Role of Maximal Heart Rate and Arterial O2 Saturation on the Decrement of V·O2max in Moderate Acute Hypoxia in Trained and Untrained Men

2007 ◽  
Vol 28 (3) ◽  
pp. 186-192 ◽  
Author(s):  
P. Mollard ◽  
X. Woorons ◽  
M. Letournel ◽  
J. Cornolo ◽  
C. Lamberto ◽  
...  
Medicina ◽  
2019 ◽  
Vol 55 (11) ◽  
pp. 735
Author(s):  
Papadopoulou ◽  
Papadopoulou ◽  
Alipasali ◽  
Hatzimanouil ◽  
Rosemann ◽  
...  

Background and objectives: Maximal heart rate (HRmax) is an important training and testing tool, especially in the context of evaluating intensity in exercise prescription; however, few studies have examined the validity of prediction equations of HRmax in physically active female adolescents and the role of maturation level. Therefore, the aim of the present study was to examine the differences between measured and predicted HRmax in a sample of physically active female adolescents. Materials and Methods: Seventy-one selected volleyball players (age 13.3 ± 0.7 years, body mass 62.0 ± 7.2 kg, height 1.72 ± 0.06 m) performed a 20 m shuttle run endurance test, and the actual HRmax was compared with Tanaka HRmax (‘208 − 0.7 × age’) and Fox HRmax (‘220 − age’). Results: A large main effect of assessment method on HRmax was found (p < 0.001, η2 = 0.486) with Fox overestimating actual HRmax by 6.8 bpm (95% confidence intervals, CI; 4.2, 9.3) and Tanaka underestimating actual HRmax by −2.6 bpm (95% CI; −5.1, −0.1). The more matured participants had similar actual HRmax (mean difference −2.4 bpm; 95% CI; −6.5, 1.7; p = 0.242, d = −0.28), difference Fox − actual HRmax (1.5 bpm; 95% CI; −2.6, 5.6, p = 0.466, d = 0.17), and difference Tanaka − actual HRmax (1.7 bpm; 95% CI; −2.4, 5.8; p = 0.414, d = 0.19) to the less matured participants. Conclusions: These findings suggest that age-based prediction equations of HRmax developed in adult populations should be applied with caution in physically active female adolescents, and Tanaka should be preferred instead of the Fox equation.


2020 ◽  
Vol 25 (2) ◽  
pp. 83-98
Author(s):  
Stacey L. Parker ◽  
Sabine Sonnentag ◽  
Nerina L. Jimmieson ◽  
Cameron J. Newton

Author(s):  
Rubina Yasmin ◽  
AKM Akhtaruzzaman ◽  
Paresh Chandra Sarker ◽  
Neaz Ahmed ◽  
Ranadhir Kumar Kundu ◽  
...  

This prospective clinical study was carried out in the Dept. of Anaesthesia, Analgesia and Intensive Care Medicine, BSMMU, Dhaka, during the period of May 2003 to July 2003. The study was done to emphasize the importance of giving analgesics preemptively instead of waiting for the child to complain of pain and to produce smooth recovery after surgery by decreasing immediate postoperative pain in children by a simple, safe acceptable drug. The children scheduled for tonsillectomy under general anaesthesia were recruited in this study. The analgesic efficiency of rectal paracetamol in two doses, 25 mg/kg bodywt.(Gr-P25) and 50 mg/kg. bodywt. (Gr-P50) were compared with Diclofenac Sodium suppository 1mg/ kg body weight (Gr-D) given half an hour before induction of anaesthesia. Pain scoring was done by TPPPS (Toddler Pre-schooler postoperative pain scale). Heart rate and blood pressure were stable in Gr-P50 and Gr-D. Time of first demand of analgesic was delayed in Gr-P50 and Gr-D. Total paracetamol consumption in 24 hours was less in Gr-P50(181±14.25) and Gr-D (212±25) than Gr-P25(318± 26.39). Total duration of analgesia in Gr- P50 (657±9.94) mins. and in Gr- D(502±10.63) mins. and in Gr-P25(288±23.17) mins. Pre-emptive high dose rectal paracetamol appears to be more effective than diclofenac sodium suppository for postoperative analgesia in children undergoing tonsillectomy. Journal of BSA, Vol. 18, No. 1 & 2, 2005 p.9-16


1995 ◽  
Vol 133 (6) ◽  
pp. 723-728 ◽  
Author(s):  
Ettore C degli Uberti ◽  
Maria R Ambrosio ◽  
Marta Bondanelli ◽  
Giorgio Transforini ◽  
Alberto Valentini ◽  
...  

degli Uberti EC, Ambrosio MR, Bondanelli M, Trasforini G, Valentini A, Rossi R, Margutti A, Campo M. Effect of human galanin on the response of circulating catecholamines to hypoglycemia in man. Eur J Endocrinol 1995;133:723–8. ISSN 0804–4643 Human galanin (hGAL) is a neuropeptide with 30 amino acid residues that has been found in the peripheral and central nervous system, where it often co-exists with catecholamines. In order to clarify the possible role of hGAL in the regulation of sympathoadrenomedullary function, the effect of a 60 min infusion of hGAL (80 pmol·kg−1 · min−1) on plasma epinephrine and norepinephrine responses to insulin-induced hypoglycemia in nine healthy subjects was investigated. Human GAL administration significantly reduced both the release of basal norepinephrine and the response to insulin-induced hypoglycemia, whereas it attenuated the epinephrine response by 26%, with the hGAL-induced decrease in epinephrine release failing to achieve statistical significance. Human GAL significantly increased the heart rate in resting conditions and clearly exaggerated the heart rate response to insulin-induced hypoglycemia, whereas it had no effect on the blood pressure. We conclude that GAL receptor stimulation exerts an inhibitory effect on basal and insulin-induced hypoglycemia-stimulated release of norepinephrine. These findings provide further evidence that GAL may modulate sympathetic nerve activity in man but that it does not play an important role in the regulation of adrenal medullary function. Ettore C degli Uberti, Chair of Endocrinology, University of Ferrara, Via Savonarola 9, I-44100 Ferrara, Italy


1996 ◽  
Vol 27 (2) ◽  
pp. 398-399
Author(s):  
Tohru Kaji ◽  
Tetsuro Kohya ◽  
Fumishi Tomita ◽  
Tomohide Ono ◽  
Akira Kitabatake

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Daisuke Hasegawa ◽  
Ryota Sato ◽  
Osamu Nishida

Abstract Background The use of ultrashort-acting β1-blockers recently has attracted attention in septic patients with non-compensatory tachycardia. We summarized the metabolic and hemodynamic effects and the clinical evidence of ultrashort-acting β1-blockers. Main body A recent meta-analysis showed that ultrashort-acting β1-blockers reduced the mortality in septic patients with persistent tachycardia. However, its mechanism to improve mortality is not fully understood yet. We often use lactate as a marker of oxygen delivery, but an impaired oxygen use rather than reduced oxygen delivery has been recently proposed as a more reasonable explanation of hyperlactatemia in patients with sepsis, leading to a question of whether β1-blockers affect metabolic systems. While the stimulation of the β2-receptor accelerates glycolysis and lactate production, the role of β1-blocker in lactate production remains unclear and studies investigating the role of β1-blockers in lactate kinetics are warranted. A meta-analysis also reported that ultrashort-acting β1-blockers increased stroke volume index, while it reduced heart rate, resulting in unchanged cardiac index, mean arterial pressure, and norepinephrine requirement at 24 h, leading to an improvement of cardiovascular efficiency. On the other hand, a recent study reported that heart rate reduction using fast esmolol titration in the very early phase of septic shock caused hemodynamic instability, suggesting that ultrashort-acting β1-blockers should be started only after completing initial resuscitation. While many clinicians still do not feel comfortable controlling sinus tachycardia, one randomized controlled trial in which the majority had sinus tachycardia suggested the mortality benefit of ultrashort-acting β1-blockers. Therefore, it still deems to be reasonable to control sinus tachycardia with ultrashort-acting β1-blockers after completing initial resuscitation. Conclusion Accumulating evidence is supporting the use of ultrashort-acting β1-blockers while larger randomized controlled trials to clarify the effect of ultrashort-acting β1-blockers are still warranted.


2019 ◽  
Vol 27 (5) ◽  
pp. 526-535 ◽  
Author(s):  
Pietro Laforgia ◽  
Francesco Bandera ◽  
Eleonora Alfonzetti ◽  
Marco Guazzi

Background Chronotropic insufficiency (CI) is defined as the inability of the heart to increase its rate commensurate with increased demand. Exercise CI is an established predictor of major adverse cardiovascular events in patients with cardiovascular diseases. Aim The aim of this study was to evaluate how exercise CI phenotypes different levels of cardiovascular risk and how it may better perform in defining cardiovascular risk when analysed in the context of cardiopulmonary exercise test (CPET)-derived measures and standard echocardiography in a healthy population with variable cardiovascular risk profile. Methods Apparently healthy individuals ( N = 702, 53.8% females) with at least one major cardiovascular risk factor (MCVRF; hypertension, diabetes, tabagism, dyslipidaemia, body mass index > 25), enrolled in the Euro-EX prevention trial, underwent CPET. CI was defined as the inability to reach 80% of the chronotropic index, that is, the ratio of peak heart rate – rest heart rate/peak heart rate – age predicted maximal heart rate (AMPHR: 220 – age), they were divided into four groups according to the heart rate reserve (<80%>) and respiratory gas exchange ratio (RER; < 1.05>) as a marker of achieved maximal performance. Subjects with a RER < 1.05 ( n = 103) were excluded and the final population ( n = 599) was divided into CI group ( n = 472) and no-CI group ( n = 177). Results Compared with no-CI, CI subjects were more frequently females with a history of hypertension in a high rate. CI subjects also exhibited a significantly lower peak oxygen uptake (VO2) and circulatory power and an echocardiographic pattern indicative of higher left atrial volume index and left ventricular mass index. An inverse stepwise relationship between heart rate reserve and number of MCVRFs was observed (one MCVRF: 0.71 ± 0.23; two MCVRFs: 0.68 ± 0.24, three MCVRFs: 0.64 ± 0.20; four MCVRFs: 0.64 ± 0.23; five MCVRFs: 0.57 ± 18; p < 0.01). In multivariate analysis the only variable found predicting CI was peak VO2 ( p < 0.05; odds ratio 0.91; confidence interval 0.85–0.97). Conclusions In a population of apparently healthy subjects, exercise CI is common and phenotypes the progressive level of cardiovascular risk by a tight relationship with MCVRFs. CI patients exhibit some peculiar abnormal exercise gas exchange patterns (lower peak VO2 and exercise oscillatory ventilation) and echo-derived measures (higher left atrium size and left ventricle mass) that may well anticipate evolution toward heart failure.


Mathematics ◽  
2020 ◽  
Vol 8 (8) ◽  
pp. 1205
Author(s):  
Timur Gamilov ◽  
Philipp Kopylov ◽  
Maria Serova ◽  
Roman Syunyaev ◽  
Andrey Pikunov ◽  
...  

In this work we present a one-dimensional (1D) mathematical model of the coronary circulation and use it to study the effects of arrhythmias on coronary blood flow (CBF). Hydrodynamical models are rarely used to study arrhythmias’ effects on CBF. Our model accounts for action potential duration, which updates the length of systole depending on the heart rate. It also includes dependency of stroke volume on heart rate, which is based on clinical data. We apply the new methodology to the computational evaluation of CBF during interventricular asynchrony due to cardiac pacing and some types of arrhythmias including tachycardia, bradycardia, long QT syndrome and premature ventricular contraction (bigeminy, trigeminy, quadrigeminy). We find that CBF can be significantly affected by arrhythmias. CBF at rest (60 bpm) is 26% lower in LCA and 22% lower in RCA for long QT syndrome. During bigeminy, trigeminy and quadrigeminy, respectively, CBF decreases by 28%, 19% and 14% with respect to a healthy case.


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