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Mode of exercise and sex are not important for oxygen consumption during and in recovery from sprint interval training

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Most sprint interval training (SIT) research involves cycling as the mode of exercise and whether running SIT elicits a similar excess postexercise oxygen consumption (EPOC) response to cycling SIT is unknown. As running is a more whole-body-natured exercise, the potential EPOC response could be greater when using a running session compared with a cycling session. The purpose of the current study was to determine the acute effects of a running versus cycling SIT session on EPOC and whether potential sex differences exist. Sixteen healthy recreationally active individuals (8 males and 8 females) had their gas exchange measured over ∼2.5 h under 3 experimental sessions: (i) a cycle SIT session, (ii) a run SIT session, and (iii) a control (CTRL; no exercise) session. Diet was controlled. During exercise, both SIT modes increased oxygen consumption (cycle: male, 1.967 ± 0.343; female, 1.739 ± 0.296 L·min(-1); run: male, 2.169 ± 0.369; female, 1.791 ± 0.481 L·min(-1)) versus CTRL (male, 0.425 ± 0.065 L·min(-1); female, 0.357 ± 0.067; P < 0.001), but not compared with each other (P = 0.234). In the first hour postexercise, oxygen consumption was still increased following both run (male, 0.590 ± 0.065; female, 0.449 ± 0.084) and cycle SIT (male, 0.556 ± 0.069; female, 0.481 ± 0.110 L·min(-1)) versus CTRL and oxygen consumption was maintained through the second hour postexercise (CTRL: male, 0.410 ± 0.048; female, 0.332 ± 0.062; cycle: male, 0.430 ± 0.047; female, 0.395 ± 0.087; run: male, 0.463 ± 0.051; female, 0.374 ± 0.087 L·min(-1)). The total EPOC was not significantly different between modes of exercise or males and females (P > 0.05). Our data demonstrate that the mode of exercise during SIT (cycling or running) is not important to O2 consumption and that males and females respond similarly.
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ARTICLE
Mode of exercise and sex are not important for oxygen
consumption during and in recovery from sprint interval
training
Logan K. Townsend, Katie M. Couture, and Tom J. Hazell
Abstract: Most sprint interval training (SIT) research involves cycling as the mode of exercise and whether running SIT elicits a
similar excess postexercise oxygen consumption (EPOC) response to cycling SIT is unknown. As running is a more whole-body–
natured exercise, the potential EPOC response could be greater when using a running session compared with a cycling session.
The purpose of the current study was to determine the acute effects of a running versus cycling SIT session on EPOC and whether
potential sex differences exist. Sixteen healthy recreationally active individuals (8 males and 8 females) had their gas exchange
measured over 2.5 h under 3 experimental sessions: (i) a cycle SIT session, (ii) a run SIT session, and (iii) a control (CTRL; no
exercise) session. Diet was controlled. During exercise, both SIT modes increased oxygen consumption (cycle: male, 1.967 ± 0.343;
female, 1.739 ± 0.296 L·min
−1
; run: male, 2.169 ± 0.369; female, 1.791 ± 0.481 L·min
−1
) versus CTRL (male, 0.425 ± 0.065 L·min
−1
;
female, 0.357 ± 0.067; P< 0.001), but not compared with each other (P= 0.234). In the first hour postexercise, oxygen consumption
was still increased following both run (male, 0.590 ± 0.065; female, 0.449 ± 0.084) and cycle SIT (male, 0.556 ± 0.069; female,
0.481 ± 0.110 L·min
−1
) versus CTRL and oxygen consumption was maintained through the second hour postexercise (CTRL: male,
0.410 ± 0.048; female, 0.332 ± 0.062; cycle: male, 0.430 ± 0.047; female, 0.395 ± 0.087; run: male, 0.463 ± 0.051; female, 0.374 ±
0.087 L·min
−1
). The total EPOC was not significantly different between modes of exercise or males and females (P> 0.05). Our data
demonstrate that the mode of exercise during SIT (cycling or running) is not important to O
2
consumption and that males and
females respond similarly.
Key words: EPOC, energy expenditure, sprint exercise, metabolism, postexercise.
Résumé : La majorité des études sur l’entraînement par intervalles au moyen du sprint (« SIT ») utilise le cyclisme comme
modalité d’exercice; toutefois, on ne sait pas si les études sur le SIT utilisant la course rapportent un surplus d’oxygène
consommé postexercice (« EPOC ») similaire a
`celui observé au cyclisme. Du fait que la course sollicite davantage l’organisme en
entier, l’EPOC a
`la course devrait être plus élevé qu’a
`vélo. La présente étude se propose de déterminer les effets immédiats d’une
séance de SIT a
`la course sur l’EPOC comparativement a
`une séance de SIT a
`vélo et de relever les différences liées au sexe, le cas
échéant. On évalue durant 2,5 h les échanges gazeux chez seize personnes en santé, actives par loisir (huit femmes et huit
hommes) et soumises a
`trois conditions: (i) SIT a
`vélo, (ii) SIT a
`la course et (iii) contrôle (« CTRL »), soit sans exercice. La diète est
sous contrôle. Les deux séances d’exercice suscitent une augmentation de la consommation d’oxygène (vélo : hommes, 1,967 ±
0,343; femmes, 1,739 ± 0,296 L·min
–1
; course : hommes, 2,169 ± 0,369; femmes, 1,791 ± 0,481 L·min
–1
) comparativement a
`CTRL
(hommes, 0,425 ± 0,065 L·min
–1
; femmes, 0,357 ± 0,067; P< 0,001), mais on n’observe pas de différences entre les deux conditions
d’exercice (P= 0,234). Durant la première heure postexercice, le de la consommation d’oxygène demeure élevé a
`la course
(hommes, 0,590 ± 0,065; femmes, 0,449 ± 0,084) et a
`vélo (hommes, 0,556 ± 0,069; femmes, 0,481 ± 0,110 L·min
–1
) comparative-
ment a
`CTRL; le de la consommation d’oxygène demeure élevé durant la deuxième heure postexercice (CTRL : hommes, 0,410 ±
0,048; femmes, 0,332 ± 0,062; vélo : hommes, 0,430 ± 0,047; femmes, 0,395 ± 0,087; course : hommes, 0,463 ± 0,051; femmes,
0,374 ± 0,087 L·min
–1
). L’EPOC total ne diffère pas significativement entre les deux modalités d’exercice et entre les deux sexes
(P> 0,05). D’après nos observations, la modalité d’exercice durant une séance de SIT (vélo ou course) n’a pas d’influence sur la
consommation d’oxygène; les femmes présentent un ajustement similaire a
`celui des hommes. [Traduit par la Rédaction]
Mots-clés : EPOC, dépense énergétique, exercice de sprint, métabolisme, postexercice.
Introduction
Because of the prevalence of excess caloric intake and the adop-
tion of increasingly sedentary lifestyles, obesity has reached
epidemic proportions (Hawley and Gibala 2009). While regular
physical activity is an obvious remedy, people often do not exer-
cise because of a perceived lack of time and enjoyment (Godin
et al. 1994;Leslie et al. 1999;Reichert et al. 2007;Sallis et al. 1997;
Stutts 2002;Trost et al. 2002). High-intensity interval training
(HIIT) has emerged as a time-efficient training method to improve
body composition (Boutcher 2011) and participants recently dem-
onstrated high confidence in their ability complete the intervals
(1 min at 70% or 100% peak work rate followed by 1 min of rest) as
well as schedule HIIT into their weekly routine (Boyd et al. 2013).
Further, other research has suggested that HIIT (6 bouts of 3 min
Received 21 April 2014. Accepted 27 August 2014.
L.K. Townsend and T.J. Hazell. Department of Kinesiology and Physical Education, Faculty of Science, Wilfrid Laurier University, Waterloo,
ON N2L 3C5, Canada.
K.M. Couture. Department of Kinesiology and Physical Education, Faculty of Arts and Science, University of Lethbridge, Lethbridge, AB T1K 3M4,
Canada.
Corresponding author: Tom J. Hazell (e-mail: thazell@wlu.ca).
1388
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at 90% maximal oxygen consumption (V
˙O
2max
) followed by 3 min
of rest) was more enjoyable than traditional moderate-intensity
continuous exercise of 50 min at 70% V
˙O
2max
(Bartlett et al. 2011).
A more potent form of HIIT is sprint interval training (SIT), which
can be distinguished from more conventional HIIT by its in-
creased intensity (i.e., super-maximal) and its shorter durations
(10–30 s) (Weston et al. 2014). Specifically, SIT is a time-efficient
training method that involves repeated 30-s “all-out” exercise ef-
forts separated by 4 min of active recovery amounting to 2–3 min
of exercise in an 18–27-min exercise session. This SIT paradigm
has proven to be a time-effective method to accrue metabolic and
performance adaptations similar to those of traditional continu-
ous aerobic exercise training (Gibala et al. 2006;MacPherson et al.
2011), while also improving body composition (Hazell et al. 2014;
MacPherson et al. 2011). Some SIT research has demonstrated no
change in body mass (Burgomaster et al. 2008) or body composi-
tion measured with skinfold fat measures (Astorino et al. 2011) and
air displacement plethysmography (Hazell et al. 2010), though
these were only over 2 weeks of SIT (6 exercise sessions) and
potential changes were not expected.
While the potential mechanisms for improved body composi-
tion with SIT are not well understood, it would appear that some
increase in postexercise metabolism is likely a contributing factor
as the oxygen consumption (V
˙O
2
) during an SIT session is much
less than a continuous aerobic exercise session (Hazell et al. 2012).
Excess postexercise oxygen consumption (EPOC) is the increased
oxygen utilized above resting postexercise (Gaesser and Brooks
1984) and depends on both exercise intensity and duration
(Borsheim and Bahr 2003;Laforgia et al. 2006;Sedlock et al. 1989).
A single SIT session has been demonstrated to increase EPOC
(14 L or 70 kcal) in the 2-h postexercise session (Chan and Burns
2013) and perhaps more importantly to increase total O
2
con-
sumed over 24 h versus continuous aerobic exercise (Hazell et al.
2012). However, there is also research suggesting that very little
EPOC occurs in response to a single SIT session versus continuous
aerobic exercise (Williams et al. 2013). This limited research on SIT
and EPOC has also been limited to male participants and whether
the responses are similar in females is unknown. Furthermore,
women performing SIT may have smaller decreases in fat mass
following training (MacPherson et al. 2011), suggesting there may
be a sex-specific response to SIT.
As running SIT has demonstrated fat loss (Hazell et al. 2014;
MacPherson et al. 2011) with potential contribution from an in-
crease in EPOC, only cycling SIT has been measured postexercise
(Hazell et al. 2012;Skelly et al. 2014) and whether running SIT
elicits a similar EPOC response to cycling SIT is unknown. Differ-
ent physiological responses to cycling and running have been
previously demonstrated where fat oxidation is significantly
higher while running than cycling at the same relative intensity
(Achten et al. 2003;Capostagno and Bosch 2010). In addition, V
˙O
2
is 7%–10% higher for running as compared with cycling (Achten
et al. 2003;Hill et al. 2003) and time to achieve V
˙O
2max
is more
rapid when running (Hill et al. 2003). As running is a more whole-
body–natured exercise, these data suggest the potential EPOC
response should be greater when using a running mode of SIT
compared with a cycling mode. Therefore, the purpose of the
present study was to determine the acute effects of a single run
versus a cycle SIT session on EPOC and whether there are potential
sex differences. We hypothesized that running will elicit a greater
EPOC than cycling and males and females would respond simi-
larly.
Materials and methods
Protocol overview
Sixteen healthy recreationally active individuals (8 males and
8 females) had their gas exchange measured over 2.5 h under
3 experimental sessions: (i) a cycling SIT session, (ii) a running SIT
session; and (iii) a control (CTRL; no exercise) session. All treat-
ments were separated by a minimum of 72 h. All participants were
nonsmokers, physically active but not involved in an exercise
training program at the time of data collection (or for at least
4 months prior to data collection), and none were taking dietary
supplements. Participants were instructed to perform no physical
activity or ingest any caffeine for 48 h prior to data collection.
Nutritional intake the morning of the first data collection section
was recorded and provided to the participants before their next
session so they could replicate that intake. No other physical ac-
tivity other than the prescribed exercise was performed. To avoid
order effects, the 3 treatments were administered via balanced
randomized exposure to treatment order (Hazell et al. 2012).
Prior to the initiation of the study all participants provided
their informed written consent, passed the Physical Activity
Readiness Questionnaire health survey (Thomas et al. 1992),
and participated in a familiarization visit (5 days before the
first experimental session). During the familiarization session,
participants were fitted with a respiratory mask to become accus-
tomed to breathing with the mask on as well as practicing using
the cycle ergometer and specialized treadmill. The University of
Lethbridge Human Subjects Research Committee approved this
study in accordance with the ethical standards of the 1964 Decla-
ration of Helsinki.
Experimental protocol
Participants arrived in the lab at 1100 h after having not eaten
for 3 h. Upon arrival, participants sat quietly in a chair for 20 min.
Participants were fitted with a silicone collection facemask (Vmask,
Hans Rudolph Inc., Shawnee, Kans., USA). Gas exchange was then
gathered continuously for the next 163 min (15 min resting, 5-min
warm-up, 18-min SIT session, 5-min cool-down, 120-min postexer-
cise; Fig. 1). All gas exchange measurements (V
˙O
2
, carbon dioxide
output) were made using an online breath-by-breath gas collec-
tion and analysis system (Quark CPET, Cosmed, Rome, Italy). Prior
to data collection the gas analyzers were calibrated with gases of
known concentrations and flow with a 3-L syringe. All measures
were collected while each participant was seated in a chair in a
temperature-controlled room (21 °C). Heart rate (HR) was also col-
lected continuously using a Cosmed HR belt. To calculate EPOC,
the V
˙O
2
from the CTRL session was subtracted from the V
˙O
2
of
either the running SIT or cycling SIT data. Total session V
˙O
2
was
calculated by using the average V
˙O
2
for the distinct phases of the
session: rest (15 min), warm-up (5 min), exercise session (18 min),
and recovery (120 min). These values were then multiplied by the
associated time period to convert to litres of O
2
. Total kilocalories
(kcal) was calculated using the total V
˙O
2
from exercise and post-
exercise and an assumed relationship of 5 kcal per litre of V
˙O
2
as
respiratory exchange ratio (RER) is not an accurate measure of
fuel utilization after sprint interval training (Binzen et al. 2001;
Thornton and Potteiger 2002).
Fig. 1. Experimental session timeline. CTRL, control.
1100
TIME (h)
1400
- Continuous gas collection
1200 1300
Arrive
at Lab
1
1. CTRL
2. CYCLE
3. RUN - Seated rest
Townsend et al. 1389
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Exercise sessions
The cycle SIT session consisted of a 5-min warm-up (at 1 kg
resistance, 70 W) followed by an 18-min SIT session and a 5-min
cool down (for a total session duration of 28 min). The sprint bouts
included 4 repeated 30-s “all-out” efforts on a cycle ergometer
(model 874-E, Monark Exercise, Stockholm, Sweden) at 7.5% body
mass. Each sprint bout was followed by 4 min of active recovery
(light cycling) with no added resistance. Instructions to begin
pedalling as fast as possible against the inertial resistance of
the ergometer were given and the appropriate load was applied
instantaneously (within 3 s). Verbal encouragement was provided
for the remainder of the 30-s test. Peak power (highest output over
first 5 s), average power (over the entire effort), and minimum
power (lowest output) were determined using an online data
acquisition system (SMI power version 5.2.8, SMI optosensor,
St. Cloud, Minn., USA).
The run SIT session was performed in an identical manner to
the cycling, except participants ran on a self-propelled treadmill
(Curve, Woodway, Waukesha, Wis., USA), which allowed the par-
ticipant to be the power source for the running belt, i.e., the
treadmill would move as fast as the participant could possibly
run. The warm-up speed was 3 miles/h (4.8 km/h) while the
“all-out” efforts had each participant run as fast as possible. Each
sprint bout was also followed by 4 min of active recovery (walking
slowly on treadmill). Instructions to begin running as fast as pos-
sible were given upon test initiation. Verbal encouragement was
provided for the remainder of the 30-s test. Peak speed (km/h) was
recorded as the fastest speed attained in the first 5–10 s, and speed
(km/h) was recorded at every 5-s interval to calculate average
speed (speed at each interval divided by 6) and minimum speed
(lowest speed reached during the test).
Nutritional intake
Dietary control was maintained by having all participants re-
cord their food intake for breakfast on the first day of data collec-
tion. This dietary intake was provided to them (via email) before
any subsequent data collection with the instruction to reproduce
this diet (2814 ± 1463 kJ; 672 ± 349 kcal; 97.1 ± 68.8 g carbohydrate;
21.4 ± 14.3 g fat; 34.5 ± 21.9 g protein).
Statistical analysis
All data were analyzed using IBM SPSS Statistics for Windows
(version 22.0; IBM Corp., Armonk, N.Y., USA). Two-way repeated
measures ANOVA with sex as a between-subjects factor was used
to determine differences in V
˙O
2
, RER, and HR among the 3 treat-
ments (cycle SIT, run SIT, and CTRL) at each time point (during,
first hour postexercise, second hour postexercise). All data are
presented as means ± SD and the level of statistical significance is
set at P< 0.05.
Results
Eight men (age, 24.4 ± 3.8 years; height, 180.8 ± 6.7 cm; body
mass, 83.6 ± 10.1 kg) and 8 women (age, 22.4 ± 1.4 years; height,
168.9 ± 6.2 cm; body mass, 65.4 ± 9.2 kg) completed all experimen-
tal sessions. There was no difference in age (P= 0.186), though the
males were taller (P= 0.003) and heavier (P= 0.002) than the
females.
V
˙O
2
There was no mode of exercise, time, and sex interaction (P= 0.189).
There was no interaction between mode of exercise and sex
(P= 0.657). There was a significant interaction for time and mode of
exercise (P< 0.001), where V
˙O
2
(Fig. 2) was significantly greater
(P< 0.001) during run (1.980 ± 0.458) and cycle SIT (1.853 ± 0.331)
versus CTRL (0.391 ± 0.073), but not between each other (P= 0.234).
In the first hour postexercise (Fig. 2), V
˙O
2
following run (0.519 ±
0.103) and cycle (0.518 ± 0.097) SIT was still increased (P< 0.001)
versus CTRL (0.382 ± 0.077), though not different between each
other (P= 0.957). In the second hour postexercise (Fig. 2), V
˙O
2
following run (0.418 ± 0.083) and cycle (0.413 ± 0.070) SIT were still
increased (P< 0.005) versus CTRL (0.371 ± 0.067), with no differ-
ences between cycle and run SIT (P= 0.760).
Total oxygen consumed (L)
There was no interaction between mode of exercise and sex
(P= 0.253). There was a main effect for mode (P< 0.001) where total
V
˙O
2
(Table 1) was increased with cycle and run SIT (P< 0.001)
versus CTRL though there were no differences between cycle and
run SIT (P= 0.976). There was a main effect for sex (P= 0.021) where
males had increased V
˙O
2
versus females.
EPOC
There was no interaction between mode of exercise and sex
(P= 0.238) for EPOC (Fig. 3), no main effect for mode (P= 0.361), and
no main effect for sex (P= 0.288).
RER
There was a significant interaction between mode of exercise,
time, and sex (P= 0.033). Both males and females had increased
RER (Table 2) during run and cycle SIT versus CTRL (P< 0.001),
though males had a greater RER than females during both run
and cycle SIT (P< 0.002). In the first hour postexercise (Table 2),
RER for CTRL was still increased versus run and cycle SIT in both
males and females (P< 0.001), with no differences between sexes
Fig. 2. Oxygen consumption (V
˙O
2
; L·min
−1
) during exercise and postexercise between treatments (in both males (A) and females (B)).
*, Significantly increased versus control (CTRL) at all time points (P< 0.001).
*
*
*
*
A) B)
During
1st h postexercise
2nd h postexercise
0.0
0.5
1.0
1.5
2.0
2.5
3.0
VO2 (L min-1)
Male VO2
CTRL
CYCLE
RUN
During
1st h postexercise
2nd h postexercise
0.0
0.5
1.0
1.5
2.0
2.5
3.0
VO2 (L min-1)
CTRL
CYCLE
RUN
••
Female VO2
1390 Appl. Physiol. Nutr. Metab. Vol. 39, 2014
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Table 1. Total oxygen consumed (L) during exercise and postexercise between treatments.
Males Females
CTRL Cycle Run CTRL Cycle Run
Litres O
2
66.9±9.7
a,b
107.6±12.1
a,b
116.6±12.1
a,b
54.0±9.1 95.6±18.3 94.4±20.6
Energy (kcal) 334.4±48.4
a,b
537.9±60.6
a,b
583.0±60.3
a,b
269.9±45.6 478.0±91.6 472.0±103.1
a
Significantly increased versus females (P< 0.021).
b
Significantly increased versus control (CTRL) (P< 0.001).
Fig. 3. Excess postexercise oxygen consumption (EPOC) (L) produced during the first hour postexercise in both males (A) and females (D).
EPOC produced during the second hour postexercise in both males (B) and females (E). The total EPOC produced in males (C) and females (F)
during the entire postexercise period (2.5 h).
0
5
10
15
Litre s O2
Male - 1st h EPOC
0
5
10
15
Litre s O2
Male - 2nd h EPOC
0
5
10
15
Litre s O2
Female - 2nd h EPOC
0
5
10
15
Litres O2
Female - 1st h EPOC
A)
B)
C)
D)
E)
F)
CYCLE
RUN
0
5
10
15
20
25 Female - Total EPOC
Litres O2
CYCLE
RUN
0
5
10
15
20
25
Litre s O2
Male - Total EPOC
Table 2. Respiratory exchange ratio (RER) and heart rate responses during exercise and postexercise between treatments.
Males Females
CTRL Cycle Run CTRL Cycle Run
RER
During exercise 0.83±0.05 1.10±0.06
a,b
1.14±0.07
a,b
0.82±0.04 1.00±0.03
a
1.04±0.07
a
1st h postexercise 0.82±0.05 0.74±0.02
c
0.72±0.04
c
0.80±0.01 0.74±0.03
c
0.74±0.03
c
2nd h postexercise 0.79±0.02 0.76±0.05 0.74±0.06
d
0.81±0.06 0.78±0.03 0.73±0.06
d
Heart rate (beats/min)
During exercise 68±10 136±20* 149±10* 72±14 147±9* 150±1*
1st h postexercise 66±9 95±13* 106±17* 70±12 107±25* 103±12*
2nd h postexercise 64±8 79±8* 93±24* 69±11 82±6* 79±10*
a
Significantly increased versus control (CTRL) during exercise (P< 0.001).
b
Significantly increased versus females during exercise (P< 0.001).
c
Significantly decreased versus CTRL 1st h postexercise (P< 0.001).
d
Significantly decreased versus CTRL 2nd h postexercise (P= 0.028).
*Significantly increased versus CTRL at all time points (P< 0.001).
Townsend et al. 1391
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(P> 0.701) or cycle and run SIT (P= 0.494). In the second hour
postexercise (Table 2), RER for CTRL was still increased versus run
(P= 0.028) but not cycle SIT (P> 0.135) in males and females,
though there were no differences between males and females
(P= 0.482) or between cycling and CTRL (P= 0.296) or cycle and run
SIT (P= 0.147).
HR
There was no mode of exercise, time, and sex interaction
(P= 0.358), and no interaction between sex and time (P= 0.219) or
sex and mode (P= 0.154), but there was a time and mode of exer-
cise interaction (P= 0.004). At all time points, HR (Table 2) for run
and cycle SIT were increased versus CTRL (P< 0.001) but were not
different between cycle and run SIT (P> 0.157).
Work output
During cycle SIT (Table 3), there was no interaction for relative
peak power output between bout number and sex (P= 0.916), no
main effect for sex (P= 0.460), and no main effect for bout (P= 0.457).
For relative average power output there was no interaction be-
tween bout number and sex (P= 0.354) and no main effect for sex
(P= 0.289); however, there was a main effect for bout number
(P= 0.013) where power output was increased in bout 1 versus
bout 4 (P= 0.044) and bout 2 versus bout 4 (P= 0.038). For relative
minimum power (RMPO) there was no interaction between bout
number and sex (P= 0.662) and no main effect for sex (P= 0.672).
There was a main effect for bout number (P< 0.001) where bout 1
RMPO was increased versus bout 3 (P= 0.017) and bout 4 (P= 0.003)
and bout 2 was increased versus bout 4 (P= 0.045).
During run SIT (Table 3), there was no interaction for relative
peak speed between bout number and sex (P= 0.842) and no main
effect for sex (P= 0.648). There was a main effect for bout number
where peak speed was increased in bout 1 versus bout 4 (P= 0.028),
bout 2 versus bout 4 (P= 0.001), and bout 3 versus bout 4 (P= 0.001).
For relative average speed there was no interaction between bout
number and sex (P= 0.842) and no main effect for sex (P= 0.648);
however, there was a main effect for bout number where average
speed was increased in bout 1 versus bout 4 (P= 0.028), bout 2
versus bout 4 (P= 0.001), and bout 3 versus bout 4 (P= 0.001). For
relative minimum speed there was no interaction between bout
number and sex (P= 0.573) and no main effect for sex (P= 0.774).
There was a main effect for bout number (P< 0.001) where bout 1
minimum speed was increased versus bout 3 (P= 0.021) and bout 4
(P= 0.004) and bout 2 was increased versus bout 3 (P= 0.014) and
bout 4 (P= 0.001).
Discussion
The current study demonstrates no difference in V
˙O
2
or EPOC
between run and cycle SIT. The current results also demonstrate
that V
˙O
2
was increased using either mode of SIT compared with a
CTRL no-exercise condition and remained elevated for 2 h post-
exercise in response to both modes of exercise. Males consumed
35 L during cycle SIT and 39 L during run SIT, which was
similar to the 31 and 32 L consumed by females during cycle
and run SIT, respectively. In recovery, EPOC in response to cycle
SIT was 9 and 12 L in males and females, respectively, while in
response to run SIT was 13 and 9 L in males and females,
respectively. Combined, these data suggest that the mode of exer-
cise performed during a single session of SIT does not affect the
oxygen consumed during exercise or in the immediate 2-h recov-
ery period and that both males and females respond similarly.
The current during-exercise data are in agreement with previ-
ous work measuring V
˙O
2
during a cycle SIT exercise session in
males (Hazell et al. 2012). This previous during-exercise V
˙O
2
of
35L(175 kcal) was very similar to our current data during both
cycle (170 kcal) and run SIT (178 kcal) in both males and fe-
males. Similarly, the average HR response during exercise was
150 beats/min in during both modes of SIT for both sexes, which
Table 3. Work output during cycling and running sprint interval training sessions.
Males Females
Cycle Run Cycle Run
PPO (W) APO (W) MPO (W)
Peak
speed
(km/h)
Average
speed
(km/h)
Minimum
speed
(km/h) PPO (W) APO (W) MPO (W)
Peak
speed
(km/h)
Average
speed
(km/h)
Minimum
speed
(km/h)
Bout 1 1143.6±278.2 664.3±125.3
a
434.0±77.3
a,b
13.6±1.6
a
12.5±1.5
a
11.2±1.3
a,b
755.4±235.9 434.0±138.5
a
308.9±73.3
a,b
10.9±2.2
a
10.0±1.7
a
9.0±1.6
a,b
Bout 2 1193.8±257.8 586.6±110.8
a
396.3±79.5
a
13.8±1.2
a
12.3±1.0
a
10.8±0.9
a,b
767.9±142.5 408.4±75.0
a
282.1±61.5
a
11.1±1.8
a
9.9±1.5
a
8.8±1.5
a,b
Bout 3 1132.6±217.9 511.3±101.2 315.0±97.7 13.3±1.2
a
11.8±1.0
a
10.4±1.1 746.4±106.2 390.6±73.6 249.4±73.4 10.9±1.7
a
9.5±1.4
a
8.2±1.3
Bout 4 1103.5±313.2 522.0±85.3 302.6±139.1 12.4±1.7 11.2±1.4 10.1±1.1 703.4±88.6 374.6±82.4 228.1±116.7 10.0±1.4 9.0±1.2 7.8±1.0
Notes: APO, average power output; MPO, minimum power output; PPO, peak power output.
a
Significantly increased versus bout 4 (P< 0.05).
b
Significantly increased versus bout 3 (P< 0.05).
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is also comparable with our previous cycle SIT data (Hazell et al.
2012). As expected, both exercise sessions resulted in significantly
increased V
˙O
2
compared with the CTRL session in both males
(145 kcal) and females (130 kcal). These data demonstrate the
similar during-exercise response for both cycle and run SIT.
The current EPOC response to both the running and cycling SIT
exercise sessions is similar to previous cycle SIT work (Chan and
Burns 2013;Williams et al. 2013) and demonstrate that running
SIT results in a similar magnitude of EPOC (45–65 kcal) in the
rst2hofrecovery. While these effects are statistically signifi-
cant, such a small increase in energy consumed in recovery may
not be practically important for any improvements in body com-
position with SIT. Previous research on running HIIT (20 bouts of
60-s intervals at 105% V
˙O
2max
with 2-min rest periods) induced
15L(75 kcal) of EPOC over9h(Laforgia et al. 1997). There also
remains controversy over whether SIT results in an increased
EPOC compared with traditional aerobic exercise (Williams et al.
2013); however, exploring only the immediately acute postexer-
cise period (2–3 h) may not be sufficient to detect the full EPOC
response. Recent evidence has demonstrated that cycling SIT and
HIIT (10 bouts of 60-s intervals at 90% maximum HR with 60 s of
active recovery) can result in a significant increase in total 24-h
V
˙O
2
(Hazell et al. 2012;Skelly et al. 2014) while traditional aerobic
exercise has little effect on EPOC (Hazell et al. 2012).
While the physiological mechanisms inducing EPOC, such as
metabolic cost of glycogen resynthesis, dissipation of lactate, res-
toration of phosphocreatine levels, normalization of blood pH,
catecholamine-induced increases in metabolism and lipolysis,
thermic effect of exercise, and increased muscle-protein turnover
have been documented previously (see reviews by Borsheim and
Bahr 2003;Laforgia et al. 2006), they are beyond the scope of the
current study. Further, recent data have demonstrated that de-
spite SIT increasing circulating concentrations of catecholamines,
there was no increase in free fatty acid availability or oxidation
(Williams et al. 2013), suggesting that enhanced lipolysis does not
play a role in any SIT-induced EPOC.
Regardless of the mechanism inducing EPOC, the current data
suggest that both cycling and running modes of SIT have similar
effects on V
˙O
2
both during exercise and in the brief recovery
period postexercise. Run SIT has demonstrated fat loss in both
men and women (Hazell et al. 2014;MacPherson et al. 2011),
though at present there are no cycle SIT studies demonstrating
decreases in fat mass. However, it should be noted that cycle HIIT
(10 bouts of 60-s intervals at 90% maximum HR with 60 s of
active recovery) induced fat loss in overweight females (Gillen
et al. 2013). The current data demonstrate that the EPOC response
in the 2-h immediately post-SIT plays only a minor role in any
potential fat loss with SIT regardless of mode of exercise (cycle or
run). This suggests that any increase in fat loss with SIT may be via
other mechanisms, such as appetite suppression (Boutcher 2011;
Deighton et al. 2013;Sim et al. 2014;Williams et al. 2013). How-
ever, it should be noted that previous work over 24-h V
˙O
2
with SIT
and HIIT (Hazell et al. 2012;Skelly et al. 2014) suggest that small
but protracted increases in EPOC could be effective in inducing fat
loss if these acute 24-h increases in V
˙O
2
are similar over a chronic
training study.
While sex was not important for V
˙O
2
, RER during exercise was
significantly greater in males compared with females with no sex
differences in recovery. Both run and cycle SIT sessions induced a
significantly depressed RER immediately postexercise similar to
previous research (Chan and Burns 2013;Hazell et al. 2012;Williams
et al. 2013). While this decrease in RER may be accompanied with
an increase in plasma epinephrine and norepinephrine, the im-
mediate recovery period from a SIT exercise session was not asso-
ciated with any increase in fat oxidation (Williams et al. 2013).
This decrease in RER is likely due to CO
2
retention to replenish
bicarbonate stores in response to the intensity of exercise com-
pleted (Laforgia et al. 1997).
With the V
˙O
2
response being similar between males and fe-
males across both modes of exercise it is likely not surprising that
there were no differences in the relative power outputs generated
during the cycling exercise session and the relative speeds gener-
ated during the running exercise session. As this was not matched-
work exercise, participants were encouraged to pedal or run as fast
as possible for the entire 30 s of each bout. Work output was
generally higher during the first 2 bouts compared with the last
bout, demonstrating increasing fatigue and lack of adequate re-
covery over the duration of the exercise session.
Limitations
While we used considerable experimental control over the en-
tire data collection session, some discussion of limitations is nec-
essary. The exercise intensity of the SIT sessions performed in this
study involved supramaximal intensities in young, healthy males
and females and such exercise intensities may not be appropriate
for all populations. While it is still unclear what intensity and
duration of HIIT/SIT is necessary to improve health and fitness,
recent results using a low-volume HIIT model (10 bouts of 60-s
intervals at 90% maximum HR with 60 s of active recovery) has
shown impressive results on both 24-h V
˙O
2
(Skelly et al. 2014),
body composition (Gillen et al. 2013), and insulin sensitivity (Gillen
et al. 2012;Little et al. 2011). Further, we did not allow any food
intake in recovery, so any potential effects of feeding on V
˙O
2
were
not measured.
Conclusion
The current study compared the V
˙O
2
response both during ex-
ercise and postexercise to 2 different modes of SIT (cycle vs run).
Our data demonstrate that both run and cycle SIT result in a
similar during-exercise V
˙O
2
and EPOC in males and females.
While the induced EPOC may not be of a large magnitude (45–
65 kcal), it is still present through the second hour of recovery
from an 18-min bout of SIT (either run or cycle). These EPOC
results are also similar to previous research; though future work
should measure any potential differences between mode of SIT
over longer periods (i.e., 24 h).
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... The cycle ergometer was the most common modality of exercise (eight studies), 4,5,15,34,36,37,41,43 followed by the Treadmill (seven studies), 4,32,33,35,37,38,44 and resistance exercise was the least common modality of exercise (two studies). 1,42 Table 2 shows a large effect in favor of high-intensity training for VO 2 post-exercise using a cycle ergometer or treadmill. ...
... The cycle ergometer was the most common modality of exercise (eight studies), 4,5,15,34,36,37,41,43 followed by the Treadmill (seven studies), 4,32,33,35,37,38,44 and resistance exercise was the least common modality of exercise (two studies). 1,42 Table 2 shows a large effect in favor of high-intensity training for VO 2 post-exercise using a cycle ergometer or treadmill. ...
... Several studies 1,5,15,37,40,41,43,45 have shown that high-intensity interval training does not elevate oxygen consumption. However, other studies 4,32,34,35,38,39,42,44 have shown positive results when the intervention used comprises of high-intensity interval training. ...
Article
Full-text available
Introduction: The objective of this study was to present a systematic review and meta-analysis to compare total excess post-exercise oxygen consumption (EPOC) for two training intervention models in healthy individuals, and the secondary objective was to understand whether oxygen consumption after exercise could really promote a meaningful help. Design: To design a meta-analysis review to compare two training intervention models (expe-rimental: high-intensity interval training; and control: continuous moderate-intensity) and their effects on total EPOC in healthy individuals. Participants: Seventeen studies were considered to be of good methodological quality and with a low risk of bias. Methods: Literature searches were performed using the electronic databases with no restriction on year of publication. The keywords used were obtained by consulting Mesh Terms (PubMed) and DeCS (BIREME Health Science Descriptors). Results: The present study findings showed a tendency (random-effects model: 0.87, 95%-CI [0.35,1.38], I2=73%, p<0.01) to increase EPOC when measured following high-intensity interval training. Conclusions: Our study focused on the analysis of high-and moderate-intensity oxygen uptake results following exercise. Despite the growing popularity of high-intensity interval training, we found that the acute and chronic benefits remain limited. We understand that the lack of a standard protocol and standard training variables provides limited consensus to determine the magnitude of the EPOC. We suggest that longitudinal experimental studies may provide more robust conclusions. Another confounding factor in the studies investigated was the magnitude (time in minutes) of VO2 measurements when assessing EPOC. Measurement times ranged from 60 min to 720 min. Longitudinal studies and controlled experimental designs would facilitate more precise measurements and correct subject numbers would provide accurate effect sizes. Systematic reviewb of Level II studies.
... As a typical SIT session involves 2 min to 3 min of exercise expending~140 kcal to 180 kcal (Hazell, Olver, Hamilton, & Lemon, 2012;Townsend, Couture, & Hazell, 2014), SITinduced fat loss has been partially attributed to an increase in excess postexercise oxygen consumption (EPOC; Bahr & Sejersted, 1991;Hazell et al., 2012;Laforgia, Withers, Shipp, & Gore, 1997;Townsend et al., 2014). In fact, protracted increases in resting metabolism in the hours after SIT result in comparable 24-hr energy expenditure to that observed after 30 min of MICT, despite a drastically lower exercise duration (Hazell et al., 2012). ...
... As a typical SIT session involves 2 min to 3 min of exercise expending~140 kcal to 180 kcal (Hazell, Olver, Hamilton, & Lemon, 2012;Townsend, Couture, & Hazell, 2014), SITinduced fat loss has been partially attributed to an increase in excess postexercise oxygen consumption (EPOC; Bahr & Sejersted, 1991;Hazell et al., 2012;Laforgia, Withers, Shipp, & Gore, 1997;Townsend et al., 2014). In fact, protracted increases in resting metabolism in the hours after SIT result in comparable 24-hr energy expenditure to that observed after 30 min of MICT, despite a drastically lower exercise duration (Hazell et al., 2012). ...
... Collectively, these findings confirm the importance of exercise intensity for elevating postexercise metabolism and promoting a substrate shift that favors fat utilization. The EPOC response observed after VICT and SIT was similar to that observed in previous studies during an acute (< 3 hr) postexercise period following intense interval exercise (Chan & Burns, 2013;Townsend et al., 2014). The ability of SIT to elicit a similar EPOC response to that of VICT despite a~95% lower exercise duration is likely a consequence of the metabolic perturbations associated with supramaximal exercise (i.e., glycogen depletion, increased oxygen debt, circulating catecholamines, lactate) and the subsequent processes required to restore the physiological equilibrium (Laforgia et al., 2006(Laforgia et al., , 1997McCartney et al., 1986). ...
Article
Purpose: Few studies have directly compared excess postexercise oxygen consumption (EPOC) and fat utilization following different exercise intensities, and the effect of continuous exercise exceeding 75% of maximal oxygen uptake (VO2max) on these parameters remains unexplored. The current study examined EPOC and fat utilization following acute moderate- and vigorous-intensity continuous training (MICT and VICT) and sprint interval training (SIT). Methods: Eight active young men performed 4 experimental sessions: (a) MICT (30 min of running at 65% VO2max); (b) VICT (30 min of running at 85% VO2max); (c) SIT (4 30-s "all-out" sprints with 4 min of rest); and (d) no exercise (REST). Excess postexercise oxygen consumption and fat oxidation were estimated from gas measurements (VO2 and carbon dioxide production [VCO2]) obtained during a 2-hr postexercise period. Results: Total EPOC was similar (p = .097; effect size [ES] = 0.3) after VICT (8.6 ± 4.7 L) and SIT (10.0 ± 4.2 L) and greater after both (VICT, p = .025, ES = 0.3, and SIT, p < .001, ES = 0.6) versus MICT (6.0 ± 4.3 L). Fat utilization increased after MICT (0.047 ± 0.018 g· min-1, p = .018, ES = 1.3), VICT (0.066 ± 0.020 g•min-1, p = .034, ES = 2.2), and SIT (0.115 ± 0.026 g•min-1, p < .001, ES = 4.0) versus REST (0.025 ± 0.018 g•min-1) and was greatest after SIT (p < .001, ES = 3.0 vs. MICT; p = .031, ES = 2.1 vs. VICT). Conclusion: Acute exercise increases EPOC and fat utilization in an intensity-dependent manner.
... Similar values are reported in studies examining EPOC following Wingatebased SIT vs MICT or control (Tables 1 and 3), with an average total EPOC magnitude of ~17.7 L and a per hour average of ~5.4 L across ten studies. 24,32,34,36,[38][39][40][41]44,46 Again, these values are greater than that which is seen following MICT at ~8.4 L total and ~2.9 L/h, demonstrating the ability of SIT to induce EPOC above control levels or compared to MICT post-exercise. Seven of the studies recorded a significantly elevated EPOC following SIT vs MICT, 24,25,[33][34][35]40,42,43 with the mean EPOC totaling to ~6.74 L/h. ...
... For instance, running is a more whole-body exercise involving greater muscle mass recruitment for a given submaximal workload, and this exercise modality may elevate V O 2 to a greater extent than cycling. 88,89 However, we have previously demonstrated similar EPOC values following a running and cycling SIT session 41 suggesting mode has little effect on EPOC, though the post-exercise data collection period was brief (2 hours) and cannot be generalized to the late post-exercise period. Differences in fitness level may also contribute to EPOC, though the evidence is equivocal. ...
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The post‐exercise recovery period is associated with an elevated metabolism known as excess post‐exercise oxygen consumption (EPOC). The relationship between exercise duration and EPOC magnitude is thought to be linear whereas the relationship between EPOC magnitude and exercise intensity is thought to be exponential. Accordingly, near‐maximal and supramaximal protocols such as high‐intensity interval training (HIIT) and sprint interval training (SIT) protocols have been hypothesized to produce greater EPOC magnitudes than submaximal moderate‐intensity continuous training (MICT). This review updates previous reviews by focusing on the impact of HIIT and SIT on EPOC. Research to date suggests small differences in EPOC post‐HIIT compared to MICT in the immediate (<1 h) recovery period, but greater EPOC values post‐HIIT when examined over 24 h. Conversely, differences in EPOC post‐SIT are more pronounced, as SIT tends to produce a larger EPOC vs. MICT at all time points. We discuss potential mechanisms that may drive the EPOC response to interval training (e.g. glycogen resynthesis, mitochondrial uncoupling, and protein turnover among others) and also consider the role of EPOC as one of the potential contributors to fat loss following HIIT/SIT interventions. Lastly, we highlight a number of methodological shortcomings related to the measurement of EPOC following HIIT and SIT.
... EPOC is the increased oxygen utilized after exercise compared with resting levels (Gaesser and Brooks 1984). Due to its supramaximal intensity, SIT has been shown to lead to elevated EPOC compared with control conditions (Burns et al. 2012;Chan and Burns 2013;Hazell et al. 2012;Islam et al. 2017aIslam et al. , 2017bTownsend et al. 2014;Williams et al. 2013) and traditional endurance exercise (Laforgia et al. 1997;Townsend et al. 2013). EPOC translates to elevated energy expenditure, which would contribute to generating an energy deficit and potentially lead to a decrease in fat mass. ...
... V O 2 , and thus energy expenditure, was elevated compared with rest through the entire 3-h postexercise period, indicating that significant EPOC was present in response to a modified SIT protocol (Islam et al. 2017a). The EPOC was 12.3 and 14.1 L in FAST and FED, respectively, in line with previous research with similar populations (Chan and Burns 2013;Islam et al. 2017a;Townsend et al. 2014;Williams et al. 2013). Total energy expenditure in both FAST and FED (504.0 and 504.8 kcal, respectively) was also similar to energy expenditure observed in previous studies with similar participants and protocols (Chan and Burns 2013;Islam et al. 2017a). ...
Article
Sprint interval training (SIT) has demonstrated reductions in fat mass through potential alterations in postexercise metabolism. This study examined whether exercising in the fasted or fed state affects postexercise metabolism following acute SIT. Ten active males performed a bout of modified SIT (8 × 15-s sprints; 120 s recovery) in both a fasted (FAST) and fed (FED) state. Gas exchange was collected through 3 h postexercise, appetite perceptions were measured using a visual analog scale, and energy intake was recorded using dietary food logs. There was no difference in energy expenditure between conditions at any time point (p > 0.329) or in total session energy expenditure (FED: 514.8 ± 54.9 kcal, FAST: 504.0 ± 74.3 kcal; p = 0.982). Fat oxidation at 3 h after exercise was higher in FED (0.110 ± 0.04 g·min ⁻¹ ) versus FAST (0.069 ± 0.02 g·min ⁻¹ ; p = 0.013) though not different between conditions across time (p > 0.340) or in total postexercise fat oxidation (FED: 0.125 ± 0.04 g·min ⁻¹ , FAST: 0.105 ± 0.02 g·min ⁻¹ ; p = 0.154). Appetite perceptions were lower in FED (–4815.0 ± 4098.7 mm) versus FAST (–707.5 ± 2010.4 mm, p = 0.022); however, energy intake did not differ between conditions (p = 0.429). These results demonstrate the fasted or fed state does not augment postexercise metabolism following acute SIT in a way that would favour fat loss following training. Novelty Energy expenditure was similar between conditions, while fat oxidation was significantly greater in FED at 3 h after exercise. Appetite perceptions were significantly lower in FED; however, energy intake was not different between conditions. Current findings suggest that performing SIT in the fed or fasted state would not affect fat loss following training.
... These variables, along with heart rate (HR) indicate the physiological intensity of exercise, while rating of perceived exertion (RPE) indicates the psychologically perceived intensity of treadmill running (19). Upon completion of treadmill running, excess post-exercise oxygen consumption (EPOC) can also be an indication of the physiological intensity of an acute exercise bout, as oxygen consumption will remain elevated above baseline in proportion to the intensity of the exercise bout (17). ...
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International Journal of Exercise Science 15(4): 1262-1273, 2022. Treadmills are utilized as a training tool to improve aerobic fitness, but precise understanding of intensity and the corresponding physiological strain is critical for optimizing exercise prescription and associated adaptations. Running on non-motorized, curved treadmills may result in greater oxygen uptake (VO2), increased heart rate (HR), and increased rating of perceived exertion (RPE) compared to traditional motorized treadmills. The purpose of this study was to investigate the physiological responses on non-motorized versus traditional motorized treadmills during speed-matched running. Participants were 4 college-aged, recreationally active females. HR, VO2, respiratory exchange ratio (RER), and RPE were monitored during 3 speed-matched stages of incremental exercise in two conditions: the non-motorized Assault AirRunner and a traditional motorized treadmill, as well as for 5 minutes post-exercise. VO2, RER, and HR were greater in the Assault condition (ESVO2 = 0.998, ESRER = 0.839, ESHR = 0.972, p < 0.05). While not significant between groups, RPE showed a greater increase with increasing speeds in the Assault condition (ES = 0.728), as did RER (ES = 0.800, p < 0.05). Cumulative excess-post exercise oxygen consumption (EPOC) during a five-minute period post-exercise was also greater in the Assault condition, and HR and RER remained higher five minutes post-exercise in the Assault condition (ESEPOC = 0.738, ESHR = 1.600, ESRER = 2.075, p < 0.05). The Assault AirRunner elicited greater physiological responses (VO2, carbohydrate usage, and HR) in response to speed-matched running in comparison to a traditional motorized treadmill in active college-aged females. Collectively, aerobic exercise conducted on the Assault AirRunner has a greater physiological and perceived intensity and need to be taken into consideration when designing and implementing training programs or testing.
... [11][12][13][14][15] There is a paucity of research that examines the sex-based difference in the effects of HIIT on body composition. Townsend et al 16 reported that the total postexercise oxygen consumption, a key mechanism of exercise reducing body fat, was not significantly different between men and women, which suggests that HIIT may be able to elicit the same health benefit for both men and women. ...
Article
Objective: To examine the effect of high-intensity interval training (HIIT) on body fat mass and distribution in patients with myocardial infarction (MI) who underwent cardiac rehabilitation (CR). Patients and methods: We retrospectively screened 391 consecutive patients with MI enrolled in CR between September 1, 2015, and February 28, 2018. We included 120 patients who completed 36 CR sessions and underwent pretest-posttest dual-energy x-ray absorptiometry; 90 engaged in HIIT, and 30 engaged in moderate-intensity continuous training (MICT). High-intensity interval training included 4 to 8 alternating intervals of high- (30-60 seconds at a rating of perceived exertion [RPE] of 15-17 [Borg scale range, 6-20]) and low-intensity (1-5 minutes at RPE <14), and MICT performed for 20 to 45 minutes of exercise at an RPE of 12 to 14. Body weight, fat mass, and lean mass were measured via dual-energy x-ray absorptiometry with lipid profile measured via clinical procedures. Results: The HIIT and MICT groups were similar in age (67 vs 67 years), sex (26.7% [24 of 90 patients in the HIIT group] vs 26.7% [8 of 30 in the MICT group), and body mass index (30.3 vs 29.5 kg/m2) at baseline. The HIIT group had greater reductions in body fat percentage (P<.001), fat mass (P<.001), abdominal fat percentage (P<.001), waist circumference (P=.01), total cholesterol (P=.002), low-density lipoprotein cholesterol (P<.001), and triglycerides (P=.006). Improvements in total body mass and body mass index were not different across groups. After matching exercise duration, exercise intensity, and energy expenditure, HIIT-induced improvements in total fat mass (P=.02), body fat percentage (P=.01), and abdominal fat percentage (P=.02) persisted. Conclusion: Our data suggest that supervised HIIT results in significant reductions in total fat mass (P<.001) and abdominal fat percentage (P<.001) and improved lipid profile in patients with MI who undergo CR.
Article
Background: High-intensity functional training is a popular form of exercise, but little is known about how it compares to more traditional exercise patterns. Methods: Thirty healthy, physically active adults (15 males, 15 females) performed a high-intensity functional training workout (HIFT) and a traditional workout (TRAD). Cardiorespiratory responses were measured during and for 15 min after each workout. Results: Peak heart rate (males: 187 ± 7 vs. 171 ± 10 bpm, p < .001; females: 191 ± 9 vs. 175 ± 6 bpm, p < .001), peak VO2 (males: 3.80 ± 0.58 vs. 3.26 ± 0.60 L/min, p < .001; females: 2.65 ± 0.26 vs. 2.36 ± 0.21, p < .001), and average 15 min recovery VO2 (males: 1.15 ± 0.20 vs. 0.99 ± 0.17 L/min, p < .001; females: 0.77 ± 0.10 vs. 0.71 ± 0.07 L/min, p = .019) were significantly higher in HIFT vs. TRAD. Aerobic energy expenditure was significantly higher in HIFT compared to TRAD in males (9.01 ± 1.43 vs. 8.53 ± 1.38 kcal/min, p = .002) but was not significantly different between the two workouts in females (6.04 ± 0.53 vs. 5.97 ± 0.50 kcal/min, p = .395). Post-exercise systolic blood pressure (SBP) was significantly higher than pre-exercise SBP following both HIFT (males: 124 ± 13 mmHg pre to 154 ± 28 mmHg post, p < .001; females: 110 ± 7 mmHg pre to 140 ± 15 mmHg post, p < .001) and TRAD (males: 124 ± 13 mmHg pre to 142 ± 16 mmHg post, p = .002; females: 112 ± 8 mmHg pre to 123 ± 10 mmHg post, p = .002), however, HIFT led to a greater increase compared to TRAD in females (p = .001). Post-exercise diastolic blood pressure (DBP) was significantly lower than pre-exercise DBP following both HIFT (males: 77 ± 9 mmHg pre to 64 ± 6 mmHg post, p < .001; females: 71 ± 8 mmHg pre to 64 ± 7 mmHg post, p = .011) and TRAD (males: 82 ± 7 mmHg pre to 72 ± 7 mmHg post, p < .001; females: 73 ± 8 mmHg pre to 65 ± 8 mmHg post, p < .001). Mean arterial blood pressure was unchanged following both workouts. Conclusions: High-intensity functional training may be an effective form of exercise for caloric expenditure and may elicit greater cardiorespiratory stress than traditional exercise.
Article
Matthews, ARD, Astorino, TA, Crocker, GH, and Sheard, AC. Acute effects of high-intensity interval exercise while wearing a sauna suit on energy expenditure and excess post-exercise oxygen consumption. J Strength Cond Res XX(X): 000-000, 2020-The use of sauna suits has increased because of claims that they enhance weight loss and increase body temperature during exercise. Therefore, the purpose of this study was to examine changes in energy expenditure (EE) and excess post-exercise oxygen consumption (EPOC) in response to high-intensity interval exercise (HIIE) while wearing a sauna suit. Twelve recreationally active men and women age = (28.7 ± 6.0 years) initially completed assessment of resting metabolic rate and maximal oxygen uptake. On two separate days, subjects completed HIIE consisting of ten 1-minute intervals at 85% peak power output, both with and without a sauna suit. Oxygen consumption, heart rate, and core temperature were continuously measured during and 1 hour after exercise. Energy expenditure during (285 ± 57 kcal vs. 271 ± 58 kcal) and post-exercise (123 ± 30 kcal vs. 113 ± 16 kcal) was significantly higher (p = 0.025) with a sauna suit than without a sauna suit. However, EPOC (6.19 ± 4.46 L of O2 vs. 4.25 ± 3.36 L of O2; p = 0.05) was not significantly different 1 hour after exercise, and core temperature was similar (p = 0.62) between conditions. Fat oxidation was significantly increased for 60 minutes after HIIE with a sauna suit (p = 0.009). Wearing a sauna suit during HIIE elicits greater EE vs. not wearing a sauna suit, but the increase of 23 kcal may not benefit weight loss.
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Forsyth, JJ and Burt, D. Sex differences in recovery from sprint interval exercise. J Strength Cond Res XX(X): 000-000, 2019-The purpose of the study was to examine whether there were differences between men and women in energy metabolism after a bout of sprint interval training (SIT). Sixteen men (mean ± SD [95% confidence interval] for age, stature, body mass, and fat-free mass [FFM] of 25.4 ± 5.9 [22.3-28.6] years, 181.3 ± 7.0 [177.6-185.0] cm, 82.7 ± 13.3 [75.6-89.8] kg, and 69.0 ± 10.6 [63.4-74.6] kg FFM, respectively) and 16 eumenorrheic women (26.1 ± 5.5 [23.1-29.8] years, 164.1 ± 8.7 [159.5-168.7] cm, 72.0 ± 15.4 [63.8-80.2] kg, and 51.6 ± 8.5 [47.0-56.1] kg FFM), tested in the mid-luteal phase of their menstrual cycle, completed a SIT protocol, consisting of 4 × 30-seconds Wingate sprints at 0.065% FFM. Respiratory variables were used to estimate energy metabolism after (post-SIT) and 24 hours after the bout of SIT (24 hours post-SIT). Compared with women, men had significantly higher post-SIT mean fat oxidation rates (0.10 g·min and 0.17 g·min, respectively, F(1,30) = 34.82, p < 0.001, ηp = 0.54), energy expenditure (1.28 ± 0.26 and 1.82 ± 0.40 kcal·min, respectively, F(1,30) = 20.759, p < 0.001, ηp = 0.41), excess post-exercise oxygen consumption values (1.91 ± 0.60 and 3.02 ± 1.58 L, F(1,30) = 6.882, p < 0.014, ηp = 0.19), and lower relative carbohydrate oxidation rates (0.0007 ± 0.0013 and 0.0018 ± 0.0007 g·min per kg FFM, respectively, F(1,30) = 10.506, p < 0.003, ηp = 0.26). The higher metabolic values post-SIT for the men compared with the women might be explained by the men having a greater FFM and having exercised at a higher exercise intensity. Practically, these findings could mean that, if prescribing SIT as a strength and conditioning professional, men and women could respond differently in terms of energy expenditure after exercise.
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High-intensity intermittent exercise (HIIE) elicits large improvements in health and cardiorespiratory fitness (CRF). HIIE can be applied with calisthenics exercises to improve strength and endurance. The acute effects of high-intensity circuit training (HICT) considering different CRF on myological variables are unknown. The aim was measure acute effects of HICT in young women considering different levels of CRF. Twelve women were allocated in two groups, who achieve 41mLO2•kg-1•min-1 or more= High Physical Fitness (HPF, n=5) and who achieve less than 41mLO2•kg-1•min-1= Low Physical Fitness (LPF,n=7). Protocol: 2x4 sets of 20 seconds at maximum intensity (all-out fashion) interspersed with 10 seconds of passive rest (jumping jacks, squat and thrust using 2kg dumbbells, mountain climber, and burpees). Blood samples were collected before, immediately after, 15minutes, 30minutes, one hour and 24 hours after. Heart rate, serum myoglobin, lactate, and creatine kinase (CK) concentration were analyzed. The HR achieved 94.1±3.7% of HRmax for LPF and 104.5±20.3% for HPF, p=0.03. The mean of delta lactate was similar between groups. The highest myoglobin has reached at 1h after the exercise protocol, with 50.0±30.2 ng/mL for LPF and 36.9±9.25 ng/mL for HPF. The delta of total CK before and after the exercise protocol shows that the serum CK level in LPF was significantly higher than HPF group (p=0.042). HICT composed by calisthenic protocol produced elevated and similar effects on HRmax, serum lactate and myoglobin in the woman with HPF and LPF. However, LPF group presented higher muscle damage inferred by serum CK concentrations.
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Data on whether sprint interval training (SIT) (repeated supermaximal intensity, short-duration exercise) affects body composition are limited, and the data that are available suggest that men respond more favourably than do women. Moreover, most SIT data involve cycling exercise, and running may differ because of the larger muscle mass involved. Further, running is a more universal exercise type. This study assessed whether running SIT can alter body composition (air displacement plethysmography), waist circumference, maximal oxygen consumption, peak running speed, and (or) the blood lipid profile. Fifteen recreationally active women (age, 22.9 ± 3.6 years; height, 163.9 ± 5.1 cm; mass, 60.8 ± 5.2 kg) completed 6 weeks of running SIT (4 to 6, 30-s "all-out" sprints on a self-propelled treadmill separated by 4 min of rest performed 3 times per week). Training decreased body fat mass by 8.0% (15.1 ± 3.6 to 13.9 ± 3.4 kg, P = 0.002) and waist circumference by 3.5% (80.1 ± 4.2 to 77.3 ± 4.4 cm, P = 0.048), whereas it increased fat-free mass by 1.3% (45.7 ± 3.5 to 46.3 ± 2.9 kg, P = 0.05), maximal oxygen consumption by 8.7% (46 ± 5 to 50 ± 6 mL/(kg·min), P = 0.004), and peak running speed by 4.8% (16.6 ± 1.7 to 17.4 ± 1.4 km/h, P = 0.026). There were no differences in food intake assessed by 3-day food records (P > 0.329) or in blood lipids (P > 0.595), except for a slight decrease in high-density lipoprotein concentration (1.34 ± 0.28 to 1.24 ± 0.24 mmol/L, P = 0.034). Running SIT is a time-efficient strategy for decreasing body fat while increasing aerobic capacity, peak running speed, and fat-free mass in healthy young women.
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Subjects performed high-intensity interval training (HIIT) and continuous moderate-intensity training (END) to evaluate 24-h oxygen consumption. Oxygen consumption during HIIT was lower versus END; however, total oxygen consumption over 24 h was similar. These data demonstrate that HIIT and END induce similar 24-h energy expenditure, which may explain the comparable changes in body composition reported despite lower total training volume and time commitment.
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The purpose of this study was to investigate the acute effects of endurance exercise (END; 65% V̇O2peak for 60 min) and high-intensity interval exercise (HIE; four 30 s Wingates separated by 4.5 min of active rest) on cardiorespiratory, hormonal, and subjective appetite measures that may account for the previously reported superior fat loss with low volume HIE compared with END. Recreationally active males (n = 18) completed END, HIE, and control (CON) protocols. On each test day, cardiorespiratory measures including oxygen uptake (V̇O2), respiratory exchange ratio (RER), and heart rate were recorded and blood samples were obtained at baseline (BSL), 60 min after exercise, and 180 min after exercise (equivalent times for CON). Subjective measures of appetite (hunger, fullness, nausea, and prospective consumption) were assessed using visual analogue scales, administered at BSL, 0, 60, 120, and 180 min after exercise. No significant differences in excess postexercise oxygen consumption (EPOC) were observed between conditions. RER was significantly (P < 0.05) depressed in HIE compared with CON at 60 min after exercise, yet estimates of total fat oxidation over CON were not different between HIE and END. No differences in plasma adiponectin concentrations between protocols or time points were present. Epinephrine and norepinephrine were significantly (P < 0.05) elevated immediately after exercise in HIE compared with CON. Several subjective measures of appetite were significantly (P < 0.05) depressed immediately following HIE. Our data indicate that increases in EPOC or fat oxidation following HIE appear unlikely to contribute to the reported superior fat loss compared with END.
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Cardiorespiratory fitness (CRF) is a strong determinant of morbidity and mortality. In athletes and the general population, it is established that high-intensity interval training (HIIT) is superior to moderate-intensity continuous training (MICT) in improving CRF. This is a systematic review and meta-analysis to quantify the efficacy and safety of HIIT compared to MICT in individuals with chronic cardiometabolic lifestyle diseases. The included studies were required to have a population sample of chronic disease, where poor lifestyle is considered as a main contributor to the disease. The procedural quality of the studies was assessed by use of a modified Physiotherapy Evidence Base Database (PEDro) scale. A meta-analysis compared the mean difference (MD) of preintervention versus postintervention CRF (VO2peak) between HIIT and MICT. 10 studies with 273 patients were included in the meta-analysis. Participants had coronary artery disease, heart failure, hypertension, metabolic syndrome and obesity. There was a significantly higher increase in the VO2peak after HIIT compared to MICT (MD 3.03 mL/kg/min, 95% CI 2.00 to 4.07), equivalent to 9.1%. HIIT significantly increases CRF by almost double that of MICT in patients with lifestyle-induced chronic diseases.
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The purpose of this research was to determine if the adaptations to high intensity interval training (HIT) are mitigated when both intensity and training volume (i.e. exercise energy expenditure) are reduced. 19 overweight/obese, sedentary males (Age: 22.7±3.9 yrs, Body Mass Index: 31.4±2.6 kg/m(2), Waist Circumference: 106.5±6.6 cm) performed 9 sessions of interval training using a 1-min on, 1-min off protocol on a cycle ergometer over three weeks at either 70% (LO) or 100% (HI) peak work rate. Cytochrome oxidase I protein content, cytochrome oxidase IV protein content, and citrate synthase maximal activity all demonstrated similar increases between groups with a significant effect of training for each. β-hydroxyacyl-CoA dehydrogenase maximal activity tended to increase with training but did not reach statistical significance (p = 0.07). Peroxisome proliferator-activated receptor gamma coactivator-1α and silent mating type information regulator 2 homolog 1 protein contents also increased significantly (p = 0.047), while AMP-activated protein kinase protein content decreased following the intervention (p = 0.019). VO2peak increased by 11.0±7.4% and 27.7±4.4% in the LO and HI groups respectively with significant effects of both training (p<0.001) and interaction (p = 0.027). Exercise performance improved by 8.6±7.6% in the LO group and 14.1±4.3% in the HI group with a significant effect of training and a significant difference in the improvement between groups. There were no differences in perceived enjoyment or self-efficacy between groups despite significantly lower affect scores during training in the HI group. While improvements in aerobic capacity and exercise performance were different between groups, changes in oxidative capacity were similar despite reductions in both training intensity and volume.
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Objective: To examine the acute effects of high-intensity intermittent exercise (HIIE) on energy intake, perceptions of appetite and appetite-related hormones in sedentary, overweight men. Design: Seventeen overweight men (body mass index: 27.7±1.6 kg m(-2); body mass: 89.8±10.1 kg; body fat: 30.0±4.3%; VO(2peak): 39.2±4.8 ml kg(-1) min(-1)) completed four 30-min experimental conditions using a randomised counterbalanced design. CON: resting control, MC: continuous moderate-intensity exercise (60% VO(2peak)), HI: high-intensity intermittent exercise (alternating 60 s at 100% VO(2peak) and 240 s at 50% VO(2peak)), VHI: very-high-intensity intermittent exercise (alternating 15 s at 170% VO(2peak) and 60 s at 32% VO(2peak)). Participants consumed a standard caloric meal following exercise/CON and an ad-libitum meal 70 min later. Capillary blood was sampled and perceived appetite assessed at regular time intervals throughout the session. Free-living energy intake and physical activity levels for the experimental day and the day after were also assessed. Results: Ad-libitum energy intake was lower after HI and VHI compared with CON (P=0.038 and P=0.004, respectively), and VHI was also lower than MC (P=0.028). Free-living energy intake in the subsequent 38 h remained less after VHI compared with CON and MC (P≤0.050). These observations were associated with lower active ghrelin (P≤0.050), higher blood lactate (P≤0.014) and higher blood glucose (P≤0.020) after VHI compared with all other trials. Despite higher heart rate and ratings of perceived exertion (RPE) during HI and VHI compared with MC (P≤0.004), ratings of physical activity enjoyment were similar between all the exercise trials (P=0.593). No differences were found in perceived appetite between trials. Conclusions: High-intensity intermittent exercise suppresses subsequent ad-libitum energy intake in overweight inactive men. This format of exercise was found to be well tolerated in an overweight population.
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Unlabelled: This study examined the acute effect of sprint interval exercise (SIE) on postexercise oxygen consumption, substrate oxidation, and blood pressure. The participants were 10 healthy males aged 21-27 years. Following overnight fasts, each participant undertook 2 trials in a random balanced order: (i) four 30-s bouts of SIE on a cycle ergometer, separated by 4.5 min of recovery, and (ii) resting (control) in the laboratory for an equivalent period. Time-matched measurements of oxygen consumption, respiratory exchange ratio, and blood pressure were made for 2 h into recovery. Total 2-h oxygen consumption was significantly higher in the SIE than in the control trial (mean ± SD: Control: 31.9 ± 6.7 L vs Exercise: 45.5 ± 6.8 L, p < 0.001). The rate of fat oxidation was 75% higher 2 h after the exercise trial compared with the control trial ( Control: 0.08 ± 0.05 g·min(-1) vs Exercise: 0.14 ± 0.06 g·min(-1), p = 0.035). Systolic blood pressure ( Control: 117 ± 8 mm Hg vs Exercise: 109 ± 8 mm Hg, p < 0.05) and diastolic blood pressure ( Control: 84 ± 6 mm Hg vs Exercise: 77 ± 5 mm Hg, p < 0.05) were significantly lower 2 h after the exercise trial compared with the control trial. These data showed a 42% increase in oxygen consumption (∼13.6 L) over 2 h after a single bout of SIE. Moreover, the rate of fat oxidation increased by 75%, whereas blood pressure was reduced by ∼8 mm Hg 2 h after SIE. Whether these acute benefits of SIE can translate into long-term changes in body composition and an improvement in vascular health needs investigation.
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Sprint interval exercise improves several health markers but the appetite and energy balance response is unknown. This study compared the effects of sprint interval and endurance exercise on appetite, energy intake and gut hormone responses. Twelve healthy males [mean (SD): age 23 (3) years, body mass index 24.2 (2.9) kg m(-2), maximum oxygen uptake 46.3 (10.2) mL kg(-1) min(-1)] completed three 8 h trials [control (CON), endurance exercise (END), sprint interval exercise (SIE)] separated by 1 week. Trials commenced upon completion of a standardised breakfast. Sixty minutes of cycling at 68.1 (4.3) % of maximum oxygen uptake was performed from 1.75-2.75 h in END. Six 30-s Wingate tests were performed from 2.25-2.75 h in SIE. Appetite ratings, acylated ghrelin and peptide YY (PYY) concentrations were measured throughout each trial. Food intake was monitored from buffet meals at 3.5 and 7 h and an overnight food bag. Appetite (P < 0.0005) and acylated ghrelin (P < 0.002) were suppressed during exercise but more so during SIE. Peptide YY increased during exercise but most consistently during END (P < 0.05). Acylated ghrelin was lowest in the afternoon of SIE (P = 0.018) despite elevated appetite (P = 0.052). Exercise energy expenditure was higher in END than that in SIE (P < 0.0005). Energy intake was not different between trials (P > 0.05). Therefore, relative energy intake (energy intake minus the net energy expenditure of exercise) was lower in END than that in CON (15.7 %; P = 0.006) and SIE (11.5 %; P = 0.082). An acute bout of endurance exercise resulted in lower appetite perceptions in the hours after exercise than sprint interval exercise and induced a greater 24 h energy deficit due to higher energy expenditure during exercise.
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Six weeks (3 times/wk) of sprint-interval training (SIT) or continuous endurance training (CET) promote body-fat losses despite a substantially lower training volume with SIT. In an attempt to explain these findings, the authors quantified VO2 during and after (24 h) sprint-interval exercise (SIE; 2 min exercise) vs. continuous endurance exercise (CEE; 30 min exercise). VO2 was measured in male students (n = 8) 8 times over 24 hr under 3 treatments (SIE, CEE, and control [CTRL, no exercise]). Diet was controlled. VO2 was 150% greater (p < .01) during CEE vs. SIE (87.6 ± 13.1 vs. 35.1 ± 4.4 L O2; M ± SD). The observed small difference between average exercise heart rates with CEE (157 ± 10 beats/min) and SIE (149 ± 6 beats/min) approached significance (p = .06), as did the difference in peak heart rates during CEE (166 ± 10 beats/min) and SIE (173 ± 6 beats/min; p = .14). Total O2 consumed over 8 hr with CEE (263.3 ± 30.2 L) was greater (p < .01) than both SIE (224.2 ± 15.3 L; p < .001) and CTRL (163.5 ± 16.1 L; p < .001). Total O2 with SIE was also increased over CTRL (p < .001). At 24 hr, both exercise treatments were increased (p < .001) vs. CTRL (CEE = 500.2 ± 49.2; SIE = 498.0 ± 29.4; CTRL = 400.2 ± 44.6), but there was no difference between CEE and SIE (p = .99). Despite large differences in exercise VO2, the protracted effects of SIE result in a similar total VO2 over 24 hr vs. CEE, indicating that the significant body-fat losses observed previously with SIT are partially due to increases in metabolism postexercise.
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Objective: To investigate the effects of low-volume high-intensity interval training (HIT) performed in the fasted (FAST) versus fed (FED) state on body composition, muscle oxidative capacity, and glycemic control in overweight/obese women. Design and methods: Sixteen women (27 ± 8 years, BMI: 29 ± 6 kg/m(2) , VO2peak : 28 ± 3 ml/kg/min) were assigned to either FAST or FED (n = 8 each) and performed 18 sessions of HIT (10× 60-s cycling efforts at ∼90% maximal heart rate, 60-s recovery) over 6 weeks. Results: There was no significant difference between FAST and FED for any measured variable. Body mass was unchanged following training; however, dual energy X-ray absorptiometry revealed lower percent fat in abdominal and leg regions as well as the whole body level (main effects for time, P ≤ 0.05). Fat-free mass increased in leg and gynoid regions (P ≤ 0.05). Resting muscle biopsies revealed a training-induced increase in mitochondrial capacity as evidenced by increased maximal activities of citrate synthase and β-hydroxyacyl-CoA dehydrogenase (P ≤ 0.05). There was no change in insulin sensitivity, although change in insulin area under the curve was correlated with change in abdominal percent fat (r = 0.54, P ≤ 0.05). Conclusion: Short-term low-volume HIT is a time-efficient strategy to improve body composition and muscle oxidative capacity in overweight/obese women, but fed- versus fasted-state training does not alter this response.