Eur J Appl Physiol (1992) 65:94-98
European
oum.,A p p l i e d Physiology and Occupational Physiology © Springer-Verlag1992
Venous responses to rhythmic exercise in contralateral forearm and calf Daniel A. Duprez, Marc De Buyzere, Johan M. De Sutter, Sophie A. Deman, Nicole Y. De Pue, and Denis L. Clement Department of Cardiology-Angiology, University Hospital, De Pintelaan 185, B-9000 Gent, Belgium Accepted February 28, 1992
Summary. Ten normal healthy subjects performed a rhythmic handgrip at 30°7o MVC (maximal voluntary contraction) with and without arterial occlusion of the same limb. Contralateral forearm and calf venous capacitance were simultaneously measured by venous occlusion plethysmography. During rhythmic handgrip at 3007o MVC contralateral venous capacitance decreased by -7.17070 in the forearm and by -5.14070 in the calf. With arterial occlusion the decreases in venous capacitance were even more pronounced: contralateral forearm -14.4070 and calf -13.1°70. In a second set of experiments (n = 5) rhythmic handgrip at 30070 MVC with arrest of the forearm circulation 5 s prior to the cessation of contraction was applied to examine the influence of chemically sensitive metaboreceptors per se on the evoked limb venoconstriction. During the postexercise arterial occlusion forearm venous volume decreased further to -30.607o whereas calf venous volume increased slightly but remained below the control value. After the cessation of the arterial occlusion both forearm and calf capacitance returned to baseline values. Thus, this study provided evidence that as well as a chemically generated reflex arising f r o m the working muscle, central comm a n d was found to be involved in the increase in venom o t o r tone in the nonexercising limbs during rhythmic handgrip at 30% MVC.
mainly caused by the reflex stimulation of sympathetic outflow by ischaemic metabolites acting on chemically sensitive muscle afferents (Simon and Riedel 1975; Rush et al. 1981; Shepherd et al. 1981; Victor and Seals 1989). This "exercise pressor reflex" (Simon and Riedel 1975; Valbo et al. 1979; Rowell 1986; Rowell and O ' L e a r y 1990) has been considered to be particularly important in causing sympathetic activation during static exercise. However, the importance of this reflex mechanism in sympathetic regulation during rhythmic exercise is less well understood. In most studies of isometric exercise and rhythmic exercise the forearm circulation was studied. The changes in the forearm circulation were then extrapolated to the other vascular systems. There is less information about the reaction of the venous capacitance vessels to exercise. B~veggtrd and Shepherd (1966) have found an increase of the venomotor tone at the forearm during leg exercise. However, evidence has been provided that forearm and calf circulation are not always controlled in a homogenous way (Shepherd and Vanhoutte 1975; Essandoh et al. 1987; Duprez et al. 1989). Therefore, the aim of the present study was to investigate the venomotor response simultaneously in the forearm and the calf during rhythmic exercise.
Key words: Plethysmography - Rhythmic exercise - Ve-
Methods
nous capacitance - Venomotor response Subjects
Introduction
Ten healthy male subjects, age 20-22 years, were studied. Each subject gave informed consent and was familiarized with the procedures prior to the study. The project was approved by the institutional review board on human investigations of the University Hospital. The experiments were conducted during the morning in a quiet room at a temperature of 24° + 1° C.
Exercise of ischaemic muscles is characterized by a large increase in arterial blood pressure (Alam and Smirk 1937; McCloskey and Mitchell 1972; Christensen and Calbo 1983; Mitchell and Schmidt 1983). There is increasing evidence that this pressor response has been
R h y t h m i c exercise
Offprint requests to: D. Duprez
Protocol 1. The rhythmic exercise was performed in a supine position. The subjects were asked to perform a maximal handgrip with
95 a strain gauge strength meter in the right hand and the force was recorded. During the procedure the right forearm was immobilized to avoid extraneous muscle movement. The maximal force was recorded on a monitor and 30% of the maximal voluntary contraction (MVC) was calculated. Rhythmic handgrip consisted of 1-s intermittent (40 contractions.min-1) static contractions of 30% MVC with the right hand during a period of 3 min. To examine the influence of ischaemia during rhythmic handgrip, the forearm circulation to the right arm was arrested by inflating a cuff at the upper arm to 200 mmHg (26.7 kPa). This was done 1 rain prior to the start of the rhythmic handgrip test and maintained during the whole exercise period. The rhythmic exercise was then performed in the same way as described above. The cuff was deflated at the cessation of the rhythmic handgrip. This rhythmic handgrip with and without arterial occlusion in the exercising forearm was done by each subject in a randomized order and with a 30 min interval between the two tests. The following haemodynamic parameters were measured: arterial blood pressure, heart rate and venous volume in the contralateral forearm and calf.
The arterial blood pressure was measured continuously at the third left finger with an automatic device, Finapress (Molhoek et al. 1984; Smith et al. 1985) while heart rate was derived from beatby-beat analysis from the electrocardiogram.
Protocol 2. To examine the influence of the chemically sensitive
Protocol 1
metaboreceptors per se on exercise-evoked limb venoconstriction, a second set of experiments was carried out with five other subjects, who performed rhythmic handgrip which consisted of 1-s intermittent static contractions with the right hand at a rate of 40 contractions, m i n - 1 during 1.5 min. Right forearm circulatory arrest was induced by inflating a cuff to 200 mHg (26.7 kPa) at the upper arm 5 s prior to the cessation of the contractions. The postexercise arterial occlusion was then maintained for 1.5 min. The response could then be studied during this postexercise period. It has been found that in this condition the chemically sensitive metaboreceptors dominate (Rowell 1979; Mark et al. 1985; Victor and Seals 1989). However, as well as these metaboreceptors shortterm potentiation of mechanisms in the central nervous system may still be involved. To rule out possible Valsalva manoeuvres during the rhythmic exercise, the respiratory pattern of each subject was recorded by thorax impedance plethysmography. The same haemodynamic parameters were measured as in the protocol 1.
Statistical analysis For each parameter measured (arterial blood pressure, heart rate, forearm and calf venous capacitance), analysis of variance was used to test the significance of the changes from the control values during rhythmic exercise. For significant differences the data were compared with the Student's t-test. When P values were less than 0.05, the differences were considered to be statistically significant.
Results
Arterial blood pressure and heart rate. D u r i n g r h y t h m i c h a n d g r i p there was a significant ( P < 0 . 0 1 , exercise vs rest) increase in systolic [from 121 (SD 15) to 149 (SD 15) m m H g , 16.1 (SD 2.0) to 19.9 (SD 2.0) kPa], diastolic [from 66 (SD 9) to 83 (SD 6) m m H g , 8.8 (SD 1.2) to 11.1 (SD 0.8) kPa] a n d m e a n arterial b l o o d pressure [from 85 (SD 9) to 105 (SD 9) m m H g , 11.3 (SD 1.2) to 14.0 (SD 1.2) kPa]. There was also a significant ( P < 0 . 0 0 5 , exercise vs rest) increase in heart rate [from 70 (SD 6) to 87 (SD 9) beats, r a i n - 1 ] . T h e arterial b l o o d pressure a n d heart rate steadily increased with the progression of r h y t h m i c exercise. Systolic, diastolic b l o o d pressure a n d heart rate r e t u r n e d to the c o n t r o l levels within 1 m i n after the cessation of the r h y t h m i c h a n d grip. Arterial occlusion per se did n o t affect either arterial b l o o d pressure or heart rate.
Haemodynamic measurements
Venous capacitance in contralateral forearm and calf (Fig. 1). D u r i n g r h y t h m i c h a n d g r i p c o n t r a l a t e r a l fore-
The equilibration technique was used to measure the venous tone and capacitance (Whitney 1953; Cooper et al. 1955; Wood and Eckstein 1958; Gascho et al. 1989). This technique consisted of rapidly inflating an upper arm cuff to a pressure of 50 mmHg (6.7 kPa). The change in venous volume of the contralateral forearm after equilibration at 50 mmHg (6.7 kPa), expressed in percentage volume, was considered to be an index of venous tone or venous capacitance. Left forearm and calf venous capacitance were measured simultaneously by venous occlusion plethysmography using strain gauges. To exclude hand and foot circulation, the circulation to left hand and foot was arrested by inflating a wrist and ankle cuff to suprasystolic pressure, 1 min prior to the beginning of the rhythmic handgrip. The left arm and leg were supported at the wrist and ankle and elevated to 15° above horizontal. After each experiment the venous occlusion cuff was deflated to obtain a complete emptying of the forearm and calf veins. The circumference of the forearm and calf at the level of the strain gauge was measured each time before cuff inflation and after inflation when a constant volume level was reached. This confirmed that the limb vasculature was at a comparable volume before each experiment. The circumference measurements were also reproducible. As it is impossible to assess concomitantly both left forearm venous capacitance and arterial blood pressure in the nonexercising upper limb, the latter parameter had to be measured in separate experiments.
a r m v e n o u s capacitance decreased ( P < 0.02, exercise vs rest) f r o m 100 (SD 3) v o l % to 92.83 (SD 4.67) vol %. T h e v e n o u s capacitance of the c o n t r a l a t e r a l calf decreased ( P < 0.05, exercise vs rest) f r o m 100 (SD 3) vol % to 94.86 (SD 5.43) v o l % . Both v e n o u s capacitance of the c o n t r a l a t e r a l f o r e a r m a n d calf decreased progressively d u r i n g the r h y t h m i c exercise. W i t h arterial occlusion, the decrease in v e n o u s capacitance in the c o n t r a l a teral f o r e a r m a n d calf was even m o r e p r o n o u n c e d ( P < 0 . 0 0 5 , occluded vs u n o c c l u d e d ) d u r i n g r h y t h m i c h a n d g r i p to 85.6 (SD 12.0) v o l % a n d 86.9 (SD 6.6) vol % , respectively.
Protocol 2 Arterial blood pressure and heart rate (Fig. 2). I n the second set o f experiments d u r i n g r h y t h m i c h a n d g r i p systolic b l o o d pressure increased ( P < 0 . 0 0 5 , exercise vs rest) f r o m 132 (SD 6) to 177 (SD 16) m m H g [17.6 (SD 0.8) to 23.6 (SD 2.1) kPa], diastolic b l o o d pressure f r o m 74 (SD 11) to 97 (SD 15) m m H g [9.9 (SD 1.5) to 12.9
96 105
CALF
100
m 100
=, o>
I .-T"[
75
95 0 Z
,oz, ~o >
%#
I 11/2
50
0
85
I 3
I 41/2
I 6 T I M E (min)
iI 105
FOREARM
t-t"t,,,k
~o 100
~
Fig. 3. Changes in venous volume (vol %) in contralateral forearm (in) and calf (O) during rhythmic handgrip at 30% maximal voluntary contraction and during postexercise arterial occlusion. C, control; RE, rhythmic exercise; O, arterial occlusion; R, recovery. Data are mean and SD (n = 5), * P < 0.05, ** P
European
oum.,A p p l i e d Physiology and Occupational Physiology © Springer-Verlag1992
Venous responses to rhythmic exercise in contralateral forearm and calf Daniel A. Duprez, Marc De Buyzere, Johan M. De Sutter, Sophie A. Deman, Nicole Y. De Pue, and Denis L. Clement Department of Cardiology-Angiology, University Hospital, De Pintelaan 185, B-9000 Gent, Belgium Accepted February 28, 1992
Summary. Ten normal healthy subjects performed a rhythmic handgrip at 30°7o MVC (maximal voluntary contraction) with and without arterial occlusion of the same limb. Contralateral forearm and calf venous capacitance were simultaneously measured by venous occlusion plethysmography. During rhythmic handgrip at 3007o MVC contralateral venous capacitance decreased by -7.17070 in the forearm and by -5.14070 in the calf. With arterial occlusion the decreases in venous capacitance were even more pronounced: contralateral forearm -14.4070 and calf -13.1°70. In a second set of experiments (n = 5) rhythmic handgrip at 30070 MVC with arrest of the forearm circulation 5 s prior to the cessation of contraction was applied to examine the influence of chemically sensitive metaboreceptors per se on the evoked limb venoconstriction. During the postexercise arterial occlusion forearm venous volume decreased further to -30.607o whereas calf venous volume increased slightly but remained below the control value. After the cessation of the arterial occlusion both forearm and calf capacitance returned to baseline values. Thus, this study provided evidence that as well as a chemically generated reflex arising f r o m the working muscle, central comm a n d was found to be involved in the increase in venom o t o r tone in the nonexercising limbs during rhythmic handgrip at 30% MVC.
mainly caused by the reflex stimulation of sympathetic outflow by ischaemic metabolites acting on chemically sensitive muscle afferents (Simon and Riedel 1975; Rush et al. 1981; Shepherd et al. 1981; Victor and Seals 1989). This "exercise pressor reflex" (Simon and Riedel 1975; Valbo et al. 1979; Rowell 1986; Rowell and O ' L e a r y 1990) has been considered to be particularly important in causing sympathetic activation during static exercise. However, the importance of this reflex mechanism in sympathetic regulation during rhythmic exercise is less well understood. In most studies of isometric exercise and rhythmic exercise the forearm circulation was studied. The changes in the forearm circulation were then extrapolated to the other vascular systems. There is less information about the reaction of the venous capacitance vessels to exercise. B~veggtrd and Shepherd (1966) have found an increase of the venomotor tone at the forearm during leg exercise. However, evidence has been provided that forearm and calf circulation are not always controlled in a homogenous way (Shepherd and Vanhoutte 1975; Essandoh et al. 1987; Duprez et al. 1989). Therefore, the aim of the present study was to investigate the venomotor response simultaneously in the forearm and the calf during rhythmic exercise.
Key words: Plethysmography - Rhythmic exercise - Ve-
Methods
nous capacitance - Venomotor response Subjects
Introduction
Ten healthy male subjects, age 20-22 years, were studied. Each subject gave informed consent and was familiarized with the procedures prior to the study. The project was approved by the institutional review board on human investigations of the University Hospital. The experiments were conducted during the morning in a quiet room at a temperature of 24° + 1° C.
Exercise of ischaemic muscles is characterized by a large increase in arterial blood pressure (Alam and Smirk 1937; McCloskey and Mitchell 1972; Christensen and Calbo 1983; Mitchell and Schmidt 1983). There is increasing evidence that this pressor response has been
R h y t h m i c exercise
Offprint requests to: D. Duprez
Protocol 1. The rhythmic exercise was performed in a supine position. The subjects were asked to perform a maximal handgrip with
95 a strain gauge strength meter in the right hand and the force was recorded. During the procedure the right forearm was immobilized to avoid extraneous muscle movement. The maximal force was recorded on a monitor and 30% of the maximal voluntary contraction (MVC) was calculated. Rhythmic handgrip consisted of 1-s intermittent (40 contractions.min-1) static contractions of 30% MVC with the right hand during a period of 3 min. To examine the influence of ischaemia during rhythmic handgrip, the forearm circulation to the right arm was arrested by inflating a cuff at the upper arm to 200 mmHg (26.7 kPa). This was done 1 rain prior to the start of the rhythmic handgrip test and maintained during the whole exercise period. The rhythmic exercise was then performed in the same way as described above. The cuff was deflated at the cessation of the rhythmic handgrip. This rhythmic handgrip with and without arterial occlusion in the exercising forearm was done by each subject in a randomized order and with a 30 min interval between the two tests. The following haemodynamic parameters were measured: arterial blood pressure, heart rate and venous volume in the contralateral forearm and calf.
The arterial blood pressure was measured continuously at the third left finger with an automatic device, Finapress (Molhoek et al. 1984; Smith et al. 1985) while heart rate was derived from beatby-beat analysis from the electrocardiogram.
Protocol 2. To examine the influence of the chemically sensitive
Protocol 1
metaboreceptors per se on exercise-evoked limb venoconstriction, a second set of experiments was carried out with five other subjects, who performed rhythmic handgrip which consisted of 1-s intermittent static contractions with the right hand at a rate of 40 contractions, m i n - 1 during 1.5 min. Right forearm circulatory arrest was induced by inflating a cuff to 200 mHg (26.7 kPa) at the upper arm 5 s prior to the cessation of the contractions. The postexercise arterial occlusion was then maintained for 1.5 min. The response could then be studied during this postexercise period. It has been found that in this condition the chemically sensitive metaboreceptors dominate (Rowell 1979; Mark et al. 1985; Victor and Seals 1989). However, as well as these metaboreceptors shortterm potentiation of mechanisms in the central nervous system may still be involved. To rule out possible Valsalva manoeuvres during the rhythmic exercise, the respiratory pattern of each subject was recorded by thorax impedance plethysmography. The same haemodynamic parameters were measured as in the protocol 1.
Statistical analysis For each parameter measured (arterial blood pressure, heart rate, forearm and calf venous capacitance), analysis of variance was used to test the significance of the changes from the control values during rhythmic exercise. For significant differences the data were compared with the Student's t-test. When P values were less than 0.05, the differences were considered to be statistically significant.
Results
Arterial blood pressure and heart rate. D u r i n g r h y t h m i c h a n d g r i p there was a significant ( P < 0 . 0 1 , exercise vs rest) increase in systolic [from 121 (SD 15) to 149 (SD 15) m m H g , 16.1 (SD 2.0) to 19.9 (SD 2.0) kPa], diastolic [from 66 (SD 9) to 83 (SD 6) m m H g , 8.8 (SD 1.2) to 11.1 (SD 0.8) kPa] a n d m e a n arterial b l o o d pressure [from 85 (SD 9) to 105 (SD 9) m m H g , 11.3 (SD 1.2) to 14.0 (SD 1.2) kPa]. There was also a significant ( P < 0 . 0 0 5 , exercise vs rest) increase in heart rate [from 70 (SD 6) to 87 (SD 9) beats, r a i n - 1 ] . T h e arterial b l o o d pressure a n d heart rate steadily increased with the progression of r h y t h m i c exercise. Systolic, diastolic b l o o d pressure a n d heart rate r e t u r n e d to the c o n t r o l levels within 1 m i n after the cessation of the r h y t h m i c h a n d grip. Arterial occlusion per se did n o t affect either arterial b l o o d pressure or heart rate.
Haemodynamic measurements
Venous capacitance in contralateral forearm and calf (Fig. 1). D u r i n g r h y t h m i c h a n d g r i p c o n t r a l a t e r a l fore-
The equilibration technique was used to measure the venous tone and capacitance (Whitney 1953; Cooper et al. 1955; Wood and Eckstein 1958; Gascho et al. 1989). This technique consisted of rapidly inflating an upper arm cuff to a pressure of 50 mmHg (6.7 kPa). The change in venous volume of the contralateral forearm after equilibration at 50 mmHg (6.7 kPa), expressed in percentage volume, was considered to be an index of venous tone or venous capacitance. Left forearm and calf venous capacitance were measured simultaneously by venous occlusion plethysmography using strain gauges. To exclude hand and foot circulation, the circulation to left hand and foot was arrested by inflating a wrist and ankle cuff to suprasystolic pressure, 1 min prior to the beginning of the rhythmic handgrip. The left arm and leg were supported at the wrist and ankle and elevated to 15° above horizontal. After each experiment the venous occlusion cuff was deflated to obtain a complete emptying of the forearm and calf veins. The circumference of the forearm and calf at the level of the strain gauge was measured each time before cuff inflation and after inflation when a constant volume level was reached. This confirmed that the limb vasculature was at a comparable volume before each experiment. The circumference measurements were also reproducible. As it is impossible to assess concomitantly both left forearm venous capacitance and arterial blood pressure in the nonexercising upper limb, the latter parameter had to be measured in separate experiments.
a r m v e n o u s capacitance decreased ( P < 0.02, exercise vs rest) f r o m 100 (SD 3) v o l % to 92.83 (SD 4.67) vol %. T h e v e n o u s capacitance of the c o n t r a l a t e r a l calf decreased ( P < 0.05, exercise vs rest) f r o m 100 (SD 3) vol % to 94.86 (SD 5.43) v o l % . Both v e n o u s capacitance of the c o n t r a l a t e r a l f o r e a r m a n d calf decreased progressively d u r i n g the r h y t h m i c exercise. W i t h arterial occlusion, the decrease in v e n o u s capacitance in the c o n t r a l a teral f o r e a r m a n d calf was even m o r e p r o n o u n c e d ( P < 0 . 0 0 5 , occluded vs u n o c c l u d e d ) d u r i n g r h y t h m i c h a n d g r i p to 85.6 (SD 12.0) v o l % a n d 86.9 (SD 6.6) vol % , respectively.
Protocol 2 Arterial blood pressure and heart rate (Fig. 2). I n the second set o f experiments d u r i n g r h y t h m i c h a n d g r i p systolic b l o o d pressure increased ( P < 0 . 0 0 5 , exercise vs rest) f r o m 132 (SD 6) to 177 (SD 16) m m H g [17.6 (SD 0.8) to 23.6 (SD 2.1) kPa], diastolic b l o o d pressure f r o m 74 (SD 11) to 97 (SD 15) m m H g [9.9 (SD 1.5) to 12.9
96 105
CALF
100
m 100
=, o>
I .-T"[
75
95 0 Z
,oz, ~o >
%#
I 11/2
50
0
85
I 3
I 41/2
I 6 T I M E (min)
iI 105
FOREARM
t-t"t,,,k
~o 100
~
Fig. 3. Changes in venous volume (vol %) in contralateral forearm (in) and calf (O) during rhythmic handgrip at 30% maximal voluntary contraction and during postexercise arterial occlusion. C, control; RE, rhythmic exercise; O, arterial occlusion; R, recovery. Data are mean and SD (n = 5), * P < 0.05, ** P
