scholarly journals Exponential Hyperbolic Sine Function Fitting of Heart Rate Response to Constant Load Exercise.

2000 ◽  
Vol 50 (4) ◽  
pp. 405-412 ◽  
Author(s):  
Jun Mizuo ◽  
Takaaki Nakatsu ◽  
Takashi Murakami ◽  
Shozo Kusachi ◽  
Youkou Tominaga ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heart Rate Response ◽  
Constant Load ◽  
Sine Function ◽  
Function Fitting ◽  
Hyperbolic Sine ◽  
Hyperbolic Sine Function ◽  
Constant Load Exercise

Greater Exercise Pressor Response Is Associated With Impaired Claudication Outcomes in Symptomatic Peripheral Artery Disease

Angiology ◽  
2018 ◽  
Vol 70 (3) ◽  
pp. 220-228 ◽  
Author(s):  
Andrew W. Gardner ◽  
Polly S. Montgomery ◽  
Ming Wang ◽  
Chixiang Chen ◽  
Marcos Kuroki ◽  
...  
Keyword(s):  
Heart Rate ◽  
Peripheral Artery Disease ◽  
Pressor Response ◽  
Constant Load ◽  
Rate Pressure Product ◽  
Treadmill Test ◽  
Peripheral Artery ◽  
Negatively Associated ◽  
Artery Disease ◽  
Constant Load Exercise

We determined whether a greater exercise pressor response during a constant-load treadmill test was associated with lower peak walking time (PWT) and claudication onset time (COT) measured during a graded maximal treadmill test in 304 patients with symptomatic peripheral artery disease (PAD). The exercise pressor response was assessed by measuring heart rate and blood pressure (BP) at rest and during a constant-load treadmill test (speed = 2 mph, grade = 0%). After only 2 minutes of walking, mean heart rate increased by 26 beats/min from rest and mean systolic BP increased by 16 mm Hg. In adjusted analyses, increases in systolic BP ( P = .021), heart rate ( P = .002), mean arterial pressure ( P = .034), and rate–pressure product ( P < .001) from rest to 2 minutes of constant-load exercise were negatively associated with COT. Similarly, increases in heart rate ( P = .012) and rate–pressure product ( P = .018) from rest to 2 minutes of constant-load exercise were negatively associated with PWT. A greater exercise pressor response observed after only 2 minutes of walking at no incline was independently associated with impaired claudication outcomes in patients with symptomatic PAD. The implication is that the exercise pressor response is an important and easily obtained clinical measurement that partially explains differences in PWT and COT.

scholarly journals Effects of surgical face masks on cardiopulmonary parameters during steady state exercise

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
J. Lässing ◽  
R. Falz ◽  
C. Pökel ◽  
S. Fikenzer ◽  
U. Laufs ◽  
...  
Keyword(s):  
Heart Rate ◽  
Steady State ◽  
Airway Resistance ◽  
Perceived Exertion ◽  
Endurance Performance ◽  
Constant Load ◽  
Rating Of Perceived Exertion ◽  
Lactate Minimum ◽  
Load Tests ◽  
Constant Load Exercise

AbstractWearing face masks reduce the maximum physical performance. Sports and occupational activities are often associated with submaximal constant intensities. This prospective crossover study examined the effects of medical face masks during constant-load exercise. Fourteen healthy men (age 25.7 ± 3.5 years; height 183.8 ± 8.4 cm; weight 83.6 ± 8.4 kg) performed a lactate minimum test and a body plethysmography with and without masks. They were randomly assigned to two constant load tests at maximal lactate steady state with and without masks. The cardiopulmonary and metabolic responses were monitored using impedance cardiography and ergo-spirometry. The airway resistance was two-fold higher with the surgical mask (SM) than without the mask (SM 0.58 ± 0.16 kPa l−1 vs. control [Co] 0.32 ± 0.08 kPa l−1; p < 0.01). The constant load tests with masks compared with those without masks resulted in a significantly different ventilation (77.1 ± 9.3 l min−1 vs. 82.4 ± 10.7 l min−1; p < 0.01), oxygen uptake (33.1 ± 5 ml min−1 kg−1 vs. 34.5 ± 6 ml min−1 kg−1; p = 0.04), and heart rate (160.1 ± 11.2 bpm vs. 154.5 ± 11.4 bpm; p < 0.01). The mean cardiac output tended to be higher with a mask (28.6 ± 3.9 l min−1 vs. 25.9 ± 4.0 l min−1; p = 0.06). Similar blood pressure (177.2 ± 17.6 mmHg vs. 172.3 ± 15.8 mmHg; p = 0.33), delta lactate (4.7 ± 1.5 mmol l−1 vs. 4.3 ± 1.5 mmol l−1; p = 0.15), and rating of perceived exertion (6.9 ± 1.1 vs. 6.6 ± 1.1; p = 0.16) were observed with and without masks. Surgical face masks increase airway resistance and heart rate during steady state exercise in healthy volunteers. The perceived exertion and endurance performance were unchanged. These results may improve the assessment of wearing face masks during work and physical training.

scholarly journals Convexity of the generalized sine function and the generalized hyperbolic sine function

2013 ◽  
Vol 174 ◽  
pp. 1-9 ◽  
Author(s):  
Wei-Dong Jiang ◽  
Miao-Kun Wang ◽  
Yu-Ming Chu ◽  
Yue-Ping Jiang ◽  
Feng Qi
Keyword(s):  
Sine Function ◽  
Hyperbolic Sine ◽  
Hyperbolic Sine Function

Impression Creep of a Sn-Pb Eutectic Alloy

1994 ◽  
Vol 362 ◽  
Author(s):  
Fuqian Yang ◽  
J. C. M. Li
Keyword(s):  
Creep Rate ◽  
Eutectic Alloy ◽  
Constitutive Law ◽  
Sine Function ◽  
Impression Creep ◽  
Creep Tests ◽  
Hyperbolic Sine ◽  
Element Simulation ◽  
Shearing Mechanism ◽  
Hyperbolic Sine Function

AbstractImpression creep tests on a Sn-Pb eutectic alloy showed a hyperbolic sine stress dependence of impressing velocity and an activation energy of 55 kJ/mole which is independent of the punching stress. A finite element simulation showed that this phenomena could be explained by a constitutive law in which the creep rate is also a hyperbolic sine function of stress. This simulation also gives an impressing velocity which is proportional to the punch size for the same punching stress. Then by using lubrication theory, it is possible to relate this constitutive law to an interphase shearing mechanism in which the rate of interphase shear is a hyperbolic sine function of the shear stress. This theory gives a creep rate which depends inversely on the third power of grain size at low stresses.

scholarly journals Normobaric Hypoxia Exposure During Treadmill Aerobic Exercise After Stroke: A Safety and Feasibility Study

2021 ◽  
Vol 12 ◽  
Author(s):  
Liam P. Kelly ◽  
Fabien Andre Basset ◽  
Jason McCarthy ◽  
Michelle Ploughman
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Constant Load ◽  
Normobaric Hypoxia ◽  
Stroke Survivors ◽  
Hypoxia Exposure ◽  
Hemiparetic Stroke ◽  
Chronic Hemiparetic Stroke ◽  
Cardiovascular Strain ◽  
Constant Load Exercise

ObjectiveTo evaluate the safety and feasibility of performing treadmill aerobic exercise in moderate normobaric hypoxia among chronic hemiparetic stroke survivors.DesignObservational study using convenience sampling.SettingResearch laboratory in a tertiary rehabilitation hospital.ParticipantsChronic hemiparetic stroke survivors who could walk at least 10-m with or without assistance and had no absolute contraindications to exercise testing.InterventionParticipants (three male and four female) were asked to complete three normobaric hypoxia exposure protocols within a single session. First, they were passively exposed to normobaric hypoxia through gradual reductions in the fraction of inspired oxygen (FIO2 = 20.9, 17.0, and 15.0%) while seated (5-min at each level of FIO2). Participants were then exposed to the same reductions in FIO2 during constant-load exercise performed on a treadmill at 40% of heart rate reserve. Finally, participants completed 20-min of exercise while intermittently exposed to moderate normobaric hypoxia (5 × 2-min at FIO2 = 15.0%) interspaced with 2-min normoxia intervals (FIO2 = 20.9%).Outcome MeasuresThe primary outcome was occurrence of adverse events, which included standardized criteria for terminating exercise testing, blood oxygen saturation (SpO2) &lt;80%, or acute mountain sickness score &gt;2. The increased cardiovascular strain imposed by normobaric hypoxia exposure at rest and during exercise was evaluated by changes in SpO2, heart rate (HR), blood pressure, and rating of perceived exertion (RPE).ResultsOne participant reported mild symptoms of nausea during exercise in normobaric hypoxia and discontinued participation. No other adverse events were recorded. Intermittent normobaric hypoxia exposure was associated with reduced SpO2 (MD = −7.4%, CI: −9.8 to −5.0) and increased HR (MD = 8.2, CI: 4.6 to 11.7) compared to intervals while breathing typical room air throughout the 20-min constant-load exercise period. The increase in HR was associated with a 10% increase in relative effort. However, reducing FIO2 had little effect on blood pressure and RPE measurements.ConclusionModerate normobaric hypoxia appeared to be a safe and feasible method to increase the cardiovascular strain of submaximal exercise in chronic hemiparetic stroke survivors. Future studies evaluating the effects of pairing normobaric hypoxia exposure with existing therapies on secondary prevention and functional recovery are warranted.

scholarly journals Ventilatory and chronotropic incompetence during incremental and constant load exercise in end-stage renal disease: a comparative physiology study

2020 ◽  
Vol 319 (3) ◽  
pp. F515-F522
Author(s):  
S. McGuire ◽  
E. J. Horton ◽  
D. Renshaw ◽  
K. Chan ◽  
N. Krishnan ◽  
...  
Keyword(s):  
Heart Rate ◽  
Renal Disease ◽  
End Stage Renal Disease ◽  
Constant Load ◽  
Left Ventricular ◽  
Exercise Intolerance ◽  
Chronotropic Incompetence ◽  
Stage Renal Disease ◽  
End Stage ◽  
Constant Load Exercise

Maximal O2 uptake is impaired in end-stage renal disease (ESRD), reducing quality of life and longevity. While determinants of maximal exercise intolerance are well defined, little is known of limitation during submaximal constant load exercise. By comparing individuals with ESRD and healthy controls, the aim of this exploratory study was to characterize mechanisms of exercise intolerance in participants with ESRD by assessing cardiopulmonary physiology at rest and during exercise. Resting spirometry and echocardiography were performed in 20 dialysis-dependent participants with ESRD (age: 59 ± 12 yr, 14 men and 6 women) and 20 healthy age- and sex-matched controls. Exercise tolerance was assessed with ventilatory gas exchange and central hemodynamics during a maximal cardiopulmonary exercise test and 30 min of submaximal constant load exercise. Left ventricular mass (292 ± 102 vs. 185 ± 83 g, P = 0.01) and filling pressure ( E/ e′: 6.48 ± 3.57 vs. 12.09 ± 6.50 m/s, P = 0.02) were higher in participants with ESRD; forced vital capacity (3.44 ± 1 vs. 4.29 ± 0.95 L/min, P = 0.03) and peak O2 uptake (13.3 ± 2.7 vs. 24.6 ± 7.3 mL·kg−1·min−1, P < 0.001) were lower. During constant load exercise, the relative increase in the arterial-venous O2 difference (13 ± 18% vs. 74 ± 18%) and heart rate (32 ± 18 vs. 75 ± 29%) were less in participants with ESRD despite exercise being performed at a higher percentage of maximum minute ventilation (48 ± 3% vs. 39 ± 3%) and heart rate (82 ± 2 vs. 64 ± 2%). Ventilatory and chronotropic incompetence contribute to exercise intolerance in individuals with ESRD. Both are potential targets for medical and lifestyle interventions.

Heart rate kinetics during exercise in patients with subclinical hypothyroidism

2017 ◽  
Vol 122 (4) ◽  
pp. 893-898 ◽  
Author(s):  
Saulo Peters Almas ◽  
Francisco Zacaron Werneck ◽  
Emerson Filipino Coelho ◽  
Patrícia de Fátima dos Santos Teixeira ◽  
Mario Vaisman
Keyword(s):  
Physical Activity ◽  
Heart Rate ◽  
Subclinical Hypothyroidism ◽  
Menopausal Status ◽  
Constant Load ◽  
Control Group ◽  
Subjective Perception ◽  
Rate Kinetics ◽  
Heart Rate Kinetics ◽  
Constant Load Exercise

Studies suggest that patients with subclinical hypothyroidism (SH) have sympathovagal imbalance, which could lead to a slower heart rate (HR) response in the transition from rest to exercise. Thus the objective of this study was to investigate the behavior of the HR kinetics in patients with SH during the transition from rest to exercise. The study included 18 SH women [thyroid stimulating hormone (TSH) = 6.95 ± 2.94 μIU/ml and free thyroxine (FT4) = 0.96 ± 0.15 ng/dl] and 17 euthyroid women (TSH = 2.28 ± 0.84 μIU/ml and FT4 = 0.98 ± 0.07 ng/dl). Both groups were matched for physical activity, menopausal status, and age. The HR kinetics was obtained during the course of a constant-load exercise (50 W), for 6 min, in a cycle ergometer, and quantified from the mean response time (MRT), which is equivalent to the time taken to reach 63% of the HR at steady state. SH patients showed slower HR kinetics than the control group (MRT = 48.5 ± 17.6 vs. 36.0 ± 10.3 s, P = 0.015). The MRT has been shown to correlate with the level of physical activity ( r = −0.361; P = 0.033) and with the subjective perception of exertion at the end of the exercise ( r = 0.365; P = 0.031). It is concluded that SH patients have slower HR kinetics in the transition from rest to exercise compared with euthyroid women, with this impairment being associated with lower levels of physical activity. NEW & NOTEWORTHY Subclinical hypothyroidism patients have slower heart rate kinetics in the transition from rest to exercise when performing a constant-load exercise at 50 W.

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