Delayed vagal withdrawal slows circulatory but not oxygen uptake responses at work increase

1998 ◽  
Vol 274 (5) ◽  
pp. R1268-R1273 ◽  
Author(s):  
Naoyuki Hayashi ◽  
Ayumu Tanaka ◽  
Mutsuhisa Ishihara ◽  
Takayoshi Yoshida
Keyword(s):  
Oxygen Uptake ◽  
Cold Water ◽  
Ventilatory Threshold ◽  
Muscle Blood Flow ◽  
Cycle Ergometer ◽  
Vagal Activity ◽  
Mean Response Time ◽  
Sympathetic Vasoconstriction ◽  
Ergometer Exercise ◽  
The Face

The effect of delayed vagal activity withdrawal on cardiorespiratory responses at an increase in workload was examined. Eleven volunteers (21 ± 3 yr, 66 ± 4 kg) performed cycle ergometer exercise at a work rate corresponding to 80% of ventilatory threshold after 3 min of unloaded cycling. Facial stimulation was given by applying a vinyl bag filled with cold water (3–5°C) to the face 1 min before to 1 min after the increase in workload (S2 trial) or no stimulation was given (Nr trial). Oxygen uptake (V˙o 2), heart rate (HR), and cardiac output (Q˙) were continuously recorded in four transitions for each trial. Data were averaged for each subject and trial. Mean response time (MRT, sum of delay and time constant) was calculated with a monoexponential fitting. Facial stimulation induced acute bradycardia (−10 ± 5 beats/min in S2 trial). The MRT of HR and Q˙ was significantly longer in the S2 trials (46 ± 35 and 37 ± 23 s) than in the Nr trials (26 ± 18 and 28 ± 19 s, respectively), but no significant change inV˙o 2 MRT was shown (36 ± 7 vs. 38 ± 12 s). These findings suggest that increased vagal activity delays the central circulatory responses, which does not alter the V˙o 2 kinetics at the onset of stepwise increase in workload. The maintenance ofV˙o 2 kinetics during acute bradycardia may either reflect the fact that some intramuscular processes (such as oxidative enzyme inertia) limitV˙o 2 kinetics or alternatively that increased sympathetic vasoconstriction at some remote site defends exercising muscle blood flow.

Central and peripheral adaptations of the gas transport system to one-leg training

1981 ◽  
Vol 59 (11) ◽  
pp. 1146-1154 ◽  
Author(s):  
S. G. Thomas ◽  
D. A. Cunningham ◽  
M. J. Plyley ◽  
D. R. Boughner ◽  
R. A. Cook
Keyword(s):  
Cardiac Output ◽  
Oxygen Uptake ◽  
Endurance Training ◽  
Maximal Oxygen Uptake ◽  
Enzyme Activities ◽  
Cardiovascular Responses ◽  
Cycle Ergometer ◽  
Left Ventricular ◽  
Enzyme Analysis ◽  
Ergometer Exercise

The role of central and peripheral adaptations in the response to endurance training was examined. Changes in cardiac structure and function, oxygen extraction, and muscle enzyme activities following one-leg training were studied.Eleven subjects (eight females, three males) trained on a cycle ergometer 4 weeks with one leg (leg 1), then 4 weeks with the second leg (leg 2). Cardiovascular responses to exercise with both legs and each leg separately were evaluated at entry (T1), after 4 weeks of training (T2), and after a second 4 weeks of training (T3). Peak oxygen uptake ([Formula: see text] peak) during exercise with leg 1 (T1 to T2 increased 19.8% (P < 0.05) and during exercise with leg 2 (T2 to T3 increased 16.9% (P < 0.05). Maximal oxygen uptake with both legs increased 7.9% from T1 to T2 and 9.4% from T2 to T3 (P < 0.05). During exercise at 60% of [Formula: see text] peak, cardiac output [Formula: see text] was increased significantly only when the trained leg was exercised. [Formula: see text] increased 12.2% for leg 1 between T1 and T2 and 13.0% for leg 2 between T2 and T3 (P < 0.05). M-mode echocardiographic assessment of left ventricular internal diameter at diastole and peak velocity of circumferential fibre shortening at rest or during supine cycle ergometer exercise at T1 and T3 revealed no training induced changes in cardiac dimensions or function. Enzyme analysis of muscle biopsy samples from the vastus lateralis (At T1, T2, T3) revealed no consistent pattern of change in aerobic (malate dehydrogenase and 3-hydroxyacyl-CoA dehydrogenase) or anaerobic (phosphofructokinase, lactate dehydroginase, and creatine kinase) enzyme activities. Increases in cardiac output and maximal oxygen uptake which result from short duration endurance training can be achieved, therefore, without measurable central cardiac adaptation. The absence of echocardio-graphically determined changes in cardiac dimensions and contractility and the absence of an increase in cardiac output during exercise with the nontrained leg following training of the contralateral limb support this conclusion.

Analysis on Ventilatory Threshold and Muscle Fatigue in an Adolescent with Blindness during Cycle Ergometer Exercise

2009 ◽  
Vol 38 ◽  
pp. 709-718
Author(s):  
Dong Yup Han ◽  
Tae Beom Seo ◽  
Dong Hee Lee ◽  
Kwang Sub Byun ◽  
Il Gue Jeong ◽  
...  
Keyword(s):  
Muscle Fatigue ◽  
Ventilatory Threshold ◽  
Cycle Ergometer ◽  
Cycle Ergometer Exercise ◽  
Ergometer Exercise

Acute effects of an arginine-based supplement on neuromuscular, ventilatory, and metabolic fatigue thresholds during cycle ergometry

2015 ◽  
Vol 40 (4) ◽  
pp. 379-385 ◽  
Author(s):  
Roksana B. Zak ◽  
Clayton L. Camic ◽  
Ethan C. Hill ◽  
Molly M. Monaghan ◽  
Attila J. Kovacs ◽  
...  
Keyword(s):  
Oxygen Uptake ◽  
Ventilatory Threshold ◽  
Grape Seed ◽  
Peak Oxygen Uptake ◽  
Cycle Ergometer ◽  
Cycle Ergometry ◽  
Fatigue Threshold ◽  
Incremental Test ◽  
Paired Samples ◽  
Mean Differences

The purpose of the present study was to examine the effects of an acute dose of an arginine-based supplement on the physical working capacity at the fatigue threshold (PWCFT), lactate threshold (LT), ventilatory threshold (VT), and peak oxygen uptake during incremental cycle ergometry. This study used a double-blinded, placebo-controlled, within-subjects crossover design. Nineteen untrained men (mean age ± SD = 22.0 ± 1.7 years) were randomly assigned to ingest either the supplement (3.0 g of arginine, 300 mg of grape seed extract, and 300 mg of polyethylene glycol) or placebo (microcrystalline cellulose) and performed an incremental test on a cycle ergometer for determination of PWCFT, LT, VT, and peak oxygen uptake. Following a 1-week period, the subjects returned to the laboratory and ingested the opposite substance (either supplement or placebo) prior to completing another incremental test to be reassessed for PWCFT, LT, VT, and peak oxygen uptake. The paired-samples t tests indicated there were significant (P < 0.05) mean differences between the arginine and placebo conditions for the PWCFT (192 ± 42 vs. 168 ± 53 W, respectively) and VT (2546 ± 313 vs. 2452 ± 342 mL·min−1), but not the LT (135 ± 26 vs. 138 ± 22 W), absolute peak oxygen uptake (3663 ± 445 vs. 3645 ± 438 mL·min−1), or relative peak oxygen uptake (46.5 ± 6.0 vs. 46.2 ± 5.0 mL·kg−1·min−1). These findings suggested that the arginine-based supplement may be used on an acute basis for delaying the onset of neuromuscular fatigue (i.e., PWCFT) and improving the VT in untrained individuals.

scholarly journals Effects of music, video, and 360‐degree video on cycle ergometer exercise at the ventilatory threshold

2019 ◽  
Vol 29 (8) ◽  
pp. 1161-1173 ◽  
Author(s):  
Jonathan M. Bird ◽  
Costas I. Karageorghis ◽  
Steven J. Baker ◽  
David A. Brookes
Keyword(s):  
Ventilatory Threshold ◽  
Cycle Ergometer ◽  
Music Video ◽  
Cycle Ergometer Exercise ◽  
Ergometer Exercise

O2 uptake kinetics after acetazolamide administration during moderate- and heavy-intensity exercise

1998 ◽  
Vol 85 (4) ◽  
pp. 1384-1393 ◽  
Author(s):  
Barry W. Scheuermann ◽  
John M. Kowalchuk ◽  
Donald H. Paterson ◽  
David A. Cunningham
Keyword(s):  
Energy Demand ◽  
Ventilatory Threshold ◽  
Venous Blood ◽  
Lactate Concentration ◽  
Exponential Model ◽  
Constant Load ◽  
Cycle Ergometer ◽  
Work Rate ◽  
Ergometer Exercise ◽  
Single Response

Inhibition of carbonic anhydrase (CA) is associated with a lower plasma lactate concentration ([La−]pl) during fatiguing exercise. We hypothesized that a lower [La−]plmay be associated with faster O2uptake (V˙o 2) kinetics during constant-load exercise. Seven men performed cycle ergometer exercise during control (Con) and acute CA inhibition with acetazolamide (Acz, 10 mg/kg body wt iv). On 6 separate days, each subject performed 6-min step transitions in work rate from 0 to 100 W (below ventilatory threshold, <V˙eT) or to a V˙o 2 corresponding to ∼50% of the difference between the work rate atV˙eT and peakV˙o 2(>V˙eT). Gas exchange was measured breath by breath. Trials were interpolated at 1-s intervals and ensemble averaged to yield a single response. The mean response time (MRT, i.e., time to 63% of total exponential increase) for on- and off-transients was determined using a two- (<V˙eT) or a three-component exponential model (>V˙eT). Arterialized venous blood was sampled from a dorsal hand vein and analyzed for [La−]pl. MRT was similar during Con (31.2 ± 2.6 and 32.7 ± 1.2 s for on and off, respectively) and Acz (30.9 ± 3.0 and 31.4 ± 1.5 s for on and off, respectively) for work rates <V˙eT. At work rates >V˙eT, MRT was similar between Con (69.1 ± 6.1 and 50.4 ± 3.5 s for on and off, respectively) and Acz (69.7 ± 5.9 and 53.8 ± 3.8 s for on and off, respectively). On- and off-MRTs were slower for >V˙eT than for <V˙eT exercise. [La−]plincreased above 0-W cycling values during <V˙eT and >V˙eT exercise but was lower at the end of the transition during Acz (1.4 ± 0.2 and 7.1 ± 0.5 mmol/l for <V˙eT and >V˙eT, respectively) than during Con (2.0 ± 0.2 and 9.8 ± 0.9 mmol/l for <V˙eT and >V˙eT, respectively). CA inhibition does not affect O2 utilization at the onset of <V˙eT or >V˙eT exercise, suggesting that the contribution of oxidative phosphorylation to the energy demand is not affected by acute CA inhibition with Acz.

Impeding O2 unloading in muscle delays oxygen uptake response to exercise onset in humans

1999 ◽  
Vol 277 (5) ◽  
pp. R1274-R1281 ◽  
Author(s):  
Naoyuki Hayashi ◽  
Mutsuhisa Ishihara ◽  
Ayumu Tanaka ◽  
Takayoshi Yoshida
Keyword(s):  
Oxygen Uptake ◽  
Time Constant ◽  
Ventilatory Threshold ◽  
Oxygen Dissociation Curve ◽  
Dissociation Curve ◽  
Leftward Shift ◽  
Oxygen Dissociation ◽  
Significant Difference ◽  
Ergometer Exercise ◽  
Exercise Onset

We tested whether the leftward shift of the oxygen dissociation curve of hemoglobin with hyperpnea delays the oxygen uptake (V˙o 2) response to the onset of exercise. Six male subjects performed cycle ergometer exercise at a work rate corresponding to 80% of the ventilatory threshold (VT) V˙o 2 of each individual after 3 min of 20-W cycling under eupnea [control (Con) trial]. A hyperpnea procedure (minute ventilation = 60 l/min) was undertaken for 2 min before and during 80% VT exercise in hypocapnia (Hypo) and normocapnia (Normo) trials. In the Normo trial, the inspired CO2 fraction was 3% to prevent hypocapnia. The subjects completed two repetitions of each trial. To determine the kinetic variables ofV˙o 2 and heart rate (HR) at the onset of exercise, a nonlinear least-squares fitting was applied to the data averaged from two repetitions by a monoexponential model. The end-tidal CO2 partial pressure before the onset of exercise was significantly lower in the Hypo trial than in the Con and Normo trials (22 ± 1 vs. 38 ± 3 and 36 ± 1 mmHg, respectively, P < 0.05). The time constant ofV˙o 2 and HR was significantly longer in the Normo trial (28 ± 7 and 39 ± 18 s, respectively) than in the Con trial (21 ± 7, 34 ± 16 s, respectively, P < 0.05). TheV˙o 2 time constant of the Hypo trial (37 ± 12 s) was significantly longer than that of the Normo trial, although no significant difference in the HR time constant was seen (Hypo, 41 ± 28 s). These findings suggested that respiratory alkalosis delayed the kinetics of oxygen diffusion in active muscle as a result of the leftward shift of the oxygen dissociation curve of hemoglobin. This supports an important role for hemoglobin-O2 offloading in setting the V˙o 2 kinetics at exercise onset.

scholarly journals Oxygen uptake as related to work rate increment during cycle ergometer exercise

1988 ◽  
Vol 57 (2) ◽  
pp. 140-145 ◽  
Author(s):  
James E. Hansen ◽  
Richard Casaburi ◽  
Dan M. Cooper ◽  
Karlman Wasserman
Keyword(s):  
Oxygen Uptake ◽  
Cycle Ergometer ◽  
Work Rate ◽  
Cycle Ergometer Exercise ◽  
Ergometer Exercise
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