Effects of Different TrainingIntensities 24-Hour Blood ...

2803

Effects of Different Training Intensities
on 24-Hour Blood Pressure
in Hypertensive Subjects

Mireille Marceau, MSc; N'guessan Kouame, MSc; Yves Lacourciere, MD; Jean Cleroux, PhD

Background. It is generally accepted that physical training decreases blood pressure in hypertensive
subjects, but the importance of training intensity has not been established. This study compared the
effects of endurance training at different intensities on ambulatory blood pressure and on blood pressure
load (percentage of readings above 140/90 and 120/80 mm Hg during the waking and sleeping periods,

respectively).
Methods and Results. Previously sedentary subjects with mild to moderate hypertension were evaluated

in a crossover fashion according to a Latin square after a sedentary control period and after training at
low and at moderate intensity corresponding to 50%o and 70%o of maximal oxygen uptake, respectively.
Each period lasted 10 weeks. After training at moderate intensity, a higher maximal oxygen uptake was
found compared with sedentary values but not after training at low intensity. Both training intensities
exerted a similar antihypertensive effect of about 5 mm Hg for systolic and diastolic 24-hour blood
pressures. However, training at low intensity reduced blood pressure exclusively during the waking hours,
whereas training at a moderate intensity reduced blood pressure only during the evening and sleeping
hours. Waking blood pressure load decreased from 66% to 49%v after training at low intensity, whereas
sleeping blood pressure load decreased from 61% to 34% after training at moderate intensity (both
P<.05).

Conclusions. Low- and moderate-intensity training produce similar 24-hour blood pressure reductions,
but each training intensity may interfere with different pathogenic effects associated with different blood
pressure profiles. (Circulation. 1993;88:2803-2811.)

KEY WORDs * hypertension * blood pressure * blood volume * oxygen * exercise

O ver the past decade, several studies with well- Among various possibilities for these discrepancies,
controlled experimental designs examined the
effects of exercise training in hypertension differences in training regimen, and more specifically in

and generally found that training exerted a significant training intensity, might have been involved. Indeed, in
antihypertensive effect (see reviews by Fagard et al,1
Hagberg,2 and Tipton3). This recently prompted the their reviews, Hagberg2 and Tipton3 noted that a signif-
World Hypertension League to conclude that exercise
training can contribute to the management of essential icant reduction of (sphygmomanometric) blood pres-
hypertension.4 These investigations were carried out by
measuring blood pressure over short periods with a sure was found more often in the studies that used a low
sphygmomanometer and a stethoscope in a laboratory
environment. In recent years, ambulatory blood pres- training intensity than in those that used a more stren-
sure monitoring has become a useful tool to examine the
effects of antihypertensive treatment in subjects under- uous intensity. One study in hypertensive animals9 and
going daily life activities during the course of a 24-hour
cycle. Since the recommendation of the World Hyper- another in hypertensive elderly subjects10 further indi-
tension League,4 four studies used this approach to cated that training at a low intensity may exert a more
examine the blood pressure lowering effects of training pronounced blood pressure lowering effect than train-
in hypertensive subjects. However, two studies found a ing at a higher intensity. Among the studies that used
decrease in ambulatory blood pressure5.6 and two stud- ambulatory monitoring, Seals and Reiling6 reportedly
ies did not report any difference after training.7,8 trained their subjects at an intensity approximating 50%
of maximal oxygen uptake, whereas Blumenthal et a18
Received June 2, 1992; revision accepted June 2, 1993. and Gilders et a17 used an intensity close to 70% of
From the Hypertension Research Unit, CHUL Research Cen- maximal oxygen uptake. However, different training
ter, Laval University, Qu6bec, Canada. modes (walking, jogging, bicycling) were used, and the
Reprint requests to Dr Clroux, Hypertension Research Unit, training intensity or the maximal oxygen uptake was not
CHUL Research Center, 2705 Blvd Laurier, Quebec, Quebec, systematically measured. Furthermore, no single study
Canada G1V 4G2. has yet examined the effects of different training inten-
sities on ambulatory blood pressure in hypertensive
subjects.

In the present study, we compared the effects of
endurance training on cycle ergometers at a low inten-
sity and at a moderate intensity, ie, training at 50%
versus 70% of maximal oxygen uptake, respectively, on
24-hour ambulatory blood pressure. A Latin square

Downloaded from http://circ.ahajournals.org/ by guest on July 27, 2016

2804 Circulation Vol 88, No 6 December 1993 baseline period. The subsequent evaluations were per-
formed after each of three 10-week periods during
crossover design that comprised an evaluation after a which the patients remained sedentary, trained at 50%
sedentary control period in addition to a baseline of maximal oxygen uptake, and trained at 70% of
evaluation was used. maximal oxygen uptake, according to the Latin square
sequences. These sequences were "train 70% - seden-
Methods tary-train 50%," "sedentary-train 50% -train 70%,"
and "train 50% - train 70% - sedentary" in the present
Subjects study.

Eleven sedentary subjects (10 men and 1 woman) The following measurements were performed at each
with uncomplicated established mild to moderate hy- evaluation: 24-hour ambulatory blood pressure and
pertension gave informed consent to participate in this heart rate, 24-hour urinary electrolyte excretion, blood
study, which was approved by our institutional ethics volume, supine blood pressure in the laboratory, and
committee on human research. Secondary hypertension maximal oxygen uptake. These were made on three
was ruled out by clinical and laboratory evaluation. separate days at 2- to 3-day intervals. Additional exer-
None of the patients was receiving antihypertensive cise sessions were performed during these intervals such
therapy or any other medication during the study. that each measurement was performed 40 to 64 hours
Medication was gradually withdrawn in those previously after the previous exercise session. Twenty-four-hour
on antihypertensive therapy, and they remained without ambulatory blood pressure and urinary electrolyte mea-
treatment during an additional 6-week period before surements were made first. Blood volume was measured
entering the study. next. Laboratory supine blood pressure and maximal
oxygen uptake determinations were made last. Seated
Except for the prescribed level of physical activity, blood pressure and heart rate were also measured
the patients were encouraged to maintain their usual during the week preceding each evaluation.
lifestyle and dietary habits. To assess the sedentary
lifestyle of the subjects who took part in this study, Training Program
standardized questions were asked. These were catego-
rized by type of activity, eg, home activities (gardening The patients exercised three sessions per week on
or shoveling snow according to season, dish washing, cycle ergometers (model 819, Monark, Varberg, Swe-
cooking, laundry, etc), travel to work (car, bicycle, bus, den) in a well-ventilated room in the research center
walking), work (desk work, walking around work area, under supervision of trained personnel. The sessions
etc), occasional sports (racket sports, swimming, walk- were held between 4:30 PM and 6:30 PM on Mondays,
ing, golf, etc). When appropriate, the subjects were Wednesdays, and Fridays. Each exercise session in-
asked how many hours per week were spent doing a cluded a 5-minute warm-up period, a period of exercise
given activity. The general format of the questions was: at the predetermined work rate that gradually increased
"How many hours per week do you spend doing this from 30 to 45 minutes over 2 weeks, and a 10-minute
activity and how intense do you feel this activity is, ie, cool-down period. The work rate required to induce an
light, moderate, heavy?" Subjects were considered to be increase in oxygen uptake up to 50% or 70% of maximal
sedentary if they did not practice any activity requiring values was determined by interpolation of results during
more than 3 kcal/kg body wt per hour (3 METs) on a the maximal oxygen uptake test. The individual heart
regular basis, ie, at least 3 hours per week. Average rate at each work rate was noted at 15 and 30 minutes
weekly energy expenditure in routine activities" was during the first training sessions and was used as
assessed at entry into the study as well as at midpoint reference in order to keep the training intensity con-
and at the end of each study period. This allowed stant over the entire 10-week period. The work rate was
verification that the subjects did not vary systematically increased when heart rate was 5 beats per minute lower
their level of activities outside of the prescribed exer- than the reference value for two consecutive exercise
cises during the course of the study. Body weight and sessions. Exercise blood pressure and heart rate were
urinary excretion of electrolytes were monitored to take monitored every 15 minutes.
into account the possible confounding effects of changes
in dietary intake. Measurements

All patients had their blood pressure measured Seated blood pressure and heart rate. Blood pressure
weekly during 1 month preceding entry into the study. (standard mercury sphygmomanometer and stetho-
Office blood pressure was taken as the mean of three scope) and heart rate (palpation at the wrist) were
measurements in the seated position at 5-minute inter- measured twice at 2-minute intervals after the subjects
vals not differing by more than 5 mm Hg. Hypertensive had remained seated on a chair (baseline and sedentary
patients qualified for the study if their diastolic blood periods) or on a cycle ergometer (before each exercise
pressure was between 90 and 114 mm Hg in the last two session during the training programs at 50% and 70% of
visits of this period. As part of the screening procedure, maximal oxygen uptake) for 10 minutes. A cuff with a
all subjects underwent a clinical treadmill test (Bruce large bladder (15 x 31 cm) was used,12 and the first and
protocol) with 12-lead ECG recording under supervi- fifth Korotkoff sounds were taken as the systolic and
sion of a cardiologist to rule out ischemic heart disease. diastolic values, respectively. The average of three series
of measurements (six measurements total) made on
Study Protocol three different days at a 1-day interval during the week
preceding each evaluation is reported. These measure-
This study used a 3 x 3 Latin square crossover design ments were made between 4:30 and 6:30 PM, ie, during
to compare the effects of training at two different
intensities with those of a control sedentary period on
blood pressure. The subjects were evaluated at four
time points. The first evaluation occurred after a 4-week

Downloaded from http://circ.ahajournals.org/ by guest on July 27, 2016

Marceau et al Physical Training and Ambulatory Pressure 2805

the time of the training sessions, and were always sured with the same sphygmomanometer and cuff and
performed by the same investigator (M.M.). by the same investigator (M.M.) as during measurement
of seated blood pressure. Heart rate was measured with
Twenty-four-hour blood pressure and heart rate. Twen- a tachograph triggered by the R wave of the ECG
ty-four-hour ambulatory blood pressure and heart rate (model 7P4, Grass Instrument Co, Quincy, Mass).
measurements were made using an automatic noninva-
sive recorder (model 90202, SpaceLabs Inc, Redmond, Exercise evaluation. Maximal oxygen uptake was deter-
Wash) that uses an oscillometric method for the deter- mined by analysis of expired gases (Energy Expenditure
mination of systolic and diastolic blood pressures. The Unit 2900, Sensormedics, Anaheim, Calif) during an in-
accuracy and reproducibility of blood pressure deter- creased work test schedule on a cycle ergometer (Ergo-
mined with this device were previously established.13 medic 829E, Monark, Varberg, Sweden) with increments
of 50 W every 2 minutes up to the point of volitional
Measurements were made at 30-minute intervals be- exhaustion. Blood pressure and heart rate were measured
twice at each step. Maximal oxygen uptake was considered
tween 6:00 AM and 6:00 PM and at 60-minute intervals to be reached when the respiratory exchange ratio was
between 6:00 PM and 6:00 AM. The patients were en- greater than 1.10 and oxygen uptake and heart rate did
couraged to go about their usual daily activities and to not further increase with increasing work rate.'8 This test
relax their arm during cuff inflation and deflation. took place between the hours of 9:00 and 11:00 AM, ie,
Ambulatory blood pressure monitoring was always per- after the supine evaluation.
formed on a working day. All patients worked on
daytime shifts, and their tasks involved mainly desk Statistical Analysis
work. After the 24-hour recording, the data were down-
loaded from the monitor to a computer for analysis. The results are reported as mean+SEM and were
Values of systolic pressure less than 70 or more than 250 compared by ANOVA for repeated measurements.'9 A
mm Hg, diastolic pressure less than 40 or more than probability of <.05 was set as the level of significance.
150, and heart rate less than 40 or more than 150 beats Differences were located using Fisher's protected least
significant difference test.
per minute were excluded from the analysis. Average
blood pressure was calculated from single readings for Results

each 1-hour period, for waking (7:00 AM to 10:00 PM) Of the 11 mild to moderate hypertensive subjects
and sleeping (11:00 PM to 6:00 AM) segments, and for the enrolled in the study, 9 (1 woman and 8 men; age, 43±2
entire 24-hour period. years; height, 175+±2 cm) completed all the stages and
were included in the analysis (Table 1). Two patients
The blood pressure load was calculated as the per- withdrew for reasons unrelated to the study. The ran-
centage of ambulatory systolic and diastolic pressure domization with the Latin square design was therefore
readings exceeding 140/90 mm Hg, respectively, during complete, with 3 subjects receiving each of the prede-
the waking period, and 120/80 mm Hg during the sleep- termined sequences. In addition, analysis of variance of
ing period.14"15 Average blood pressure load values are hemodynamic variables during the first, second, third,
given separately for waking and sleeping periods and and fourth evaluations, irrespective of the intervention,
also for the entire 24-hour period. showed no significant differences, indicating there was
no significant order effect.
Twenty-four-hour urinary electrolytes. The 24-hour
urinary excretion of sodium, potassium, and chloride During the baseline evaluation, seated blood pressure
was determined with standard analytical methods by the was 156±4 mm Hg systolic (range, 138 to 180 mm Hg)
clinical biochemical laboratory of our institution. and 102±2 mm Hg diastolic (range, 90 to 111 mm Hg),
whereas average ambulatory blood pressure between
Blood volume. Blood volume was measured with a 7:00 AM and 10:00 PM was 152+3 mm Hg systolic (range,
technique using radioactive sodium chromate to tag red 136 to 163 mm Hg) and 97±2 mm Hg diastolic (range,
blood cells.16 In this procedure, a blood sample is 87 to 106 mm Hg) in this group of subjects. Average
withdrawn, the red blood cells are tagged with sodium energy expenditure assessed during baseline evaluation
chromate, and the sample is reinjected into the subject. (16 490+605 kcal/wk) was unchanged during the seden-
Blood samples are withdrawn at 10 and 30 minutes after tary period (16 595+±585 kcallwk, P=.91, NS). Energy
the injection, and the volume occupied by the red blood expenditure for routine activities outside of prescribed
cell is calculated by the principle of dilution. Plasma exercises during training at 50% (16 532±689 kcal/wk,
volume and whole blood volume were obtained by P=.94, NS) and at 70% of maximal oxygen uptake
taking the hematocrit into account. This technique has
been shown to have a between-measurement variation (16 749±610 kcal/wk, P=.86, NS) remained constant
compared with the sedentary period. Thus, the subjects
under 6% both for red blood cell and plasma volume.'7 did not systematically vary their level of activities out-
Blood volume was always measured in the morning in side of the prescribed exercises during the course of the
the present study. study.

Supine blood pressure and heart rate. Supine blood The mean heart rate and work rate were 123 +9 beats
pressure and heart rate were measured between 8:00 per minute and 90+8 W, respectively, during training at
and 10:00 AM in the laboratory over 60 minutes during
three 10-minute baseline periods at 10-minute inter- 50% of maximal oxygen uptake and 145+±9 beats per
vals. During intervals, leg raising and lower body nega- minute and 124±9 W during training at 70% of maximal
tive pressure maneuvers were applied. The responses to oxygen uptake. Training at 50% and at 70% of maximal
these maneuvers are discussed elsewhere (unpublished oxygen uptake was associated with excess weekly energy
results). The maneuvers did not affect resting values.
Two measurements were made during the last 5 minutes expenditures of 852±+75 and 1068±69 kcal/wk (P<.01),
of each 10-minute period. The values reported there-
fore represent the mean of six baseline blood pressure respectively. Training at 50% of maximal oxygen uptake
and heart rate measurements. Blood pressure was mea-

Downloaded from http://circ.ahajournals.org/ by guest on July 27, 2016

2806 Circulation Vol 88, No 6 December 1993

TABLE 1. Characteristics of Subjects Including Type and Duration of Previous Antihypertensive Pharmacotherapy

AWeight

Previous Duration of
Subject Sex Age, y Treatment Treatment, y Height, cm Weight, kg T50-SED, kg T70-SED, kg

1 M 54 ... 0 173 69.0 -3.0 -2.0

2 M 46 FIB 0.5 180 80.0 -3.0 -1.0

3 M 52 ACEI 3 178 84.0 0.1 -1.4

4 F 47 FIB 2 175 75.0 -1.2 -1.0

5 M 40 ... 0 173 70.0 -1.0 -0.9

6 M 35 ACEI 2 168 65.0 -2.0 -0.8

7 M 45 DIUR 4 181 92.0 3.0 0.0

8 M 39 ACEI 2 175 76.9 -0.5 1.0

9 M 51 813 4 170 72.0 -1.5 -0.5

Individual changes in weight (Aweight) after training at 50% (T50) and at 70% of maximal aerobic capacity (T70) compared with after

the sedentary period (SED) are shown. None of the subjects received antihypertensive pharmacotherapy during the study. PB indicates

3-blocker; ACEI, angiotensin converting enzyme inhibitor; and DIUR, diuretic.

did not significantly affect maximal aerobic capacity shows that blood pressure and heart rate were similar
(P>.10), whereas training at 70% of maximal oxygen
uptake induced a 14% increase (P<.01) (Fig 1). Maxi- during the baseline and sedentary evaluations along the
mal oxygen uptake was found to be higher after the
sedentary period than at baseline (P<.05). Training at 24-hour period. Figs 3 and 4 illustrate that blood
50% and 70% of maximal oxygen uptake induced small pressure was significantly (P<.05) lower at several time
and similar decreases in body weight, although only the points after training at 50% and 70%, respectively, of
difference after training at 70% was statistically signif- maximal oxygen uptake. Heart rate was not altered
icant (P<.05) (Table 1 and Fig 1). Compliance was after training at 50% of maximal oxygen uptake, but a
98±2% during training at 50% of maximal oxygen significant reduction was found at one time point after
uptake and 96±3% during training at 70% of maximal training at 70% of maximal aerobic capacity.
aerobic capacity.
Fig 5 shows that the mean systolic and diastolic blood
The hourly blood pressure and heart rate values
during a 24-hour cycle at each evaluation appear in Figs pressure values calculated over the 24-hour cycle de-
2 through 4. In each figure, the results are compared creased similarly after both interventions, although the
with those of the sedentary control evaluation. Fig 2 difference was only significant (P<.05) for systolic blood
pressure after training at 50% of maximal aerobic
V02 max (/mmn)
capacity. In addition, blood pressure load was reduced
3.5 to a similar extent after both training regimens, al-

though the difference was significant after training at
70% (P<.05) but not after training at 50% of maximal
aerobic capacity (P=.06, NS). Fig 5 also illustrates that
the 24-hour mean data was superimposable during the

baseline and sedentary evaluations.
Although training at 50% and 70% of maximal oxy-

gen uptake induced similar effects on average 24-hour

160 -B_

140v

Weight (kg) .E 120-
807

0 M

K...1--X.. --- 4.. 1-<1~~~.~.~..~~~~~~~~~~~~~EE

75 - I~~l

7n 1 9 1 60 ---e--- SEDENTARY

TRAIN 50% TRAIN 70% -* BASELINE

BASELINE SEDENTARY

FIG 1. Maximal oxygen uptake (V02 max) and weight of 40 - . ..
8 10 12 14 16 18 20 22 0 2 4 6

subjects at the end of the initial 4-week baseline period and, HOUR OF DAY

in a crossover fashion according to a 3x3 Latin square, FIG 2. Hourly systolic (SBP) and diastolic (DBP) blood

after 1 0-week periods while remaining sedentary and train- pressure and heart rate (HR) of the subjects over 24 hours

ing at 50% and 70% of maximal oxygen uptake. *P<.05 vs after the sedentary period and at the end of the baseline

sedentary. period.

Downloaded from http://circ.ahajournals.org/ by guest on July 27, 2016

Marceau et al Physical Training and Ambulatory Pressure 2807

160' .O.. ~~SBP ASLEEP 150- 24-HOUR

140- o0 z L ,T 1451 . ..................
E
r 120- ,0-~zO ~ ~ 'O ..0 E

° 100- ..O-0-01 DBP IL 140]

I 1351

E 95 -

9--E 80' 901-

60 -- SEDENTARY 0UE

*--- TRAIN 50% V02 MAX 85 -

An) . . .... . . . . . . . . . . . . . . .. 0

8 10 12 14 16 18 20 22 0 246 80-
80 -
HOUR OF DAY

FIG 3. Hourly systolic (SBP) and diastolic (DBP) blood

pressure and heart rate (HR) of the subjects over 24 75'75~~-~~~~~~~~......._... =...........

hours after the sedentary period and after training at 50% ccc

of maximal oxygen uptake (TRAIN 50% V02 MAX). A

*P<.05 vs sedentary at indicated time points. Note the 70

effect of this training intensity on the morning rise of DBP. 65-

blood pressure and blood pressure load, the blood 801

pressure lowering effect was distributed differently dur- 601 *
ing the course of the day according to the intensity of a

the training program. Thus, during the waking period, 0. 40 '

systolic blood pressure (-6±2 mm Hg, P<.01), diastolic 20 SEDENTARY TRAIN 50% TRAIN 70%
blood pressure (-5±2 mm Hg, P<.05), and blood pres- BASELINE

sure load (-17±7%, P<.05) were all significantly re- FIG 5. Mean 24-hour systolic (SBP) and diastolic (DBP)
duced after training at 50% of maximal oxygen uptake,
whereas no significant changes (all P..05) were seen blood pressure, heart rate (HR), and blood pressure load
after training at 70% of maximal oxygen uptake (Fig 6).
On the other hand, during sleep, diastolic blood pres- (BP LOAD) of the subjects at the end of the initial 4-week
sure (-5±1 mm Hg, P<.01) and blood pressure load
(-27±9%, P<.01) were significantly reduced after baseline period and after 10-week periods while remain-
training at 70% of maximal oxygen uptake, but no
significant changes (all P>.10) were seen after training ing sedentary and training at 50% and 70% of maximal
at 50% of maximal oxygen uptake (Fig 7).
oxygen uptake. *P<.05 vs sedentary.

1 60- lio SBP Further detailed examination of the blood pressure

ALE patterns during specific time segments after each train-

140- ing regimen indicated that the maximal antihyperten-
c 120- sive effect of training at 50% of maximal oxygen uptake

0 10 - was seen during the morning hours (Fig 3), whereas the

EE ] maximal effect of training at 70% of maximal oxygen
E 80
uptake was seen during the evening hours (Fig 4). Also,
60 ---0--- SEDENTARY training at 50% of maximal oxygen uptake affected
*TRAIN 70% V02 MAX
mostly diastolic blood pressure, whereas training at 70%
8 10 12 14 16 18 20 22 0 2 4 6 of maximal oxygen uptake reduced mostly systolic blood
HOUR OF DAY pressure. Thus, from 7:00 to 11:00 AM, diastolic blood

FIG 4. Hourly systolic (SBP) and diastolic (DBP) blood pressure increased by 14±3 mm Hg (from 88±3 to
pressure and heart rate (HR) of the subjects over 24
hours after the sedentary period and after training at 70% 102±3 mm Hg) after the sedentary period but increased
of maximal oxygen uptake (TRAIN 70% V02 MAX).
*P<.05 vs sedentary at indicated time points. Note the only by 5±2 mm Hg (from 88±3 to 93±3 mm Hg) after
absence of effect of this training intensity on blood training at 50% of maximal oxygen uptake, amounting
pressure during work hours (8:00-17:00 hours).
to a net antihypertensive effect of 9 mm Hg (P<.05).
From 4:00 to 9:00 PM, systolic blood pressure remained

stable after the sedentary period (153±4 and 151±3
mm Hg), whereas it decreased by 16±6 mm Hg (from
152±3 to 136±5 mm Hg) after training at 70% of
maximal oxygen uptake, representing a net antihyper-
tensive effect of 14 mm Hg (P<.05). The changes in
ambulatory blood pressure (calculated over specific
time segments or over 24 hours) did not correlate with
the changes in maximal oxygen uptake or in body weight
after training at 50% or 70% of maximal oxygen uptake

Downloaded from http://circ.ahajournals.org/ by guest on July 27, 2016

2808 Circulation Vol 88, No 6 December 1993

0. L155- AWAKE (7-22H) ASLEEP (23-6H)

oh I.. . .. T
150] ..... .................. .........
ca
E *
E E
1451
C. CL
CD 0

1401 S

0

90 -

- 85 - .......................................................
E
95 ~~~~~~~~* e
E a0 80-

9090 - 75
70
S 85

85-

80 .c ......... 65
..........

75- 60

70 55
80
e0o. ' ' .80
................... 60....................................................
a
0 0

0 _i

40 CL 40-

o-~n~~~~~~~ 0

gn~~~~~~~~~~~~~

BASELINE SEDENTARY TRAIN 50% TRAIN 70% IBASELINE SEDENTARY TRAIN 50% TRAIN 70%

FIG 6. Mean awake systolic (SBP) and diastolic (DBP) FIG 7. Mean asleep systolic (SBP) and diastolic (DBP)

blood pressure, heart rate (HR), and blood pressure load blood pressure, heart rate (HR), and blood pressure load

(BP LOAD) of the subjects at the end of the initial 4-week (BP LOAD) of the subjects at the end of the initial 4-week

baseline period and after 10-week periods while remain- baseline period and after 10-week periods while remain-

ing sedentary and training at 50% and 70% of maximal ing sedentary and training at 50% and 70% of maximal

oxygen uptake. *P<.05 vs sedentary. oxygen uptake. *P<.05 vs sedentary.

or with age, duration of previous treatment, or waking Discussion

ambulatory blood pressure at baseline. The results of the present study show that 10 weeks of

With regard to blood pressure measured during 60 closely supervised physical training on cycle ergometers at
minutes of supine rest, during 10 minutes in the sitting 50% of maximal oxygen uptake and at 70% of maximal

position, or during 2 minutes of submaximal exercise at oxygen uptake induce comparable decreases in average
24-hour ambulatory blood pressure and in average 24-
100 W, no differences were seen after training at 50% or hour blood pressure load. However, blood pressure and
70% of maximal oxygen uptake compared with after the blood pressure load were reduced exclusively during the
waking period after training at 50% of maximal oxygen
sedentary period (Table 2). In the supine position and uptake, whereas they were reduced only during the
evening and sleeping periods after training at 70% of
during submaximal exercise, somewhat higher blood maximal oxygen uptake. In earlier studies that assessed
blood pressure with a sphygmomanometer and a stetho-
pressure values were found during the baseline evalua- scope, measurements were made during the waking pe-
riod. Our findings may therefore help explain why a
tion compared with the sedentary evaluation. Supine reduction in blood pressure was found more often in the
heart rate was not different after either training regi-
studies that used a low training intensity than in those that
men, but in the seated position, higher values were used a more strenuous intensity.2,3
found after training at 50% of maximal aerobic capacity
and during the baseline evaluation than after the sed- In addition, training at 50% of maximal oxygen
entary period (Table 2). uptake almost completely blunted the morning blood
pressure rise. This effect would appear to be unique to
Blood volume and plasma volume were not signifi- physical training since pharmacological antihyperten-
cantly affected by training, but blood volume was signif- sive therapy has been reported to lower 24-hour blood
icantly higher at the baseline evaluation than after the pressure without affecting the normal pattern of the
sedentary period (Table 3). Red blood cell volume was circadian blood pressure curve, ie, the morning blood
found to be increased after training at 50% and 70% of pressure rises by the same amount but starts from a
maximal oxygen uptake compared with after the seden-
tary period, but it was also increased during the baseline
evaluation. The 24-hour urinary excretion of sodium,
potassium, and chloride ions was not different during
the study.

Downloaded from http://circ.ahajournals.org/ by guest on July 27, 2016

Marceau et al Physical Training and Ambulatory Pressure 2809

TABLE 2. Effects of Two Intensities of Physical Training to expect that these activities may produce similar
effects. A word of caution is in order concerning the
on Blood Pressure and Heart Rate at Rest in Supine
and Seated Positions and During Submaximal (100 W) adequacy of brisk walking or jogging, since only the
Cycle Ergometer Exercise
effects of exercising on cycle ergometers in the labora-
Supine rest Train Train tory were examined in the present study.
SBP, mmHg Baseline Sedentary 50% 70%
With regard to blood pressure load, mild hyperten-
138±4* 130±3 132±3 128±3 sion on ambulatory monitoring is defined as the pres-

DBP, mm Hg 94±2* 87±1 90±2* 87±2 ence of at least 50% of the total awake readings greater
Heart rate, bpm 65±3 64±3 65±3 62±3 than 140/90 mm Hg and of at least 50% of the total
asleep readings greater than 120/80 mm Hg.26 Our
Seated rest results show that the awake blood pressure load de-
creased from 66% after the sedentary period to 49%
SBP, mmHg 156±4 152±4 153±2 155±3 after training at 50% of maximal oxygen uptake. The
100±3 99+3 103±2 asleep blood pressure load decreased from 61% after
DBP, mmHg 102±2 74±3 79±3* 75±3 the sedentary period to 34% after training at 70% of
maximal oxygen uptake. Thus, each training regimen
Heart rate, bpm 80±4* 169±8 166±6 167±6 exerted clinically relevant reductions of blood pressure
89±2 93±2 90±2 load based on the definition of mild hypertension, albeit
Submaximal exercise each during specific time periods.

SBP, mmHg 178±6 Our findings are based on the comparison of the
results obtained after each training regimen with those
DBP, mm Hg 97±2* obtained after the control sedentary period. Because
training and sedentary periods occurred in a crossover
Heartrate, bpm 135±5 128±7 130±5 128±5 fashion according to a Latin square, it is not likely that
the differences were related to any significant extent to
Values are mean±SEM. SBP and DBP indicate systolic and ambulatory blood pressure monitoring habituation. In
diastolic blood pressures, respectively; train 50% and train 70%, fact, identical 24-hour blood pressure profiles were
training at 50% and at 70% of maximal aerobic capacity, respec- observed during the sedentary and baseline evaluations.
tively; bpm indicates beats per minute. The concordance of baseline and sedentary results
agrees with earlier results showing the good reproduc-
*P<.05 vs sedentary. ibility of ambulatory blood pressure monitoring'3 and
further indicate that a period of 10 weeks was sufficient
lower level.20 It has been well established that there is a to reverse the antihypertensive effects of a previous
training period. It is noteworthy that the higher maximal
greater risk of cardiovascular morbid events and mor- oxygen uptake found after the sedentary period than
after the initial baseline period was not associated with
tality between 6:00 AM and noon.21-23 It also has been a change in the circadian blood pressure curve.

suggested that the morning increase in blood pressure The findings of the present study were independent of a
change in body weight, in 24-hour urinary excretion of
may be one of the triggering mechanisms of cardiac electrolytes, or in blood volume. This is in agreement with
previous reports showing that the antihypertensive effect
events.22 On the other hand, it has been reported that of training was unrelated to weight loss2 or to a change in
ambulatory blood pressure decline from day to night is urinary excretion of electrolytes' 278 and that blood
associated with a lower left ventricle mass index,24 and volume was not different after low- and moderate-inten-
echocardiographic left ventricular hypertrophy has been sity training.'0 Urata et aP28 reported a fall in blood volume
suggested to be an independent predictor of cardiovas- in hypertensive subjects after training at a low intensity. In
cular morbidity.25 Thus, the morning blood pressure that study,28 the posttraining results were compared with
lowering effect of training at 50% of maximal oxygen those obtained after a 4-week baseline period. It should be
uptake and the night blood pressure lowering effect of noted that the comparison of our results after training at
training at 70% of maximal oxygen uptake may both
constitute important clinical advantages by interfering
with different pathogenic effects associated with differ-
ent blood pressure profiles. Since exercising at 50% of
maximal oxygen uptake represents an intensity that is
typically attained during brisk walking, whereas an
intensity corresponding to 70% of maximal oxygen
uptake is usually reached during jogging, it is reasonable

TABLE 3. Effects of Two Intensities of Physical Training on Blood Volume and on
24-Hour Urinary Excretion of Electrolytes

Baseline Sedentary Train 50% Train 70%

Blood volume, mL 4573±208* 4333±191 4354±233 4457±240

Plasma volume, mL 2810±141 2721+±105 2669+±144 2705±+137

RBC volume, mL 1764±99* 1611±111 1684±95* 1753±109*

Nal, mmol/L 157±18 156±10 166±16 162±24

K', mmol/L 73±7 73±5 75+6 64+8

Cl-, mmol/L 164±16 155±10 172±17 174+27

Results are mean±SEM. RBC indicates red blood cells; train 50% and train 70% indicate training at

50% and at 70% of maximal aerobic capacity, respectively.
*P<.05 vs sedentary.

Downloaded from http://circ.ahajournals.org/ by guest on July 27, 2016

2810 Circulation Vol 88, No 6 December 1993 Comparison With Sphygmomanometer Measurements

50% of maximal oxygen uptake with those obtained after In the present study, a significant decrease in supine
the initial 4-week baseline period yields a similar conclu- blood pressure was found after the sedentary period
sion. Thus, the fall in blood volume reported by Urata et compared with the baseline evaluation. Reduction in
al may be related to their study design. The antihyperten- sphygmomanometric blood pressure during a control pe-
sive effect also was not related to the increase in physical riod is a well-known phenomenon in hypertension studies.
fitness, as evidenced by the lack of correlation between the For example, Blumenthal et a18 and Seals and Reiling6
changes in blood pressure and in maximal oxygen uptake noted that clinic blood pressure decreased after 4 and 6
after each training regimen. This is further supported by months, respectively, in their control group of hyperten-
the observation of decreased circadian blood pressure sive subjects. Kiyonaga et a127 reported that clinic blood
curves in the presence of an unchanged maximal oxygen pressure decreased during a control period of 4 weeks and
uptake after training at 50% of maximal aerobic capacity thereafter stabilized. Since the baseline evaluation also
compared with the sedentary evaluation. occurred after a period of 4 weeks in the present study, we
interpret our findings as indicating that a longer period
Relation With Previous Studies may be required for stabilization of sphygmomanometric
blood pressure. This further underlines the importance of
Concerning the discrepancies between the few stud- the control sedentary period, or of evaluating a parallel
ies that used ambulatory monitoring to assess the group of control sedentary subjects, to avoid artifactual
antihypertensive effect of training, several consider- amplification of the antihypertensive effect when blood
ations support our hypothesis that differences in train- pressure is measured by sphygmomanometry.
ing intensity may have been involved. Our results show-
ing a reduced ambulatory blood pressure during the Supine, seated, and submaximal exercise blood pres-
waking period and an unchanged blood pressure during sures measured with the sphygmomanometer were unal-
the sleeping period after training at 50% of maximal tered after either training regimen compared with after
oxygen uptake agree with the results of Somers et a15 the sedentary period. The absence of a change after
and Seals and Reiling6 in hypertensive subjects and also training at 70% of maximal oxygen uptake is in accor-
with those of Van Hoof et a129 in normotensive subjects. dance with our findings with ambulatory monitoring dur-
The amplitude of the blood pressure reduction during ing the waking period. However, there is an inconsistency
the waking period was similar in the present study between the decrease in awake ambulatory blood pressure
(-6/-5 mm Hg) and in the study of Somers et al and failure to detect a lower blood pressure with the
(-5/-8 mm Hg). Seals and Reiling and Van Hoof et al sphygmomanometer after training at 50% of maximal
also reported similar but isolated decreases in awake oxygen uptake. The reasons for this discrepancy are not
systolic (-7 mm Hg) and diastolic blood pressures (-5 readily apparent. Nonetheless, the time of day at which
mm Hg), respectively. The subjects from the study of measurements were made may have intervened, at least
Seals and Reiling6 trained by walking at a pace eliciting for seated measurements. In the present study, seated
=50% of maximal oxygen uptake as determined by the blood pressure during baseline and sedentary periods was
measurement of individual heart rates. The studies of measured during the regular training hours, ie, between
Somers et al and Van Hoof et al involved mixed 4:30 and 6:30 PM. It can be advocated that the failure to
exercises including calisthenics, walking, and jogging for detect lower values in the seated position at the end of
continuous periods of less than 10 minutes, during training at 50% of maximal oxygen uptake may have been
which training intensity was not monitored. Because related to the time of day, since ambulatory blood pres-
these exercises usually elicit a mild increase in energy sure was not different during these hours after the same
output, it can be assumed that the training intensity was intervention. It may be noted that seated blood pressure
closer to 50% than to 70% of maximal oxygen uptake. values also agree with ambulatory blood pressure values
during this specific time frame after training at 70% of
On the other hand, our results showing that daytime maximal oxygen uptake.
ambulatory blood pressure was not different after train-
ing at 70% of maximal oxygen uptake agree with the Further support of this hypothesis would have re-
results of the studies by Blumenthal et a18 and Gilders et quired measurement of seated blood pressure with the
al.7 In those studies, training intensity was closely sphygmomanometer during the morning hours, which
monitored to ensure that at least 70% of maximal was not done in the present study. Nevertheless, among
oxygen uptake was sustained for periods exceeding 35 other studies on the effects of low-intensity training in
minutes of continuous exercise. Thus, the results from hypertensive subjects that found significant reductions
the present study and those from Blumenthal et al and in seated blood pressure,610272830 it can be safely pre-
Gilders et al are concordant in indicating that waking sumed that a greater proportion of measurements took
blood pressure is unchanged after training at 70% of place during morning and early afternoon hours com-
maximal oxygen uptake. Although Blumenthal et al did pared with late afternoon hours.
not measure sleeping blood pressure, Gilders et al did
not report any change in evening or sleeping blood Potential Mechanisms
pressure, whereas our results show that ambulatory
blood pressure was significantly lower during the Several mechanisms, including hemodynamic, meta-
evening and sleeping hours after training at 70% of bolic, and neural mechanisms, have been proposed to
maximal oxygen uptake. The present results after train- participate in the antihypertensive action of physical train-
ing at 50% and 70% of maximal oxygen uptake are ing.2,3 With regard to mechanisms underlying the ambula-
therefore consistent with the hypothesis that discrepan- tory blood pressure reduction during waking hours after
cies between earlier studies with ambulatory blood training at a low intensity versus during evening and night
pressure monitoring, at least during waking hours, may
have been related to differences in training intensity. hours after training at a moderate intensity, these can only

Downloaded from http://circ.ahajournals.org/ by guest on July 27, 2016

Marceau et al Physical Training and Ambulatory Pressure 2811

be speculated upon. Training at a low intensity induced its 9. Tipton CM, Mathes RD, Marcus KD, Rowlett KA, Leininger JR.
antihypertensive action during the active period of the
day, ie, when one changes from a seated to a standing Influences of exercise intensity, age, and medication on resting
position most often. Thus, mechanisms involving reflex blood pressure of SHR populations. J Appl Physiol. 1983;55:
regulation of circulation in response to a change in venous
return were probably solicited to the greatest extent 1305 -1310.
during this period. One possible theory could therefore 10. Hagberg JM, Montain SJ, Martin WH, Eshani AA. Effect of
implicate an exercise intensity-specific alteration in
baroreflex regulation of circulation. This hypothesis is exercise training in 60-69-year-old persons with essential hyper-
supported by the observation that low-intensity training tension. Am J Cardiol. 1989;64:348-353.
was found to potentiate cardiopulmonary baroreflex con- 11. Ainsworth BE, Haskell WL, Leon AS, Jacobs DR Jr, Montoye HJ,
trol of forearm vascular resistance,3' whereas moderate-
intensity training was reported to attenuate this reflex Sallis JF, Paffenbarger RS Jr. Compendium of physical activities:
response in normotensive subjects.32
classification of energy costs of human physical activities. Med Sci
Conclusions Sports Exerc. 1993;25:71-80.
12. American Society of Hypertension. Recommendations for routine
The results of the present study demonstrate that blood pressure measurements by indirect cuff sphygmomanometry.
ambulatory blood pressure is decreased during the
waking period-mainly during the morning hours- Am J Hypertens. 1992;5:207-209.
after training at a low intensity corresponding to 50% of 13. Pickering TG, Blank SG. Blood pressure measurement and ambu-
maximal oxygen uptake, whereas the antihypertensive
effect occurs during the evening and the sleeping period latory blood pressure monitoring: evaluation of available
after training at a moderate intensity corresponding to equipment. In: Laragh JH, Brenner BM, eds. Hypertension: Patho-
70% of maximal oxygen uptake. Notwithstanding some physiology, Diagnosis, and Management. New York: Raven Press;
inconsistencies between training-induced changes in
blood pressure as assessed by ambulatory monitoring 1990:1429-1441.
and sphygmomanometry, and taking into account the 14. Zacharia PK. Blood pressure load -a better determinant of hyper-
limitations inherent to the present study in a relatively
small sample of subjects, these results, taken together tension. Mayo Clin Proc. 1988;63:1085-1091.
with evidence that morning blood pressure elevation 15. White W, Dey H, Schulman P. Assessment of the daily blood
may contribute to precipitation of cardiovascular events
and that night blood pressure may be linked to left pressure load as a determinant of cardiac function in patients with
ventricular hypertrophy, suggest that training at 50%
and at 70% of maximal oxygen uptake may be equally mild-to-moderate hypertension. Am Heart J. 1989;118:782-795.
efficacious in preventing cardiovascular events linked to 16. Gray SJ, Sterling K. Determination of circulating red cell volume
high blood pressure.
by radioactive chromium. Science. 1950;112:179-180.
Acknowledgments
17. Green HJ, Sutton JR, Coates G, Ali M, Jones S. Response of red
This work was supported by grants from the Fonds de la cell and plasma volume to prolonged training in humans. J Appl
Recherche en Sante du Quebec and from the Fondation des
Maladies du Coeur du Quebec. Physiol. 1991;70:1810-1815.
18. Astrand PO, Rodhal K. Textbook of Work Physiology: Physiological
References
Bases of Exercise. New York: McGraw-Hill; 1977.
1. Fagard R, Bielen E, Hespel P, Lijnen P, Staessen J, Vanhees L, 19. Snedecor GW, Cochran WG. Statistical Methods. Ames, Iowa: Iowa
Van Hoof R, Amery A. Physical exercise in hypertension. In:
Laragh JH, Brenner BM, eds. Hypertension: Pathophysiology, State University Press; 1982.
Diagnosis, and Management. New York: Raven Press; 1990: 20. Materson BJ, Preston RA. Classic therapeutic trials in hyper-
1985-1998.
tension: were patients vulnerable to unsuppressed peak morning
2. Hagberg JM. Exercise, fitness, and hypertension. In: Bouchard C, blood pressure? Am J Hypertens. 1991;4:449S-453S.
Shephard RJ, Stephens T, Sutton JR, McPherson BD, eds. 21. Muller JE, Stone PH, Turi ZG, Rutherford JD, Czeisler CA,
Exercise, Fitness, and Health: A Consensus of Current Knowledge. Parker C, Poole WK, Passami E, Roberts R, Robertson T, Sobel
Champaign, Ill: Human Kinetics Books; 1990:455-466. BE, Willerson JT, Braunwald E, Group MS. Circadian variation in
the frequency of onset of acute myocardial infarction. N Engl J
3. Tipton CM. Exercise, training and hypertension: an update. In:
Holloszy JO, ed. Exercise and Sport Sciences Reviews. Baltimore, Med. 1985;313:1315-1322.
Md: Williams & Wilkins; 1991:447-505. 22. Muller JE, Tofier GH, Stone GH. Circadian variation and triggers

4. Fagard R. Physical exercise in the management of hypertension: a of onset of acute cardiovascular disease. Circulation. 1989;79:
consensus statement by the world hypertension league.
J Hypertens. 1991;9:283-287. 733-743.
23. Rocco MB, Barry J, Campbell S. Circadian variation of transient
5. Somers VK, Conway J, Johnston J, Sleight P. Effects of endurance
training on baroreflex sensitivity and blood pressure in borderline myocardial ischemia in patients with coronary artery disease. Cir-
hypertension. Lancet. 1991;337:1363-1368. culation. 1987;75:395-400.
24. Verdecchia P, Schillaci G, Guerrieri M, Gatteschi C, Benemio G,
6. Seals DR, Reiling MJ. Effect of regular exercise on 24-hour Boldrini F, Porcellati C. Circadian blood pressure changes and left
arterial pressure in older hypertensive humans. Hypertension. 1991; ventricular hypertrophy in essential hypertension. Circulation.
18:583-592.
1990;81:528-536.
7. Gilders RM, Voner C, Dudley GA. Endurance training and blood 25. Casale PN, Devereux RB, Milner M, Zullo G, Harshfield GA,
pressure in normotensive and hypertensive adults. Med Sci Sports
Exerc. 1989;21:629-636. Pickering TG, Laragh JH. Value of echocardiographic mea-
surement of left ventricular mass in predicting cardiovascular
8. Blumenthal JA, Siegel WC, Appelbaum M. Failure of exercise to morbid events in hypertensive men. Ann Intern Med. 1986;105:
reduce blood pressure in patients with mild hypertension: results
of a randomized controlled trial. JAMA. 1991;266:2098-2104. 173-178.
26. White WB, Morganroth J. Usefulness of ambulatory monitoring of

blood pressure in assessing antihypertensive therapy. Am J Cardiol.

1989;63:94-98.
27. Kiyonaga A, Arakawa K, Tanaka H, Shindo M. Blood pressure

and hormonal responses to aerobic exercise. Hypertension. 1985;7:
125-131.
28. Urata H, Tanabe Y, Kiyonaga A, Ikeda M, Tanaka H, Shindo M,
Arakawa K. Antihypertensive and volume-depleting effects of mild
exercise on essential hypertension. Hypertension. 1987;9:245-252.
29. Van Hoof R, Hespel P, Fagard R, Lijnen P, Staessen J, Amery A.
Effect of endurance training on blood pressure at rest, during
exercise and during 24 hours in sedentary men. Am J Cardiol.
1989;63:945 -949.
30. Martin JE, Dubbert PM, Cushman WC. Controlled trial of aerobic
exercise in hypertension. Circulation. 1990;81:1560-1567.
31. Jingu S, Takeshita A, Imaizumi T, Nakamura M, Shindo M,
Tanaka H. Exercise training augments cardiopulmonary baroreflex
control of forearm vascular resistance in middle-aged subjects. Jpn
Circ J. 1988;52:162-168.
32. Mack GW, Thompson CA, Doerr DF, Nadel ER, Convertino VA.
Diminished baroreflex control of forearm vascular resistance fol-

lowing training. Med Sci Sports Exerc. 1991;23:1367-1374.

Downloaded from http://circ.ahajournals.org/ by guest on July 27, 2016

Effects of different training intensities on 24-hour blood pressure in hypertensive subjects.
M Marceau, N Kouamé, Y Lacourcière and J Cléroux

Circulation. 1993;88:2803-2811
doi: 10.1161/01.CIR.88.6.2803

Circulation is published by the American Heart Association, 7272 Greenville Avenue, Dallas, TX 75231
Copyright © 1993 American Heart Association, Inc. All rights reserved.
Print ISSN: 0009-7322. Online ISSN: 1524-4539

The online version of this article, along with updated information and services, is located on the
World Wide Web at:

http://circ.ahajournals.org/content/88/6/2803

Permissions: Requests for permissions to reproduce figures, tables, or portions of articles originally published in
Circulation can be obtained via RightsLink, a service of the Copyright Clearance Center, not the Editorial Office.
Once the online version of the published article for which permission is being requested is located, click Request
Permissions in the middle column of the Web page under Services. Further information about this process is
available in the Permissions and Rights Question and Answer document.
Reprints: Information about reprints can be found online at:
http://www.lww.com/reprints
Subscriptions: Information about subscribing to Circulation is online at:
http://circ.ahajournals.org//subscriptions/

Downloaded from http://circ.ahajournals.org/ by guest on July 27, 2016