatory threshold, end-tidal partial pressure of carbon dioxide at the first ventilatory threshold and ventilatory equivalents for carbon dioxide were measured using the Bruce test and gas analyzer in 2 pretest and posttest stages.
RESULTS
There were significant improvements in oxygen at the first ventilatory threshold, time to reach first ventilatory threshold, and end-tidal partial pressure of carbon dioxide at the first ventilatory threshold and a significant decrease in end-tidal partial pressure of oxygen at the first ventilatory threshold ( < 0.05). Also, no significant changes were found in VO, carbon dioxide at the first ventilatory threshold, carbon dioxide at the second ventilatory threshold, oxygen at the second ventilatory threshold, TTE, VE, ventilatory equivalents for oxygen, and ventilatory equivalents for carbon dioxide after 3 wk of iron supplementation ( > 0.05).
CONCLUSIONS
The study found that 3 wk of off-season iron supplementation positively impacted female handball players' aerobic capacity; however, it did not significantly improve their VO.
PubMed: 38868615
DOI: 10.1016/j.cdnut.2024.103767 -
Journal of Applied Physiology... Jun 2024Revisiting classical experiments on the impact of air resistance on metabolic rate, we aimed to overcome limitations of previous research, notably: low participant...
Revisiting classical experiments on the impact of air resistance on metabolic rate, we aimed to overcome limitations of previous research, notably: low participant numbers (n=1-3), highly turbulent wind, and confounding effects of rising body temperature. In a custom-built wind tunnel with reduced turbulence, 14 participants (8 males, 6 females) walked (5 km.h) and ran on a treadmill (70%V̇O) at 0, 2, 4 and 6 m.s headwind or tailwind in a counterbalanced design, with rest-breaks between each exposure to avoid rises in body core temperature. Oxygen consumption (V̇O) exhibited strong linear relationships versus wind direction, dynamic pressure and air speed squared(V), lower in magnitude for headwind than tailwind. A moderate linear relationship was observed between heart rate, wind direction, dynamic pressure and V. Below 4 m⸱s, the effect of wind was well within inter- and intra-individual variation and equipment uncertainty, and only at wind speeds ≥4 m⸱s did the differences in physiological responses reach statistical significance. Our data indicate that at running speeds below 4 m⸱s (14.4 km/h), indoor treadmill and outdoor running are comparable in terms of the metabolic impact of air movement relative to the person. However, this does not extend to the thermoregulatory effect of wind, with outdoor running providing a higher cooling rate due to the self-generated wind created during running. By removing the confounding impact of core temperature rises, the observed effects of headwind were lower and those of tailwind larger than observed previously. In the context of middle-distance running, headwind created by running at 21.5 km.h would result in a 2.2% increase of V̇O. A relative tailwind of the same speed would lead to a 3.1% reduction.
PubMed: 38867667
DOI: 10.1152/japplphysiol.00159.2024 -
Magnetic Resonance in Medical Sciences... Jul 2024The metabolic rate of oxygen (MRO) is fundamental to tissue metabolism. Determination of MRO demands knowledge of the arterio-venous difference in hemoglobin-bound... (Review)
Review
The metabolic rate of oxygen (MRO) is fundamental to tissue metabolism. Determination of MRO demands knowledge of the arterio-venous difference in hemoglobin-bound oxygen concentration, typically expressed as oxygen extraction fraction (OEF), and blood flow rate (BFR). MRI is uniquely suited for measurement of both these quantities, yielding MRO in absolute physiologic units of µmol O min/100 g tissue. Two approaches are discussed, both relying on hemoglobin magnetism. Emphasis will be on cerebral oxygen metabolism expressed in terms of the cerebral MRO (CMRO), but translation of the relevant technologies to other organs, including kidney and placenta will be touched upon as well. The first class of methods exploits the blood's bulk magnetic susceptibility, which can be derived from field maps. The second is based on measurement of blood water T, which is modulated by diffusion and exchange in the local-induced fields within and surrounding erythrocytes. Some whole-organ methods achieve temporal resolution adequate to permit time-series studies of brain energetics, for instance, during sleep in the scanner with concurrent electroencephalogram (EEG) sleep stage monitoring. Conversely, trading temporal for spatial resolution has led to techniques for spatially resolved approaches based on quantitative blood oxygen level dependent (BOLD) or calibrated BOLD models, allowing regional assessment of vascular-metabolic parameters, both also exploiting deoxyhemoglobin paramagnetism like their whole-organ counterparts.
Topics: Humans; Brain; Magnetic Resonance Imaging; Oxygen; Cerebrovascular Circulation; Oxygen Consumption; Animals
PubMed: 38866481
DOI: 10.2463/mrms.rev.2024-0028 -
Redox Biology Aug 2024Hydrogen sulfide (HS) has recently been recognized as an important gaseous transmitter with multiple physiological effects in various species. Previous studies have...
Hydrogen sulfide (HS) has recently been recognized as an important gaseous transmitter with multiple physiological effects in various species. Previous studies have shown that HS alleviated heat-induced ganoderic acids (GAs) biosynthesis, an important quality index of Ganoderma lucidum. However, a comprehensive understanding of the physiological effects and molecular mechanisms of HS in G. lucidum remains unexplored. In this study, we found that heat treatment reduced the mitochondrial membrane potential (MMP) and mitochondrial DNA copy number (mtDNAcn) in G. lucidum. Increasing the intracellular HS concentration through pharmacological and genetic means increased the MMP level, mtDNAcn, oxygen consumption rate level and ATP content under heat treatment, suggesting a role for HS in mitigating heat-caused mitochondrial damage in G. lucidum. Further results indicated that HS activates sulfide-quinone oxidoreductase (SQR) and complex III (Com III), thereby maintaining mitochondrial homeostasis under heat stress in G. lucidum. Moreover, SQR also mediated the negative regulation of HS to GAs biosynthesis under heat stress. Furthermore, SQR might be persulfidated under heat stress in G. lucidum. Thus, our study reveals a novel physiological function and molecular mechanism of HS signalling under heat stress in G. lucidum with broad implications for research on the environmental response of microorganisms.
Topics: Hydrogen Sulfide; Reishi; Triterpenes; Mitochondria; Homeostasis; Heat-Shock Response; Membrane Potential, Mitochondrial; Quinone Reductases; DNA, Mitochondrial; Electron Transport Complex III
PubMed: 38865903
DOI: 10.1016/j.redox.2024.103227 -
Arquivos Brasileiros de Cardiologia 2024
Topics: Humans; Exercise Test; Oxygen Consumption; Pulmonary Ventilation
PubMed: 38865567
DOI: 10.36660/abc.20240184