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The acute effect of exercise modality and nutrition manipulations on post-exercise resting energy expenditure and respiratory exchange ratio in women: a randomized trial

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The acute effect of exercise modality and nutrition manipulations on post-exercise resting energy expenditure and respiratory exchange ratio in women: a randomized trial

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The purpose of this study was to examine the effect of exercise modality and pre-exercise carbohydrate (CHO) or protein (PRO) ingestion on post-exercise resting energy expenditure (REE) and respiratory exchange ratio (RER) in women. Twenty recreationally active women (mean ± SD; age 24.6 ± 3.9 years; height 164.4 ± 6.6 cm; weight 62.7 ± 6.6 kg) participated in this randomized, crossover, double-blind study. Each participant completed six exercise sessions, consisting of three exercise modalities: aerobic endurance exercise (AEE), high-intensity interval running (HIIT), and high-intensity resistance training (HIRT); and two acute nutritional interventions: CHO and PRO. Salivary samples were collected before each exercise session to determine estradiol-β-17 and before and after to quantify cortisol. Post-exercise REE and RER were analyzed via indirect calorimetry at the following: baseline, immediately post (IP), 30 minutes (30 min) post, and 60 minutes (60 min) post exercise. A mixed effects linear regression model, controlling for estradiol, was used to compare mean longitudinal changes in REE and RER. On average, HIIT produced a greater REE than AEE and HIRT (p < 0.001) post exercise. Effects of AEE and HIRT were not significantly different for post-exercise REE (p = 0.1331). On average, HIIT produced lower RER compared to either AEE or HIRT after 30 min (p < 0.001 and p = 0.0169, respectively) and compared to AEE after 60 min (p = 0.0020). On average, pre-exercise PRO ingestion increased post-exercise REE (p = 0.0076) and decreased post-exercise RER (p < 0.0001) compared to pre-exercise CHO ingestion. HIIT resulted in the largest increase in REE and largest reduction in RER.
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O R I G I N A L R E S E A R C H A R T I C L E Open Access
The acute effect of exercise modality and
nutrition manipulations on post-exercise resting
energy expenditure and respiratory exchange
ratio in women: a randomized trial
Hailee L Wingfield
1
, Abbie E Smith-Ryan
1*
, Malia N Melvin
1
, Erica J Roelofs
1
, Eric T Trexler
1
, Anthony C Hackney
1,2
,
Mark A Weaver
3
and Eric D Ryan
1
Abstract
Background: The purpose of this study was to examine the effect of exercise modality and pre-exercise carbohydrate (CHO)
or protein (PRO) ingestion on post-exercise resting energy expenditure (REE) and respiratory exchange ratio (RER) in women.
Methods: Twenty recreationally active women (mean ± SD; age 24.6 ± 3.9 years; height 164.4 ± 6.6 cm; weight
62.7 ± 6.6 kg) participated in this randomized, crossover, double-blind study. Each participant completed six exercise
sessions, consisting of three exercise modalities: aerobic endurance exercise (AEE), high-intensity interval running (HIIT),
and high-intensity resistance training (HIRT); and two acute nutritional interventions: CHO and PRO. Salivary samples were
collected before each exercise session to determine estradiol-β-17 and before and after to quantify cortisol. Post-exercise
REE and RER were analyzed via indirect calorimetry at the following: baseline, immediately post (IP), 30 minutes (30 min)
post, and 60 minutes (60 min) post exercise. A mixed effects linear regression model, controlling for estradiol, was used to
compare mean longitudinal changes in REE and RER.
Results: On average, HIIT produced a greater REE than AEE and HIRT (p< 0.001) post exercise. Effects of AEE and HIRT
were not significantly different for post-exercise REE (p= 0.1331). On average, HIIT produced lower RER compared to
either AEE or HIRT after 30 min (p<0.001andp= 0.0169, respectively) and compared to AEE after 60 min (p= 0.0020).
On average, pre-exercise PRO ingestion increased post-exercise REE (p= 0.0076) and decreased post-exercise RER
(p< 0.0001) compared to pre-exercise CHO ingestion.
Conclusion: HIIT resulted in the largest increase in REE and largest reduction in RER.
Key points
HIIT elicited the largest increase in post-exercise
energy expenditure.
HIIT resulted in the largest reduction in post-exercise
RER, increasing fat oxidation, compared to AEE
and HIRT.
In combination with varying exercise modalities, PRO
intake elevated post-exercise REE and fat oxidation
(via RER) to a greater extent than CHO.
Integrating HIIT and pre-exercise PRO intake into
exercise routines for women, may have positive
implications on weight and body composition.
Background
More than 60% of women in the United States are
overweight, and 1/3 of those women are obese [1]. In
addition, 75% of normal weight women believe they are
overweight and 90% overestimate their body size [2]. With
such high obesity and body dissatisfaction rates, it is
important for women to receive reliable health and weight
loss recommendations. In addition, lack of time has shifted
the focus on more practical time-efficient strategies for
exercise.
* Correspondence: abbsmith@email.unc.edu
1
Department of Exercise and Sport Science, University of North Carolina, 209
Fetzer Hall, CB #8700, Chapel Hill, NC 27599-8700, USA
Full list of author information is available at the end of the article
© 2015 Wingfield et al.; licensee Springer. This is an Open Access article distributed under the terms of the Creative Commons
Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction
in any medium, provided the original work is properly credited.
Wingfield et al. Sports Medicine - Open (2016) 2:11
DOI 10.1186/s40798-015-0010-3
For health and weight maintenance, aerobic endurance
exercise (AEE) is usually prescribed [3]. However, more
recently, higher-intensity exercise modalities have been
suggested as more time-efficient strategies for improve-
ments in health and energy expenditure [4-6].
Post-exercise resting energy expenditure (REE) has been
reported to increase following a 20-min treadmill run
[4], while high-intensity interval training (HIIT) has
increased total caloric energy expenditure (EE) in half
the time [7]. In addition, high-intensity resistance training
(HIRT) with short rest intervals has been shown to
enhancepost-exerciseREEabovethatseenwithmore
commonly prescribed resistance training [8] of lesser
intensity and longer rest periods. While these three
common exercise modes seem to be successful at
expending calories, previous research has indicated that
high-intensity exercise stimulates similar increases in
post-exercise REE in comparison to lower intensity
exercise, in half the time [9,10]. Research is still conflicted
on whether aerobic or resistance exercise is more effective
for augmenting EE. Higher intensity exercise has also been
linked to higher rates of fat oxidation, measured by
respiratory exchange ratio (RER) [6,11,12].
The combined effect of varying exercise modalities and
pre-workout nutrition on energy substrate utilization and
EE in women is limited. Pre-exercise ingestion of protein
(PRO) has been found to increase post-exercise REE more
than that of pre-exercise ingestion of carbohydrate (CHO)
[13,14]. While women rely heavily on fat as an energy
substrate during exercise, previous data has demonstrated
theimportanceofpre-exercise feedings on augmenting
lipolysis [15]. In addition, a higher rate of fat oxidation in
womenthanmeninthefastedstate,butnotinthe
postprandial state, has been reported [16]. Pre-exercise
nutrient timing and content may be important when
evaluating exercise substrate utilization in women.
When evaluating exercise and nutritional responses in
women, it is important to consider hormonal variances,
such as the sex-specific hormone estradiol that varies
throughout the menstrual cycle. Estradiol has been
shown to have an impact on REE [17-19]. Controlling
for estradiol concentrations in metabolic evaluations is
crucial for determining the practical effects an interven-
tion may have [18]. High-intensity aerobic exercise has
been shown to stimulate increases in cortisol [20], a
stress hormone that regulates energy substrate utilization
by mobilizing amino acids from skeletal muscle and
promoting gluconeogenic activity [21]. Elevated corti-
sol concentrations have been reported as a primary
hormonal factor augmenting exercise adaptations from
high-intensity exercise, as well as impacting rates of
lipolysis [20].
To date, no investigations have evaluated the com-
bined effects of varying exercise modalities and acute
nutritional supplementation in women. Therefore, the
purpose of the current study was to examine the effect
of common exercise modalities, AEE, HIIT, and HIRT,
combined with pre-exercise CHO or PRO ingestion, on
post-exercise REE and RER in women.
Methods
Experimental design
To test the study hypotheses, a randomized, crossover,
factorial design was used. After preliminary resting heart
rate, body composition, and strength testing, each
participant completed six randomly ordered exercise
sessions consisting of three exercise modalities: AEE,
HIIT, and HIRT; and two acute randomized nutritional
interventions: CHO and PRO (Figure 1). Participants
performed each exercise mode twice, with a different
nutritional intervention each time. Salivary samples were
collected before each exercise session to determine
estradiol and cortisol concentrations and after each
exercise session to determine cortisol concentrations.
Exercise sessions were performed at the same time of day,
within 2 h, with at least 48 h between each session, and the
order was randomly assigned using random allocation soft-
ware (version 1.0.0; Isfahan, Iran). Subjects were instructed
to stay well hydrated, to be 3 h postprandial, to refrain from
caffeine 5 h prior, and to refrain from strenuous exercise
24 h prior to all exercise sessions.
Participants
Twenty-one eumenorrheic, college-aged, recreationally
active women were enrolled to participate in this study; one
participant withdrew due to unrelated injury. Twenty
women (n= 20) completed the study (Table 1) and were
included in the statistical analyses. The study protocol was
approved by the Universitys Institutional Review Board,
and all procedures followed were in accordance with the
Helsinki Declaration of 1975, as revised in 2008. Prior to
participation, all participants provided written informed
consent and completed a health history questionnaire. To
be included in this study, participants had to be a woman
between the ages of 18 and 35 and be recreationally active,
defined as accumulating 1 to 5 h per week of aerobic and/
or resistance exercise, excluding competitive athletes.
Participants were excluded if they were unfit, pregnant,
had any cardiovascular or neuromuscular health risks,
had injuries, or had any heart, lung, kidney, or liver disease.
Heart rate reserve measurement and body composition
assessment
Participants reported to the Applied Physiology Laboratory
after an 8-h fast, where they rested for 15 min. Resting
heart rate (RHR) was measured using a polar heart rate
monitor(PolarFT1,PolarUSA,PortWashington,NY,
USA), while age-predicted maximal heart rate (MHR) was
Wingfield et al. Sports Medicine - Open (2016) 2:11 Page 2 of 11
determined. Exercise target heart rate (THR) was calculated
using the Karvonen equation [THR = ((MHR RHR) %
intensity) + MHR] [3]. During each exercise bout, heart
rate (HR) was measured using the aforementioned HR
monitor. Exercises were matched for caloric expenditure
(pilot data not published), opposed to time, in order to
control for exercise length.
For baseline data, whole body composition was mea-
sured using a Hologic Dual Energy X-ray Absorptiometer
(DEXA, Hologic Discovery W, Bedford, MA, USA) using
the devices default software (Apex software version 3.3).
The device uses rectilinear fan beam acquisition to give a
three-compartment assessment of body composition,
including fat mass (FM), lean mass (LM), and percent
body fat (% fat). After removing all metal objects, subjects
laid supine in the middle of the platform with hands
facedown near their sides. Subjects were instructed to
remain still and breathe normally for the duration of
the scan. All scans were performed by the same
DEXA-certified technician. The device was calibrated
according to the manufacturer recommendations
before testing to ensure valid results. Previous
test-retest reliability in our lab were FM: ICC = 0.98,
SEM = 0.85 kg; LM: ICC = 0.99, SEM = 1.07 kg; % fat:
ICC = 0.98, SEM = 1.0%.
Maximal strength test
In a standard post-absorptive state, each participant
performed a one-repetition maximum (RM) strength test
for bench press and leg press, using free weights and a
spotter, according to standard guidelines previously used
in this laboratory. After a 5-min warm-up and light
stretching, participants were familiarized with the
equipment and the motion of the movements. Each
participant then performed eight to ten repetitions at
50% of their predicted 1RM. After a 1-min rest period,
each participant performed four to six repetitions at 80%
of their predicted 1RM. Following a 1-min rest period,
the weight was increased to an estimated 1RM load,
which participants lifted one time. After each successful
set of one repetition, the weight was increased until a
failed attempt occurred, within four attempts. Two to
three minutes of rest was given between 1RM attempts.
Figure 1 Experimental protocol schematic. REE, resting energy expenditure (kcal/day); RER, respiratory exchange ratio; CHO,
carbohydrate; PRO, protein; HRR, heart rate reserve; AEE, aerobic endurance exercise; HIIT, high-intensity interval run; HIRT, high-intensity
resistance training.
Table 1 Descriptive statistics for all subjects (n= 20) at
baseline
Mean ± SD
Age (years) 24.6 ± 3.9
Height (cm) 164.4 ± 6.6
Weight (kg) 62.7 ± 6.6
Fat mass (kg) 17.6 ± 4.0
Lean mass (kg) 42.5 ± 4.4
Percent body fat (%) 28.2 ± 4.8
Wingfield et al. Sports Medicine - Open (2016) 2:11 Page 3 of 11
After the 1RM tests, participants performed a multiple-
RM strength test for four accessory exercises: alternating
stationary lunge, overhead shoulder press, biceps curls,
and overhead triceps extension. With free weights and a
spotter, participants performedeachexercisewitha
weight they could lift for one set of no less than three,
and no more than ten repetitions. The weight for each
exercise, set by the lab assistants, was based on each
participants past strength training experience. If the
participant was unable to perform the exercise for three
repetitions or was able to perform more than ten repeti-
tions, the weight was decreased or increased, respectively,
and the test was redone. A 2- to 3-min rest was given
between each exercise.
The multiple RM obtained from the strength tests was
used to estimate 1RM for the accessory exercises using
the following equation [22]:
1RM ¼RepWt
0:522 þ0:419 0:055 RTFðÞ
where RepWt = amount of weight lifted (lbs) with each
repetition and RTF = amount of repetitions to fatigue.
Once the participants 1RM was determined for all ex-
ercises, 80% to 85% was calculated for the 6RM to 8RM
used for the HIRT sessions.
Energy intake assessment
All participants completed a baseline 3-day food record
to assess their regular nutrient intake. Participants were
educated on food portions and were asked to eat similar
diets the day prior to each exercise session to facilitate
similar macronutrient profiles. Nutrition intake was an-
alyzed using a nutrition software program (The Food
Processor, version 10.12.0, Esha Research, Salem, OR,
USA). On average, subjects ingested 2,078.7 ± 679.9
kcal, 253.7 ± 97.6 g CHO (approximately 48.8% CHO),
84.3 ± 29.9 g PRO (approximately 16.2% PRO), and 80.9 ±
36.7 g of fat (approximately 35.0% fat) per day.
Saliva collection and analysis
In order to account for possible energy substrate utilization
differences between the exercise sessions, estradiol was
measured. Estradiol concentrations were determined by a
2.5 to 5.0 mL saliva sample prior to each exercise bout,
using an ELISA assay for salivary estradiol-β-17 (estrogen)
(Salivary 17β-Estradiol Enzyme Immunoassay Kit,
Salimetrics, LLC, State College, PA, USA). To ensure
valid saliva collection results, participants were asked
to avoid drinking alcohol for 12 h and eating a major
meal for 3 h prior to giving saliva samples. Participants
were asked to rinse their mouth with water 10 min prior
to saliva collection, to remove food residue. To avoid
blood in saliva collections, participants were asked to
avoid brushing teeth for 45 min and obtaining dental work
for 48 h prior to giving saliva samples. All samples were
maintained at 4°C no longer than necessary before freez-
ing them at 20°C. Intra-assay precision coefficient of
variation (CV) for estrogen was 8.7% to 18.6%; inter-assay
precision CV was 3.9%. Due to the physiological role of
estradiol-β-17 on energy substrate utilization in women
[17,19], baseline estradiol levels were used as covariates in
the REE and RER analyses.
Cortisol was measured to account for the stress re-
sponse from each modality of exercise. Cortisol concen-
trations were determined by a 2.5 to 5.0 mL saliva sample
prior to and following each exercise bout, using an ELISA
Assay for salivary cortisol (Salivary Cortisol Enzyme
Immunoassay Kit,Salimetrics, LLC, State College, PA,
USA); the aforementioned protocol for collection and
storage was used. Once all samples were collected, smaller
subsamples were pooled between the two supplements to
produce one pre- and one post-exercise sample to deter-
mine the effect of each modality on cortisol, independent
of treatment. Intra-assay precision CV for cortisol was
12.0% to 17.1%; inter-assay precision CV was 4.9%.
Nutritional intervention
After providing a saliva sample and immediately prior to
beginning each exercise session, in a double-blind fashion,
participants orally ingested 25 g of CHO (maltodextrin) or
PRO (whey isolate; Elite Whey Protein Isolate, Dymatize
Nutrition, Farmers Branch, TX, USA) mixed with 6 oz of
water in an opaque bottle. Treatment order was randomly
assigned using random allocation software. In accordance
to the CONSORT guidelines, nutritional products were
blinded by the company prior to arrival to the laboratory.
All participants and research team members were blinded
to the treatment, until after the statistical analyses.
Aerobic endurance exercise (AEE)
An AEE bout consisted of a self-selected 5-min warm-
up, followed by a 30-min treadmill (Q65 Series 90,
Quinton Instrument Co., Seattle, WA, USA) jog at 45%
to 55% HRR [4]. RPE (Borg scale) was recorded, and HR
was measured at the end of each minute; both were av-
eraged over the 30-min exercise period.
High-intensity interval running (HIIT)
A HIIT bout consisted of a self-selected 5-min warm-up,
followed by ten rounds of a 60-s treadmill run at 85% to
95% HRR with a 60-s passive rest period. The entire exer-
cise bout lasted approximately 20 min. RPE was recorded,
and HR was measured at the end of each interval; and
an average of the ten 60-s exercise intervals was used
for statistical analysis.
Wingfield et al. Sports Medicine - Open (2016) 2:11 Page 4 of 11
High-intensity resistance training (HIRT)
Data obtained from the strength assessment were used
to determine an appropriate weight load for the HIRT
session. Exercises were performed in the following order:
leg press and bench press (York Barbell Co., York, PA,
USA), lunges, shoulder press, biceps curl, and triceps exten-
sion using free weights. Subjects performed a self-selected
warm-up prior to starting. A HIRT bout consisted of three
sets of 6RM to 8RM followed by a 20- to 30-s rest for
each exercise. There was a rest period of 2.5 min
between each exercise [8]. The average length of HIRT
sessions was approximately 25 min. HR was measured
at the end of each set, and RPE was recorded at the end
of each exercise; the average of HR and RPE of each of
the six exercises was used in the statistical analyses.
Metabolic measurements
REE and RER were analyzed using a metabolic cart and
internal software (TrueOne 2400, ParvoMedics, Inc.,
Sandy, UT, USA). Indirect assessments of oxygen uptake
(VO
2
) and carbon dioxide production (VCO
2
) were
measured and used in the following equations to calcu-
late REE [23] and RER [24], respectively:
REE kcal=dayðÞ¼½3:9VO2Lmin1

þ1:1VCO2Lmin1

ÞÞ  1440 min
RER ¼VCO2Lmin1

VO2Lmin1

The gas analysis was performed via a mouthpiece and
hose immediately prior to each exercise session, for
15 min, to obtain resting measures (base). Immediately
after the conclusion of the exercise sessions, participants
were seated and reconnected to the metabolic cart for
15 min to obtain immediately post- (IP) exercise mea-
sures. The participants were then disconnected from the
cart and remained quietly seated. Measurements were
taken again during minutes 25 to 35 (30 min) and 50 to
60 (60 min).
Statistical analyses
A one-way repeated measures ANOVA was performed
to determine baseline differences in salivary estradiol
and cortisol levels. An analysis of covariance (ANCOVA)
mixed effects linear model was used to compare mean
longitudinal changes in REE and RER. Initial models in-
cluded fixed effects for nutritional treatment (CHO vs.
PRO), exercise modality (AEE vs. HIIT vs. HIRT), time
(baseline vs. IP vs. 30 min vs. 60 min), two-way and
three-way interactions, as well as baseline salivary estra-
diol level. The three-way interaction was tested first; if
non-significant, a reduced model was fit without the
three-way interaction. Multiple degree of freedom con-
trasts were then used to test for any evidence of differ-
ences between nutritional interventions or exercise
modalities over time. Only if those overall contrasts were
significant, pairwise comparisons were completed. An
ANCOVA was performed on the change in cortisol, co-
varied for baseline differences. A repeated measures
ANOVA was performed on HR and RPE differences in
modalities. SPSS version 20 (IBM; Armonk, NY, USA)
was used to perform the statistical analyses. All tests
were conducted at the 5% significance level.
Results
Estradiol
There was no significant difference (p= 0.636; ES = 0.035)
between baseline estradiol concentrations for each exer-
cise session. While this pvalue was not significant, the
concentrations obtained were physiologically different be-
tween and within subjects. Concentrations spanned from
0.00 to 5.04 pg/mL between subjects, with one subject
ranging 0 to 4.70 pg/mL between testing days.
REE (kcal/day)
The three-way interaction for REE was non-significant
(p= 0.634), so it was removed from the model. The modal-
ity and treatment interaction was not significant (p=0.060)
(Additional file 1: Appendix 1), so main effects over time
are reported. Significant two-way interactions were found
between modality and time (p< 0.001) and time and treat-
ment (p= 0.008), indicating differential changes over time.
Significant modality differences were found between
HIIT and AEE (p< 0.001), and HIIT and HIRT (p<0.001)
over time, but not between AEE and HIRT (p=0.133).
Mean REE significantly increased more with HIIT com-
pared to AEE from baseline to IP exercise (p<0.001),
30 min post (p= 0.002), and 60 min post (p= 0.002);
(Additional file 1: Appendix 1 and Figure 2A). Mean
REE significantly increased more with HIIT than HIRT
from baseline to IP exercise (p<0.001) but was not
significantly different at 30 min (p= 0.335) or 60 min
(p= 0.143). Mean REE significantly increased more fol-
lowing PRO compared to CHO IP (p=0.007), 30 min
(p= 0.010), and 60 min (p= 0.002) (Figure 2B).
RER
The three-way interaction for RER was non-significant
(p= 0.161), so it was removed from the model. The
interaction between modality and treatment was not sig-
nificant (p= 0.650), so main effects were over time. Signifi-
cant two-way interactions were found between modality
Wingfield et al. Sports Medicine - Open (2016) 2:11 Page 5 of 11
and time (p< 0.001) and time and treatment (p<0.001),
indicating differential changes over time.
Significant over-time differences were found between
HIIT and AEE (p< 0.001), HIIT and HIRT (p< 0.001),
and AEE and HIRT (p= 0.002). As a result of HIIT, mean
RER increased significantly more than AEE and HIRT
from baseline to IP exercise (p< 0.001) (Additional file 1:
Appendix 2 and Figure 3A). However, mean RER signifi-
cantly decreased more at 30 (p< 0.001) and 60 min post
exercise (p= 0.002) for HIIT than AEE. Mean RER sig-
nificantly reduced more from baseline to 30 min (p=
0.017) but was not significantly different at 60 min post (p=
0.360) for HIIT when compared to HIRT. When compar-
ing HIRT and AEE, there was no significant difference
from baseline to IP exercise (p= 0.337), but mean RER
was significantly lower for HIRT to 30 (p< 0.001) and
60 min (p= 0.027). Mean RER was significantly different
over time between CHO and PRO IP exercise (p<
0.001) and was significantly lower for PRO compared
to CHO from baseline to 30 (p= 0.001) and 60 min
post (p< 0.001) (Figure 3B).
Cortisol
ANCOVA change scores demonstrated no significant ef-
fect of exercise modality on cortisol values (p= 0.168;
ES = 0.015) (Table 2).
HR and RPE
There was a modality effect on average HR (p< 0.001)
and RPE (p< 0.001). Compared to HIIT, AEE produced
a significantly lower mean HR (Δ=58 bpm; p< 0.001)
and RPE (Δ=6; p< 0.001) (Table 3). There was no
difference in HR (Δ=3 bpm; p= 0.834) between AEE
and HIRT. Mean RPE was significantly lower for AEE
Figure 2 Energy expenditure (REE; kcal/day) as a result of A) modality and time and B) treatment and time. Values expressed as mean ±
SD. A) Asterisk indicates significant difference between AEE and HIIT (p< 0.001 to p= 0.002); Number sign indicates significant difference between
HIIT and HIRT (p< 0.001). B) Asterisk indicates significant difference between CHO and PRO (p= 0.002 to p= 0.010). REE, resting energy
expenditure (kcal/day); CHO, carbohydrate; PRO, protein; AEE, aerobic endurance exercise; HIIT, high-intensity interval run; HIRT, high-intensity
resistance training; Base, baseline measurement; IP, immediately post-exercise measurement; 30 min, 30 minutes post-exercise measurement;
60 min, 60 minutes post-exercise measurement.
Wingfield et al. Sports Medicine - Open (2016) 2:11 Page 6 of 11
compared to HIRT (Δ=5; p< 0.001). HIIT resulted in
significantly higher mean HR (Δ= 54 bpm; p< 0.001)
and RPE (Δ=1; p= 0.001) compared to HIRT.
Discussion
Previous research evaluating the effect of AEE, HIIT,
and HIRT individually on energy expenditure and en-
ergy substrate utilization have failed to provide direct
comparisons between exercise modes; as well as failing
to evaluate these effects in women. The current study is
the first to compare common exercise modalities, with
acute nutritional intake, on post-exercise REE and RER
in women. Results of the current study indicate that
HIIT produces a significantly higher REE than AEE up
Figure 3 Respiratory exchange ratio as a result of A) modality and time and B) treatment and time. Values expressed as
mean ± SD. A) Asterisk indicates significant difference between AEE and HIIT (p< 0.001 to p= 0.002); Number sign indicates significant
difference between HIIT and HIRT (p< 0.001 to p= 0.017); Section sign indicates significant difference between AEE and HIRT (p=0.001
to 0.027). B) Asterisk indicates significant difference between CHO and PRO (p< 0.001 to p= 0.001). RER, respiratory exchange ratio;
CHO, carbohydrate; PRO, protein; AEE, aerobic endurance exercise; HIIT, high-intensity interval run; HIRT, high-intensity resistance
training; Base, baseline measurement; IP, immediately post-exercise measurement; 30 min, 30 minutes post-exercise measurement;
60 min, 60 minutes post-exercise measurement.
Table 2 Change in cortisol (μg/dL) as a result of modality
(mean ± SD)
Modality Base Post Δ
AEE 0.39 ± 0.31 0.39 ± 0.33 0.00 ± 0.22
HIIT 0.44 ± 0.40 0.59 ± 0.50 0.15 ± 0.23
HIRT 0.35 ± 0.18 0.40 ± 0.20 0.05 ± 0.14
AEE, aerobic endurance exercise; HIIT, high-intensity interval run; HIRT, high-intensity
resistance training; Base, baseline measurement; Post, post-exercise measurement;
Δ,changeincortisol(μg/dL).
Table 3 Average HR and RPE during the duration of each
modality (Mean ± SD)
HR (bpm) RPE
AEE 126 ± 7* 10 ± 1*
§
HIIT 184 ± 29
#
16 ± 1
#
HIRT 129 ± 17 15 ± 1
AEE, aerobic endurance exercise; HIIT, high-intensity interval run; HIRT,
high-intensity resistance training; HR, heart rate (bpm); RPE, rating of perceiv ed
exertion (Borg scale).
*
Indicates significant difference between AEE and HIIT (p< 0.0001).
#
Indicates significant difference between HIIT and HIRT (p< 0.0001
to p= 0.001).
§
Indicates significant difference between AEE and HIRT (p< 0.0001).
Wingfield et al. Sports Medicine - Open (2016) 2:11 Page 7 of 11
to 60 min post exercise and a significantly higher post-
exercise REE than HIRT IP exercise; while AEE and
HIRT produced similar post-exercise REE responses.
HIIT and HIRT both also stimulated greater fat utilization
(via a lower RER) when compared to AEE. In the current
study, ingesting PRO prior to exercise produced an increased
post-exercise resting energy expenditure, compared to CHO
consumption. PRO ingestion also resulted in significantly
augmented fat utilization 30 and 60 min post exercise.
REE
As hypothesized, a single bout of HIIT produced a sig-
nificantly higher post-exercise REE than AEE through
60 min post exercise (Δ= 189.2 kcal/day). Similar to the
current study, higher post-exercise net EE with high-
intensity short-duration cycling (75% VO
2max
) compared
to shorter and longer durations at a low intensity (50%
VO
2max
) has been found in men [9], indicating that exer-
cise intensity affects the magnitude and duration of
excess post-exercise oxygen consumption (EPOC). HIITs
metabolic inefficiency has been contributed to rapid
changes in skeletal muscle oxidative capacity due to the
high level of muscle fiber recruitment, particularly in
type II fibers [25]. In contrast to the current study,
bouts of 60 s of work with 60 s rest, at 90% VO
2max
,
have been found to have the same total net EE as 20-
min bouts at 70% VO
2max
[7]. Perhaps the difference in
exercise intensities for the two sessions was not sub-
stantial enough to elicit significant differences, such as
those found in the current study. Additionally, it is un-
clear if differences between exercise intensities were
controlled for [7]. Subjects in the present study com-
pleted 30 min, instead of 20 min, of AEE in order to
closely match EE during HIIT (determined during pilot
testing; unpublished data).
In contrast to our hypothesis, when compared to HIIT,
REE from HIRT was significantly lower from baseline to
IP exercise (Δ=169.3 kcal/day), with no differences at
30 and 60 min post exercise. Additionally, there was no
difference between AEE and HIRT (Δ= 19.8 kcal/day).
Research that has examined REE differences between
AEE or HIIT and HIRT is limited. However, single bouts
of resistance training and running performed at the
same intensity have both resulted in elevated REE up to
10 h post exercise [26]. Contrary to the current study,
total body circuit weight training (three sets of 15 repeti-
tions at 65% 1RM) has been shown to elicit a higher post-
exercise REE in women than a treadmill run matched for
aerobic energy cost [27]. The current study also matched
EE demands of AEE and HIRT during pilot testing, with
HIRT being slightly lower, yet at a higher intensity than
that of Braun et al. [27]. Post-exercise REE data from the
current study eludes to exercise intensity, instead of dur-
ation, as the primary determinant of EPOC variance,
similar to several studies [4-6]. Collectively, it seems as if
HIIT is the most time-effective exercise modality for in-
creasing EE in women.
Combined acute PRO feedings with exercise resulted
in a significantly higher REE for PRO than for CHO up
to 60 min post exercise (Δ= 59.3 kcal/day). This is similar
to previous findings [13,14] that demonstrate greater post-
exercise REE and fat oxidation following a pre-exercise
meal or snack with higher PRO content. The increase in
post-exercise REE with PRO ingestion can be contributed
to PROs thermic effect of food, which is higher and more
prolonged than that of CHO and fat [28]. In women,
higher PRO diets have elicited an increased effect on diet-
induced EE, in comparison to a lower PRO diet [28,29],
which may be explained by amino acid absorption and
disposal costs [29]. Consuming an additional 100 kcal of
PRO prior to exercise, as done in the current study, may
increase EE up to an hour after exercise.
RER
Exercise intensity has previously been shown to be a
driving factor for energy substrate utilization during and
after exercise. Immediately after HIIT, RER was signifi-
cantly increased compared to AEE, indicating a higher
utilization of CHO during and immediately after exer-
cise. Within 25 min afterward, RER was significantly
lower than AEE (p< 0.001), demonstrating higher fat
utilization, which was maintained up to 60 min post.
Similar to the current study, previous studies have
reported a significantly lower RER post exercise with
repeated bouts of moderate intensity cycling, compared
to a single bout [12] and a lower RER with a lower vs.
higher intensity cycle bout (50% and 70% VO
2max
)
through 3 h post exercise, indicating increased fat
utilization [11]. Previous data demonstrates differing ex-
ercise intensity can augment post-exercise REE and fat
oxidation, but intervals do not produce differences com-
pared to continuous exercise if total EE, duration, and
intensity between the two remain the same throughout
the exercise bout. In contrast to the current study, exer-
cise bouts at 45% and 65% VO
2max
resulted in similar
RER values when EE of exercise was matched [30].
Although diets were kept constant, residual effects of
pre-exercise meals could cause similar RER values, since
a fasting period of only 2 h was implemented prior to
exercise.
During the post-exercise period, oxygen consumption
is elevated for a period of time as a result of homeostasis
disruption caused by exercise. Physiological changes,
such as those in cellular ion concentrations, tissue tem-
peratures, and metabolite and hormone levels, take place
into recovery, disabling oxygen consumption to lower
back to resting levels [24]. This process of EPOC is
related to exercise duration and intensity and can be
Wingfield et al. Sports Medicine - Open (2016) 2:11 Page 8 of 11
influenced by sex-based hormones (estrogen) and
macronutrient availability, among other things [24].
CHO is the primary fuel used during moderate- to high-
intensity exercise; but post exercise, the body shifts from
CHO to lipid energy sources, which lowers RER [30].
The current study demonstrates the fuel shift within
25 min post exercise, indicating greater post-exercise fat
utilization with HIIT. When comparing HIIT and HIRT,
RER was significantly higher IP, significantly lower at
30 min, but similar 60 min after exercise. RER was lower
for HIRT than AEE at 30 (p< 0.001) and 60 min post ex-
ercise (p= 0.027). Little research has compared RER be-
tween aerobic and resistance training, but investigations
that have been done present conflicting results. In con-
trast to this study, no post-exercise differences in RER
were found between a 60-min circuit weight training
bout (four sets of ten repetitions, 70% 1RM) and a cyc-
ling bout (70% VO
2max
) in men [31]. Similar to the
current study, a lower RER was demonstrated 22 h after
HIRT compared to more traditional resistance training
(four sets of 8 to 12 repetitions, 1- to 2-min rest) [8]. In
relation to sex, no differences were reported in post-
circuit weight training RER between men and women
[32]. It is important to examine the menstrual cycle due
to the effects estrogen may have on energy substrate
utilization, as the mid-luteal phase is characterized by
high estrogen levels, which can enhance lipid utilization
with exercise in women [19,33].
In the present study, no differences were found in RER
between CHO and PRO IP exercise; but supporting our
hypothesis, RER was significantly decreased for PRO
compared to CHO at 30 min (Δ= 0.036; p= 0.001) and
60 min post exercise (Δ= 0.052; p< 0.001). Similarly,
higher fat oxidation has been reported with a low CHO
diet compared to a moderate CHO diet at 1 h post exer-
cise [14]. Substrate oxidation can be influenced by sub-
strate availability from dietary intake and physical activity.
While this study only evaluated acute feedings, low CHO
diets have been shown to decrease circulating insulin
levels, which promotes fatty acid utilization in skeletal
muscle [14], perhaps supporting the lower RER for PRO
ingestion in the current study.
Dietary intake
Chronic dietary manipulations have an impact on sub-
strate utilization. Based on 3-day diet logs, participants
consumed on average 48.8% CHO, 16.8% PRO, and
34.2% fat daily. Although intakes were within the
Acceptable Macronutrient Distribution Ranges for
Americans, average baseline PRO intake was 1.3 gkg
1
day
1
(0.5 gkg
1
day
1
higher than the Recommended
Dietary Allowance) [34]. Interestingly, while average PRO
intake was relatively high, an additional acute feeding of
25 g of PRO significantly augmented REE in the current
study, perhaps supporting the suggestion that higher pro-
tein needs (1.63 gkg
1
day
1
) may be necessary for women
to maintain nitrogen balance [35]. While the importance
of chronic dietary manipulations is apparent, the current
study supports the benefit of acute PRO feedings on EE,
in healthy women eating within dietary guidelines. Acute
pre-exercise feedings have positively influenced fat oxida-
tion, in comparison to a fasted state that blunted fat oxi-
dation [16]. Future long-term studies identifying the acute
effects on weight loss and body composition improve-
ments in women would be valuable.
Limitations
A limitation in the current study was the use of indirect
calorimetry to measure REE and RER, rather than whole
body direct calorimetry, which is considered the gold
standard. Also, excluding the acute PRO and CHO sup-
plementation, no dietary modifications were made, which
could have a potential effect on the acute RER measure-
ment. However, because no modifications were made, the
study results may be more practical for a woman who only
wants to change her pre-workout nutrition rather than
her whole diet. In addition, since this was an acute inter-
vention, and post-exercise measurements were only
conducted for 60 min, it is difficult to predict longer
term EE and energy substrate utilization. Specifically,
EE calculations extrapolate our 60-min findings to a 24-h
period (using Weir et al. [23] equation), potentially ele-
vating the actual caloric differences (i.e. approximately
800 kcal). Future research should focus on determining
the effects of chronic exercise and nutrition modifica-
tions in women using whole body calorimetry.
Conclusion
This study indicates that HIIT elicited the largest increase
in post-exercise REE, as well as augmented RER, com-
pared to AEE and HIRT. Immediately post exercise, there
was a heightened caloric effect from the HIIT bout stimu-
lating approximately 800 kcal/day more than HIRT and
AEE. Beginning around 30 min post exercise, HIIT and
HIRT both had a higher fat utilization than AEE; at
60 min post, HIIT and HIRT resulted in similar energy
substrate utilization in comparison to each other. In
combination with varying exercise modalities, PRO intake
elevated post-exercise REE and fat oxidation to a greater
extent than CHO. PRO ingestion prior to exercise may
help further maximize the caloric effect, with an additional
approximately 90 kcal/day expended compared to CHO.
Around 30 min post exercise, PRO increased fat utilization
compared to CHO. Collectively, these findings suggest a
potential benefit of integrating HIIT and pre-exercise PRO
intake into exercise routines. Specifically in women, this
strategy may have positive implications on their health,
weight, and body composition.
Wingfield et al. Sports Medicine - Open (2016) 2:11 Page 9 of 11
Additional file
Additional file 1: Appendix 1. REE (kcal/day) for each modality and
time (mean ± SD). Appendix 2. RER for each modality, treatment, and
time (mean ± SD).
Competing interests
The authors declare that they have no competing interests.
Authorscontributions
HWL assisted with study design, carried out data collection, and drafted
manuscript; ASR conceived study design, carried out statistical analysis, and
drafted manuscript; EJR and ETT carried out data collection, reviewed
results, and manuscript draft; MAW assisted with study design and statistical
analysis; ACH assisted with biochemical analyses; EDR contributed to study
design and reviewed results and manuscript draft. All authors read and
approved the final manuscript.
Acknowledgements
This study was supported by the National Strength and Conditioning Association
Foundation. CHO and PRO were blinded and donated by Dymatize Nutrition
(Farmers Branch, TX, USA). ASR and MW declare that they were supported by the
National Center for Advancing Translational Sciences, National Institutes of Health,
through Grants 1KL2TR001109 and 1UL1TR001111. The content is solely the
responsibility of the authors and does not necessarily represent the official views
of the NIH.
Author details
1
Department of Exercise and Sport Science, University of North Carolina, 209
Fetzer Hall, CB #8700, Chapel Hill, NC 27599-8700, USA.
2
Department of
Nutrition - Gillings School of Global Public Health, University of North
Carolina, Chapel Hill, NC, USA.
3
Departments of Medicine and Biostatistics,
University of North Carolina, Chapel Hill, NC, USA.
Received: 27 July 2014 Accepted: 9 February 2015
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... A variety of investigations have demonstrated that the consumption of caffeine-containing energy drinks may acutely increase metabolic rate [11][12][13], which could potentially result in preferential changes in body composition over time with prolonged use [14]. Similar short-term metabolic effects have also been noted following the acute consumption of supplemental protein prior to an exercise session [15][16][17]. For example, Wingfield and colleagues [16] examined the metabolic impact of supplemental protein ingestion prior to aerobic exercise, high-intensity interval training, and resistance training. ...
... Similar short-term metabolic effects have also been noted following the acute consumption of supplemental protein prior to an exercise session [15][16][17]. For example, Wingfield and colleagues [16] examined the metabolic impact of supplemental protein ingestion prior to aerobic exercise, high-intensity interval training, and resistance training. Compared to a calorie-matched carbohydrate condition, protein ingestion resulted in greater energy expenditure and a lower respiratory exchange ratio, suggesting increased fat oxidation and/or decreased exogenous carbohydrate oxidation, during the hour following exercise. ...
... Importantly, EE in the energy drink condition was found to be approximately 0.77 kcal·min − 1 higher than placebo during the post-beverage time period, and approximately 0.37 kcal·min − 1 higher than placebo during the post-exercise time period. These results align with the findings of previous studies which reported significant elevations in EE following consumption of caffeine-containing energy drinks [11][12][13] as well as those which administered supplemental protein prior to exercise [15][16][17]. Several physiological mechanisms are responsible for these results. ...
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... [10][11][12]25 The second one [10 × 1 minutes at 80%-90% HR max − 1-min recovery] is regularly used in different population types (ie, normal weight, overweight, obese people, young or older, trained, or untrained subjects). [26][27][28] We hypothesized that for the same exercise duration, the longer active phase of HIIE (10 minutes for HIIE 2 vs 8 minutes for HIIE 1) could induce greater post-exercise VO 2 uptake and/or fat utilization. However, our results showed no difference in post-exercise VO 2 and fat utilization among the three exercise modalities. ...
... 14 In this context, our study did not demonstrate the hypothesis that compared with MICE, HIIE induces higher VO 2 consumption due to the higher intensities reached. In agreement, among the eight studies on HIIE and MICE effect on EPOC within 0.5-3 hours post-exercise, only three reported a significant effect of HIIE on post-exercise VO 2 , 26,29,30 whereas the others did not find any difference between modalities. 24,[31][32][33][34] These discrepancies are probably linked to the fact that these studies were performed in different populations (young, old, healthy, not healthy, trained, untrained, men, women) and using different HIIE and MICE protocols (intensity, duration, ergometer used). ...
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... Accordingly, high-intensity aerobic exercise in the postabsorptive state may dampen protein synthesis in the initial hours post-exercise [59]. Furthermore, respiratory exchange ratio has also been reported to decrease during recovery from exercise at the same time that energy expenditure (i.e., oxygen consumption) is increased [51]. Thus, it is unclear if our predicted VCO 2 was indeed elevated after our RE and, subsequently, leucine retention was lower after exercise than at rest. ...
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Home-based resistance exercise (RE) has become increasingly prevalent, but its effects on protein metabolism are understudied. We tested the effect of an essential amino acid formulation (EAA+: 9 g EAAs, 3 g leucine) and branched-chain amino acids (BCAAs: 6 g BCAAs, 3 g leucine), relative to a carbohydrate (CHO) placebo, on exogenous leucine retention and myofibrillar protein breakdown following dynamic bodyweight RE in a home-based setting. Twelve recreationally active adults (nine male, three female) participated in a double-blind, placebo-controlled, crossover study with four trial conditions: (i) RE and EAA+ (EX-EAA+); (ii) RE and BCAAs (EX-BCAA); (iii) RE and CHO placebo (EX-CHO); and (iv) rest and CHO placebo (REST-CHO). Total exogenous leucine oxidation and retention (estimates of whole-body anabolism) and urinary 3-methylhistidine:creatinine ratio (3MH:Cr; estimate of muscle catabolism) were assessed over 5 h post-supplement. Total exogenous leucine oxidation and retention in EX-EAA+ and EX-BCAA did not significantly differ (p = 0.116) but were greater than EX-CHO (p < 0.01). There was a main effect of condition on urinary 3MH:Cr (p = 0.034), with post hoc analysis revealing a trend (p = 0.096) for reduced urinary 3MH:Cr with EX-EAA+ (32%) compared to EX-CHO. By direct comparison, urinary 3MH:Cr was significantly lower (23%) in EX-EAA+ than EX-BCAA (p = 0.026). In summary, the ingestion of EAA+ or BCAA provided leucine that was ~60% retained for protein synthesis following home-based bodyweight RE, but EAA+ most effectively attenuated myofibrillar protein breakdown.
... À la suite d'un exercice de type HIIT, l'EPOC est augmenté et pourrait expliquer la perte de MG totale, abdominale dont viscérale (Boutcher 2011). Plusieurs études ont montré qu'un EPOC augmenté, augmentait la DE post-exercice favorisant ainsi la lipolyse adipocytaire après un exercice de type HIIT comparativement à un MICT (Greer et al., 2015;Karstoft et al., 2016;Schaun et al., 2017;Skelly et al., 2014;Wingfield et al., 2015). Cependant d'autres études ne montrent pas ce lien entre EPOC et DE post-exercice (Tucker et al., 2016;Warren et al., 2009) n'expliquant donc pas la majoration de la perte de MG suite à un HIIT par l'augmentation de l'EPOC. ...
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La prévention primaire et secondaire des pathologies inflammatoires chroniques telles que l’obésité et la maladie de Crohn (MC) reposent majoritairement sur des mesures hygiéno-diététiques incluant l’activité physique et la nutrition. Dans le cadre de ce travail de thèse, l’objectif principal était d’étudier l’influence de modalités d’exercice - exercice imposé de type intermittent de haute intensité (HIIT) ou activité de roue spontanée - associé à un apport en lin, riche en acides gras polyinsaturés (AGPI) n-3, sur les interrelations « composition corporelle – inflammation – microbiote intestinal » dans un contexte de pathologies inflammatoires chroniques (obésité, MC) sur modèles murins. Le deuxième objectif était d’étudier spécifiquement deux formes de lin, à travers la graine ou l’huile, afin de déterminer si la matrice de la graine de lin extrudée pouvait avoir des effets qui lui sont propres. Nos résultats indiquent qu’un programme de type HIIT est efficace pour prévenir la prise de poids et de masse grasse, et que le lin, indépendamment de sa forme, diminue l’inflammation. Nos travaux ont également montré un effet majeur du HIIT et de la graine de lin extrudée (TRADILIN, Valorex®) sur la modulation de la composition du microbiote intestinal associé à la muqueuse. Certaines de ces variations étaient corrélées aux modulations de la composition corporelle mais non à l’inflammation. Nos travaux ont montré spécifiquement un effet synergique du HIIT et de l’huile de lin sur l’abondance d’Oscillospira spp. et sur la conversion de l’acide α-linolénique en acide docosahexaénoïque. En conclusion, nos résultats montrent qu’un apport en lin, et particulièrement sous forme de graines extrudées, associé à une activité physique imposée et suffisamment intense, pourraient être efficace dans la prévention et/ou la prise en charge des pathologies inflammatoires chroniques telles que l’obésité et la MC. Les interrelations « composition corporelle – inflammation – microbiote intestinal », restent toutefois à approfondir et les mécanismes sous-jacents à explorer.
... Alternatively, exercising in a fed state will result in a greater total daily energy expenditure and increased fat oxidation and, indirectly, improve the body composition. A recent analysis suggests that consuming a bolus of protein prior to exercise, as opposed to consuming a bolus of carbohydrate, significantly augments energy expenditure and enhances fat oxidation postexercise for aerobic exercise, highintensity interval training, and resistance training (93). When this approach is combined with resistance training, it appears that pre-exercise nutrition may be more efficacious for women to see improvements in strength and lean body mass, compared to postexercise nutrition (94). ...
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In the United States, women, while having a longer life expectancy, experience a differential risk for chronic diseases and have unique nutritional needs based on physiological and hormonal changes across the lifespan. However, much of what is known about health is based on research conducted in men. Additional complexity in assessing nutritional needs within gender include the variation in genetics, body composition, hormonal milieu, underlying chronic disease, and medication usage, with this list expanding as we consider these variables across the life course. It is clear women experience nutrient shortfalls during key periods of their lives, which may differentially impact their health. Consequently, as we move in to the era of precision nutrition, understanding these sex- and gender-based differences may help optimize recommendations and interventions chosen to support health and weight management. Recently, a scientific conference was convened with content experts to explore these topics from a life-course perspective at biological, physiological, and behavioral levels. This publication summarizes the presentations and discussions from the workshop and provides an overview of important nutrition and related lifestyle considerations across the life course. The landscape of addressing female specific nutritional needs continues to grow; now more than ever, it is essential to increase our understanding of the physiological differences between men and women, and how these physiological considerations may aid in optimizing nutritional strategies to support certain personal goals related to health, quality of life, sleep, and exercise performance among women.
... This strategy enables less-fit individuals to accumulate periods of exercise that would otherwise not be possible if executed continuously. However, one drawback to the protocols employed in the majority of previous resistance-training HIIT studies is that they were not actually timeefficient [12][13] . For resistance training HIIT to be a feasible option to improve public health, it must be time-efficient as lack of time has consistently been identified as one of the primary perceived barriers to preventing inactive individuals from becoming and remaining physically active. ...
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Purpose: The purpose of this study was to compare muscular fitness, anthropometric, and cardiorespiratory fitness outcomes between personalized, adaptive resistance training (ARX) and traditional moderate-intensity resistance exercise (MI-RE). Methods: Apparently healthy men and women (N=45) who reported no resistance training within the previous six months were randomized to a non-exercise control group or one of two resistance exercise training treatment groups (MI-RE or ARX). Measurements of all primary (muscular fitness) and secondary (anthropometric and cardiorespiratory) outcomes were obtained both before and after the 12wk resistance training intervention. Additionally, measures of the primary outcome variable (muscular fitness) were also obtained at the 6wk midpoint. Muscular fitness was assessed by one-repetition maximum (1RM) and five-repetition maximum (5RM) testing for 10 different resistance training exercises. Results: Percentage body fat and cardiorespiratory fitness (VO2max) improved significantly (p < 0.05) following 12wk resistance training in both groups; however, these improvements were more pronounced (p < 0.05) in the ARX group. Furthermore, similar findings were also observed for changes in weight and waist circumference across the 12wk intervention with both MI-RE and ARX groups showing favorable reductions, with the ARX group exhibiting superior changes. At 6wk (i.e., midpoint) and 12wk, all 1RM and 5RM measures for all resistance exercises, were significantly greater (p < 0.05) relative to the control group. In the ARX treatment group, the baseline to 12wk ∆ in all 1RM and 5RM measures were significantly greater (p < 0.05) to those in the control and MI-RE treatment group, with the exception (p > 0.05) of the MI-RE baseline to 12wk ∆ in leg press 5RM, tricep extension 1RM and 5RM, and bicep curl 5RM. Conclusion: The tremendous potential for different modalities of evidence-based exercise programming to enhance training efficacy warrants ongoing scientific inquiry. Given that 'lack of time' is the most often cited reason for not exercising regularly, this study aimed to provide preliminary evidence that extended application of the reduced exertion high intensity training (REHIT) paradigm from aerobic to resistance exercise using technology in the form of the ARX, which permitted personalized, effective, and safe programming. Collectively, these findings have the potential to provide exercise professionals with another important training paradigm to assist individuals with achieving their health and fitness goals.
... Interestingly, this same study also demonstrated increased fat oxidation at 30-min post-exercise in the women who consumed the supplement pre-training. Another study by Wingfield and colleagues [126], may offer insight into this increased fat oxidation as they showed that pre-exercise protein ingestion increased REE and decreased RER at both 30-and 60-min following exercise compared to isocaloric CHO consumption. This study also assessed exercise modality and found that high intensity interval training (HIIT) yielded the greatest increase in REE and decrease in RER post-exercise, suggesting that a combination of preexercise protein consumption coupled with HIIT may have benefits for body composition and weight reduction in women. ...
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Although there is a plethora of information available regarding the impact of nutrition on exercise performance, many recommendations are based on male needs due to the dominance of male participation in the nutrition and exercise science literature. Female participation in sport and exercise is prevalent, making it vital for guidelines to address the sex-specific nutritional needs. Female hormonal levels, such as estrogen and progesterone, fluctuate throughout the mensural cycle and lifecycle requiring more attention for effective nutritional considerations. Sex-specific nutritional recommendations and guidelines for the active female and female athlete have been lacking to date and warrant further consideration. This review provides a practical overview of key physiological and nutritional considerations for the active female. Available literature regarding sex-specific nutrition and dietary supplement guidelines for women has been synthesized, offering evidenced-based practical information that can be incorporated into the daily lives of women to improve performance, body composition, and overall health.
... This measurement was used to estimate the RQ, which indicates the fuel (e.g. carbohydrate or fat) metabolized to supply energy for the body during the exercises [22]. ...
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Aerobic fitness assessment in patients with low back pain (LBP) may help clinicians to plan how to progress the aerobic training. This was a pilot study designed to evaluate the performance of people with LBP on two different aerobic fitness tests performed on a treadmill and to compare the measure of aerobic fitness between people with LBP and healthy individuals. Ten people with LBP and 10 healthy individuals underwent two aerobic fitness protocols, the modified Bruce and maximum incremental test protocols, performed on a treadmill. Data collected during the protocols were: oxygen consumption, heart rate (HR), blood lactate concentration, respiratory quotient, rating of perceived exertion response, and pain intensity. Independent t-test and two-way analysis of variance were used respectively to assess difference between groups characteristics and physiological responses to the protocols. Our results showed that both groups were similar with regards to age (P = 0.839) or HRrest (P = 0.730) but the LBP group showed higher BMI compared to the healthy group (P = 0.031). Regarding the performance of both groups on the aerobic fitness tests, the only significant difference was reported for respiratory quotient which showed a main effect of test (P = 0.015) with higher values favoring the modified Bruce over the incremental test. Our study showed that most people with LBP are able to perform and tolerate both aerobic fitness tests but no significant differences between people with LBP and healthy individuals on both protocols were reported.
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Objective: To explore the effects of essential amino acid (EAA) supplementation on high-intensity interval training (HIIT) fatigue, perceived exertion, and training progression in overweight and obese adults. A secondary aim was to explore potential sex-differences on these outcomes. Methods: Thirty-seven untrained adults (51% female; 36.2 ± 5.9 yrs; 35.5 ± 6.7% body fat) completed eight weeks of HIIT, 2d/wk on a cycle ergometer, either with EAA supplementation (HIIT + EAA; 3.6 g of EAA twice daily, 30 minutes pre and post HIIT) or without supplementation (HIIT). Heart rate (HR) and ratings of perceived exertion (RPE) were recorded throughout each session as indices of within training fatigue. Time to exhaustion (TTE) was recorded for the final interval of each session. Workload progression was determined by change in watts. Differences between groups (with and without EAA) were evaluated at 1wk, 4wks, and 8wks by repeated measure ANOVAs (α = 0.05). Results: There were no differences in TTE (p = 0.983) or workload progression (p = 0.655) with EAA supplementation at any time point. HR and RPE within HIIT sessions were not significantly different with EAA supplementation at any time point (p > 0.05). Results were similar when evaluating males and females separately, but in females, RPE was significantly lower with EAA supplementation at 4wks (Δ: 1.1-2.2; p = 0.016). Conclusion: EAA supplementation did not extend TTE during exercise or enhance workload progression across eight weeks of HIIT in untrained, overweight and obese adults. However, EAA consumed 30 minutes before exercise may reduce perceived exertion during the first four weeks of training in women, which may have implications for overall exercise enjoyment and long-term adherence.
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High-intensity interval training (HIIT) promotes positive cardiometabolic and body composition changes. Essential amino acids (EAA) may support changes associated with HIIT, but evaluation of potential synergistic effects is lacking. The purpose of this study was to compare independent and combined effects of HIIT and EAA on total body composition and metabolism in men and women considered overweight/obese; an exploratory aim was to evaluate the modulatory effects of sex. Sixty-six healthy adults (50% female; Age: 36.7 ± 6.0 years; BMI: 32.0 ± 4.2 kg/m2) completed 8 weeks of: (1) HIIT, 2 days/weeks; (2) EAA supplementation, 3.6 g twice daily; (3) HIIT + EAA; or (4) control. Body composition, resting metabolic rate (RMR), substrate metabolism (respiratory exchange ratio; RER), and cardiorespiratory fitness were measured at baseline, 4 weeks, and 8 weeks; cardiometabolic blood markers were measured at baseline and 8 weeks. Differences between groups were assessed by linear mixed models covaried for baseline values, followed by 95% confidence intervals (CI) on adjusted mean change scores. There were no significant changes in body composition (p > 0.05) for any group. Changes in RER, but not RMR, occurred with HIIT (mean change; [95% CI]: − 0.04; [− 0.07, − 0.02]) and EAA (− 0.03; [− 0.06, − 0.01]) after 8 weeks. Cardiorespiratory fitness increased following 8 weeks of HIIT (+ 5.1 ml/kg/min [3.3,6.8]) and HIIT + EAA (+ 4.1 ml/kg/min [1.0,6.4]). Changes with HIIT + EAA were not significantly different from HIIT. There were no changes in cardiometabolic markers (p > 0.05) and no sex interaction (p > 0.05). HIIT is efficacious for promoting positive changes in cardiorespiratory fitness and resting substrate metabolism in adults considered overweight/obese. Addition of EAA did not significantly enhance HIIT-induced adaptations. ClinicalTrials.gov ID#NCT04080102.
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A single bout of exercise can alter subsequent resting metabolism for many hours and into the next day. However, differences between men and women, effects of nutritional state, and relative effects of resting metabolic rate (RMR) and respiratory exchange ratio (RER) in controlling the increase in lipid oxidation (Lox) after exercise are not yet clear. Effects of aerobic capacity (VO2peak) and exercise bout parameters (intensity and volume) also remain to be clearly elucidated as does the time course of changes after exercise. We performed a meta-analysis to assess these potential moderators of the impact of endurance exercise (effect sizes, ESs) on subsequent Lox at rest (ES=0.91; 95% CI: 0.69-1.12) on the day of exercise (ES=1.22; 95% CI: 0.89-1.55) and on the following day (ES=0.60; 95% CI: 0.35-0.85). ES for the exercise-related increase in resting Lox was significantly greater in men than women in the postabsorptive state but similar in the postprandial state. The ES for depression of RER after exercise was similar between men and women, while the ES for RMR in the postabsorptive state tended to be higher in men than women. Finally, VO2peak and energy expenditure of exercise (EEE), but not intensity, were predictive of postexercise Lox. The findings indicate importance of EEE and fitness for ability to achieve robust enhancement of Lox after exercise. The results additionally indicate a gender difference in postexercise Lox that is dependent on nutritional state, as the ES for Lox was lower in women only in the postabsorptive state.
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Background The benefits of exercise are well established but one major barrier for many is time. It has been proposed that short period resistance training (RT) could play a role in weight control by increasing resting energy expenditure (REE) but the effects of different kinds of RT has not been widely reported. Methods We tested the acute effects of high-intensity interval resistance training (HIRT) vs. traditional resistance training (TT) on REE and respiratory ratio (RR) at 22 hours post-exercise. In two separate sessions, seventeen trained males carried out HIRT and TT protocols. The HIRT technique consists of: 6 repetitions, 20 seconds rest, 2/3 repetitions, 20 secs rest, 2/3 repetitions with 2′30″ rest between sets, three exercises for a total of 7 sets. TT consisted of eight exercises of 4 sets of 8–12 repetitions with one/two minutes rest with a total amount of 32 sets. We measured basal REE and RR (TT0 and HIRT0) and 22 hours after the training session (TT22 and HIRT22). Results HIRT showed a greater significant increase (p < 0.001) in REE at 22 hours compared to TT (HIRT22 2362 ± 118 Kcal/d vs TT22 1999 ± 88 Kcal/d). RR at HIRT22 was significantly lower (0.798 ± 0.010) compared to both HIRT0 (0.827 ± 0.006) and TT22 (0.822 ± 0.008). Conclusions Our data suggest that shorter HIRT sessions may increase REE after exercise to a greater extent than TT and may reduce RR hence improving fat oxidation. The shorter exercise time commitment may help to reduce one major barrier to exercise.
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During exercise, substrate utilization plays a major role in performance and disease prevention. The contribution of fat and carbohydrates to energy expenditure during exercise is modulated by several factors, including intensity and duration of exercise, age, training and diet, but also gender. Because sex hormone levels change throughout a woman's lifetime (in connection with puberty, the menstrual cycle, use of oral contraceptives and menopause), the female population has to be considered specifically in terms of substrate utilization, and metabolic and hormonal responses to exercise. Before puberty, there is no difference between males and females when it comes to substrate oxidation during exercise. This is not the case during adulthood, since women are known to rely more on fat than men for the same relative intensity of exercise. Among adult women, the menstrual cycle and use of oral contraceptives may influence substrate oxidation. While some authors have noted that the luteal phase of the menstrual cycle is connected with greater lipid oxidation, compared with the follicular stage, other authors have found no difference. Among oral contraceptive users, fat oxidation is sometimes increased during prolonged exercise with a concomitant rise in lipolytic hormones, as well as growth hormone. If this result is not always observed, the type of oral contraceptive (monophasic vs triphasic) and hormone doses may be implicated. Menopause represents a hormonal transition in a woman's life, leading to a decline in ovarian hormone production. A decrease in fat oxidation is consequently observed, and some studies have demonstrated a similar respiratory exchange ratio during prolonged exercise in postmenopausal women and in men. As is the case during puberty, no sex difference should thus appear after menopause in the absence of hormonal replacement therapy (HRT). Results concerning women who take HRT remain conflicting. HRT may act on fat loss by increasing lipid metabolism, but this depends on how the treatment is administered (orally vs transdermally). To better understand the role of ovarian hormones in substrate oxidation, studies have made use of animal protocols to investigate cellular mechanisms. Estradiol and progesterone seem to have opposite effects, with greater lipid oxidation when estradiol is used alone. However, the concentrations used (physiological levels or pharmacological doses) may considerably modify fuel selection. In cases where conflicting data are observed in studies of substrate utilization and prolonged exercise in women, methodological reasons must be called into question. Too many parameters, which oftentimes are not specified, may modulate substrate utilization and metabolic and hormonal responses to prolonged exercise. Although information is generally provided about the type of exercise, its duration and the subjects' training level, detailed information is not always given about the subjects' nutritional state and, more specifically, the hormonal status of female subjects. The primary purpose of this review was to identify the impact of hormonal status on substrate oxidation among female subjects at rest and during exercise. A second aim was to describe gender differences in substrate utilization during exercise.
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Indirect estimates of the mean daily protein requirement for female endurance athletes are 1.2-1.4 g·kg(-1)·day(-1); however, an empirical estimate using nitrogen balance is absent. A 72-h nitrogen balance was determined during the mid-follicular phase of 10 female cyclists and triathletes training for 10.8 h·week(-1) (SD 2.8) following 2 habituated protein intakes: (i) normal habitual (NH) (protein 85 g·day(-1)), and (ii) isocaloric high-protein (HP) (∼2-fold increase in protein). Total 72-h nitrogen intake was determined from Leco total combustion of ingested food samples. Nitrogen loss was determined from micro-Kjeldahl analysis of 72-h total urinary nitrogen and representative resting and exercise sweat output, plus estimates for fecal and miscellaneous losses. Habituated (steady state) protein requirement was estimated from the mean regression of adapted nitrogen balance vs nitrogen intake. Mean (SD) 24-h dietary protein and energy intake was NH: 1.4 g·kg(-1)·day(-1) (0.2), energy: 9078 kJ·day(-1) (1492), HP: 2.7 g·kg(-1)·day(-1) (0.3) 8909 kJ·day(-1) (1411). Average 24-h urinary nitrogen and sweat urea nitrogen outputs were 13.2 g·day(-1) (2.4) and 0.33 g·day(-1) (0.08) in NH; 21.5 g·day(-1) (3.9) and 0.54 g·day(-1) (0.12) in HP, respectively. Nitrogen balance was negative in NH (-0.59 gN·day(-1) SD 1.64) but positive in HP (2.69 gN·day(-1) SD 3.09). Estimated mean protein requirement was 1.63 g·kg(-1)·day(-1) (95% confidence interval: 1.1-3.8). In conclusion the snapshot of follicular phase dietary protein requirement conformed with previous estimates for men, but was higher than previous nonempirical estimates for endurance-training women; low self-selected energy and carbohydrate intakes may explain the higher than expected nitrogen turnover, and consequently protein requirement.
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The purpose of this study was to determine the accuracy of using relative muscular endurance performance to estimate 1 RM bench press strength. College students (184 men and 251 women) were tested for 1 RM strength following 14 weeks of resistance training. Each subject was then randomly assigned a relative endurance load (rep weight) corresponding to 55-95 percent of the 1 RM and required to perform as many bench press repetitions (reps) as possible in one minute. Men had significantly greater 1 RM strength, rep weight, percent 1 RM, and reps than women. Since the regression of percent 1 RM on reps was not significantly different between the men and women, the data were combined to produce the following exponential equation: percent 1 RM = 52.2 + 41.9e -0.055 reps (r = 0.80, p < 0.001). Bench press strength could be estimated from the equation 1 RM = rep weight/predicted percent 1 RM/l00 with an accuracy of r = 0.98 and a standard error of estimate of +/- 4.8 kg. Applications of these equations to a comparable cross-validation group (70 men and 101 women) indicated acceptable validity (r = 0.98, p < 0.001) with an error of only +/- 5.4 kg. Applying the same equations to high school male athletes (n = 25), high school male nonathletes (n = 74) and college football players (n = 45) also produced good cross validation (r > 0.95, p < 0.001) with relatively small standard errors (+/- 3.1 to +/- 5.6 kg). It appears that relative muscular endurance performance can be used to accurately estimate 1 RM bench press strength in a wide variety of individuals. (C) 1992 National Strength and Conditioning Association
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Post-exercise energy expenditure has not been studied after resistance exercise. In this study, metabolic rate was measured by indirect calorimetry for nine volunteers after 40 minutes of cycling (80 percent of maximal heart rate), 40 minutes of circuit training (50 percent of individuals' maximum lift [1 RM] x 15 repetitions x 4 sets), 40 minutes of heavy resistance lifting (80 to 90 percent of 1 RM x 3-8 repetitions x 3 sets) and a control interval. Weight training included use of eight stations of Universal multi- and unistation equipment. All forms of exercise increased the metabolic rate immediately after exertion (p < 0.01). For circuit and heavy resistance lifting, the increase also was significant 30 minutes after exertion (p < 0.05). The absolute total increment in caloric use (mean +/- standard deviation) after exertion was comparable among circuit training (49 +/- 20 kilocalories), heavy lifting (51 +/- 31 kilocalories), and cycling (32 +/- 16 kilocalories). However, cycling was less (p < 0.05) than both forms of weight training. Our findings suggest that dynamic exertion is not required to augment post-exercise oxygen consumption (EPOC), and that the amount of exercising skeletal mass is an additional variable to consider when relating exercise to EPOC. (C) 1992 National Strength and Conditioning Association
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Ortego, AR, Dantzler, DK, Zaloudek, A, Tanner, J, Khan, T, Panwar, R, Hollander, DB, and Kraemer, RR. Effects of gender on physiological responses to strenuous circuit resistance exercise and recovery. J Strength Cond Res 23(3): 932-938, 2009-Few studies have focused upon the physiological responses to circuit weight training (CWT) in men and women, and an investigation of possible gender differences could lead to optimal exercise prescriptions and improved adaptation outcomes. The purpose of the study was to determine the effects of gender on cardiovascular and metabolic responses to CWT and consequent recovery. Ten healthy men and 10 healthy women completed an initial session to collect descriptive data and determine a 12 repetition maximum (12RM) for 6 different upper- and lower-body resistance exercises. This was followed by 2 identical sessions of a CWT protocol on 2 separate days at least 48 hours apart. The first session was used to familiarize subjects with the equipment and the testing protocol. The second session was used to determine physiological responses. Each subject performed 10 repetitions of 6 exercises for 3 circuits at a 12RM load. V̇o2 and respiratory exchange ratio (RER) were continuously monitored, whereas heart rate (HR) and blood pressure (BP) were taken at the end of each circuit. Across the exercise session, men revealed greater absolute and relative V̇o2, relative lean body mass V̇o2, systolic BP (SBP), RER, and recovery V̇o2 when compared with the female subjects. There were no differences in HR, diastolic BP (DBP), or recovery RER. The present study provides a greater insight into gender differences in cardiovascular and metabolic responses to circuit weight training. These gender differences should be taken into consideration for development of CWT protocols for men and women.
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Metabolic response of different high-intensity aerobic interval exercise protocols. J Strength Cond Res 26(10): 2866-2871, 2012-Although high-intensity sprint interval training (SIT) employing the Wingate protocol results in significant physiological adaptations, it is conducted at supramaximal intensity and is potentially unsafe for sedentary middle-aged adults. We therefore evaluated the metabolic and cardiovascular response in healthy young individuals performing 4 high-intensity (̃90% VO2max) aerobic interval training (HIT) protocols with similar total work output but different workto- rest ratio. Eight young physically active subjects participated in 5 different bouts of exercise over a 3-week period. Protocol 1 consisted of 20-minute continuous exercise at approximately 70% of VO2max, whereas protocols 2-5 were interval based with a work-active rest duration (in seconds) of 30/30, 60/30, 90/30, and 60/60, respectively. Each interval protocol resulted in approximately 10 minutes of exercise at a workload corresponding to approximately 90% VO2max, but differed in the total rest duration. The 90/30 HIT protocol resulted in the highest VO2, HR, rating of perceived exertion, and blood lactate, whereas the 30/30 protocol resulted in the lowest of these parameters. The total caloric energy expenditure was lowest in the 90/30 and 60/30 protocols (;150 kcal), whereas the other 3 protocols did not differ (;195 kcal) from one another. The immediate postexercise blood pressure response was similar across all the protocols. These finding indicate that HIT performed at approximately 90% of VO2max is no more physiologically taxing than is steady-state exercise conducted at 70% VO 2max, but the response during HIT is influenced by the work-to-rest ratio. This interval protocol may be used as an alternative approach to steady-state exercise training but with less time commitment.