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Eur J Appl Physiol (2014) 114:2387–2397
DOI 10.1007/s00421-014-2956-0
ORIGINAL ARTICLE
Operating lung volumes are affected by exercise mode but not
trunk and hip angle during maximal exercise
Joseph W. Duke · Jonathon L. Stickford ·
Joshua C. Weavil · Robert F. Chapman ·
Joel M. Stager · Timothy D. Mickleborough
Received: 19 November 2013 / Accepted: 12 July 2014 / Published online: 2 August 2014
© Springer-Verlag Berlin Heidelberg 2014
Conclusion Since OLV are altered by exercise mode, but
cycling position did not have a significant impact on OLV,
we conclude that trunk/hip angle is likely not the primary
factor determining OLV during maximal exercise.
Keywords Ventilation · Pulmonary mechanics ·
Breathing patterns · Elite athletes
Abbreviations
EELV End-expiratory lung volumes
EILV End-inspiratory lung volumes
fb Frequency of breathing
FEO2 Fraction of expired O2
FECO2− Fraction of expired CO2
FEV1 Forced expired volume in 1 s
FEV1/FVC Forced expired volume in 1 s to forced vital
capacity ratio
FVC Forced vital capacity
HR Heart rate
IC Inspiratory capacity
MEF50 Maximal expiratory flow at 50 % of forced
vital capacity
OLV Operating lung volumes
PEF Peak expired flow rate
rpm Revolutions per minute
RER Respiratory exchange ratio
Ti/TTotal Inspiratory duty cycle as a percentage of total
breathing cycle time
TLC Total lung capacity
TTotal Total breathing cycle time
VE Minute ventilation
VE/VO2 Ventilatory equivalents for oxygen (O2)
VE/VCO2 Ventilatory equivalents for carbon dioxide
(CO2)
VO2peak Peak oxygen consumption
Abstract
Introduction Despite VO2peak being, generally, greater while
running compared to cycling, ventilation (VE) during maxi-
mal exercise is less while running compared to cycling. Dif-
ferences in operating lung volumes (OLV) between maximal
running and cycling could be one explanation for previously
observed differences in VE and this could be due to differ-
ences in body position e.g., trunk/hip angle during exercise.
Purpose We asked whether OLV differed between maxi-
mal running and cycling and if this difference was due to
trunk/hip angle during exercise.
Methods Eighteen men performed three graded maxi-
mal exercise tests; one while running, one while cycling in
the drop position (i.e., extreme hip flexion), and one while
cycling upright (i.e., seated with thorax upright). Resting
flow-volume characteristics were measured in each body
position to be used during exercise. Tidal flow-volume
loops were measured throughout the exercise.
Results VE during maximal running (148.8 ± 18.9 L min−1)
tended to be lower than during cycling in the drop position
(158.5 ± 24.7 L min−1; p = 0.07) and in the upright position
(158.5 ± 23.7 L min−1; p = 0.06). End-inspiratory and end-
expiratory lung volumes (EILV, EELV) were significantly
larger during drop cycling compared to running (87.1 ± 4.1
and 35.8 ± 6.2 vs. 83.9 ± 6.0 and 33.0 ± 5.7 % FVC), but
only EILV was larger during upright cycling compared to
running (88.2 ± 3.5 % FVC). OLV and VE did not differ
between cycling positions.
Communicated by Guido Ferretti.
J. W. Duke (*) · J. L. Stickford · J. C. Weavil · R. F. Chapman ·
J. M. Stager · T. D. Mickleborough
Human Performance Laboratory, Department of Kinesiology,
Indiana University, Bloomington, IN 47405, USA
e-mail: jduke@uoregon.edu
2388 Eur J Appl Physiol (2014) 114:2387–2397
1 3
VT Tidal volume
W Watts
Introduction
Previous studies have demonstrated that the cardiopulmo-
nary responses to exercise differ as a function of exercise
mode (Astrand and Saltin 1961; Smith et al. 1994; Gavin
and Stager 1999; Elliott and Grace 2010; Tanner et al.
2014). Peak oxygen consumption (VO2peak), in particular,
has been shown to be nearly 10 % greater while running
compared to cycling (Hermansen et al. 1970; Gavin and
Stager 1999; Tanner et al. 2014), which is likely due to
the larger muscle mass recruited while running (Astrand
and Saltin 1961). In addition, minute ventilation (VE) has
been shown to be significantly greater during maximal
cycling compared to maximal running (Astrand and Sal-
tin 1961; Smith et al. 1994; Gavin and Stager 1999; Elli-
ott and Grace 2010). The differing VE between maximal
running and cycling may be explained by two proposed
mechanisms. The first proposed mechanism is that the
chemical and/or neural stimuli to breathe may be greater
during maximal cycling compared to maximal running
(Koyal et al. 1976; Millet et al. 2009). Of note, it has
been reported that the ventilatory equivalents for both
oxygen (VE/VO2) and carbon dioxide (VE/VCO2) were
higher during maximal cycling compared to running, pos-
sibly implying an increased chemical (i.e., CO2) drive to
breathe (Gavin and Stager 1999; Tanner et al. 2014). The
second proposed mechanism, and the objective of this
study, focuses on how pulmonary mechanics may influ-
ence how VE is achieved (Hopkins et al. 2000; Millet et al.
2009). Due to the mechano-elastic properties of the lung,
chest wall, and respiratory muscles responsible for active
inspiration and expiration, expiratory airflow rate varies as
a function of the lung volumes at which ventilation takes
place (Sharratt et al. 1987; Klas and Dempsey 1989; Babb
et al. 1991; McClaran et al. 1999), referred to as exercise
operating lung volumes (OLV). OLV are examined using
end-inspiratory and end-expiratory lung volumes (EILV
and EELV, respectively) and a number of studies have
examined OLV in healthy individuals during running
(Henke et al. 1988; Johnson et al. 1990, 1991a, 1992) or
cycling (Stubbing et al. 1980; Younes and Kivinen 1984;
Sharratt et al. 1987; Henke et al. 1988; Klas and Demp-
sey 1989; Babb et al. 1991; McClaran et al. 1999). Only
recently, however, EILV and EELV were compared in indi-
viduals asked to perform both exercise modalities (Tan-
ner et al. 2014). Although we reported significantly larger
EILV and EELV (i.e., closer to total lung capacity; TLC)
during maximal cycling compared to maximal treadmill
running, we failed to observe a significantly larger VE
while cycling. The effect of body position on OLV was not
directly tested.
The body positions used while running on a treadmill, as
well as cycling on an ergometer may influence OLV. While
running, an individual is in an erect posture with the thorax
upright and roughly perpendicular to the treadmill. How-
ever, while cycling, individuals are seated on the ergometer
with at least a slight flexion of the hip (angle less than 90°)
and forward lean of the thorax. The effect of body posi-
tion on lung volumes at rest has been extensively studied
(see Agostoni and Hyatt 1986 for a review on this topic).
In young, healthy individuals functional residual capacity
(i.e., EELV at rest) is ~50 % of TLC while standing, but
increases to ~57 % of TLC while seated and leaning for-
ward with arms rested at roughly sternum height (Agostoni
and Hyatt 1986). This implies that the position of the tho-
racic cavity (i.e., hip flexion), even at rest, has an impact
on OLV and our previously published differences in OLV
at rest while standing compared to seated on an ergometer
support this supposition (Tanner et al. 2014). Furthermore,
only a few studies have investigated the impact of body
position (e.g., trunk/hip angle) during cycling on various
cardiopulmonary parameters (Faria et al. 1978; Origenes
et al. 1993; Berry et al. 1994). These studies compared var-
ious performance and metabolic measures between cycling
positions (VO2peak, power output, etc.) and found only VE
during maximal exercise to differ between cycling posi-
tions (drop > upright; Faria et al. 1978), but did not quan-
tify OLV (Faria et al. 1978; Origenes et al. 1993; Berry
et al. 1994).
Therefore, the primary purpose of this investigation was
to determine if OLV differed during submaximal and maxi-
mal exercise between running on a treadmill and cycling on
an ergometer within the same, well-trained, individual. We
also sought to determine if the observed difference on OLV
between submaximal and maximal running and cycling
was due to the trunk/hip angle by directly comparing OLV
in drop and upright cycling. Because of the difference in
trunk/hip angle and its effects on respiratory mechanics, we
hypothesized that OLV would be significantly larger (i.e.,
EILV and EELV will be closer to TLC) during submaximal
and maximal cycling in the drop position compared to run-
ning. Furthermore, we hypothesized that OLV in upright
cycling would not differ from running owing to the similar
trunk/hip angle.
Methods
Subjects
Thirty-five college-aged males volunteered to participate in
the study after being advised both verbally and in writing
2389Eur J Appl Physiol (2014) 114:2387–2397
1 3
as to the nature of the experiments and providing written
informed consent. These documents and procedures were
approved by the Indiana University review board, which
governs human research, and in according with the Dec-
laration of Helsinki. Each subject was required to meet a
set of inclusion criteria: a history of extensive, high-level
endurance training (as determined by a questionnaire about
training history), and no indication of pulmonary disease or
dysfunction. Fifteen subjects did not meet the aerobic fit-
ness criteria (VO2peak ≤ 60 mL kg−1 min−1 while cycling
or ≤65 mL kg−1 min−1 while running), and two subjects
voluntarily withdrew from the study prior to completion.
Of the initial thirty-five screened individuals, eighteen
met all of the screening criteria and were invited to par-
ticipate further. Eight indicated they were primarily trained
by running, six indicated cycling was their predominant
training mode, and the remaining four considered them-
selves to be triathletes (i.e., equally trained in both run-
ning and cycling). The individuals that qualified and com-
pleted the entire study were aged 21 ± 2 years, weighed
71.3 ± 7.6 kg, and stood 180.5 ± 6.4 cm tall. All subjects
were well-trained endurance athletes as indicated by their
self-reported assessment of current training and fitness
level.
Experimental sequence
Each subject performed a total of three graded exercise
tests (i.e., two additional tests after the initial screening
test) to volitional exhaustion; once on a motor driven tread-
mill and twice on an electronically braked cycle ergometer
with each visit separated by at least 24 h and a maximum
of 2 weeks. Following the initial screening test, the remain-
ing two maximal exercise tests were done in a random
order. The initial screening involved completing a maximal
graded exercise test on either a motor driven treadmill or a
cycle ergometer, depending upon which mode the subject
considered himself more trained. Individuals who indicated
they were more trained on a bicycle performed their initial
test on the cycle ergometer in the ‘drop position’. This posi-
tion was chosen for the initial testing because it reflected
a cycling position to which well-trained cyclists are more
accustomed compared to the upright position used in this
study. In the drop position, the subject’s hands rested on the
lowermost portion of the standard cycling racing handle-
bars with a great deal of hip flexion, such that the thorax
was nearly parallel with the top tube of the cycle ergom-
eter (i.e., in the horizontal plane). In addition, this trunk/
hip angle is most similar to that used during exercise in the
previous studies from our laboratory comparing maximal
running and maximal cycling (Gavin and Stager 1999; Tan-
ner et al. 2014). The remaining cycling test was performed
in the ‘upright’ position. This position required subjects to
rest their hands at sternum height on a polyvinylchloride
pipe that was constructed to go over the cycle ergometer.
The polyvinylchloride pipe was constructed such that it
could be moved away from or towards the subject to ensure
they had a comfortable reach to the pipe and that there was
minimal forward lean (i.e., hip flexion). Resting their hands
on this pipe kept the hips minimally flexed and the tho-
racic cavity vertical and near-perpendicular to the top tube
of the cycle ergometer. The contrast in cycling positions
was intentionally chosen to best test the impact of trunk/
hip angle on ventilatory parameters during maximal cycle
ergometry. Maximal treadmill running was performed
while in an erect posture with no or little hip flexion and
the thoracic cavity nearly perpendicular to the treadmill
belt.
Experimental procedures
Prior to each test, three to five forced vital capacity (FVC)
manoeuvres were performed in the body position in which
exercise would take place. From each FVC manoeuvre,
forced expiratory volume in 1 s (FEV1), peak expiratory
flow rate (PEF), and maximal expiratory flow at 50 % of
vital capacity (MEF50) were calculated. Tests were done
in accordance with the standards set by the American Tho-
racic Society for repeatability (Miller et al. 2005). Flow
and volume values were corrected to body temperature,
pressure, saturated, and the largest FVC, FEV1, PEF, and
MEF50 selected. Of the three repeatable FVC manoeuvres
performed, the manoeuvre that produced the largest FVC
and FEV1 was selected as a representation of the subject’s
pulmonary function.
Treadmill test
After collecting resting metabolic data for 5 min, the speed
of the treadmill (model 18–60, Quinton, Bothell, WA,
USA) was increased to one that would allow the test to last
approximately 10–15 min. The selected speed was based
on the individual subject’s training history and treadmill
running experience. Speeds ranged from 9.2 to 14.5 km h−1
(5.3–9.0 mi h−1) and remained constant throughout the
duration of the test. Subjects began the test by running on a
flat treadmill (0 % grade). After 2 min, the treadmill grade
was increased to 4 %, and the grade continued to be raised
2 % every 2 min thereafter until volitional fatigue (Balke
and Ware 1959).
Cycle ergometry tests
Similar to the treadmill test, the maximal cycling pro-
tocol began with 5 min of seated resting measurements.
2390 Eur J Appl Physiol (2014) 114:2387–2397
1 3
Following rest, the subject began cycling on an electroni-
cally braked cycle ergometer (Velotron, Elite Model, Racer
Mate, Seattle, WA, USA) at a workload of 100 W. The
workload was increased by 25 W every minute thereaf-
ter until the subject could no longer continue or cadence
decreased below ~60 rpm. Both cycling positions followed
identical exercise protocols.
During the maximal exercise, test subjects were verbally
encouraged to exercise as long as possible. VO2peak was
assessed using the following criteria: (1) a heart rate ≥90 %
of the age-predicted maximal heart rate (220 − age), (2) a
respiratory exchange ratio (RER) ≥1.10, and (3) identifi-
cation of a plateau (≤150 ml) in VO2 with an increase in
workload. If two of the three criteria were met, the highest
1 min average VO2 was chosen as the subject’s VO2peak.
During the maximal exercise tests, heart rate (HR) was
measured using a telemetry transmitter affixed to the sub-
ject’s chest (Polar Electro Inc., Lake Success, NY, USA)
and recorded at the end of every minute. Ventilatory and
metabolic variables were continuously measured during
rest and exercise via open-circuit calorimetry. Subjects
breathed through a low resistance, two-way non-rebreath-
ing valve (model 2700, Hans Rudolph, Shawnee, KS,
USA), from which expired gases entered a 5 L mixing
chamber. Fractional concentrations of O2 and CO2 (FEO2
and FECO2, respectively) were sampled from the mix-
ing chamber at a constant rate (300 mL × min−1) with O2
quantified using an Applied Electrochemistry S-3A (Ame-
tek, Thermox Instruments, Pittsburgh, PA, USA) oxygen
analyzer and CO2 with a CD-3A carbon dioxide analyzer
(Ametek, Thermox Instruments, Pittsburgh, PA, USA).
Analyzers were calibrated immediately pre-test with a gas
of a known concentration in the physiological range and
checked/corrected for any drift immediately following the
test’s completion. A pneumotachograph (series 3,813 Hans
Rudolph, Shawnee, KS, USA) placed on the inspired side
was used to measure inspired airflow, which was integrated
and converted to yield VE. Ventilatory and metabolic vari-
ables were averaged over each minute of exercise. The
above variables, as well as, FEO2 and FECO2, frequency of
breathing (fb), and tidal volume (VT), were continuously
measured and monitored with a data acquisition software
(DASYLab, Measurement Computing, Norton, MA, USA)
sampling at 50 Hz.
Flow-volume relationships
Flow-volume loops were collected during all progressive
exercise tests. Maximal flow-volume loops were collected
pre- and post-exercise and obtained in triplicate by having
the subject perform FVC manoeuvres, again in accord-
ance with ATS standards (Miller et al. 2005). The largest
maximal flow-volume loop, regardless of whether it was
obtained pre- or post-exercise, was chosen for further anal-
ysis using the same criteria outlined with respect to pulmo-
nary function above. Of the 54 maximal flow-volume loops
(18 subjects × 3 trials = 54) obtained, 9 were constructed
from post-exercise manoeuvres and 45 from pre-exercise
manoeuvres. To measure FVC, subjects were told to expire
to residual volume, maximally inspire to TLC and maxi-
mally expire to residual volume. Inspired and expired flow
rates were measured using pneumotachographs on both the
inspired and expired sides. The pneumotachograph on the
expired side was heated to allow for calculation of body,
temperature, pressure, saturated values despite changes in
expired gas temperature during exercise. Exercise flow-
volume data were collected over the last 30 s of each stage
of exercise using a technique described elsewhere (Derchak
et al. 2000; Tanner et al. 2014). Briefly, tidal breath flow-
volume loops were averaged over approximately 12–15
breaths during each minute. Average tidal breath flow-
volume loops were placed into the proper position on the
volume axis within the maximal flow-volume loop using
an in-house data analysis program specifically designed
for this purpose (Clipper 5.2, Computer Associates, Islan-
dia, NY, USA). Inspiratory capacity manoeuvres were per-
formed at 30 and 55 s of each stage and were used to esti-
mate average inspiratory reserve volume during this period
as previously described (Babb 1997). EELV and EILV were
mathematically determined by, first, subtracting inspira-
tory capacity volume from FVC (EELV = FVC−IC) and
adding VT to EELV (EILV = EELV + VT). Prior to the
initial exercise test, the procedure and importance of the
inspiratory capacity manoeuvre were described in detail to
each subject. Correct performance was demonstrated and
subjects performed several unmeasured practice manoeu-
vres. During exercise, strong encouragement was provided
immediately prior to and during each manoeuvre during
exercise. Our data acquisition software allowed visualiza-
tion of real-time measurement so if a manoeuvre appeared
inadequate; the subject was prompted to perform another.
The in-house data analysis program also provided measures
of total breathing cycle time, from which the inspiratory
duty cycle as a percentage of total breathing cycle time was
calculated (Ti/TTotal). Expiratory flow limitation was con-
sidered to be present when the tidal flow-volume loop met
or exceeded the maximal flow-volume loop and the extent
of expiratory flow limitation was calculated as a percentage
of the expired tidal volume that met or exceeded the maxi-
mal flow-volume loop (Johnson et al. 1995).
Statistical analysis
To address the primary purpose of the study (maximal
exercise), all variables (OLV, VE, VO2peak, VCO2, VT, and
fb) were analyzed using a priori planned comparisons
2391Eur J Appl Physiol (2014) 114:2387–2397
1 3
between (1) running and drop cycling, (2) drop cycling
and upright cycling, and (3) running and upright cycling.
For these comparisons, the familywise error rate (αfam)
was set to equal 0.05 and was adjusted to control Type I
error (αcomp) using the Bonferroni adjustment, such that
αcomp = αfam/c, where c is the number of comparisons to
be made. We chose to analyze the maximal exercise data
in this manner because we wanted to utilize our statistical
power for the pairwise comparisons that would allow us
to answer our primary research question rather than test
for a significant overall test first. To address the second-
ary, more exploratory, purpose (submaximal exercise)
we utilized a more conservative statistical approach and
multiple one-way repeated measures ANOVAs were com-
puted (i.e., (1) between running, drop cycling, and upright
cycling at 70 % of VO2peak and (2) between running, drop
cycling, and upright cycling at 85 % of VO2peak). When
a significant omnibus test was observed a Tukey post-
test was computed to determine where pairwise differ-
ences existed. This allowed us to determine if differences
observed during maximal exercise were apparent at lower
intensity exercise or did not appear until maximal exer-
cise. The prevalence of expiratory flow limitation was
tested using a two-sample z test (because proportions
follow a Normal distribution) for (1) running and drop
cycling, (2) drop cycling and upright cycling, and (3)
running and upright cycling. The Bonferroni adjustment
was made as described above. Statistical analyses were
performed using PASW version 19.0 for Windows (IBM,
Chicago, IL, USA).
Results
Pulmonary function
Absolute and percent predicted values (mean ± SD) for
pulmonary function in the respective exercise mode are dis-
played in Table 1. All values were within the normal ranges
for healthy men aged 18–35 years (Hankinson et al. 1999).
No differences in pulmonary function existed between
exercise modes or cycling positions (p > 0.05).
Operating lung volumes during exercise
EILV and EELV expressed as % of FVC are displayed in
Fig. 1. Tidal flow-volume loops within a maximal flow-
volume loop during maximal exercise in each trial are dis-
played in Fig. 2. EILV and EELV were significantly larger
during maximal cycling in the drop position compared to
maximal running (p < 0.05), but did not differ between
cycling positions (p > 0.05). EILV was significantly larger
during maximal cycling in the upright position compared
to maximal running (p < 0.05). The maximal flow-volume
loops (i.e., FVC, FEV1, PEF50) did not differ between trials
(p > 0.05). EILV was significantly greater during submaxi-
mal drop and upright cycling compared to while running.
Submaximal and maximal tidal flow-volume loops for each
exercise trial for a single subject are displayed in Fig. 3.
The prevalence of extent of expiratory flow limitation dur-
ing maximal exercise did not differ between exercise trials
(p > 0.05; Table 2).
Submaximal and maximal exercise response data
Metabolic and ventilatory values for the three exercise tests
are presented in Table 2 and Fig. 4. VE during maximal
exercise did not differ between maximal running and maxi-
mal cycling in either position (drop; p = 0.07 and upright;
p = 0.06). VE during submaximal exercise was significantly
greater during upright cycling compared to drop cycling at
70 % of VO2peak only. No other differences existed on VE
between exercise trials. VT did not differ between maximal
running and drop cycling (p > 0.05), but was significantly
larger during upright cycling compared to running and drop
cycling (p < 0.05). VT during submaximal exercise was sig-
nificantly larger during upright cycling compared to running
at 70 and 85 % of VO2peak, but not different between run-
ning and drop cycling or cycling positions. Similarly, fb did
not differ between maximal running and maximal cycling
Table 1 Resting pulmonary function data
No variables were significantly different between trials. Data are displayed as mean ± SD. Values in parentheses are mean ± SD percent pre-
dicted for each pulmonary function parameter
FVC forced vital capacity, FEV1 forced expiratory volume in 1 s, MEF50 maximal expiratory flow at 50 % of vital capacity
Running Drop cycle Upright cycle
FVC (L) 5.22 ± 0.52 (90.6 ± 6.7) 5.27 ± 0.56 (91.4 ± 6.8) 5.28 ± 0.55 (91.6 ± 7.3)
FEV1 (L) 4.61 ± 0.49 (96.4 ± 7.3) 4.66 ± 0.50 (97.3 ± 6.9) 4.60 ± 0.53 (96.2 ± 8.2)
FEV1/FVC (%) 88.5 ± 4.3 (105.6 ± 4.8) 88.5 ± 4.0 (105.6 ± 4.5) 87.3 ± 4.5 (104.2 ± 5.1)
PEF (L sec−1) 10.05 ± 1.26 10.19 ± 1.58 10.46 ± 1.44
MEF50 (L sec−1) 4.98 ± 1.26 5.32 ± 1.26 5.50 ± 1.89
2392 Eur J Appl Physiol (2014) 114:2387–2397
1 3
in either position (p > 0.05), but did differ between cycling
positions (p < 0.05). The fb during submaximal exercise was
significantly lower during drop cycling compared to while
running at 70 % of VO2peak, but not different at any other
submaximal time point. VE/VO2, and VE/VCO2 were signifi-
cantly less during maximal running compared to maximal
cycling in both the drop and upright positions (p < 0.05), but
did not differ between cycling positions (p > 0.05).
Discussion
The purpose of this study was to determine if OLV signifi-
cantly differed during submaximal and maximal exercise
while running on a treadmill versus cycling on an ergom-
eter. We additionally sought to determine if the observed
difference in OLV between running and cycling was due
to differences in the trunk/hip angle. As hypothesized,
OLV (i.e., EILV and EELV) were significantly larger (i.e.,
closer to TLC) during maximal cycling in the drop position
compared to maximal running, but not during submaximal
exercise. However, contrary to our hypothesis, the observed
difference in OLV was likely not due to the difference in
trunk/hip angle between exercise modes. Furthermore, we
found that trunk/hip angle had no impact on VE, but did sig-
nificantly impact the “strategy” utilized to achieve this VE
(i.e., VT and fb).
Operating lung volumes during submaximal and maximal
exercise
We hypothesized that OLV would be greater during maxi-
mal cycling in the drop position compared to running
because the hip flexion (i.e., forward lean of the thorax)
achieved in this position would compress the abdominal
compartment and force the diaphragm higher into the tho-
racic cavity, thereby causing individuals to ventilate at a
lung volume closer to TLC (Tanner et al. 2014). If this was
the case, it would explain differences in VE during maxi-
mal exercise between running and drop cycling because
ventilating at a lung volume closer to TLC could allow for
greater expiratory flow rates and therefore a greater fb (i.e.,
same VT breathed over a shorter period of time). Interest-
ingly, the observed difference in OLV between running and
drop cycling was not significant until maximal exercise,
suggesting that like VE, the differences between modes is
not apparent until the “stimulus” is maximal. We found
70% 85% 100%
0
30
70
80
90
100
%VO
2peak
%VO2peak %VO2peak
70% 85% 100%
0
30
70
80
90
100
*
*
*
70% 85% 100%
0
30
70
80
90
100
*
*
OLV (% FVC)
OLV (% FVC)
OLV (% FVC)
EELV
EILV
ABC
Fig. 1 This figure displays mean ± SD EELV (hashed bars) and
EILV (solid bars) as a % of FVC during submaximal and maximal
running (a), drop cycling (b), and upright cycling (c). * Significantly
different from running (p < 0.05) within a given exercise intensity
(i.e., running vs. drop cycling vs. upright cycling at 70 % of VO2peak
012345
0
2
4
6
8
10
Volume (L)
Running
MFVL
Upright Cycling
Drop Cycling
Flow (L s-1)
VO2peak = 63.9 - 72.2 mL/kg/min
VE = 145.2 - 161.0 L/min
VT= 2.1-2.4L
EFL% = 48 - 52% of VT
Fig. 2 The figure above displays the tidal flow-volume loops of a
single subject at maximal exercise while running (thin, solid line),
cycling in the drop position (thick, dashed line), and cycling in the
upright position (thin, dotted line). This subject was chosen because
the position of his tidal flow-volume loops within the maximum
flow-volume loop (MFVL; thick, solid line) were roughly equiva-
lent to that of the mean. Maximum flow-volume loops did not differ
between trials so only one loop displayed. Pulmonary function val-
ues for this individual subject were: FVC = 4.54 L (89 % predicted);
FEV1 = 4.02 L (96 % predicted); FEV1/FVC = 89 % (106 % pre-
dicted); MEF50 = 4.84 L/sec. Parameters listed in the figure are the
range of values this individual subject attained during all three trials
2393Eur J Appl Physiol (2014) 114:2387–2397
1 3
neither EELV nor EILV to significantly differ between
cycling positions suggesting that the observed differences
in OLV during maximal exercise is not due to trunk/hip
angle, but most likely due to some other aspect of the dif-
fering exercise modalities.
Several differences exist between running and cycling,
in addition to trunk/hip angle that may explain the observed
differences on OLV. As proposed by others, the presence
and extent of expiratory flow limitation could impact OLV
(Babb 1999; Johnson et al. 1991b; Pellegrino et al. 1993;
McClaran et al. 1999; Taylor et al. 2013). Expiratory flow
limitation does not appear to play a significant role in the
present study because the prevalence and extent of expira-
tory flow limitation did not differ between modes or cycling
positions. Other differences between exercise modes
include, but are not limited to the movement of the arms
during exercise and a need to stabilize the core to keep the
torso upright during running, which are interrelated. Stand-
ing in a vertical position (De Troyer 1983) and swinging
the arms to mimic running (Hodges and Gandevia 2000)
has been shown to increase electromyographic activity of
the abdominal muscles (e.g., transverse abdominis, external
oblique, and rectus abdominis), which play important roles
in the generation of expiratory flow and core stability while
upright. In addition, the vertical displacement of the vis-
cera during running has been shown to result in an increase
in abdominal muscle tone (Grillner et al. 1978). Increased
activity of the abdominal muscles has been suggested to act
as a “shock absorber” for the spine during the planting of
the foot (Henke et al. 1988). This suggests a greater degree
of abdominal muscle recruitment, resulting in a lower
EELV, during treadmill running compared to cycling, which
supports the explanation provided in the current study with
respect to differences in OLV (Henke et al. 1988).
None of the discussed studies (Grillner et al. 1978; De
Troyer 1983; Henke et al. 1988; Hodges and Gandevia
2000) directly quantify OLV, but provide us with some
information about how respiratory muscle recruitment
could differ between exercise modes, which in turn would
impact OLV. One could speculate that if the core muscles
were as active while cycling compared to while running, to
exhibit similar OLV between the two exercise modes, the
diaphragm would have to, in effect, work against the core
muscles to do so, which would make ventilation metaboli-
cally costly. Previous work comparing different phases of
the rowing stroke has demonstrated that the function of
the respiratory pump muscles is impaired when the core
muscles are engaged for postural support (Griffiths and
McConnell 2012). Taken together, these studies allow us
to suggest that there is, perhaps, a greater activity of the
core muscles while running compared to while cycling and
that this is why OLV are different between maximal run-
ning and cycling in the drop position. However, core mus-
cle electromyographic activity is needed to confirm this
hypothesis.
Comparing OLV between maximal running and upright
cycling allows us to compare exercise modes with an equiv-
alent thorax position. EILV was significantly larger during
maximal cycling in the upright position, but EELV did not
differ. The cause of the significantly greater EILV during
maximal cycling in the upright position compared to maxi-
mal running is likely due to those reasons outlined above
(i.e., role of respiratory muscles in postural control/stabil-
ity). A similar EELV between maximal upright cycling and
running is more difficult to interpret. The need to stabilize
the trunk during maximal running may inhibit a further
increase in EILV towards TLC. However, the increased
activation of the core muscles during maximal running
01234567
0
2
4
6
8
10
12
14
Volume (L) Volume (L) Volume (L)
VO
2
= 58.0, 60.3, 72.0 mL/kg/min
V
E
= 70.8, 91.8, 134.1 L/min
V
T
= 2.1, 2.2, 2.6L
EFL%
peak
= 0% of V
T
Flow (L s
-1
)
01234567
0
2
4
6
8
10
12
14
VO
2
= 49.0, 53.7, 64.6 mL /kg/min
V
E
= 82.5, 98.3, 152.4 L/min
V
T
= 2.4, 2.7, 2.9L
EFL%
peak
= 21% of V
T
01234567
0
2
4
6
8
10
12
14
VO
2
= 41.3, 45.2, 61.1 mL /kg/min
V
E
= 68.6, 81.9, 148.3 L/min
V
T
= 2.2, 2.2, 3.0L
EFL%
peak
= 0% of V
T
BA C
MFVL
70%
85%
100%
.
Flow (Ls
-1
)
.
Flow (Ls
-1
)
.
Fig. 3 The figure above displays maximum flow-volume loops
(thick, solid line) and submaximal (thin solid line = 70 % VO2peak,
think dotted line = 85 % VO2peak) and maximal (thick dotted
line = 100 % VO2peak) tidal flow-volume loops of a single subject
while running (a), cycling in the drop position (b), and cycling in the
upright position (c). Pulmonary function values for this individual
subject were: FVC = 5.12 L (98 % predicted); FEV1 = 4.65 L (96 %
predicted); FEV1/FVC = 91 % (108 % predicted); MEF50 = 5.12 L/
sec. Parameters listed in each panel of the figure are the values this
individual subject attained during exercise in each given trial at 70,
85, and 100 % of VO2peak, respectively
2394 Eur J Appl Physiol (2014) 114:2387–2397
1 3
Table 2 Metabolic and ventilatory data during submaximal and maximal running and cycling in both body positions
VO2peak maximal oxygen uptake, RER respiratory exchange ratio, HR heart rate, VE/VO2 and VE/VCO2, ventilatory equivalents for O2 and CO2, Ti/TTotal ratio of inspiration time to total breathing
cycle, PETCO2 end-tidal partial pressure of CO2, EFL expiratory flow limitation
* Significantly different from running (p < 0.05) and † Significantly different from drop cycling (p < 0.05) within a given exercise intensity (i.e., running vs. drop cycling vs. upright cycling at
70 % of VO2peak. Data are displayed as mean ± SD
Intensity Running Drop cycling Upright cycling
70 % 85 % 100 % 70 % 85 % 100 % 70 % 85 % 100 %
%VO2peak achieved (%) 70.7 ± 1.7 85.7 ± 1.6 100.0 ± 0.0 70.6 ± 2.6 83.8 ± 3.1 100.0 ± 0.0 70.3 ± 2.2 84.3 ± 3.6 100.0 ± 0.0
VO2 (mL × kg−1 ×
min−1)
47.3 ± 5.3 56.8 ± 5.9 66.4 ± 6.5 43.8 ± 4.1* 52.0 ± 5.1* 61.9 ± 4.9* 44.5 ± 3.0 53.2 ± 5.1 62.9 ± 5.0*
HR (beats × min−1) 150 ± 9 170 ± 11 191 ± 8 144 ± 12 164 ± 8 186 ± 9* 151 ± 10 169 ± 8 188 ± 7
RER 0.88 ± 0.09 0.99 ± 0.05 1.12 ± 0.05 0.95 ± 0.06* 1.04 ± 0.07* 1.19 ± 0.08* 1.00 ± 0.07* 1.07 ± 0.07* 1.18 ± 0.07*
VE/VO219.2 ± 2.1 20.9 ± 1.7 25.6 ± 2.2 19.6 ± 1.8 22.3 ± 2.6* 28.7 ± 2.6* 20.9 ± 2.6* 23.2 ± 3.0* 28.5 ± 3.6*
VE/VCO221.8 ± 1.5 21.3 ± 1.5 22.9 ± 1.7 20.7 ± 1.7* 21.5 ± 2.1 24.5 ± 2.0* 20.9 ± 1.8* 21.4 ± 1.8 24.2 ± 2.7*
Ti/TTotal (%) 52.2 ± 6.4 51.0 ± 5.6 49.6 ± 3.7 46.8 ± 3.0* 47.4 ± 3.5 48.4 ± 2.4 47.8 ± 6.3* 47.7 ± 4.4*†49.2 ± 2.2†
PETCO2 (Torr) 32.7 ± 2.3 33.5 ± 2.4 31.1 ± 2.2 34.2 ± 2.8* 33.3 ± 3.4 29.0 ± 2.4* 34.2 ± 3.0* 32.9 ± 3.1 29.9 ± 3.0
EFL prevalence (%) – – 72.2 – – 66.7 – – 55.6
EFL (% VT)– – 36.2 ± 26.7 – – 41.2 ± 30.3 – – 32.0 ± 30.0
Test time (min) – – 11.1 ± 1.6 – – 11.8 ± 2.1 – – 11.9 ± 2.2
2395Eur J Appl Physiol (2014) 114:2387–2397
1 3
could aid in expiration, keeping EELV relatively closer to
RV. Again, if the core muscles play less of a role in trunk
stabilization during upright cycling relative to maximal
running then this may allow for EILV to be closer to TLC
(i.e., less inspiratory “impairment”) and they may be able
to contribute more to expiration allowing a smaller EELV
(i.e., closer to RV), which is similar to that attained during
maximal running. Therefore, upright cycling may represent
an ideal mode and thorax position to achieve a large VT.
Conversely, EELV is relatively closer to TLC during maxi-
mal cycling in the drop position perhaps due to the muscles
of expiration being at a mechanical disadvantage because
of the position of the thoracic cavity.
Despite no difference in OLV between cycling postures
we did observe a significantly greater VT during maximal
upright cycling compared with drop cycling at similar lev-
els of VE. This was accomplished by a slight increase in
EILV and concurrent decrease in EELV for which there
are two potential reasons for the disparity in breathing pat-
terns between cycling postures. Briefly, these reasons could
be decreased mechanical advantage of the diaphragm and
limitation to rib cage expansion during maximal cycling
in the drop position. The drop cycling position may poten-
tially affect the mechanical function of the diaphragm by
limiting its ability to shorten during inspiration compared
with the upright cycling posture (McCully and Faulker,
1983; Smith and Bellemare 1988). Furthermore, when
rib cage expansion is restricted during exercise, breathing
pattern is altered in a manner consistent with our observa-
tions (i.e., decreased VT, increased fb) (Hussain et al. 1985;
Bradley and Anthonisen 1980; Scheidt et al. 1981; Men-
donca et al. 2013) in an effort to maintain VE for a given
metabolic work rate (Hussain et al. 1985; Mendonca et al.
2013). Thus, VT may have been reduced during maximal
cycling in the drop position due to a posture-related limi-
tation to rib cage expansion or increased dynamic respira-
tory compliance (Hussain et al. 1985) compared with maxi-
mal cycling in the upright position. However, the extent to
which the factors mentioned above, either alone or in com-
bination, ultimately contributed to the observed differences
in VT between cycling positions cannot be determined in
the present study and warrants further investigation.
Cardiopulmonary responses to maximal exercise
As has been previously shown, VO2peak is significantly
greater while cycling compared to running, irrespective of
cycling position (Hermansen et al. 1970; Gavin and Stager
1999; Tanner et al. 2014). VE during maximal exercise
was approaching significance between exercise modes in
the present study (148.8 ± 18.9 vs. 158.5 ± 24.7 L min−1
while running and cycling, respectively; p = 0.07). Find-
ings on VE between maximal running and cycling are
equivocal (Astrand and Saltin 1961; Butts et al. 1991;
Gavin and Stager 1999; Tanner et al. 2014). There are
several explanations for why VE during maximal exercise
would differ between running and cycling. First, as dis-
cussed briefly above, the chemical drive to breathe may be
greater while cycling compare to running. Our data support
this idea because RER, VE/VO2, and VE/VCO2 were signifi-
cantly greater while cycling in either position compared to
running. Second, the results of these aforementioned stud-
ies suggest that the cardiopulmonary responses to running
and cycling are dependent upon training status, specialty,
or a combination of the two (Astrand and Saltin 1961;
Butts et al. 1991; Gavin and Stager 1999; Millet et al.
2009; Pierce et al. 1990; Stromme et al. 1977; Tanner et al.
2014). This is a plausible explanation given what is known
A
B
C
Fig. 4 The figures above display VE (a), VT (b), and fb during sub-
maximal and maximal exercise (c) between running and cycling in
the drop and upright positions. † Significantly different from drop
cycling (p < 0.05), * significantly different from running (p < 0.05)
within a given exercise intensity (i.e., running vs. drop cycling vs.
upright cycling at 70 % of VO2peak. Data are displayed as mean ± SD
2396 Eur J Appl Physiol (2014) 114:2387–2397
1 3
with respect to VO2max and training specificity (Stromme
et al. 1977) and there is support in the literature for a simi-
lar training specificity effect on VE (Pannier et al. 1980).
In the current study, the individuals that identified as “run-
ners,” generally, had a larger VE during maximal running
compared to cycling, while “cyclists” and “triathletes” had
a larger VE during maximal cycling compared to running.
It should be noted that VE and other ventilatory variables
(EELV, EILV, VT, fb) did not significantly differ between
“runners,” “cyclists,” and “triathletes,” nevertheless train-
ing specificity could impact our data and we simply did not
have a large enough sample size to detect these effects.
VO2peak and maximal power output were not different
between the two cycling positions in the present study,
which is supported by previous research (Origenes et al.
1993; Berry et al. 1994; Faria et al. 1978). Despite no dif-
ference observed in VE, trunk/hip angle did have a signifi-
cant impact on VT and fb during maximal exercise where
subjects adopted a rapid shallow breathing pattern associ-
ated with a reduced inspiratory duty cycle, during upright
cycling compared to drop cycling. These findings contra-
dict previous results, which found no difference in VE, VT,
fb, and inspiratory duty cycle between cycling positions
(Berry et al. 1994; Origenes et al. 1993). However, Faria
et al. (1978) did observe a significant difference in VE dur-
ing maximal drop cycling compared to while cycling in the
semi-erect position with hands resting on the uppermost
portion of the handlebars. The authors reasoned that the
forward lean of the thorax in the drop position allowed for
the weight of the arms and shoulder girdle to be relieved
and allow for greater expansion of the chest cavity. The
equivocal results on VE, VT, and fb are likely due to subtle
differences in the cycling postures used.
Limitations
We did not measure intrathoracic pressures in this study
to verify whether subjects inspired to TLC when they per-
formed IC manoeuvres during exercise. In an attempt to
confirm appropriate IC manoeuvres without intrathoracic
pressure, we first estimated RV (Pellegrino et al. 2005) and
approximated TLC (TLC = vital capacity + estimated RV).
Then, we obtained the volume of both IC manoeuvres, and
the expiratory reserve volume (ERV) during the final min-
ute of exercise. These volumes were then summed with RV
(i.e., TLC = IC + ERV + RV) and compared to our esti-
mate of TLC. On average, subjects attained 101.5 ± 8.6,
104.1 ± 4.6, and 105.3 ± 6.2 % of their estimated TLC
during maximal running, cycling in the drop position, and
cycling in the upright position, respectively. Therefore, we
are confident that our subjects adequately performed the IC
manoeuvres and that our measurements of EELV and EILV
are accurate. The method used to detect and quantify the
extent of expiratory flow limitation could have resulted in
an overestimation because we did not account for thoracic
gas compression (Guenette et al. 2010; Sharafkhaneh et al.
2007). However, this would not significantly impact the
interpretation of our data given that this is a repeated meas-
ure design. We did not rigorously control for the amount of
weight placed on the polyvinylchloride tube during upright
cycling. This could have an impact on OLV and VE as sug-
gested by Faria et al. (1978) and obscured a potential OLV
effect between trunk/hip angles. Finally, use of a treadmill
protocol that increased grade with speed constant, rather
than increasing speed on a flat treadmill could have altered
trunk/hip angle such that the torso was not perfectly upright
while running.
Conclusions
The purpose of this study was to determine if OLV differed
between maximal running and cycling and, to also, deter-
mine if the observed difference in OLV was due to trunk/
hip angle during exercise. OLV were significantly greater
during maximal cycling in the drop position compared to
running, but not during submaximal exercise and this does
not appear to be related to trunk/hip angle while cycling.
These data, in addition to work by others, contribute to
our knowledge of the regulation of OLV during maximal
exercise. Our findings on OLV and body position during
exercise could be advanced in future investigations with the
inclusion of electromyography and intrathoracic pressure
measurement. This would allow one to determine how res-
piratory muscle activity (core and accessory) is impacted
by trunk/hip angle during exercise.
References
Agostoni E, Hyatt RE (1986) Static behavior of the respiratory sys-
tem. In: Macklem PT, Mead, J (eds) Handbook of Physiology.
American Physiological Society, Bethesda
Astrand PO, Saltin B (1961) Maximal oxygen uptake and heart rate
in various types of muscular activity. J Appl Physiol 16:977–981
Babb TG (1997) Ventilatory response to exercise in subjects breathing
CO2 or HeO2. J Appl Physiol 82:746–754
Babb TG (1999) Mechanical ventilatory constraints in aging, lung
disease, and obesity: perspectives and brief review. Med Sci
Sports Exerc 31:S12–S22
Babb TG, Viggiano R, Hurley B, Staats B, Rodarte JR (1991) Effect
of mild-to-moderate airflow limitation on exercise capacity. J
Appl Physiol 70:223–230
Balke B, Ware RW (1959) An experimental study of physical fitness
of Air Force personnel. US Armed Forces Med J 10:675–688
Berry MJ, Pollock WE, van Nieuwenhuizen K, Brubaker PH (1994) A
comparison between aero and standard racing handlebars during
prolonged heavy exercise. Int J Sports Med 15:16–20
Bradley CA, Anthonisen NR (1980) Rib cage and abdominal restric-
tions have different effects on lung mechanics. J Appl Physiol
49:946–952
2397Eur J Appl Physiol (2014) 114:2387–2397
1 3
Butts NK, Henry BA, McLean D (1991) Correlations between VO2max
and performance times of recreational triathletes. J Sports Med
Phys Fitness 31:339–344
De Troyer A (1983) Mechanical role of the abdominal muscles in
relation to posture. Respir Physiol 53:341–353
Derchak PA, Stager JM, Tanner DA, Chapman RF (2000) Expiratory
flow limitation confounds ventilatory response during exercise.
Med Sci Sports Exerc 32:1873–1879
Elliott AD, Grace F (2010) An examination of exercise mode on ven-
tilatory patterns during incremental exercise. Eur J Appl Physiol
110:557–562
Faria I, Dix C, Frazier C (1978) Effect of body position during
cycling on heart rate, pulmonary ventilation, oxygen uptake and
work output. J Sports Med 18:49–56
Gavin TP, Stager JM (1999) The effect of exercise modality on exer-
cise-induced hypoxemia. Respir Physiol 115:317–323
Griffiths LA, McConnell AK (2012) The influence of towing-related
postures upon respiratory muscle pressure and flow generating
capacity. Eur J Appl Physiol 112:4143–4150
Grillner S, Nilsson J, Thorstensson A (1978) Intra-abdominal pressure
changes during natural movements in man. Acta Physiol Scand
103:275–283
Guenette JA, Dominelli PB, Reeve SS, Durkin CM, Eves ND, Sheel
AW (2010) Effect of thoracic gas compression and bronchodi-
lation on the assessment of expiratory flow limitation during
exercise in healthy humans. Respir Physiol Neurobiol 170:
279–286
Hankinson JL, Odencrantz JR, Fedan KB (1999) Spirometric refer-
ence values from a sample of the general US population. Am J
Respir Crit Care Med 159:179–187
Henke K, Sharratt M, Pegelow D, Dempsey JA (1988) Regulation
of end-expiratory lung volume during exercise. J Appl Physiol
64:135–146
Hermansen L, Ekblom B, Saltin B (1970) Cardiac output during
submaximal and maximal treadmill and bicycle exercise. J Appl
Physiol 29:82–86
Hodges PW, Gandevia SC (2000) Changes in intra-abdominal pres-
sure during postural and respiratory activation of the human dia-
phragm. J Appl Physiol 89:967–976
Hopkins SR, Barker RC, Brutsaert TD, Gavin TP, Entin P, Olfert IM,
Veisel S, and Wagner PD (2000) Pulmonary gas exchange during
exercise in women: effects of exercise type and work increment. J
Appl Physiol. 89:721–730
Hussain SN, Rabinovitch B, Macklem PT, Pardy RL (1985) Effects
of separate rib cage and abdominal restriction on exercise perfor-
mance in normal humans. J Appl Physiol 58:2020–2026
Johnson B, Seow KC, Pegelow DF, Dempsey JA (1990) Adaptation
of the inert gas FRC technique for use in heavy exercise. J Appl
Physiol 68:802–809
Johnson B, Reddan WB, Seow KC, Dempsey JA (1991a) Flow limita-
tion and regulation of functional residual capacity during exer-
cise in a physically active aging population. Am Rev Respir Dis
143:960–967
Johnson B, Reddan WG, Seow KC, Dempsey JA (1991b) Mechanical
constraints on exercise hyperpnea in a fit aging population. Am
Rev Respir Dis 143:968–977
Johnson B, Scanlon PD, Beck KC (1995) Regulation of ventila-
tory capacity during exercise in asthmatics. J Appl Physiol
79:892–901
Klas JV, Dempsey JA (1989) Voluntary versus reflex regula-
tion of maximal exercise flow-volume loops. Am Rev Respir
Dis 139:587–600
Koyal SN, Whipp BJ, Hunstman D, Bray GA, Wasserman K (1976)
Ventilatory responses to the metabolic acidosis of treadmill and
cycle ergometry. J Appl Physiol 40:864–867
McClaran S, Wetter TJ, Pegelow DF, Dempsey JA (1999) Role of
expiratory flow limitation in determining lung volumes and venti-
lation during exercise. J Appl Physiol 86:1357–1366
McCully KK, Faulkner JA (1983) Length-tension relationship of the
mamallian diaphragm muscles. J Appl Physiol 54:1681–1686
Mendonca CT, Schaeffer MR, Riley P, Jensen D (2013) Physiologi-
cal mechanisms of dyspnea during exercise with external tho-
racic restriction: role of increased neural respiratory drive. J Appl
Physiol. doi:10.1152/japplphysiol.00950.2013
Miller MR, Hankinson J, Brusasco V, Burgos F, Casaburi R, Coates A,
Crapo R, Enright P, van der Grinten CPM, Gustafsson P, Jensen
R, Johnson DC, MacIntyre N, McKay R, Navajas D, Pedersen
OF, Pellegrino R, Viegi G, Wanger J, Force AE (2005) Standardi-
sation of spirometry. Eur Respir J 26:319–338
Millet GP, Vleck VE, Bentley DJ (2009) Physiological differences
between cycling and running: lessons from triathletes. Sports
Med 39:179–206
Origenes M, Blank SE, Schoene RB (1993) Exercise ventilatory
response to upright and aero-posture cycling. Med Sci Sports
Exerc 25:608–612
Pannier JL, Vrijens J, Van Cauter C (1980) Cardiorespiratory response
to treadmill and bicycle exercise in runners. Eur J Appl Physiol
Occup Physiol 43:243–251
Pellegrino R, Brusasco V, Rodarte JR, Babb TG (1993) Expiratory
flow limitation and regulation of end-expiratory lung volume dur-
ing exercise. J Appl Physiol 74:2552–2558
Pellegrino R, Viegi G, Brusasco V, Crapo RO, Burgos F, Casaburi
R, Coates A, van der Grinten CPM, Gustafsson P, Hankinson J,
Jensen R, Johnson DC, MacIntyre N, McKay R, Miller MR, Nav-
ajas D, Pedersen OF, Wanger J (2005) Interpretative strategies for
lung function tests. Eur Respir J 26:948–968
Pierce EF, Weltman A, Seip RL, Snead D (1990) Effects of training
specificity on lactate threshold and VO2peak. Int J Sports Med
11:267–272
Scheidt M, Hyatt RE, Rehder K (1981) Effects of rib cage or abdomi-
nal restriction on lung mechanics. J Appl Physiol 49:1115–1121
Sharafkhaneh A, Babb TG, Officer TM, Hanania NA, Sharafkhaneh
H, Boriek AM (2007) The confounding effects of thoracic gas
compression on measurements of acute bronchodilator response.
Am J Respir Crit Care Med 175:330–335
Sharratt M, Henke KG, Aaron EA, Pegelow DF, Dempsey JA (1987)
Exercise-induced changes in functional residual capacity. Respir
Physiol 70:313–326
Smith J, Bellemare F (1988) Effect of lung volume on in vivo con-
traction characteristics of the human diaphragm. Respir Muscles
COPD 95–110
Smith TBRJ, Hopkins WG, Taylor NAS (1994) Respiratory responses
of elite oarsmen, former oarsmen, and highly trained non-rowers
during rowing, cycling, and running. Eur J Appl Physiol 69:44–49
Stromme SB, Ingjer F, Meen HD (1977) Assessment of maximal
aerobic power in specifically trained athletes. J Appl Physiol
42:833–837
Stubbing D, Pengelly LD, Morse JLC, Jones NL (1980) Pul-
monary mechanics during exercise in normal males. J Appl
Physiol 49:506–510
Tanner DA, Duke JW, Stager JM (2014) Ventilatory patterns differ
between maximal running and cycling. Respir Physiol Neurobiol
191:9–16
Taylor BJ, How SC, Romer LM (2013) Expiratory muscle fatigue
does not regulate operating lung volumes during high-intensity
exercise in healthy humans. J Appl Physiol 114:1569–1576
Younes M, Kivinen G (1984) Respiratory mechanics and breath-
ing pattern during and following maximal exercise. J Appl
Physiol 57:1773–1782
