scholarly journals Effect of increased inspiratory muscle work on blood flow to inactive and active limbs during submaximal dynamic exercise

2018 ◽  
Author(s):  
Keisho Katayama ◽  
Kanako Goto ◽  
Kaori Shimizu ◽  
Mitsuru Saito ◽  
Koji Ishida ◽  
...  
Keyword(s):  
Blood Flow ◽  
Dynamic Exercise ◽  
Inspiratory Muscle ◽  
Muscle Work

Effects of respiratory muscle work on cardiac output and its distribution during maximal exercise

1998 ◽  
Vol 85 (2) ◽  
pp. 609-618 ◽  
Author(s):  
Craig A. Harms ◽  
Thomas J. Wetter ◽  
Steven R. McClaran ◽  
David F. Pegelow ◽  
Glenn A. Nickele ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Respiratory Muscle ◽  
Maximal Exercise ◽  
Work Of Breathing ◽  
Venous Blood ◽  
Inspiratory Muscle ◽  
Mixed Venous Blood ◽  
Muscle Work ◽  
Mixed Venous

We have recently demonstrated that changes in the work of breathing during maximal exercise affect leg blood flow and leg vascular conductance (C. A. Harms, M. A. Babcock, S. R. McClaran, D. F. Pegelow, G. A. Nickele, W. B. Nelson, and J. A. Dempsey. J. Appl. Physiol. 82: 1573–1583, 1997). Our present study examined the effects of changes in the work of breathing on cardiac output (CO) during maximal exercise. Eight male cyclists [maximal O2 consumption (V˙o 2 max): 62 ± 5 ml ⋅ kg−1 ⋅ min−1] performed repeated 2.5-min bouts of cycle exercise atV˙o 2 max. Inspiratory muscle work was either 1) at control levels [inspiratory esophageal pressure (Pes): −27.8 ± 0.6 cmH2O], 2) reduced via a proportional-assist ventilator (Pes: −16.3 ± 0.5 cmH2O), or 3) increased via resistive loads (Pes: −35.6 ± 0.8 cmH2O). O2 contents measured in arterial and mixed venous blood were used to calculate CO via the direct Fick method. Stroke volume, CO, and pulmonary O2 consumption (V˙o 2) were not different ( P > 0.05) between control and loaded trials atV˙o 2 max but were lower (−8, −9, and −7%, respectively) than control with inspiratory muscle unloading atV˙o 2 max. The arterial-mixed venous O2difference was unchanged with unloading or loading. We combined these findings with our recent study to show that the respiratory muscle work normally expended during maximal exercise has two significant effects on the cardiovascular system: 1) up to 14–16% of the CO is directed to the respiratory muscles; and 2) local reflex vasoconstriction significantly compromises blood flow to leg locomotor muscles.

scholarly journals Fatiguing inspiratory muscle work causes reflex reduction in resting leg blood flow in humans

2001 ◽  
Vol 537 (1) ◽  
pp. 277-289 ◽  
Author(s):  
A. William Sheel ◽  
P. Alexander Derchak ◽  
Barbara J. Morgan ◽  
David F. Pegelow ◽  
Anthony J. Jacques ◽  
...  
Keyword(s):  
Blood Flow ◽  
Inspiratory Muscle ◽  
Leg Blood Flow ◽  
Muscle Work

Retrobulbar blood flow and ophthalmic perfusion in maximum dynamic exercise

2008 ◽  
Vol 36 (2) ◽  
pp. 123-129 ◽  
Author(s):  
Vassilios P Kozobolis ◽  
Efstathios T Detorakis ◽  
Anastasios G Konstas ◽  
Athanassios K Achtaropoulos ◽  
Evangelos D Diamandides
Keyword(s):  
Blood Flow ◽  
Dynamic Exercise ◽  
Retrobulbar Blood Flow

Ultrasound Doppler estimates of femoral artery blood flow during dynamic knee extensor exercise in humans

1997 ◽  
Vol 83 (4) ◽  
pp. 1383-1388 ◽  
Author(s):  
G. Rådegran
Keyword(s):  
Blood Flow ◽  
Femoral Artery ◽  
Coefficient Of Variation ◽  
Knee Extensor ◽  
Dynamic Exercise ◽  
Artery Blood Flow ◽  
Ultrasound Doppler ◽  
Femoral Artery Blood Flow ◽  
Human Limb ◽  
Exercise In Humans

Rådegran, G. Ultrasound Doppler estimates of femoral artery blood flow during dynamic knee extensor exercise in humans. J. Appl. Physiol.83(4): 1383–1388, 1997.—Ultrasound Doppler has been used to measure arterial inflow to a human limb during intermittent static contractions. The technique, however, has neither been thoroughly validated nor used during dynamic exercise. In this study, the inherent problems of the technique have been addressed, and the accuracy was improved by storing the velocity tracings continuously and calculating the flow in relation to the muscle contraction-relaxation phases. The femoral arterial diameter measurements were reproducible with a mean coefficient of variation within the subjects of 1.2 ± 0.2%. The diameter was the same whether the probe was fixed or repositioned at rest (10.8 ± 0.2 mm) or measured during dynamic exercise. The blood velocity was sampled over the width of the diameter and the parabolic velocity profile, since sampling in the center resulted in an overestimation by 22.6 ± 9.1% ( P< 0.02). The femoral arterial Doppler blood flow increased linearly ( r = 0.997, P < 0.001) with increasing load [Doppler blood flow = 0.080 ⋅ load (W) + 1.446 l/min] and was correlated positively with simultaneous thermodilution venous outflow measurements ( r = 0.996, P < 0.001). The two techniques were linearly related (Doppler = thermodilution ⋅ 0.985 + 0.071 l/min; r = 0.996, P < 0.001), with a coefficient of variation of ∼6% for both methods.

scholarly journals Exercise-induced hyperemia is associated with knee extensor fatigability in adults with type 2 diabetes

2019 ◽  
Vol 126 (3) ◽  
pp. 658-667 ◽  
Author(s):  
Jonathon W. Senefeld ◽  
Jacqueline K. Limberg ◽  
Kathleen M. Lukaszewicz ◽  
Sandra K. Hunter
Keyword(s):  
Type 2 Diabetes ◽  
Blood Flow ◽  
Lower Limb ◽  
Contractile Function ◽  
Muscle Blood Flow ◽  
Knee Extensor ◽  
Dynamic Exercise ◽  
Extensor Muscles ◽  
Exercise Induced

The aim of this study was to compare fatigability, contractile function, and blood flow to the knee extensor muscles after dynamic exercise in patients with type 2 diabetes mellitus (T2DM) and controls. The hypotheses were that patients with T2DM would demonstrate greater fatigability than controls, and greater fatigability would be associated with a lower exercise-induced increase in blood flow and greater impairments in contractile function. Patients with T2DM ( n = 15; 8 men; 62.4 ± 9.0 yr; 30.4 ± 7.7 kg/m2; 7,144 ± 3,294 steps/day) and 15 healthy control subjects (8 men, 58.4 ± 6.9 yr; 28.4 ± 4.6 kg/m2; 7,893 ± 2,323 steps/day) were matched for age, sex, body mass index, and physical activity. Fatigability was quantified as the reduction in knee extensor power during a 6-min dynamic exercise. Before and after exercise, vascular ultrasonography and electrical stimulation were used to assess skeletal muscle blood flow and contractile properties, respectively. Patients with T2DM had greater fatigability (30.0 ± 20.1% vs. 14.6 ± 19.0%, P < 0.001) and lower exercise-induced hyperemia (177 ± 90% vs. 194 ± 79%, P = 0.04) than controls but similar reductions in the electrically evoked twitch amplitude (37.6 ± 24.8% vs. 31.6 ± 30.1%, P = 0.98). Greater fatigability of the knee extensor muscles was associated with postexercise reductions in twitch amplitude ( r = 0.64, P = 0.001) and lesser exercise-induced hyperemia ( r = −0.56, P = 0.009). Patients with T2DM had greater lower-limb fatigability during dynamic exercise, which was associated with reduced contractile function and lower skeletal muscle blood flow. Thus, treatments focused on enhancing perfusion and reversing impairments in contractile function in patients with T2DM may offset lower-limb fatigability and aid in increasing exercise capacity. NEW & NOTEWORTHY Although prior studies compare patients with type 2 diabetes mellitus (T2DM) with lean controls, our study includes controls matched for age, body mass, and physical activity to more closely assess the effects of T2DM. Patients with T2DM demonstrated no impairment in macrovascular endothelial function, evidenced by similar flow-mediated dilation to controls. However, patients with T2DM had greater fatigability and reduced exercise-induced increase in blood flow (hyperemia) after a lower-limb dynamic fatiguing exercise compared with controls.

Effects of caffeine on blood pressure, heart rate, and forearm blood flow during dynamic leg exercise

1998 ◽  
Vol 85 (1) ◽  
pp. 154-159 ◽  
Author(s):  
Jason W. Daniels ◽  
Paul A. Molé ◽  
James D. Shaffrath ◽  
Charles L. Stebbins
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Blood Flow ◽  
Systolic Blood Pressure ◽  
Skin Temperature ◽  
Rectal Temperature ◽  
Forearm Blood Flow ◽  
Dynamic Exercise ◽  
Ang Ii ◽  
Leg Exercise

This study examined the acute effects of caffeine on the cardiovascular system during dynamic leg exercise. Ten trained, caffeine-naive cyclists (7 women and 3 men) were studied at rest and during bicycle ergometry before and after the ingestion of 6 mg/kg caffeine or 6 mg/kg fructose (placebo) with 250 ml of water. After consumption of caffeine or placebo, subjects either rested for 100 min (rest protocol) or rested for 45 min followed by 55 min of cycle ergometry at 65% of maximal oxygen consumption (exercise protocol). Measurement of mean arterial pressure (MAP), forearm blood flow (FBF), heart rate, skin temperature, and rectal temperature and calculation of forearm vascular conductance (FVC) were made at baseline and at 20-min intervals. Plasma ANG II was measured at baseline and at 60 min postingestion in the two exercise protocols. Before exercise, caffeine increased both systolic blood pressure (17%) and MAP (11%) without affecting FBF or FVC. During dynamic exercise, caffeine attenuated the increase in FBF (53%) and FVC (50%) and accentuated exercise-induced increases in ANG II (44%). Systolic blood pressure and MAP were also higher during exercise plus caffeine; however, these increases were secondary to the effects of caffeine on resting blood pressure. No significant differences were observed in heart rate, skin temperature, or rectal temperature. These findings indicate that caffeine can alter the cardiovascular response to dynamic exercise in a manner that may modify regional blood flow and conductance.

α-Adrenergic vasoconstriction in active skeletal muscles during dynamic exercise

1999 ◽  
Vol 277 (1) ◽  
pp. H33-H39 ◽  
Author(s):  
John B. Buckwalter ◽  
Philip S. Clifford
Keyword(s):  
Blood Flow ◽  
Exercise Intensity ◽  
Adrenergic Receptor ◽  
Skeletal Muscles ◽  
Systemic Blood Pressure ◽  
Dynamic Exercise ◽  
Iliac Arteries ◽  
Adrenergic Antagonist ◽  
Sympathetic Vasoconstriction ◽  
Adrenergic Antagonists

Sympathetic vasoconstriction in working muscles during dynamic exercise has been demonstrated by intra-arterial administration of α1-adrenergic antagonists. The purpose of this study was to examine the existence of α1- and α2-adrenergic receptor-mediated vasoconstriction in active skeletal muscles during exercise. Six mongrel dogs were instrumented chronically with flow probes on the external iliac arteries of both hindlimbs, and a catheter was inserted in one femoral artery. All dogs ran on a motorized treadmill at three exercise intensities (3 miles/h, 6 miles/h, and 6 miles/h at 10% grade) on separate days. After 5 min of exercise, a selective α1- (prazosin) or a selective α2-adrenergic antagonist (rauwolscine) was infused as a bolus into the femoral arterial catheter (only one drug per day). The doses of the antagonists were adjusted to maintain the same effective concentration at each exercise intensity. At the mild, moderate, and heavy workloads prazosin infusion produced immediate increases in iliac conductance of 65 ± 9, 35 ± 6, and 18 ± 4% (means ± SE), respectively, and increases in blood flow of 290 ± 24, 216 ± 23, and 172 ± 18 ml/min, respectively. Rauwolscine infusion produced increases in conductance of 52 ± 5%, 36 ± 5%, and 26 ± 3%, respectively, and blood flow increases of 250 ± 34, 244 ± 39, and 259 ± 35 ml/min at the three workloads. Systemic blood pressure and blood flow in the contralateral iliac artery were unaffected by any of the antagonist infusions. These results demonstrate that there is ongoing α1- and α2-adrenergic receptor-mediated vasoconstriction in exercising skeletal muscles even at heavy workloads and that the magnitude of vasoconstriction decreases as exercise intensity increases.

Nonthermoregulatory control of cutaneous vascular conductance and sweating during recovery from dynamic exercise in women

2005 ◽  
Vol 99 (5) ◽  
pp. 1816-1821 ◽  
Author(s):  
W. shane Journeay ◽  
Francis D. Reardon ◽  
Natalie H. McInnis ◽  
Glen P. Kenny
Keyword(s):  
Blood Flow ◽  
Sweat Rate ◽  
Peripheral Resistance ◽  
Dynamic Exercise ◽  
Central Command ◽  
Active Recovery ◽  
Vascular Conductance ◽  
Ergometer Exercise ◽  
Cardiopulmonary Baroreceptors ◽  
Cutaneous Vascular Conductance

The purpose of the study was to examine the effect of 1) active (loadless pedaling), 2) passive (assisted pedaling), and 3) inactive (motionless) recovery modes on mean arterial pressure (MAP), cutaneous vascular conductance (CVC), and sweat rate during recovery after 15 min of dynamic exercise in women. It was hypothesized that an active recovery mode would be most effective in attenuating the fall in MAP, CVC, and sweating during exercise recovery. Ten female subjects performed 15 min of cycle ergometer exercise at 70% of their predetermined peak oxygen consumption followed by 20 min of 1) active, 2) passive, or 3) inactive recovery. Mean skin temperature (T̄sk), esophageal temperature (Tes), skin blood flow, sweating, cardiac output (CO), stroke volume (SV), heart rate (HR), total peripheral resistance (TPR), and MAP were recorded at baseline, end exercise, and 2, 5, 8, 12, 15, and 20 min postexercise. Cutaneous vascular conductance (CVC) was calculated as the ratio of laser-Doppler blood flow to MAP. In the active recovery mode, CVC, sweat rate, MAP, CO, and SV remained elevated over inactive values ( P < 0.05). The passive mode was equally as effective as the active mode in maintaining MAP. Sweat rate was different among all modes after 12 min of recovery ( P < 0.05). TPR during active recovery remained significantly lower than during recovery in the inactive mode ( P < 0.05). No differences in either Tes or T̄sk were observed among conditions. The results indicate that CVC can be modulated by central command and possibly cardiopulmonary baroreceptors in women. However, differences in sweat rate may be influenced by factors such as central command, mechanoreceptor stimulation, or cardiopulmonary baroreceptors.

scholarly journals Inspiratory Muscle Training Improves Blood Flow to Resting and Exercising Limbs in Patients With Chronic Heart Failure

2008 ◽  
Vol 51 (17) ◽  
pp. 1663-1671 ◽  
Author(s):  
Gaspar R. Chiappa ◽  
Bruno T. Roseguini ◽  
Paulo J.C. Vieira ◽  
Cristiano N. Alves ◽  
Angela Tavares ◽  
...  
Keyword(s):  
Heart Failure ◽  
Blood Flow ◽  
Chronic Heart Failure ◽  
Inspiratory Muscle ◽  
Inspiratory Muscle Training ◽  
Muscle Training
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