Cardiorespiratory Responses to Intermittent Exercise and Relaxation as Compared with Continuous Exercise

Cardiorespiratory responses to intermittent exercise and relaxation were comparable to cardiorespiratory responses to continuous exercise. The time of workout and work loads were kept constant in both protocols. Even though in the intermittent exercise and relaxation protocol the 10 subjects rested nearly two-thirds of the duration of the workout, cardiorespiratory responses were similar to those which the same subjects attained while exercising continuously throughout the entire steady state workout at approximately 64% maximal heart rate.

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Contractile parameters and occurrence of alternans in isolated rat myocardium at supra-physiological stimulation frequency

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.01004.2011 ◽

2012 ◽

Vol 302 (11) ◽

pp. H2267-H2275 ◽

Cited By ~ 6

Author(s):

Jessica L. Slabaugh ◽

Lucia Brunello ◽

Sandor Gyorke ◽

Paul M. L. Janssen

Keyword(s):

Heart Rate ◽

Steady State ◽

Refractory Period ◽

Striated Muscle ◽

Stable Steady State ◽

Maximal Heart Rate ◽

Force Frequency ◽

Mechanical Instability ◽

Continuous Increase

The cardiac refractory period prevents the heart from tetanic activation that is typically used in noncardiac striated muscle tissue. To what extent the refractory period prevents successive action potentials to activate the excitation-contraction coupling process and contractile machinery at supra-physiological rates, such as those present during ventricular fibrillation, is unknown. Using multicellular trabeculae isolated from rat hearts, we studied amplitude and kinetics of contraction at rates well above the normal in vivo rat heart range. We show that even at twice the maximal heart rate of the rat, little or no mechanical instability is observed; twitch contractions are at steady state, albeit with an elevated active diastolic force. Although the amplitude of contraction increased within in vivo heart rates (positive force-frequency response), at frequencies beyond the maximal heart rate (10–30 Hz) a steady decline of contractile amplitude is observed. Not until 30 Hz do the majority of the isolated muscle preparations show mechanical alternans, where strong and weak beats alternate. Interestingly, unlike striated limb skeletal muscle, fusing of twitch contractions did not cause a continuous increase in peak force: at frequencies of 10 Hz and above, systolic force declines with relatively little elevation in diastolic force. Contractile kinetics continued to accelerate, from 1 Hz up to 30 Hz, whereas the relative speed of contraction and relaxation remained closely coupled, reflected by a singular linear relationship between the maximal and minimal derivative of force (dF/d t). We conclude that cardiac muscle can produce mechanically stable steady-state contractions at supra-physiological pacing rates, while these contractions continue to decline in amplitude and increase in diastolic force past maximal heart rate.

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Time to exhaustion at intermittent maximal lactate steady state is longer than continuous cycling exercise

Applied Physiology Nutrition and Metabolism ◽

10.1139/h2012-088 ◽

2012 ◽

Vol 37 (6) ◽

pp. 1047-1053 ◽

Cited By ~ 7

Author(s):

Talita Grossl ◽

Ricardo Dantas de Lucas ◽

Kristopher Mendes de Souza ◽

Luiz Guilherme Antonacci Guglielmo

Keyword(s):

Steady State ◽

Endurance Training ◽

Intermittent Exercise ◽

Cycle Ergometer ◽

Time To Exhaustion ◽

Maximal Lactate Steady State ◽

Continuous Exercise ◽

Physiological Variables ◽

Metabolic Variables ◽

Work Done

The maximal lactate steady state (MLSS) represents a submaximal intensity that may be important in prescribing both continuous and interval endurance training. This study compared time to exhaustion (TTE) at MLSS in continuous and intermittent (i.e., with pauses) exercise, investigating whether physiological variables differ between these exercise modes. Fourteen trained male cyclists volunteered for this investigation and performed an incremental test, several 30-min tests to determine two MLSS intensities (continuous and discontinuous protocol), and two randomized tests until exhaustion at MLSS intensities on a cycle ergometer. The intermittent or discontinuous protocol was performed using 5 min of cycling, with an interval of 1 min of passive rest. TTE at intermittent MLSS was 24% longer than TTE at continuous exercise (67.8 ± 14.3 min vs. 54.7 ± 10.9 min; p < 0.05; effect sizes = 1.04), even though the absolute power output of intermittent MLSS was higher than continuous (268 ± 29 W vs. 251 ± 29 W; p < 0.05). Additionally, the total mechanical work done was significantly lower at continuous exercise than at intermittent exercise. Likewise, regarding cardiorespiratory and metabolic variables, we observed greater responses during intermittent exercise than during continuous exercise at MLSS. Thus, for endurance training prescription, this is an important finding to apply in extensive interval sessions at MLSS. This result suggests that interval sessions at discontinuous MLSS should be used instead of continuous MLSS, as discontinuous MLSS allows for a larger amount of total work during the exhaustion trial.

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Predicting Maximal Lactate Steady State from Carminatti’s Shuttle Run Test in Soccer Players

International Journal of Sports Medicine ◽

10.1055/a-1224-3985 ◽

2020 ◽

Cited By ~ 1

Author(s):

Lorival José Carminatti ◽

Bruna Nunes Batista ◽

Juliano Fernandes da Silva ◽

Artur Ferreira Tramontin ◽

Vitor Pereira Costa ◽

...

Keyword(s):

Heart Rate ◽

Steady State ◽

Soccer Players ◽

Maximal Heart Rate ◽

Maximal Lactate Steady State ◽

Incremental Test ◽

Run Test ◽

Peak Speed ◽

Linear Regressions ◽

Shuttle Run

AbstractThe objective of the present study was to determine the validity of Carminatti’s shuttle run incremental test–T-Car derived parameters in estimating the maximal lactate steady state determined in shuttle run format. Eighteen soccer players performed a T-Car test, and several trials to determine the maximal lactate steady state. From T-Car were derived the heart rate deflection point, peak speed, maximal heart rate and parameters resulting from percentage of peak measures. The validity was accessed by Bland-Altman plots, linear regressions, and two one-sided tests of equivalence analysis. The results showed the speed at 80.4% of T-Car peak speed, the heart rate deflection point and the 91.4% of maximal heart rate were equivalent to maximal lactate steady state (Mean difference; ±90% compatibility interval; −0.8; ±1.5%, −0.4; ±1.1%, and 0.0; ±2.7%, respectively). Additionally, peak speed during the T-Car test was a stronger predictor of maximal lactate steady state (MLSS [km/h]=2.57+0.65 × sPeak; r=0.82 [90% CI; 0.62–0.92], standard error of the estimate=3.6%; 90% CI ×/÷1.4). Therefore, soccer players can use the T-Car derived parameters as a noninvasive and practical alternative to estimate the specific maximal lactate steady state for soccer.

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Aerobic Capacity of Elderly People after a Short 6-week Intermittent Exercise Programme

Clinical & Investigative Medicine ◽

10.25011/cim.v30i3.1720 ◽

2007 ◽

Vol 30 (3) ◽

pp. 27

Author(s):

Evelyne Lonsdorfer-Wolf ◽

Stéphane Doutreleau ◽

Ruddy Richard ◽

Bernard Geny ◽

Jean Lonsdorfer

Keyword(s):

Heart Rate ◽

Aerobic Capacity ◽

Exercise Test ◽

Ventilatory Threshold ◽

Intermittent Exercise ◽

Exercise Programme ◽

Incremental Exercise ◽

Peak Oxygen Consumption ◽

Maximal Heart Rate ◽

Incremental Exercise Test

Background: One of the most debilitating effects of advancing age is the progressive decline in aerobic exercise capacity. To prevent this decrease, exercise prescription has been proved to be effective in compensating for the age-associated decline in maximal oxygen capacity. Methods: 27 healthy sedentary elderly men (10) and women (17) aged 67±7 yr, were involved in a tailored 6-week intermittent exercise programme, with 30 min cycling per session, 3 times a week. One session alternated 4 min at a workload corresponding to the ventilatory threshold (called “bases”) and 1 min to a charge corresponding to 90% of the maximum tolerated power of the subjects (called “peaks”). This was repeated 6 times during one session. To determine these charges, all subjects underwent a 1-minute-step maximal incremental exercise test to find out their maximal tolerated power, peak oxygen consumption (VO2peak), maximal heart rate, and maximal lactate. A second maximal incremental exercise test was performed after the programme, to compare the different parameters. Results: For the whole group, maximal tolerated power increased from 113±8 watts to 13±9 watts (P < 0.001), VO2 peak increased from 19.8±0.9 ml·kg-1·min-1 to 22.2 ±0.9 ml·kg-1·min-1 (P=0.002), maximal heart rate (143±4 vs 144±4 beats·min-1) and maximal lactate (5.4±0.3 vs 5.7±0.3 mmol·L-1) did not change. VO2 at ventilatory threshold increased from 950±57 ml·min-1 to 1095±69 ml·min-1 (P=0.007), and the corresponding power increased from 65±5 watts to 82±6 watts (P < 0.001). Conclusions: Even after a short time training programme (6 weeks), we observed a significant improvement in aerobic capacity, and especially in sub-maximal workloads, which represented, for these subjects, their daily-life capacity.

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Acute Effects of High-Intensity Interval and Moderate-Intensity Continuous Exercise on GLP-1, Appetite and Energy Intake in Obese Men: A Crossover Trial

Nutrients ◽

10.3390/nu10070889 ◽

2018 ◽

Vol 10 (7) ◽

pp. 889 ◽

Cited By ~ 8

Author(s):

Victor Matos ◽

Daniel Souza ◽

Victor Santos ◽

Ítalo Medeiros ◽

Rodrigo Browne ◽

...

Keyword(s):

Heart Rate ◽

Energy Intake ◽

High Intensity ◽

Crossover Trial ◽

Moderate Intensity ◽

Maximal Heart Rate ◽

Post Exercise ◽

Continuous Exercise ◽

Glucagon Like Peptide 1 ◽

High Intensity Interval

This study investigated the effect of high-intensity interval (HIIE) and moderate-intensity continuous exercise (MICE) on glucagon-like peptide 1 (GLP-1), appetite and energy intake (EI) in obese men. In a randomized crossover trial, 12 participants (28.4 ± 2.6 years, 35.5 ± 4.5 kg/m2, 39.8 ± 2.2% body fat) performed: (I) Control (CON, no exercise); (II) MICE (20 min, 70% of maximal heart rate) and (III) HIIE (10 × 1 min at 90% of maximal heart rate with 1 min recovery). GLP-1 and appetite were assessed at: (I) PRE: pre-exercise; (II) POST: immediately post-exercise; (III) POST-1 h: 1 h post-exercise. EI was assessed after an ad libitum meal offered 1 h post-exercise and over 24 h. There was a significant time × condition interaction for GLP-1 (p = 0.035). Higher GLP-1 levels in MICE vs. CON (p = 0.024) and a trend for HIIE vs. CON (p = 0.069) POST-1h was found. Hunger was reduced immediately post-HIIE compared to CON (p < 0.01), but was not sustained POST-1 h (p > 0.05). EI did not differ between the sessions 1 h post-exercise or over 24H (p > 0.05). In summary, although MICE increased GLP-1 levels POST-1h and HIIE induced a transient reduction in hunger, both exercise protocols did not impact EI in obese men.

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Estimation of cardiovascular drift through ear temperature during prolonged steady-state cycling: a study protocol

BMJ Open Sport & Exercise Medicine ◽

10.1136/bmjsem-2020-000907 ◽

2021 ◽

Vol 7 (1) ◽

pp. e000907

Author(s):

Giovanni Polsinelli ◽

Angelo Rodio ◽

Bruno Federico

Keyword(s):

Heart Rate ◽

Steady State ◽

Body Temperature ◽

Study Protocol ◽

External Auditory Canal ◽

Exercise Intensity ◽

Core Body Temperature ◽

Cardiovascular Drift ◽

Core Body ◽

Steady State Cycling

IntroductionThe measurement of heart rate is commonly used to estimate exercise intensity. However, during endurance performance, the relationship between heart rate and oxygen consumption may be compromised by cardiovascular drift. This physiological phenomenon mainly consists of a time-dependent increase in heart rate and decrease in systolic volume and may lead to overestimate absolute exercise intensity in prediction models based on heart rate. Previous research has established that cardiovascular drift is correlated to the increase in core body temperature during prolonged exercise. Therefore, monitoring body temperature during exercise may allow to quantify the increase in heart rate attributable to cardiovascular drift and to improve the estimate of absolute exercise intensity. Monitoring core body temperature during exercise may be invasive or inappropriate, but the external auditory canal is an easily accessible alternative site for temperature measurement.Methods and analysisThis study aims to assess the degree of correlation between trends in heart rate and in ear temperature during 120 min of steady-state cycling with intensity of 59% of heart rate reserve in a thermally neutral indoor environment. Ear temperature will be monitored both at the external auditory canal level with a contact probe and at the tympanic level with a professional infrared thermometer.Ethics and disseminationThe study protocol was approved by an independent ethics committee. The results will be submitted for publication in academic journals and disseminated to stakeholders through summary documents and information meetings.

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Exercise chronotropic incompetence phenotypes the level of cardiovascular risk and exercise gas exchange impairment in the general population. An analysis of the Euro-EX prevention trial

European Journal of Preventive Cardiology ◽

10.1177/2047487319863506 ◽

2019 ◽

Vol 27 (5) ◽

pp. 526-535 ◽

Cited By ~ 2

Author(s):

Pietro Laforgia ◽

Francesco Bandera ◽

Eleonora Alfonzetti ◽

Marco Guazzi

Keyword(s):

Heart Rate ◽

Cardiovascular Risk ◽

Gas Exchange ◽

Left Ventricular ◽

Prevention Trial ◽

Volume Index ◽

Maximal Heart Rate ◽

Heart Rate Reserve ◽

Peak Heart Rate ◽

Apparently Healthy

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.

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