Effects of Two Different Recovery Postures during High-Intensity Interval Training

Abstract

The purpose of this study was to examine the effects of two different recovery postures, hands on head (HH) and hands on knees (HK), as a form of immediate recovery from high-intensity interval training (HIIT). Twenty female Division II varsity soccer players (age = 20.3 ± 1.1 yr, body mass index = 22.4 ± 1.80 kg·m−2) completed two experimental trials in a randomized, counterbalanced order. Each trial consisted of four intervals on a motorized treadmill consisting of 4 min of running (4 × 4) at 90%–95% HRmax with 3 min of passive recovery between each interval. HR recovery was collected during the first 60 s of each recovery, where volume of carbon dioxide (V[Combining Dot Above]CO2) and tidal volume (VT) were recorded each minute during the 3-min recovery period. Results showed an improved HR recovery (P < 0.001), greater VT (P = 0.008), and increased V[Combining Dot Above]CO2 (P = 0.049), with HK (53 ± 10.9 bpm; 1.44 ± 0.2 L·min−1, 1.13 ± 0.2 L·min−1) compared with HH (31 ± 11.3 bpm; 1.34 ± 0.2 L·min−1, 1.03 ± 0.2 L·min−1). These data indicate that HK posture may be more beneficial than the advocated HH posture as a form of immediate recovery from high-intensity interval training.

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Effects of Two Different Recovery Postures
during High-Intensity Interval Training
Joana V. Michaelson, Lorrie R. Brilla, David N. Suprak, Wren L. McLaughlin, and Dylan T. Dahlquist
INTRODUCTION
Athletes of all levels, from novice to elite, are constantly
looking for strategies to decrease time to recover and boost
athletic performance. It is well known that the respiratory
system plays a crucial role during rest and exercise via buffer-
ing metabolic by-products, such as hydrogen ions (H
+
)and
carbon dioxide (CO
2
), to maintain the acid–base homeostasis
and minimizing dysregulation of the excitation–contraction
coupling process in localized muscle tissue (1). Failure to main-
tain this acid–base homeostasis during exercise can have detri-
mental effects on performance (2) and often arises when the
respiratory system lacks the ability to increase alveolar
ventilation, or exercise-induced diaphrag-
matic fatigue sets (3). Thus, increasing
ventilation could subsequently lead to an
increase in tidal volume (V
T
), a conserva-
tion of respiratory rate, and a more effi-
cientworkofbreathing.
Consequently, researchers have investi-
gated the effects of different postures during
recovery from exercise and the physiologi-
cal responses to these varying recovery
postures (4,5,6). Most of the research has
focused on evaluating three different posi-
tions: supine, seated, and upright, with
upright standing posture being the most
widely used recovery posture in a sport
(field) setting (7). However, new literature
has begun to indicate that one can acceler-
ate intermediate recovery between exercise
bouts by maximizing the surface area of the diaphragmatic
zone of apposition (ZOA) (8); it has been shown that the
ZOA is maximized during spinal flexion rather than exten-
sion. Because of this, a standing posture with hands on head
(HH) may be less advantageous to postures that increase the
ZOA (e.g., flexed spine and hands on knees [HK]) (7). The
effects of HH versus HK on intermediate recovery and the ZOA
have yet to be investigated.
Furthermore, the position of recovery may also influence
autonomic function, which could lead to a quicker recovery
during performance (9). HR recovery (HRR) has been sug-
gested as a valuable tool in monitoring an athlete’s training sta-
tus and their response to certain training stimuli (10,11,12).
A faster HRR has been observed as a result of improvements
of aerobic capacity (13). Contrary to this, a delayed HRR re-
sults in impaired performance and a greater chance of fatigue
(12). Improved HRR in the supine position has been demon-
strated following repeated sprint exercise in youth soccer players
(14). HR is mediated by parasympathetic reactivation during
recovery from exercise. Baroreflex mediation and a prolonged
R-R interval in HR that occurs during exhalation is hypothe-
sized to improve the efficiency of gas exchange (15). However,
it is unknown if improved HRR during repeated work to rest
transitions in exercise influences subsequent performance in
trained subjects, especially in female athletes.
Because of the limited information on different standing
postures that could directly affect the ZOA and recovery in a
Exercise Physiology Laboratory, Health and Human Development Department,
Western, Washington University, Bellingham, WA
Address forcorrespondence:Lorrie R. Brilla, Ph.D., Health and Human Develop-
ment Department, Western Washington University, Carver 201L, 516 High
Street, Bellingham, WA 98225-9067 (E-mail: lorrie.brilla@wwu.edu).
2379-286 8/0404/0023–0027
Translational Journal of the ACSM
Copyright © 2019 The Author(s). Published by Wolters Kluwer Health, Inc. on
behalf of the American College of Sports Medicine. This is an open-access arti-
cle distributed under the terms of the Creative Commons Attribution-Non Com-
mercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to
download and share the work provided it is properly cited. The work cannot be
changed in any way or used commercially without permission from the journal.
ABSTRACT
The purpose of this study was to examine the effects of two different recovery
postures, hands on head (HH) and hands on knees (HK), as a form of immediate
recovery from high-intensity interval training (HIIT). Twenty female Division II varsity
soccer players (age = 20.3 ± 1.1 yr, body mass index = 22.4 ± 1.80 kg·m
−2
)com-
pleted two experimental trials in a randomized, counterbalanced order. Each trial
consisted of four intervals on a motorized treadmill consisting of 4 min of running
(4 4) at 90%–95% HR
max
with 3 min of passive recovery between each interval.
HR recovery was collected during the first 60 s of each recovery, where volume of
carbon dioxide (V̇CO
2
) and tidal volume (V
T
) were recorded each minute during the
3-min recovery period. Results showed an improved HR recovery (P<0.001),
greater V
T
(P= 0.008), and increased V̇CO
2
(P= 0.049), with HK (53 ± 10.9 bpm;
1.44 ± 0.2 L·min
−1
, 1.13 ± 0.2 L·min
−1
) compared with HH (31 ± 11.3 bpm;
1.34 ± 0.2 L·min
−1
, 1.03 ± 0.2 L·min
−1
). These data indicate that HK posture
may be more beneficial than the advocated HH posture as a form of immediate
recovery from high-intensity interval training.
http://www.acsm-tj.org Translational Journal of the ACSM 23
Original Investigation

controlled setting, this study was conducted to determine the
effect of using two different recovery postures during standing,
HH and HK on various cardiorespiratory functional mea-
sures. The study focused on observing minute ventilation
(V
˙
E
), carbon dioxide elimination (V
˙
CO
2
), and HRR during
the recovery intervals of high-intensity interval training (HIIT).
V
˙
E
and frequency of breathing (f
b
) were used to calculate V
T
.
We hypothesized that there would be an effect of the recovery
postures, HH and HK, during the recovery period of HIIT on
HRR, V
˙
CO
2
,andV
T
.
METHODS
Experimental Approach to the Problem
In this study, we aimed to determine whether HH and HK re-
covery postures have a differing influence on recovery of repeated
bouts of high-intensity exercise (full description insubsequent sec-
tions). The researchers examined how the two different postures
could influence cardiorespiratory function during HIIT. The
high-intensity interval exercises were performed on a treadmill
over an orientation session and two testing sessions where HRR,
carbon dioxide elimination (V
˙
CO
2
,), and tidal volume (V
T
)were
determined during the recovery phase of the testing.
Subjects
The study sample consisted of 24 female Division II soccer
players between the ages of 18–22 yr old (20.3 ± 1.1 yr). All sub-
jects were in their winter training season when they began partic-
ipation in the study, had familiarization with HIIT protocol
training, and were instructed to not modify their current training
routine. Subjects did not partake in any high-intensity activity the
day before testing, so that fatigue from previous activity would
not affect testing sessions. Subjects refrained from consuming
any caffeine the day of testing and obtained a minimal of 7 h of
sleep the night before. Uniform verbal encouragement was given
to all subjects during all treadmill running sessions. Over the dura-
tion of the study, four subjects dropped out. Three subjects
dropped out due to time conflicts with their scheduled testing
times, and one subject’s information was dropped due to incom-
plete data collection, which resulted in a final subject pool of
20 participants. Table 1 presents subject characteristics and spi-
rometer measures in all 20 subjects. All subjects were informed
of protocol, experimental risks, and time involved to complete
the study, and they completed an informed consent document
before partaking in the investigation. The research project was
reviewed and approved by Western Washington University’sHu-
man Subjects Committee.
SCREENING
Each subject completed 1 d of baseline measurements, which
included anthropometric measures and pulmonary function tests
before testing. The measures were body mass index, vital capacity,
forced expired volume in 1 s, forced expired volume in 1 s/vital
capacity ratio, and maximum voluntary ventilation. Pulmonary
measures were collected using a Parvomedics spirometer. The
recovery postures were taught and practiced during the baseline
measurement session. HH required them to stand erect with their
hands clasped on top of their head (see Fig. 1). HK required them
to place their hands on their knees, elbows locked, and flexing
through the thoracic region of the spine (see Fig. 2). HK required
additional measurement of thoracic flexion with inclinometers
(Universal Inclinometers; Lindstrom, Chisago County, MN) to
ensure at least 10° of flexion and assure consistency of posture
during recovery intervals (6). Two inclinometers were used to
measure thoracic flexion at T1 and T12.
FAMILIARIZATION AND TESTING
A multiple participant, within-subject design was conducted.
Subjects were randomly designated a recovery posture to perform,
with the alternate posture for the subsequent testing day. Subjects
performed a total of two treadmill sessions of HIIT separated by
1 wk, which consisted of 4 min of running and 3 min of recovery
TABLE 1.
Subject Characteristics and Resting Pulmonary Measures.
Subjects 20
Age (yr) 20.3 ± 1.1
Height (m) 1.71 ± 0.10
Body Weight (kg) 65 ± 6.7
BMI (kg·m
−2
)22.4±1.80
VC (L) 4.0 ± 0.6
FEV
1
(L) 3.1 ± 0.4
FEV
1
/VC (%) 80.0 ± 0.1
MVV (L·min
−1
)133±16
Data are presented as mean ± SD. BMI, body mass index; FEV, forced expired
volume; VC, vital capacity; MVV, maximum voluntary ventilation.
Figure 1: HH recovery posture.
24 Volume 4 •Number 4 •February 15 2019 Recovery Postures in High-Intensity Training

performed four times (4 4 min), assuming one of the two recov-
ery postures during the recovery period. The submaximal runs
were performed in the same laboratory on the same motorized
treadmill (Precor Treadmill, Woodinville, WA) for each visit. In-
tensities were set to mimic typical training intensities one experi-
ences in the field, set at 90%–95% of predicted HR
max
derived
from the 220 minus age equation (16). Upon arrival, subjects were
fitted with an HR monitor (Polar T31 Transmitter; Polar,
Kempele, Finland) and commenced a familiarization session to
the subsequent exercise challenges. Subjects returned for a total
of two testing sessions, separated by 1 wk. Each session consisted
of a 5-min warm-up at a running speed that elicited 70% of their
HR
max
at 0% grade on a treadmill followed by four running inter-
vals at an intensity of 90–95% of HR
max
for 4 min, with a 3-min
passive recovery between runs, assuming either HH or HK
postures during recovery. Throughout the 3-min recovery, each
subject was fixed with nose clip and a two-way breathing mouth-
piece valve interfaced with the metabolic cart (Parvomedics
TrueOne Metabolic Cart and Spirometer, Sandy, UT). V
˙
CO
2
,
V
˙
E
,andf
b
were measured every minute over the recovery period.
V
T
was calculated by dividing V˙
E
by f
b
. The averages of the respi-
ratory variables during the 3-min recovery were determined and
averaged over the four intervals. HRR is commonly defined as
the difference in HR at the end of exercise and then 60 s later
(17). Similarly, in this study, HRR was measured immediately at
the end of the exercise for 1 min.
Statistical Analysis
Descriptive statistics were determined for each variable. De-
pendent t-tests were used to detect significant differences due to
the two treatments using the Statistical Package for the Social Sci-
ences for Windows (version 25; SPSS Inc., Chicago, IL). The
dependent variables analyzed included HRR, V
˙
CO
2
,andV
T
dur-
ing each recovery posture. Significance was defined as a P≤0.05.
Cohen’sdwas calculated for effect size.
RESULTS
Subject characteristics and resting pulmonary measures
are presented in Table 1. Comparison of HRR data revealed
a significant difference between HH and HK postures. HK
posture resulted in significantly faster decrease in HR between
intervals than that of the HH posture, 53 ± 10.9 versus
31 ± 11.3 bpm (P< 0.001). The effect size was very large,
d= 1.98. Figure 1 shows the mean and standard deviation of
HRR in both postures. A difference of 22 bpm between HK
and HH was noted.
V
˙
CO
2
was averaged over the four recovery intervals to get a
mean recovery V˙CO
2
for each posture. The statistically signif-
icant (P< 0.05) effect of the postures was evident between con-
ditions, HK 1.1 ± 0.2 and HH 1.0 ± 0.2 L·min
−1
, respectively
(Fig. 2). The effect size was medium, d=0.5.Therewasasig-
nificant difference (P< 0.05) between HH and HK postures for
V
T
. There was a medium effect size, d= 0.5. The HK posture sig-
nificantly increased V
T
compared with the HH posture V
T
(1.4 ± 0.2 vs 1.3 ± 0.2 L·min
−1
,respectively).Figure3
reveals the difference in V
T
values between the two postures.
HK posture required additional measurement of thoracic
flexion with inclinometers (Universal Inclinometers, Lindstrom)
during the rest interval to assure consistency of flexion between
each rest interval. Averages of thoracic flexion were recorded at
each rest interval and were 14.6 ± 4.4°, 15.5 ± 7.0°, 17.6 ± 7.6°,
and 19.5 ± 8.2° for rest intervals 1 through 4, respectively.
DISCUSSION
The present study investigated the effects of two different
intermediate recovery postures (HH vs HK) on repeated sprint
ability in trained female soccer athletes. The results from the
investigation show an improved HRR and greater V
T
and
V
˙
CO
2
with HK posture when compared with HH posture
after fatiguing high-intensity intervals. There was substantial
improvement in HRR when athletes performed HK (22 bpm
improvement) vs HH.
HK posture causes thoracic flexion and internal rotation
of the rib cage, which has been reported to optimize the ZOA
(18,19). Optimizing the ZOA allows the diaphragm to operate
with maximal efficiency (8). This could explain the greater
cardiorespiratory response seen in the HK condition, which
has been reported in individuals experiencing chronic ob-
structive pulmonary disease and their reduced feelings of dys-
pnea (20,21,22). On average, subjects exhibited an increase in
thoracicflexionwitheachrestintervalfrom14.6±4.4°inthe
first rest to 19.5 ± 8.2° in the fourth rest interval during HK pos-
ture. The increase in thoracic flexion with each rest interval may
infer a natural increase in thoracic flexion with fatigue and exer-
cise, further enhancing the ZOA. By contrast, HH posture pro-
motes thoracic extension, which is associated with external
rotation of the rib cage and reduced ZOA (8). This mechanical
linkage between the diaphragm and ribcage (23) could explain
why individuals had a higher HRR after the recovery periods
in the HK versus HH postures.
Figure 2: HK recovery posture.
http://www.acsm-tj.org Translational Journal of the ACSM 25

Furthermore, HH posture places the diaphragm in a subop-
timal position, decreasing its mechanical efficiency. A decrease
in the ZOA reduces the ability of the diaphragm to contract
effectively because of its poor position along its length–tension
curve (10,12). Elevating the arms to 90° or more of shoulder
flexion, as observed with HH posture, changes the impedance
of the torso, rib cage, and abdominal wall (24,25,26). Raising
the arms causes a passive stretch of the thoracic wall and ab-
dominal muscles (overlengthened position), which may place
them in a less effective position for assisting in respiration.
An overlengthened abdominal region may reduce its ability
to effectively oppose the diaphragm, leading to less effective
respiratory mechanics (11,18). These muscle length differences
could explain the discrepancies observed between HH and HK
postures in the current study.
The present study showed increased V
˙
CO
2
values with
HK when compared with HH. It is suggested that the
HK posture improved exhalation ability of the abdominal
muscles, leading to a slight increase in V
˙
CO
2
exhibiting an
improved ventilatory profile response. Cavalheri et al. (27)
investigated the effects of arm bracing on respiratory muscle
strength and pulmonary function in patients with chronic ob-
structive pulmonary disease. The results showed greater
maximal inspiratory and expiratory pressures with arms
braced when compared with unbraced arms. The results of
the previous study along with the findings of the present
study suggest that bracing the arms improves respiratory
function by decreasing the postural demands of these mus-
cles, diaphragm, intercostal, abdominals, and accessory
muscles during HK.
Kera and Maruyama (21) further supported this idea of im-
proved force generating capabilities with a braced posture.
They examined the effects of posture on respiratory activity
of the abdominal muscles. The results showed an increased
abdominal activity with the braced position (seated, elbows
on knees) and was attributed to the enhanced position of the
abdominals during trunk flexion. The authors suggested that
the abdominals in this position elicited a greater stretch reflex
during expiration, thereby increasing inspiration and a reduced
feeling of dyspnea in the subjects. Furthermore, diseased popu-
lations in previous studies are known to have a low tolerance
to arm activities that is not only determined by strength or en-
durance but by position of the arm itself (28). Arm elevation at
90° shoulder flexion greatly exacerbates respiratory function,
altering static ventilatory responses when compared with arms
down and below 90° shoulder flexion (28). A study by Couser
et al. (24) examined respiratory and ventilatory muscle recruit-
ment with arms elevated and arms down in healthy subjects.
They reported an increase in metabolic demand (V
˙
O
2
,
V
˙
CO
2
, and HR) with arms elevated when compared with
arms down. These findings were associated with additional
increases in V
˙
E
. In contrast to the present study, those subjects
were seated and did not perform high-intensity bouts of exer-
cise before measurement of cardiorespiratory variables. The
arm positions also differed in both studies and did not follow
similar protocols. Our results showed that V
˙
E
was similar in
HH and HK (40.4 and 39.4 L·min
−1
,respectively).However,
V
T
was significantly greater with HK (1.4 L·min
−1
) compared
with HH (1.3 L·min
−1
). Couser et al. (24) attributed the in-
crease in V
˙
E
with arms elevated to increased V
T
and accessory
muscle activity, which could explain the discrepancies seen be-
tween the studies. Similarly, in the present study, there was a
significant increase in V
T
with HK in comparison with HH,
suggesting an improved work of breathing when adopting
HK posture. Subjects also subjectively reported more ease in
breathing in the HK posture versus the HH posture. The im-
provement in HRR with HK posture may be attributed to
the improved respiratory mechanics with HK posture, thereby
influencing participants’HR.
In addition, posture may have also influenced the interac-
tions between respiration and neurocardiovascular control of
recovery from exercise. An autonomic effect may also be
influencing the observed accelerated rate of HRR due to the al-
terations on the parasympathetic reactivation (29). The effect
of posture on HRR and parasympathetic reactivation after
exercise has been described for supine, sitting, and standing
(5,7,9,30). Specific to the present study, improved HRR was
demonstrated after repeated sprint exercise after the HK pos-
ture. Consistently, supine posture results in accelerated HRR
and has been documented in soccer players (14). However,
the supine position is not a practical alternative for athletes
recovering from repeated sprints in game competition. Thus,
Figure 3: Mean ± SD of HRR, volume of carbon dioxide (V̇CO
2
), and tidal volume (V
T
) over the four rest intervals in HH and HK postures. Error bars are
set at mean ± SD. * Results are significantly different between groups (P<0.05).
26 Volume 4 •Number 4 •February 15 2019 Recovery Postures in High-Intensity Training

the results from this study indicate HK as a viable option when
supine positions are not feasible.
CONCLUSIONS AND PRACTICAL APPLICATIONS
The ability to recover faster from multiple bouts of exer-
cise is a crucial part of optimizing performance for athletes in
a variety of sports, such as soccer, rugby, basketball, and
American football. Thus, using the best recovery modality, in
this case posture during HIIT, is crucial to minimize fatigue
and potential injuries due to altered biomechanics from the
taxing exercise. On the basis of the findings in this study, HK
posture significantly improved HRR, V
T
,andV
˙
CO
2
in compari-
son with HH posture. The positive effects of HK posture on
HRR, V
T
,andV
˙
CO
2
may suggest improved parasympathetic in-
fluences and cardiorespiratory mechanics when adopting this
posture during a recovery period from a fatiguing exercise.
The authors acknowledge the players of Western Washington
University women’s soccer team for their participation in the study.
The results of the present study do not constitute endorsement by
the American College of Sports Medicine. The results of the study
are presented clearly, honestly, and without fabrication, falsification,
or inappropriate data manipulation.
All authors declare no conflict of interest. The authors received
no specific funding for this work.
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