| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
1 Department of Human Anatomy and Physiology, University College, Dublin 2 and 2 Department of Respiratory Medicine, St. Vincent's University Hospital, Dublin 4, Ireland
 |
ABSTRACT |
|---|
 TOP
 ABSTRACT
 INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES
|
|---|
In the presence of an externally applied thoracic restriction, conflicting ventilatory responses to exercise have been reported, which could be accounted for by differences in exercise protocol. Seven male subjects performed two incremental and two constant-workload ergometer tests either unrestricted or in the presence of an inelastic corset. Ventilatory variables and arterial estimates of PCO2 were obtained breath by breath. Subjects hyperventilated in the presence of restriction during the constant-workload test (38.4 ± 3.0 vs. 32.8 ± 3.0 l/min for the average of the last 3 min of exercise, P < 0.05), whereas, at an equivalent workload during the incremental test, ventilation was similar to unrestricted values (unrestricted = 26.3 ± 1.6 vs. restricted = 27.9 ± 2.3 l/min, P = 0.36). We used a first-order linear model to describe the effects of change in workload on minute ventilation (24). When the time constants and minute ventilation values measured during unrestricted and restricted constant-workload exercise were used to predict the ventilatory response to the respective incremental exercise tests, no significant difference was observed. This suggests that hyperventilation is not seen in the restricted incremental test because the temporal dynamics of the ventilatory response are altered.
exercise protocol; time constant; predicted minute ventilation
| |
INTRODUCTION |
|---|
|
TOP
ABSTRACT
INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES
|
|---|
RESTRICTIVE LUNG DISEASE is a term used broadly to describe a number of restricted disease states, including diseases of the pleura, chest wall, or lung parenchyma (interstitial lung diseases). Methods of mimicking the effects of restrictive chest wall disease have been devised and include external thoracic restriction (1, 3, 5, 7-10, 14, 17, 21-23) and abdominal restriction (1, 3, 5, 10, 17, 22, 23).
In subjects who performed incremental exercise in the presence of an
inelastic corset, maximum minute ventilation (
E)
decreased compared with the unrestricted condition (22).
Unaltered or reduced maximum E was reported for
patients with scoliosis performing incremental exercise (6, 12,
13, 18). In marked contrast, most studies of the ventilatory
response to constant-workload exercise performed by normal subjects in
the presence of restriction and by patients with interstitial lung
disease demonstrated hyperventilation (9, 15, 19),
although a single study reported no change in E from
normal (10). Possible explanations for the discrepancy of
results between incremental and constant-workload tests in different
studies include differences in subject characteristics and the degree
of restriction present, either as a consequence of the disease state or
from the application of an external thoracic restriction.
Alternatively, chest wall restriction may affect the ventilatory
response to incremental and constant-workload exercise in different ways.
It has previously been shown that the ventilatory response to constant-workload exercise performed below the gas-exchange threshold (GET) is well described by a monoexponential function characterized by a time constant and a steady-state ventilation value (24). This implies that the ventilatory response to exercise depends not only on the workload at any time but also on the rate at which the workload changes. Thus it is possible that, if, as previously reported, the steady-state response of the system increases during thoracic restriction, an appropriate prolongation of the time constant would allow the ventilatory response to an incremental exercise test to remain unchanged.
The aim of this study was to investigate the ventilatory response to
incremental and constant-workload exercise in the presence of an
externally applied thoracic restriction in a single group of subjects
and to determine whether the differing effects are a result of
differing exercise protocols. We also used a previously described model
(24) to determine whether altered ventilatory dynamics due
to thoracic restriction, i.e., an increased steady-state value for
E and an appropriately prolonged time constant,
could account for the observed ventilatory responses to the two
exercise protocols.
| |
METHODS |
|---|
|
TOP
ABSTRACT
INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES
|
|---|
Subjects. Seven male subjects who had never engaged in aerobic training were recruited. No subject had any history of respiratory or cardiovascular disease, and all subjects were normal on clinical examination. The study was undertaken with the approval of the Ethics Committee of St. Vincent's University Hospital, Dublin, Ireland, and each subject gave written, informed consent. Subjects were aware of the procedures to be undertaken but were uninformed as to the objectives of the study. Each individual was advised not to eat for 1 h before the experimental sessions and not to engage in strenuous exercise before the test.
The subjects attended the laboratory on three different occasions and completed four exercise tests on an electrically braked cycle ergometer (Excalibur, Lode, Groningen, The Netherlands). These included two ramped exercise tests to exhaustion, one performed in the presence and one in the absence of a thoracic restriction, and two constant-workload exercise tests, performed either in the presence or absence of a thoracic restriction. On days 1 and 2, subjects performed an incremental exercise test, and on day 3 subjects performed the two constant-workload exercise tests. The subjects' work rate was independent of pedaling frequency, and they were instructed to maintain the cadence between 50-80 rpm throughout all tests. Restriction of the movement of the rib cage was achieved by use of an inexpandable corset (T&S Surgical Appliances) that was fitted to the subject after he had expired to residual volume and that was tightened with the aid of Velcro straps to achieve a minimum reduction in forced vital capacity (FVC) of at least 35%.Measurements. Subjects wore a nose clip and mouthpiece connected to a heated wire anemometer (Sensormedics) that allowed inspiratory and expiratory flows to be measured continuously. Signals were digitally integrated to obtain volume measurements. Respired gases were continuously analyzed by rapidly responding O2 (paramagnetic) and CO2 (infrared) analyzers (Sensormedics Vmax 229). Calibrations were carried out before each test by using a calibration syringe and precision O2 and CO2 gas mixes (Sensormedics). An estimate of arterial blood O2 saturation was obtained continuously by using pulse oximetry (Biox 3740, Ohmeda, Louisville, KY), with the probe positioned on the earlobe. Immediately before exercise, a topical vasodilator (Ralgex, SmithKline Beecham Health Care), the active ingredient of which is capsaicin, was applied to the earlobe to ensure adequate tissue perfusion. Heart rate was monitored continuously by means of a three-lead electrocardiogram. From this, a bipolar signal was obtained, and heart rate was determined. A visual analog scale was utilized for assessing the subjects' respiratory discomfort, which was rated by each subject by moving a dial that was linked to a needle on an analog display positioned on the handlebars of the ergometer. This dial moved the needle between two labeled extremes of respiratory discomfort, the far left indicating no urge to breathe and the far right representing maximum urge to breathe. Respiratory discomfort ratings were made every minute in response to a verbal command. After each rating was recorded, the needle was moved back to the zero position to reduce any effect a previous score might have on the next. All of these signals were digitized, and values were stored on a breath-by-breath basis for later analysis.
Spirometry was performed by using the spirometry module of the Vmax 229 system. Pulmonary function testing was performed in the seated position for a minimum of three efforts and gave values for FVC and forced expiratory volume in 1 s (FEV1). For unrestricted exercise tests, forced spirometry was undertaken before and immediately after exercise. For restricted exercise tests, the pulmonary function tests were undertaken without and with restriction before the onset of exercise and after exercise.Incremental exercise tests. On the first and second visit to the laboratory, subjects performed an incremental exercise test in either the absence or presence of a thoracic restriction. The order of these tests was randomized. Subjects commenced exercise on the cycle ergometer at an initial load of 20 W for the first minute of the test. The work rate of the ergometer was subsequently increased in a continuous ramp at a rate of 20 W/min until the subject was unable to continue. Throughout the tests, subjects were verbally encouraged to exercise to exhaustion.
Constant-workload exercise tests. On the final visit to the laboratory, each subject initially performed a 12-min unrestricted, constant-workload exercise test at a predetermined workload. This work level was set to achieve a load equivalent to midway between 20 W and the GET. The GET was determined from the unrestricted incremental test. After a 1-h break, subjects then performed a second 12-min constant-workload exercise test, at the same workload, in the presence of a restriction. Each 12-min test was preceded by a 1-min rest period and a 4-min warm-up at a load of 20 W.
To avoid day-to-day variability in ventilatory and gas-exchange responses, the two constant-workload exercise tests were performed on the same day. Recovery after subthreshold exercise of short duration is rapid and, in the absence of restriction, two such tests performed at an interval of 1 h should elicit identicalE
and gas-exchange responses (25). Preliminary studies
showed that thoracic restriction induced alterations in
FEV1 and FVC that had not returned to prerestriction values
1 h after the removal of the restriction. For this reason, the
unrestricted exercise test always preceded the restricted exercise test.
Calculations.
Expired E and O2 uptake
(O2) were calculated by using standard
formulas. Breath-by-breath end-tidal CO2 readings were adjusted by using the Jones correction equation (11) to
give an estimate of arterial CO2. The GET was identified by
using the modified V-slope method of Sue et al. (20).
European Community for Coal and Steel Working Party prediction
equations were used when calculating predicted values of FVC and
FEV1 (16).
Predicting incremental E from a
constant-workload test.
The phase 2 ventilatory component of constant-load exercise of moderate
intensity has been described by a monoexponential function of the form
|
(1) |
E(t)cwl
represents the difference between E at any time
t after the onset of constant-workload exercise and the mean
E during the last minute of cycling at 20 W,
E(ss) is the difference between mean final
steady-state E (average of final 3 min of
constant-workload exercise) and mean E at 20 W (see
above), and 
is the phase 2 time constant (24). The value for is obtained graphically by plotting
E(ss) 
E(t)cwl against time
(excluding the phase 1 component of the response) on a semilogarithmic
scale. The value is then derived from the slope of the resulting
straight line.
During a ramped exercise test, E at any workload
will be less than E at that workload in a
constant-workload steady-state test (24) because of the
time delay in the ventilatory response. The change in
E at any time t during a ramped
incremental test [E(t)incr] is
given by
![&Dgr;<A><AC>V</AC><AC>˙</AC></A><SC>e</SC>(<IT>t</IT>)<SUB>incr</SUB><IT>=&Dgr;</IT><A><AC>V</AC><AC>˙</AC></A><SC>e</SC>(ss)<SUB>pred</SUB>[<IT>t−&tgr;</IT>(<IT>1−</IT>e<SUP>−<IT>t</IT>/&tgr;</SUP>)]](/content/vol89/issue6/fulltext/2179/img002.gif)
|
(2) |
E(ss)pred is the change
in E that would occur after the change in workload
at time t if a steady state were achieved.
In the sub-lactate-threshold range, the relationship between
E(ss) and the corresponding increase in
steady-state workload above 20 W [W(ss)] is linear and is given by
|
(3) |
W at any time t during an incremental test
[W(t)incr] is represented by
|
(4) |
![&Dgr;<A><AC>V</AC><AC>˙</AC></A><SC>e</SC>(<IT>t</IT>)<SUB>incr</SUB><IT>=sbt</IT>[<IT>t−&tgr;</IT>(<IT>1−</IT>e<SUP>−<IT>t</IT>/&tgr;</SUP>)]](/content/vol89/issue6/fulltext/2179/img005.gif)
|
(5) |
E
for any time t in the ramped incremental tests with use of
the time constant derived from the constant-workload exercise test
(Eq. 1).
Data analysis. All restricted spirometry data were expressed as percentages of the unrestricted value.
In the unrestricted and restricted incremental exercise tests, cardiorespiratory variables were averaged over 20-W intervals. During the tests, the value of a variable for any 20-W period was expressed as the change () from the value during warm-up cycling at 20 W (mean
value over the minute before change in workload).
For the constant-workload exercise tests, a similar analysis was
applied to measured variables to produce values with the last
minute of the 4-min warm-up at 20 W being subtracted from the mean
value obtained at each minute interval. Values for were then
averaged for the last 3 min of exercise in a single individual, and
this value was taken as the steady-state response of that individual.
To allow for a direct comparison between the two exercise protocols,
values at the end of the submaximal constant-workload exercise tests
would need to be compared with values at an equivalent workload in the
incremental exercise tests. Therefore, the workload at which the
subjects exercised in the constant-workload test was identified in the
incremental test, and the variables were compared with the average
value of the variables for the last 3 min of constant-workload exercise.
Statistical analysis.
The mean spirometric values obtained for the restricted condition on
the consecutive days of restriction and also before and after exercise
were compared by using paired t-analysis. For the incremental tests, the values were compared between the two experimental conditions for workloads that all subjects completed by
using an appropriately designed ANOVA. Paired t-tests were performed on maximum data (last minute of exercise). The average of the
last 3 min of constant-workload exercise was compared between the two
conditions by using paired t-analysis. For a direct
comparison between the two exercise protocols, a paired
t-test was performed between the two conditions in the
incremental test and between the two conditions at an equivalent
workload in the constant-workload test. A paired t-test was
used to compare the calculated phase 2 time constants and predicted
E for the unrestricted and restricted incremental
tests. An ANOVA for repeated measures was performed between the
unrestricted and restricted conditions for predicted ventilatory data
at three different workloads (20, 40, and 60 W). In all comparisons,
P < 0.05 was taken to indicate statistical significance. All data are shown as means ± SE.
| |
RESULTS |
|---|
|
TOP
ABSTRACT
INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES
|
|---|
All seven subjects completed the four exercise tests.
Anthropometric and pulmonary function data in the unrestricted
condition are shown in Table 1. Each
subject was within the normal predicted range of FVC and
FEV1.
|
Pulmonary function tests.
Table 2 shows the mean ± SE
spirometric values during restriction before and after exercise
expressed as percentages of the unrestricted value for the incremental
and constant-workload exercise tests. There were no significant
differences between the percentage decreases in FVC and
FEV1 from before to after exercise, indicating that
the degree of restriction was maintained throughout exercise in the
incremental and constant-workload exercise tests. It can be seen that
subjects were restricted by the same amount on both occasions.
|
Incremental exercise tests.
Figure 1 illustrates mean ± SE values for workloads that all subjects completed and
also for maximum exercise in the presence and absence of
restriction.
|
E was observed between the
unrestricted and restricted conditions at submaximal exercise workloads (Fig. 1A). There was no evidence of alveolar
hyperventilation at these submaximal workloads because there were no
differences in the PCO2 values between the two
conditions (Fig. 1B). With restriction, there was a trend
for respiratory frequency to be increased and tidal volume to be
decreased at submaximal workloads (Fig. 1, C and
D).
Table 3 shows absolute values
recorded at peak workloads for the two conditions. At maximum exercise,
peak E was significantly reduced in the presence of
restriction (Table 3). Respiratory frequency was significantly
increased and tidal volume significantly decreased in the presence of
the corset. Subjects reached 83.6 ± 4.4% of unrestricted maximal
work capacity with restriction, with a significant decrease in
O2 evident at maximum restricted exercise (Table 3).
|
Constant-workload exercise tests.
Figure 2 illustrates mean ± SE
values for the full 12 min of exercise in both the unrestricted and
restricted conditions.
|
E (Fig.
2A). A concomitant significant drop in
PCO2 values (Fig. 2B) suggested
alveolar hyperventilation. Although respiratory frequency increased at
all time points throughout the test, the increase failed to reach
significance for the average of the last 3 min of exercise (Fig.
2C). The O2 value at the end
of exercise, expressed as the average of the last 3 min of the
constant-workload test, did not differ between conditions.
Comparison between incremental and constant-workload exercise
tests.
Table 4 shows the absolute mean ± SE for the average of the final 3 min of constant-workload exercise and
at an equivalent workload for incremental exercise. Total
E was significantly increased in the
constant-workload test in the presence of restriction compared with the
unrestricted state. In the incremental exercise test at an equivalent
workload, no difference in ventilation was revealed between the
unrestricted and restricted conditions. A significant drop in
PCO2 during the restricted constant-workload test confirmed the presence of an alveolar hyperventilation, whereas no
difference was observed for PCO2 in the
incremental tests. In both exercise protocols, respiratory frequency
was significantly increased in the presence of restriction. Tidal
volume was significantly decreased in the constant-workload test but
not in the incremental test in the presence of restriction. Visual
analog scale scores of respiratory discomfort were significantly
increased in both the constant-workload test and the incremental test
in the presence of restriction.
|
Predicting incremental E from a
constant-workload test.
After the onset of constant-workload exercise, E
appeared to follow the pattern of a monoexponential function, as shown in Fig. 3A, which represents a
typical response of one individual to unrestricted and restricted
constant-workload exercise. A log plot of the same individual's
unrestricted and restricted ventilatory data resulted in a linear
pattern, as shown in Fig. 3B. Also depicted in this figure
are the equations of the lines of best fit from which the time
constants were derived.
|
E values for the unrestricted and
restricted conditions. In the restricted condition, the mean
steady-state E value and the mean time constant were
significantly increased compared with the unrestricted condition. We
then asked the following question: do the altered steady-state
E and time constant values derived in the presence
of restriction predict a ventilatory response to incremental exercise
similar to that predicted in the unrestricted condition? To examine
this, the ventilatory response of each individual to unrestricted and
restricted incremental exercise at 20, 40, and 60 W was predicted by
using each individual's steady-state E and time
constant values. The mean predicted values at each of these workloads
are shown in Table 6. There were no
significant differences between the unrestricted and restricted
conditions.
|
|
E at any
given workload. Figure 4 is an
illustration of the predicted E for the unrestricted
and restricted conditions in which the mean E(ss) and time constants in both conditions were used (Table 5) and substituted into Eq. 5. Despite the differences
in time constants and steady-state values for ventilation between the
unrestricted and restricted constant-workload exercise tests, similar
ventilatory values were predicted for the unrestricted and restricted
incremental tests. The E data were not predicted for
workloads >60 W because, at higher workloads, some subjects had
reached their GET and their ventilatory responses had become nonlinear.
Because this model assumes a linear relationship between steady-state
ventilation and workload, model predictions above the GET would be
invalid.
|
| |
DISCUSSION |
|---|
|
TOP
ABSTRACT
INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES
|
|---|
The findings of the present study indicate that, in the presence
of an externally applied thoracic restriction, the ventilatory response
to exercise is dependent on the protocol utilized. Subjects hyperventilated in the presence of restriction during the
constant-workload test, whereas, at an equivalent workload during the
incremental test, ventilation was similar to unrestricted values.
E was predicted for the unrestricted and restricted
incremental tests by using the time constants and steady-state values
for E from the constant-workload tests, and no
differences were found in the predicted ventilatory data for the two
conditions. This would suggest that a hyperventilation does not occur
in the restricted incremental test because of slower ventilatory
dynamics, because it takes almost twice as long to reach a given
ventilation in the presence of an externally applied thoracic
restriction as in the unrestricted state. Whereas earlier studies have
described the ventilatory response to either incremental or
constant-workload exercise in the presence of a thoracic restriction
(9, 10, 22), this was the first study to document the
ventilatory response to both incremental and constant-workload exercise
in the same subject group, and, for the first time, it has been shown
that the differing ventilatory responses reported in the literature are
a result of the varying exercise protocols.
During incremental exercise in the present study, a lower peak
E was reported in the presence of the restriction,
reflecting a lower maximum O2 consumption. At submaximal
workloads during these tests, no differences were found in total
ventilation between the unrestricted and restricted protocols. Also, no
differences were observed for calculated alveolar
E between the two conditions at these lower
workloads, because there were no differences in the
PCO2 values reported. In a previous study
(22), an incremental exercise test elicited a
significantly lower E at maximum exercise for
similar levels of thoracic restriction. However, the authors failed to
report any ventilatory data at submaximal workloads in the incremental
tests, and, because the PCO2 values
were not documented, there is no indication of what was happening to
alveolar E. In the present study, the
constant-workload exercise tests were performed at a workload below the
GET. This mild level of work was chosen to ensure that the ventilatory
response observed was independent of the effects of increasing
concentrations of circulating lactic acid. Because recovery after
subthreshold exercise of short duration is rapid (25), an
interval of 1 h between the unrestricted and restricted
constant-workload exercise tests was of adequate duration to return
E and gas-exchange parameters to baseline values.
Because the exercise load was set at a low level, it is highly unlikely
to have induced an altered ventilatory response to the second exercise
test completed in the presence of restriction. Therefore, the
significantly increased E observed in the presence
of restriction is due to the effects of restriction alone.
In the study of Harty et al. (9), subjects exercised at 65% of maximum heart rate, and it is probable that a number of these subjects were exercising above their GET. Therefore, increasing circulating lactic acid levels may have augmented the magnitude of the hyperventilatory response to constant-workload exercise. In contrast to the findings of the above study, Hussain et al. (10) reported that an exercise test performed above the GET produced similar ventilation to that achieved in the unrestricted test. There was no difference in end-tidal PCO2 between thoracic restriction and control conditions and, therefore, no evidence of a change in alveolar ventilation. However, the authors suggested that because there was evidence of electromyographic diaphragmatic fatigue during exercise in the presence of restriction, subjects were unable to maintain ventilation at the required level to continue exercising.
There is evidence that exercise protocol also affects the ventilatory
response to exercise in patient groups. A number of studies performed
in scoliotic patients reported either a normal ventilation (6,
18) or a significantly reduced ventilation (12, 13)
at maximum incremental exercise. Shneerson et al. (18)
documented that there was a trend for a hyperventilation at submaximal
workloads during the incremental test, but it failed to reach
significance. Similarly, at submaximal workloads during an incremental
test performed in patients with pulmonary fibrosis, Burdon et al.
(2) found that there was a tendency for ventilation to be
higher than normal at each power output during an incremental test,
but, once again, it failed to reach significance. Constant-workload exercise tests performed in pulmonary fibrotic patients resulted in a
relative hyperventilation when the response was compared with normal
healthy subjects (15, 19). The results of the present
study demonstrate that the differences in the ventilatory response to
incremental and constant-workload exercise do not arise because of
differences in subject characteristics or degree of restriction.
Rather, the differences arose because the effect of restriction on
E was dependent on the manner in which the workload changed.
We asked ourselves the question: how can restriction lead to a
hyperventilation in the constant-workload exercise test and yet cause
no change in ventilation at submaximal workloads during the incremental
test? Whipp et al. (24) have shown that the ventilatory
response to mild constant-workload exercise is well described by a
first-order linear response system. It has been demonstrated that, by
using the derived time constant and measured steady-state value for
E from the constant-workload test, the ventilatory
response to incremental exercise is well predicted (24).
The results of the present study indicate that the ventilatory response
to unrestricted and restricted constant-workload exercise followed the
pattern of a first-order linear response system. However, in the
presence of the restriction, the mean time constant was significantly
greater than the unrestricted value, and the mean change in the
steady-state value for E in the presence of
restriction was significantly higher. On the basis of these results,
the predicted response to E below the GET in the
incremental test was similar for both the unrestricted and restricted
conditions (Fig. 4).
The aim of this study was to document the effects of an externally applied thoracic restriction on the ventilatory response to incremental and constant-workload exercise in the same subject group and to explore potential mechanisms that may explain the disparate responses observed. This study was not designed to address the mechanisms underlying the observed hyperventilation. However, it is the first to provide subjective measures of respiratory discomfort during both exercise conditions, and it is interesting to note that clear differences in the response to incremental and submaximal constant-workload exercise exist. Significant differences were observed in both tests, with the mean values obtained in the constant-workload tests being greater than those observed in the incremental tests in both the unrestricted and restricted conditions. These differences between the incremental and constant-workload tests may reflect temporal differences in the development of the sensory response to exercise in a fashion similar to that seen with ventilation. With regard to the incremental test, in the presence of restriction, the differences cannot be a reflection of an increased level of ventilation. However, in the constant-workload test, some of the increased level of respiratory discomfort could be attributed to the increase in ventilation (26) or the sensory consequences of an inappropriate hyperventilation (4). Direct measures of respiratory mechanics were not made in this study, but increased work of breathing presumably contributed to the increased respiratory discomfort scores observed.
The present study does not reveal the underlying mechanisms through which restriction alters the ventilatory response to exercise. However, the data show that the markedly different responses to the two exercise protocols can both be accounted for by the same underlying alteration in the response of the ventilatory control system.
In conclusion, the ventilatory response to thoracic restriction is
dependent on the protocol utilized, with differing responses being
produced in the incremental and constant-workload exercise tests. We
can understand these differences by examining both the ventilatory
dynamics of the response and the steady-state values for
E in the presence and absence of restriction.
| |
ACKNOWLEDGEMENTS |
|---|
We gratefully acknowledge the support of The Irish Health Research Board and Enterprise Ireland.
| |
FOOTNOTES |
|---|
Address for reprint requests and other correspondence: Helen R. Harty, Dept. of Human Anatomy and Physiology, Univ. College, Earlsfort Terr., Dublin 2, Ireland (E-mail: helen.harty{at}ucd.ie).
The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
Received 2 March 2000; accepted in final form 12 July 2000.
| |
REFERENCES |
|---|
|
TOP
ABSTRACT
INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES
|
|---|
1.
Bradley, CA,
and
Anthonisen NR.
Rib cage and abdominal restrictions have different effects on lung mechanics.
J Appl Physiol
49:
946-952,
1980
2.
Burdon, JG,
Killian KJ,
and
Jones NL.
Pattern of breathing during exercise in patients with interstitial lung disease.
Thorax
38:
778-784,
1983[Abstract].
3.
Caro, CG,
Butler J,
and
DuBois AB.
Some effects of restriction of chest cage expansion on pulmonary function in man: an experimental study.
J Clin Invest
39:
573-583,
1960.
4.
Chonan, T,
Mulholland MB,
Altose MD,
and
Cherniack NS.
Effects of changes in level and pattern of breathing on the sensation of dyspnea.
J Appl Physiol
69:
1290-1295,
1990
5.
DiMarco, AF,
Kelsen SG,
Cherniack NS,
Hough WH,
and
Gothe B.
Effects on breathing of selective restriction of movement of the rib cage and abdomen.
J Appl Physiol
50:
412-420,
1981
6.
DiRocco, PJ,
and
Vaccaro P.
Cardiopulmonary functioning in adolescent patients with mild idiopathic scoliosis.
Arch Phys Med Rehabil
69:
198-201,
1988[Medline].
7.
Douglas, NJ,
Drummond GB,
and
Sudlow MF.
Breathing at low lung volumes and chest strapping: a comparison of lung mechanics.
J Appl Physiol
50:
650-657,
1981
8.
Gonzalez, J,
Coast JR,
Lawler JM,
and
Welch HG.
A chest wall restrictor to study effects on pulmonary function and exercise.
Respiration
66:
188-194,
1999[Medline].
9.
Harty, HR,
Corfield DR,
Schwartzstein RM,
and
Adams L.
External thoracic restriction, respiratory sensation, and ventilation during exercise in men.
J Appl Physiol
86:
1142-1150,
1999
10.
Hussain, SN,
Rabinovitch B,
Macklem PT,
and
Pardy RL.
Effects of separate rib cage and abdominal restriction on exercise performance in normal humans.
J Appl Physiol
58:
2020-2026,
1985
11.
Jones, NL,
Robertson DG,
and
Kane JW.
Difference between end-tidal and arterial PCO2 in exercise.
J Appl Physiol
47:
954-960,
1979
12.
Kearon, C,
Vivani GR,
and
Killian KJ.
Factors influencing work capacity in adolescent idiopathic thoracic scoliosis.
Am Rev Respir Dis
148:
295-303,
1993[ISI][Medline].
13.
Kesten, S,
Garfinkel SK,
Wright T,
and
Rebuck AS.
Impaired exercise capacity in adults with moderate scoliosis.
Chest
99:
663-666,
1991
14.
Klineberg, PL,
Rehder K,
and
Hyatt RE.
Pulmonary mechanics and gas exchange in seated normal men with chest restriction.
J Appl Physiol
51:
26-32,
1981
15.
Lourenco, RV,
Turino GM,
Davidson LAG,
and
Fishman AP.
The regulation of ventilation in diffuse pulmonary fibrosis.
Am J Med
38:
199-215,
1965.
16.
Quanjer, PH,
Tammeling JE,
Cotes JE,
Pederson OF,
Peslin R,
and
Yernault JC.
Lung volumes and forced ventilatory flows. Report of working party standardization of lung function tests, European Community for Steel and Coal. Official statement of the European Respiratory Society.
Eur Respir J Suppl
6:
5-40,
1993.
17.
Scheidt, M,
Hyatt RE,
and
Rehder K.
Effects of rib cage or abdominal restriction on lung mechanics.
J Appl Physiol
51:
1115-1121,
1981
18.
Shneerson, JM.
Cardiac and respiratory responses to exercise in adolescent idiopathic scoliosis.
Thorax
35:
347-350,
1980[Abstract].
19.
Spiro, SG,
Dowdeswell RG,
and
Clark TJH
An analysis of submaximal exercise responses in patients with sarcoidosis and fibrosing alveolitis.
Br J Dis Chest
75:
169-180,
1981[ISI][Medline].
20.
Sue, DY,
Wasserman K,
Moricca RB,
and
Casaburi R.
Metabolic acidosis during exercise in patients with chronic obstructive pulmonary disease.
Chest
94:
931-938,
1988
21.
Sybrecht, GW,
Garrett L,
and
Anthonisen NR.
Effect of chest strapping on regional lung function.
J Appl Physiol
39:
707-713,
1975
22.
Vanmeenen, MT,
Ghesquiere J,
and
Demedts M.
Effects of thoracic or abdominal strapping on exercise performance.
Bull Eur Physiopath Respir
20:
127-132,
1984[ISI][Medline].
23.
VanNoord, JA,
Demedts M,
Clement J,
Cauberghs M,
and
Van de Woestijne KP.
Effect of rib cage and abdominal restriction on total respiratory resistance and reactance.
J Appl Physiol
61:
1736-1740,
1986
24.
Whipp, BJ,
Davies JA,
Torres F,
and
Wasserman K.
A test to determine parameters of aerobic function during exercise.
J Appl Physiol
50:
217-221,
1981
25.
Williams, RE,
and
Horvath SM.
Recovery from dynamic exercise.
Am J Physiol Heart Circ Physiol
268:
H2311-H2320,
1995
26.
Wilson, RC,
and
Jones PW.
A comparison of the visual analogue scale and modified Borg scale for the measurement of dyspnoea during exercise.
Clin Sci (Colch)
76:
277-282,
1989[Medline].
This article has been cited by other articles:
|
|
 |
|
  G. Ince, T. Sarpel, B. Durgun, and S. Erdogan Effects of a Multimodal Exercise Program for People With Ankylosing Spondylitis Physical Therapy, July 1, 2006; 86(7): 924 - 935. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. E. Turner, P. R. Eastwood, N. M. Cecins, D. R. Hillman, and S. C. Jenkins Physiologic Responses to Incremental and Self-Paced Exercise in COPD: A Comparison of Three Tests Chest, September 1, 2004; 126(3): 766 - 773. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. D. Miller, K. C. Beck, M. J. Joyner, A. G. Brice, and B. D. Johnson Cardiorespiratory effects of inelastic chest wall restriction J Appl Physiol, June 1, 2002; 92(6): 2419 - 2428. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |
