Hormonal and Physiological Adaptations to High-Intensity Interval Training in Professional Male Canoe Polo Athletes

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DOI: 10.1519/JSC.0000000000001161
The present study compared the effects of two different high-intensity interval training (HIIT) programs in professional male canoe polo athletes. Responses of peak oxygen uptake (VO2peak), ventilatory threshold (VT), peak and mean anaerobic power (PPO & MPO), blood volume, and hormonal adaptations to HIIT were examined. Male athletes (n=21, age: 24 ± 3 years; height : 181 ± 4 cm; mass: 85 ± 6 kg and Body fat: 12.9 ± 2.7%) were randomly assigned to one of three groups (N=7): 1) (G1) interval paddling with variable volume (6,7,8,9,9,9,8,7,6 repetitions/session from 1 to 9 session respectively) × 60-second at lowest velocity that elicited VO2peak (vVO2peak), 1:3 work to recovery ratio); 2) (G2) interval paddling with variable intensity (6 × 60-second at 100,110,120,130,130, 130,120,110,100% vVO2peak from 1 to 9 session respectively, 1:3 work to recovery); and 3) (GCON) the control group performed three 60 min paddling sessions (75% vV O2peak) per week for 3 weeks. High-intensity interval training resulted in significant (except as shown) increases compared with pretest, in: VO2peak (G1=+8.8%, G2=+8.5%), heart rate at VT (b.min) (G1=+9.7%, G2=+5.9%) and (%maximum) (G1=+6.9%; P=0.29, G2=+6.5%), PPO (G1=+9.7%, G2=+12.2%), MPO (G1=+11.1%; P=0.29, G2=+16.2%), total testosterone (G1=+29.4%, G2=+16.7%), total testosterone/cortisol ratio (G1=+40.9%, G2=+28.1%), and mean corpuscular hemoglobin (G1=+1.7%, G2=+1.3%). No significant changes were found in GCON. High-intensity interval paddling may improve both aerobic and anaerobic performances in professional male canoe polo athletes under the conditions of this study.
Department of Exercise Physiology, Islamic Azad University, Ardabil Branch, Ardabil, Iran;
Department of Exercise
Physiology, Faculty of Physical Education and Sport Sciences, Islamic Azad University, Karaj Branch, Karaj, Iran;
Department of Physical Education and Sports Sciences, Tarbiat Modares University, Tehran, Iran; and
Department of
Exercise Physiology, Faculty of Physical Education and Sport Sciences, Shahid Rajaee Teacher Training University,
Tehran, Iran
Sheykhlouvand, M, Khalili, E, Agha-Alinejad, H, and Gharaat, M.
Hormonal and physiological adaptations to high-intensity
interval training in professional male canoe polo athletes.
J Strength Cond Res 30(3): 859–866, 2016—This study com-
pared the effects of 2 different high-intensity interval training
(HIIT) programs in professional male canoe polo athletes.
Responses of peak oxygen uptake (V
peak), ventilatory
threshold (VT), peak and mean anaerobic power output (PPO
and MPO), blood volume, and hormonal adaptations to HIIT
were examined. Male athletes (n = 21, age: 24 6 3 years;
height: 181 6 4 cm; mass: 85 6 6 kg; and body fat: 12.9 6
2.7%) were randomly assigned to one of 3 groups (N = 7): (a)
) interval paddling with variable volume (6, 7, 8, 9, 9, 9, 8, 7,
6 repetitions per session from first to ninth session, respec-
tively) 3 60 second at lowest velocity that elicited V
peak), 1:3 work to recovery ratio; (b) (G
) interval pad-
dling with variable intensity (6 3 60 second at 100, 110, 120,
130, 130, 130, 120, 110, 100% vV
peak from first to ninth
session, respectively, 1:3 work to recovery); and (c) (G
control group performed three 60 minu tes paddling sessions
(75% vV
peak) per week for 3 weeks. High-intensity interval
training resulted in significan t (except as shown) increases com-
pared with pretest, in V
peak (G
= +8.8% and G
= +8.5%),
heart rate at VT (b$min
= +9.7% and G
= +5.9%) and
(%maximum) (G
= +6.9%; p = 0.29 and G
= +6.5%), PPO
= +9.7% and G
= +12.2%), MPO (G
= +11.1%; p = 0.29
and G
= +16.2%), total testosterone (G
= +29.4% and G
+16.7%), total testosterone/cortisol ratio (G
= +40.9% and
= +28.1%), and mean corpuscular hemoglobin (G
= +1.7%
and G
= +1.3%). No significant changes were found in G
High-intensity interval paddling may improve both aerobic and
anaerobic performances in professional male canoe polo ath-
letes under the conditions of this study.
KEY WORDS biochemical changes, physiological response,
training techniques
ifferent types of high-intensity interval training
(HIIT) seem to be effective in improving perfor-
mance and related physiological and biochemi-
cal variables (9,15,21,23,28,34). The rate at
which these adaptations occur is variable (37) and depends
on volume, intensity, and frequency of the training (23).
Coaches attempt to optimize the training stimulus through
manipulation of the duration and intensity of both the train-
ing and recovery phases. Such optimization depends on the
specific event in which the athlete competes (11,22,23,38).
High-intensity interval training, in a variety of forms, has
been used with cyclists, swimmers, runners, and rowers to
examine the effects on physiological and hematological
adaptations (8). However, the effect of a short period of
HIIT with incremental variation in volume and intensity
has not been examined in professional canoe polo athletes.
An official canoe polo match comprises 2 periods of
10 minutes with a 3-minute pause between periods. A match
is played between 2 teams of 5 players each. The purpose of
the game is to throw the ball into the opposing team’s goal,
which is placed 2 meters above the water (2). Players use
specific kayaks besides other mandatory accessories such as
paddles, skirts, jackets, and helmets. Unlike most other team
sports, athletes do not have predetermined positions. There-
fore, they are required to develop a number of different skills
(e.g., dribbling pivots, passing, rolling, and shooting) and
physical abilities (speed, power, aerobic capacity, and muscle
Address correspondence to Mohsen Sheykhlouvand, m.sheykhlouvand@
Journal of Strength and Conditioning Research
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VOLUME 30 | NUMBER 3 | MARCH 2016 | 859
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endurance/strength). In this regard, canoe polo consists of
high-intensity bursts of sprinting, interspersed with short
periods of low-to-moderate intensity paddling (14). Decisive
actions within a canoe polo match consist of high-intensity
intermittent efforts (2). Previous studies noted that both aer-
obic capacity and anaerobic power can improve after HIIT
in wide range of sports (8,22,27,28). Meanwhile, both explo-
sive activities and aerobic power are important for canoe
polo performance (2,14). According to these findings, it is
of practical interest for coaches to simultaneously improve
these capacities in their athletes.
Also, a study has noted that HIIT is a potent and time-
efficient strategy to induce skeletal muscle metabolic adaptations
and improve functional exercise capacity (2 7). Often, canoe polo
athletes need to reach a peak performance for competitions
several times over an annual training cycle and require a training
program to achieve fitness in a short period. Training programs
capable of improving aerobic or anaerobic metabolism are based
mainly on periods of at least 6 weeks, and such programs are
often based on continuous endurance training (31). In these
cases, low-volume HIIT may represent an alternative to endur-
ance training to improve aerobic and anaerobic performance in
a short time frame. Most of the previous studies on adaptations
to short-term low volume of HIIT have used training protocols
that consisted of repeated “all-out” maximal efforts (i.e., repeated
W ingate tests) (3,6,12,15,2 7). Wingate-based HIIT requires
a high level of motivation and can result in feelings of nausea
and discomfort due to the extreme physical exertion and thus
may not be safe or practical for some individuals (2 7).
Laursen, 2010, noted that both high-volume training and
high-intensity training are important elements of an athlete’s
training program; however, it is unclear as to how to best
manipulate these elements to obtain optimal performance in
professional athletes. They reported that although the met-
abolic adaptations that occur due to high-volume and high-
intensity training show considerable overlap, the molecular
events that signal for these adaptations are different (23).
Because of these findings, it is not clear which HIIT protocol
is more effective to improving required adaptations of pro-
fessional canoe polo athletes in short period.
Accordingly, the aim of this study was to examine and
compare the effect of a short period (3 weeks) of 2 different
HIIT programs with incremental (session by session)
intensity and volume on aerobic, anaerobic, hormonal, and
hematological adaptations in professional canoe polo
athletes using simulated paddling on the ergometer. We
hypothesized that both of the HIIT protocols would
improve both hormonal and physiological adaptations of
professional canoe polo athletes.
Experimental Approach to the Problem
The experimental protocol consisted of familiarization,
baseline testing, a 3-week exercise training intervention,
and post-training measurements.
Pretesting of the aerobic and anaerobic performances,
along with blood and biochemical parameters, was con-
ducted before the beginning of the preseason phase of the
athletes’ yearly training program, with posttesting after the
3-week HIIT training program. Before taking part in this
study, subjects performed 4 sessions of a 40-minute paddling
time trial at a self-selected pace and an incremental paddling
test to volitional fatigue on a kayak ergometer. In incremen-
tal exercise, subjects began paddling at 6 km$h
speed, and
work load was increased by 1 km$h
every 1 minute there-
after until volitional fatigue. On 2 separate days, subjects
performed 2 consecutive 30-second upper-body Wingate
tests with 4-minute recovery between the trials (27) on an
electronically braked ergometer to become familiar with
these performance tests.
In both pretesting and posttesting, the subjects first per-
formed a progressive incremental exercise test to determine
peak oxygen uptake (V
peak), ventilatory threshold (VT),
and related physiological variables. After 48 hours, participants
performed a 30-second upper-body W ingate test to determine
peak power output (PPO) and mean power output (MPO).
Subjects were also asked to complete food diaries 2 days before
baseline testing and to replicate this diet before the posttrain-
ing test session. Subjects were asked not to participate in any
physical activity 24 hours before each testing session.
Two days after finishing the last session of the 3-week
training period, all subjects repeated the same testing battery
as the pretraining in the same order and under similar
conditions. All laboratory testing was conducted in the
physiology laboratory of Iran National Canoeing, Rowing,
and Sailing Academy (Figure 1).
Twenty-one professional male canoe polo athletes (mean
age = 24 6 3 years; height = 181 6 4 cm; weight = 85 6 6
kg; body fat = 12.9 6 2.7%) gave their written informed
consent for the experiment, which included 10 athletes
who represented the Iran National Canoe Polo Team in
official international competitions throughout the year of
2013. All procedures were in accordance with ethical prin-
ciples of the Declaration of Helsinki, approved by ethical
committee of Tarbiat Modares University of Tehran. They
were randomly assigned to 2 different training groups and
a control group. The subjects performed general fitness
training including running, circuit training, and voluntary
paddling in low intensity for 2 months (off-season phase)
before testing.
Cardiorespiratory values obtained during incremental paddling
test. Subjects performed a progressive exercise test on a kayak
ergometer using a cardiorespiratory exercise test system
(Cosmed K4B2, Rome, Italy) to evaluate peak oxygen uptake
peak), heart rate at V
peak (HR@V
peak), the lowest
velocity that elicited V
peak (vV
peak), and heart rate
(HR) at VT (HR@VT). Before each test, the gas analyzer
Physiological and Biochemical Responses to HIIT
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was calibrated according to the manufacturer’s instructions.
The initial speed was set at 6 km$h
and increased by 1
every 1 minute until exhaustion (13,32). Participants
were considered to have reached their V
peak when 3 or
more of the following criteria were met: (a) a plateau in V
despite increasing paddling speed; (b) a final respiratory
exchange ratio higher than 1.1; (c) visible subject exhaustion;
(d) an HR within 10 b$min
of age-predicted maximum
HR (9,10). The vV
peak was
defined as the minimal speed
at which the athlete was pad-
dling when V
peak occurred
(within 2 ml $kg
peak (24)), as long as
this speed was sustained for at
least 1 minute (5). Also, venti-
latory (anaerobic) threshold
was determined using modified
V-slope method (4,3 3).
Determination of peak power out-
put, mean power o utput, and
Fatigue Index. Subjects performed
a 30-second all-out effort on
a mechanically braked arm
ergometer (891E; Monark, Vans-
bro, Sweden) against a resistance
equivalent to 0.040 kg per kilo-
gram body mass (1). Subjects
were instructed to begin crank-
ing as fast as possible against the
ergometer’s inertial resistance,
and then the appropriate load
was manually applied. Subjects
were verbally encouraged to
TABLE 1. Pretraining vs. posttraining values for peak oxygen uptake (V
heart rate at V
peak (%maximum), and heart rate at the ventilatory threshold
(HR@VT [b$min
and %maximum]).*
peak (L$ min
Pre 3.27 (0.37) 3.04 (0.53) 3.14 (0.37)
Post 3.56 (0.53) 3.30 (0.46) 3.21 (0.35)
%Δ +8.8 +8.5 +2.2
peak (%maximum)
Pre 86.0 (3.8) 91.4 (6.7) 88.7 (8.3)
Post 88.1 (3.8) 94.1 (4.6) 90.1 (5.4)
%Δ +2.4 +2.9 +1.5
HR@VT (b$min
Pre 143.5 (16.5) 144.1 (14.7) 135.1 (25.3)
Post 157.5 (7.9) 152.7 (14.3) 137.4 (27.8)
%Δ +9.7 +5.9 +1.7
HR@VT (%maximum)
Pre 70.6 (8.9) 72.3 (8.2) 70.0 (13.0)
Post 75.5 (3.1) 77.0 (8.4) 70.2 (9.0)
%Δ +6.9 +6.5 +0.03
*N = 7 for each group. Shown is mean (6SD).
Significantly greater than pretraining value (p # 0.05).
Figure 1. Overview of experimental protocol. PRE = pre-exercise; POST = postexercise; HIIT = high-intensity interval training. In line 1 (G
), numbers in boxes denote
number of HIIT bouts, and in line 2 (G
), percent ages in boxes (%vV
) den ote intensity of H IIT completed during each of 9 training sessions over a 3-week period.
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continue cranking as fast as possible throughout the 30-second
test. Peak power, mean power, and fatigue index were subse-
quently determined using an online data-acquisition system (12).
Training. After the testing, subjects were divided into 3
separate matched training groups as follows: group 1, G
(N =7);group2,G
(N = 7); control group, G
(N =7).
All subjects undertook a 3-week kayak ergometer training pro-
gram. The HIIT groups (G
and G
) performed 3 HIIT ses-
sions each week. Training was performed on a kayak
ergometer (Dansprint, Hvidovre, Denmark). Subjects trained
for a total of 3 weeks. In G
, the training sessions
started with six 1-minute paddling intervals performed at 100%
peak with variable volume (i.e., VVHIIT) each session (6,
7, 8, 9, 9, 9, 8, 7, 6 bouts per session). Recovery between
intervals was set at 3 minutes. All training parameters (recov-
ery time and paddling intensity) except number of intervals
were kept constant throughout the 3-week training period. In
, the training sessions consisted of six 1-minute constant-
volume paddling intervals performed at 100% vV
peak with
variable intensity (i.e., VIHIIT) session by session set in (100,
110, 120, 130, 130, 130, 120, 110, 100) %vV
peak. All training
parameters (recovery time and number of intervals) except
paddling intensity were kept constant throughout the 3-week
training period. T he subjects in control group performed 3
times of 60 minutes traditional endurance paddling (i.e., TEP)
(75% vV
peak) 3 sessions per week (11). Also, all 3 groups
followed the same canoe polo training sessions including tech-
nique drills and tactic practice 3 times a week for 3 weeks
(45 minutes) and weight lifting training 1 session per week in
3 set/8 repetitions/70% 3 1 repetition maximum (movements
including bench press, military press, bench pull, seated row,
bicep curl, trunk rotation, and pulley pushdowns) and body
weight training (pull-ups, sit-ups, and push-ups) for 3 weeks.
Blood sampling. Subjects were sampled in the morning after
an overnight fast exceeding 8 hours. All subjects were asked
to refrain from alcohol and strenuous activity 24 hours
before the blood sampling day. A venous blood sample was
collected by venipuncture from an antecubital vein (10 ml)
before and after the 3-week training period (28,2 9). For mea-
suring serum total testosterone (TT) and cortisol, a 7-ml
blood sample was immediately spun at 3000 rpm, at 48 C
for 15 minutes. The serum was separated and stored at 2808
C. The remaining 3-ml blood sample was measured for com-
plete blood count using an automated cell counter (Abacus
C; Diatron, Budapest, Hungary). Serum concentrations of
TT (DRG Diagnostics, Marburg, Germany; intra-assay coef-
ficient of variation [CV], 4.2%), and cortisol (dbc-Diagnostics
Biochem Canada, Inc., Dorchester, Ontario, Canada; intra-
assay CV, 5.7%) were determined by enzyme-linked immu-
nosorbent assay kits. All pre-exercise and postexercise speci-
mens from each individual were analyzed in the same batch
by an experienced technician who was blinded to the origin
of samples.
Statistical Analyses
All results were reported as mean 6 SD. The Kolmogorov-
Smirnov test was used to test the normality of the distribu-
tion. A paired pre-post Student’s t-test was run separately in
each specific training group to determine whether each spe-
cific HIIT program had any effect on the dependent meas-
ures. Differences between groups were analyzed using a 3 3
2 (group 3 time) repeated-measures analysis of variance
followed by Tukey’s post hoc test when a significant F-ratio
was observed. Significance was set at p # 0.05 for all anal-
yses. Statistical analyses were performed using the software
program SPSS, version 18.0 (Statistical Package for Social
Science, Chicago, IL).
Performance Measurement
peak was significantly increased from pretraining to
posttraining in G
(p = 0.048) and G
(p = 0.02), but not
Figure 2. A) Peak power output elicited during Wingate test. B) Mean power output during Wingate test. Values are mean 6 SD. *Indicates significantly
greater than pretraining values (p # 0.05). N = 7 for each group. Indicates significantly different compared with control group (p , 0.05).
Physiological and Biochemical Responses to HIIT
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in G
(Table 1). Also, the change in V
peak in G
significantly greater compared with the change in G
(p =
0.04). No significant changes were observed between groups
or over time in HR@V
peak (%maximum).
Ventilatory threshold was not significantly different
among groups when expressed as HR@VT (b$min
) and
%MHR (%maximum heart rate), but both HIIT groups sig-
nificantly improved their VT (b$min
) ranging from 5.9 to
9.7%. Ventilatory threshold (%MHR) increased from pre-
training to posttraining for G
, but no change was found in
the G
and G
(Table 1).
The PPO increased by 9.7% in G
(post: 456.4 6 42.0 vs.
pre: 416.0 6 37 .2 W; p = 0.02) and 12.2% in G
(post: 441.6 6
84.6 vs. pre: 393.5 6 81.8 W; p = 0.02) compared with pre-
training. Also, the change in PPO in G
was significantly
greater compared with the change in G
(p = 0.03) and G
(p = 0.02). The control group showed no significant change in
PPO (post: 440.5 6 30 vs. pre: 420.8 6 23 W; p = 0.12) after
the training period. Also, MPO significantly increased by
16.2% in G
(post: 308.7 6 44.1 vs. pre: 265.5 6 48.7 W; p
= 0.03), but not in G
(post: 327.3 6 50.5 vs. pre: 294.6 6 34.1
W; p = 0.12) and G
(post: 282 6 28 vs. 272 6 22 W; p =
0.08). The change in MPO in G
was significantly greater
compared with the change in G
(p = 0.01) (Figure 2).
Serum Hormones
Table 2 presents the resting hormone concentration before
and after the 3-week training period. After training, signifi-
cant increases were observed in TT in G
(p = 0.03) and G
(p = 0.05), but not in G
(p = 0.61) compared with
pretraining. No significant differ-
ences were observed among
groups. Although cortisol tended
to decrease by 6.8% in G
10.2% in G
, these were not sig-
nificantly different (p =0.17and
p = 0.36, respectively). Testoster-
one/cortisol ratio (T CR) was
not significantly different among
groups but significantly increased
from pretraining to posttraining
in G
(p =0.02)andG
(p =
0.04) and remained unchanged
in G
(p . 0.05).
Hematological Changes
Changes in the values of hema-
tological variables by group are
presented in Table 2. After
training, significant increases
were observed in mean corpus-
cular hemoglobin in G
(p =
0.009) and G
(p = 0.002), but
red blood cells (RBC), hemo-
globin (Hb), and hematocrit
did not change significantly.
No significant changes were
observed in the G
This study was the first to use
HIIT for canoe polo athletes.
The results of this study sup-
ported our hypotheses that
both the low-volume HIIT
protocols used more than 3
weeks would improve the
physiological and hematologi-
cal adaptations even in well-
trained professional canoe polo
TABLE 2. Resting serum values of testosterone (TT), cortisol, testosterone/
cortisol (T/C) ratio, red blood cell (RBC), hemoglobin (Hb), hematocrit (Hc), and
mean corpuscular hemoglobin (MCH) before and after the training.*
TT (ng$ml
Pre 5.02 (1.62) 6.26 (1.55) 6.79 (1.28)
Post 6.5 (1.07) 7.31 (1.69) 6.65 (1.65)
%Δ +29.4 +16.7 22.1
Cortisol (mg$dl
Pre 23.46 (3.53) 20.92 (4.95) 16.33 (2.92)
Post 21.95 (2.6) 18.97 (4.41) 16.63 (2.81)
%Δ 26.8 210.2 +1.8
TT (m g $ dl
Pre 0.502 (0.16) 0.626 (1.15) 0.679 (0.12)
Post 0.650 (0.10) 0.731 (1.16) 0.665 (0.16)
%Δ +29.4 +16.7 22.1
T/C ratio
Pre 0.022 (0.01) 0.032 (0.00) 0.043 (0.01)
Post 0.031 (0.00) 0.041 (0.01) 0.041 (0.01)
%Δ +40.9 +28.1 24.8
RBC (ml$mm
Pre 5.61 (0.26) 5.7 (0.44) 5.69 (0.45)
Post 5.41 (0.32) 5.58 (0.43) 5.73 (0.39)
%Δ 23.7 22.1 +0.7
Hb (g$dl
Pre 15.64 (0.77) 15.54 (1.43) 15.54 (1.37)
Post 15.25 (1.06) 15.44 (1.25) 15.81 (1.51)
%Δ 22.5 20.6 +1.7
Hc (%)
Pre 47.31 (1.54) 46.88 (3.06) 47.2 (2.94)
Post 46.35 (2.37) 46.45 (2.46) 46.98 (2.95)
%Δ 22 20.9 20.04
MCH (pg)
Pre 27.72 (1.46) 27.47 (3.52) 27.47 (3.51)
Post 28.21 (1.34) 27.84 (3.65) 27.72 (3.92)
%Δ +1.7 +1.3 +0.09
*N = 7 for each group. Shown is mean (6SD).
Significantly greater than pretraining value (p # 0.05).
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athletes in a relatively short period.
As can be seen in results, no significant changes reported
in pre-post data in G
It can be understood that tradi-
tional continuous paddling (60 minutes/75% V
peak) and
general technical and tactical canoe polo training 3 times per
week (45 minutes) together with 1 time weight lifting train-
ing 70% 3 1 repetition maximum per week for 3 weeks
would not to be expected to improve physiological and per-
formance aspects of these highly trained athletes. Also,
serum hormones and hematological factors did not change
significantly under traditional training used in this study.
peak is one of the primary determinants of aerobic
endurance performance (19). The training regimens of
VVHIIT and VIHIIT performed by professional canoe polo
athletes both revealed significantly higher absolute V
compared with pretest (Table 1). This supports the findings
of Laursen et al. (25,26) who noted significant improvements
in V
max by 5.4–8.1% in well-trained athletes after 2–4
weeks HIIT with different protocols. Improvement in
peak seems to be dependent on fitness level (19) and
may occur through increases in both oxygen delivery (11)
and oxygen consumption by active muscles (12).
In this study, no significant change in blood volume was
observed in the 2 HIIT groups. Red blood cells and Hb did
not increase for any of the groups, indicating no change in
oxygen-carrying capacity with training. Hence, blood vol-
ume and oxygen-carrying capacity of the blood do not seem
to explain the changes in V
peak in this experiment. This
supports the studies of Farzad et al. (12) and Laursen et al.
(26) who reported no change in hematological variables and
plasma volume in response to a short-term HIIT.
Burgomaster et al. (6) demonstrated that skeletal muscle
oxidative capacity can be enhanced by a brief 2-week period
of sprint training because of increase in citrate synthase
activity. They also reported that duration or intensity of
the prescribed protocol was likely responsible for these
changes. Parra et al. (30) showed that HIIT in 2 weeks
improved enzyme activities of anaerobic and aerobic metab-
olism, and these changes were affected by the distribution of
rest periods. The overall interpretation of the aforemen-
tioned studies supports the concept that, even though genet-
ics and initial fitness level contribute to improvements in
peak (8), HIIT training stimuli (intensity, duration, fre-
quency, and recovery) can play a major role in the magni-
tude of the improvement (6,8,11,22,30). Also, different
training regimens, as used in this study, can bring a range
of benefits to elite athletes.
The VT reflects the work load at which blood lactate
levels begin to rise causing an increase in the O
(4). Lactate threshold (LT) represents the first breakpoint in
the lactate profile from the resting level and also seems con-
sistent with the VT described by the V-slope method (4).
Both HIIT groups (G
and G
) showed an improvement in
VT (p # 0.05) when expressed as HR at VT (HR@VT). This
finding supports the study of Driller et al. (8) who reported
significant improvement in LT by 5% after 7 sessions of HIIT
over a 4-week period (8 3 2.5-minute intervals at 90%
peak, with individual recoveries returning to 70%
M HR). Other studies have suggested that H IIT improved
LT by increased mitochondrial enzyme activity (11) and
decreased nonoxidative ATP generation (17) as evidenced
by lower muscle glycogen degradation and lactate accumu-
lation (11,17). Burke et al. (7) demonstrated that marked
improvement in LT was concomitant with only modest
changes in the oxidative capacity of trained muscles. Helger-
ud et al. (19) stated that, because LT follows the improve-
ment in V
peak, higher LT after HIIT would be expected.
Collectively, along with aforementioned studies, our findings
support the theory of Helgerud et al. (18) who stated that
improvement in LT is a result of the change in V
After 3 weeks of HIIT, PPO significantly increased in both
HIIT groups (G
and G
). Mean power output in the VIHIIT
group significantly improved compared with pretest but not
in the VVHIIT and TEP groups. Also, the improvement in
PPO tended to be greater using VIHIIT when compared with
VVHIIT and TEP, and improvement in M PO was greater
using VIHIIT when compared with VVHIIT. It seems that
greater improvement in anaerobic power in the VIHI IT group
was affected by the higher intensity of prescribed protocol
compared with VVHIIT and TEP. These findings were in
agreement with other investigations (6,12,21,25). Laursen
et al. (21) reported increases in anaerobic power after a 2-week
period of HIIT (20 3 1-minute bouts of cycling at V
PPO by 2-minute recovery at 50 W). In another study using
cycle ergometers, it was reported that P PO and MPO
increased after 6 weeks of HIIT (15-second and 30-second
all-out repetitions) (30). Burgomaster et al. (6) demonstrated
that peak and mean anaerobic power increased after 2 weeks
of HIIT (4–7 all-out 30-second Wingate trials with 4 minutes
recovery). Adaptations in the recruitment or activation of
motor units (36), increased muscle phosphocreatine concen-
tration (31), and a significant increase in type IIa fibers, along
with a decrease in type I fibers (12), are possible explanations
of these changes.
Both HIIT programs were associated with increased TT
levels and the TCR, but no significant changes were
observed in serum cortisol. The TCR is used frequently as
an indicator of the anabolic-catabolic balance to determine
the physiological strain of training (16,35). Thus, these im-
provements after the VVHIIT and VIHIIT may indicate ana-
bolic adaptations. These results are supportive of the study
by Meckel et al. (28) who found that TCR increased after
HIIT (4 3 250-m running on a treadmill, at a constant inten-
sity of 80% of the personal maximal speed separated by
3 minutes rest). Similarly, Farzad et al. (12) observed that
TCR increased after 4 weeks of HIIT (6 3 35-m all-out
running with 10-second recovery between each sprint).
Since cortisol levels did not change during the exercise task,
it can be concluded that the increase in the TCR was caused
by the increase in TT levels. The TT elevation found in the
Physiological and Biochemical Responses to HIIT
Journal of Strength and Conditioning Research
Copyright © National Strength and Conditioning Association Unauthorized reproduction of this article is prohibited.
HIIT groups has been attributed to potential adaptations in
TT synthesis and/or the secretory capacity of the Leydig
cells in the HIIT sessions (20).
The results of this study showed that both VVHIIT and
VIHIIT regimens were able to improve V
peak, VT, anaer-
obic power, and hormonal adaptations, but there were some
differences between these 2 HIIT programs. As shown, the
major differences were that the improvement in aerobic
power in VVHIIT group was significantly higher than
VIHIIT group, and improvement in anaerobic power in
VIHIIT group was significantly higher than VVHIIT group.
Because of these results, both of these HIIT programs can
be useful according to the priority of these physiological
requirements. If the target of the training schedule is to
increase both aerobic and anaerobic power, and also
improvement in anaerobic power is more important, using
VIHIIT program will be more helpful than VVHIIT. If the
goal is to increase aerobic power more than anaerobic
power, using VVHIIT program would be more useful than
In conclusion, this study found significant increases in
peak, VT, and anaerobic power as a result of 9 HIIT
sessions over 3 weeks in trained professional canoe polo
athletes. Moreover, our results indicate that the exercise per-
formed by the VVHIIT and VIHIIT groups led to an
anabolic-type hormonal adaptation, suggesting a positive
training response. This is the first study to indicate a practical
model of HIIT for canoe polo athletes. Therefore, these
HIIT protocols could be considered as an alternative to con-
tinuous aerobic training and were able to improve aerobic
and anaerobic performances in professional male canoe polo
athletes under the conditions of this study.
This study has examined the hormonal and physiological
responses to 2 paddling-based HIIT programs in professional
male canoe polo athletes. The most important finding of our
study was that adding the HIIT protocol over 9 sessions
during the preseason conditioning phase was an effective way
of improving both aerobic and anaerobic performances in
professional male canoe polo athletes. Moreover, the changes
observed in the TCR suggest mainly exercise-related anabolic
adaptations. Considering that such training protocols have
a very low volume, canoe polo players and their coaches can
use this type of training programs when canoe polo players
have to reach several peaks over an annual cycle, particularly
when the aim is to increase performance in a limited period. It
is clear that different training protocols with longer and/or
more intense exercise, shorter rest periods, and/or different
fitness status of the athlete may lead to different responses
(28). However, the response of these adaptations to different
types of training stimulus can be used by the coaches and
athletes for designing the training load and for better training
periodization throughout the training seasons and competi-
tion periods.
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Physiological and Biochemical Responses to HIIT
Journal of Strength and Conditioning Research
Copyright © National Strength and Conditioning Association Unauthorized reproduction of this article is prohibited.
  • Article
    Brief, intense exercise training employing running and cycling as exercise interventions may induce aerobic and anaerobic adaptations in athletes from wide range of sports. However, this has not been studied extensively for those sports in which the upper-body is predominantly involved. Our purpose was to examine the effects of kayak paddling-based sprint interval training (SIT) on cardiorespiratory fitness and anaerobic performance. 16 professional female canoe polo athletes (age = 27.6 ± 1.9 years; height = 165.7 ± 5.2 cm; body mass = 62.6 ± 8.5 kg; BMI = 22.8 kg·m; Body fat = 23.8 ± 4.9 %) were randomized to either an intense exercise training consisting of sets of 5×5-second maximum sprint efforts interspersed by a 10-second recovery between each sprint (3,4,5,6 sets/session from 1 to 4 week respectively with 3 minutes of rest between each set), performed three times per week for 4 weeks (n=8), or a usual training control group (n=8). Before and after the training period, aerobic and anaerobic measurements were assessed via a kayak specific test and Wingate protocol respectively. Training increased V[Combining Dot Above]O2peak, O2 pulse, anaerobic threshold, peak and mean power output in the SIT group compared to control group (p<0.05) who showed no changes in these variables when tested 4 weeks apart without SIT. Paddling-based SIT was a potent stimulus and time-efficient strategy to induce rapid adaptations in aerobic and anaerobic performances in professional female canoe polo athletes who can use this training method to achieve fitness in a short time period.
  • Article
    The aim of this study was to compare the effect of two paddling-based high-intensity interval training (HIIT) and continuous endurance training (CET) on hematological, immunological, and cardiorespiratory adaptations in professional canoe polo athletes. Twenty one male canoe polo athletes were randomly divided into one of three groups (N=7): 1) HIIT with variable intensity (VIHIIT) (6×60-second at 100,110,120,130,130, 130,120,110,100% vV[Combining Dot Above]O2peak from 1 to 9 session respectively, 1:3 work to recovery ratio); 2) HIIT with variable volume (VVHIIT) (6,7,8,9,9,9,8,7,6 repetitions/session from 1 to 9 session respectively)×60-second at lowest velocity that elicited V[Combining Dot Above]O2peak (vV[Combining Dot Above]O2peak), 1:3 work to recovery ratio); and 3) the CET group performed 3 times × 60 min paddling sessions (75% vV[Combining Dot Above]O2peak) per week for 3 weeks. Significant increases in V[Combining Dot Above]O2peak (ml·kg·min) (VIHIIT=7.6%, VVHIIT=6.7%), ventilation (V[Combining Dot Above]E) at V[Combining Dot Above]O2peak (VIHIIT=11.5%, VVHIIT=15.2%), respiratory frequency (Rf) at V[Combining Dot Above]O2peak (VVHIIT=21.1%), V[Combining Dot Above]O2 at ventilatory threshold (VT) (VIHIIT=10.5%, VVHIIT=25.1%), V[Combining Dot Above]E at VT (VIHIIT=12.4%, VVHIIT=34.0%), tidal volume at VT (VIHIIT=11.7%, VVHIIT=33.3%), Rf at VT (VIHIIT=9.7%), V[Combining Dot Above]E/V[Combining Dot Above]O2 at VT (VVHIIT=13.1%), V[Combining Dot Above]O2/HR at VT (VIHIIT=12.9%, VVHIIT=21.4%), and V[Combining Dot Above]E/HR at VT (VIHIIT=7.8%, VVHIIT=27.2%) were seen compared to pre-training. Training interventions resulted in significant increases in mean platelet volume (VIHIIT=2.7%, VVHIIT=1.9%), mean corpuscular hemoglobin concentration (CET=3.3%), and significant decrease in red blood cell distribution width (VVHIIT=-4.3), and cell numbers of lymphocyte (CET=-27.1) compared to pre-training. This study demonstrated that paddling-based HIIT enhances aerobic capacity and respiratory makers, without negatively affecting the immune system over 3 weeks.
  • Article
    Full-text available
    Canoe polo is an emerging and growing sport. Canoe polo athletes are characterized by low body-fat percentages with high levels of upper body aerobic and anaerobic power. Canoe polo is a high intensity intermittent team sport consisting of two 10 min halves. Average heart rates during game play ranged from 146 to 159 bpm. Sixty-nine per cent of a canoe polo game is played above ventilator threshold. Due to the intensity and intermittent nature, ATP rephosphorylation occurs via non-oxidative and oxidative energy systems. A high carbohydrate diet (>6 g•kg-1•day-1) is recommended to support non-oxidative ATP re-phosphorylation during training and competitions. Following training, a rapidly digested and complete protein (e.g., whey protein; 20-40 g) provided in close proximity may maximize the muscle protein synthetic response. β-Alanine, sodium bicarbonate, creatine, caffeine, and nitrates are purported ergogenic aids to improve high intensity exercise performance and may be beneficial for canoe polo athletes.
  • Article
    Objective: To evaluate and compare the effects of high-intensity interval training (HIIT) varying in exercise intensities to traditional endurance training (TET) on physiological and performance adaptations in trained female inline speed skaters. Methods: Participants were randomly assigned to one of 3 HIIT groups: 6,8,10 (repetitions/session from 1st to 3rd week respectively)×60seconds (s) at the running speed associated with V ˙O2max (100%vV ˙O2max) (H 100, N =7), 115%vV ˙O2max (H 115, N =7), and 130%vV ˙O2max (H 130, N =7), 1:3 work to recovery ratio; and/or TET group (N =7): 60-minute running at 75%vV ˙O2max three sessions per week. Results: Significant (except as shown) improvements (p <0.05) following HIIT were found in: V ˙O2max (H 100 =+7.6%, H 115 =+6.1%, H 130 =+0.1%; p =0.4), vV ˙O2max (H 100 =+10.3%, H 115 =+6.3%, H 130 =+9.8%), peak power output (PPO) (H 100 =+10.3%, H 115 =+9.1%, H 130 =+5.5%; p =0.2), mean power output (MPO) (H 100 =+22.6%, H 115 =+24.1%, H 130 =+21.9%), 3000 meter (m) skating performance (H 100 =-15.2%, H 115 =-7.9%, H 130 =-10.6%), and T max (H 100 =+39.4%, H 115 =+5.0%; p =0.5, H 130 =+17.8%; p =0.1). No significant differences were found among groups. Also, no changes in these variables were found in the TET group. Conclusions: Present findings suggest that three weeks of HIIT program with low volume (almost 6 or 10min per session) is associated with improvements in V ˙O2max, vV ˙O2max, PPO, MPO, 3000m skating performance, and T max in trained female inline speed skaters.
  • Article
    Full-text available
    Purpose: To determine the aerobic capacities, anaerobic power, and anthropometric characteristics of elite female canoe polo players. A secondary purpose was to investigate positional differences between goalkeepers (GKs), flat 3 defenders (FDFs), and chase defenders (CHDFs). Methods: Twenty-one elite female canoe polo players (age 26.8 ± 2.1 years; height 166.9 ± 5.2 cm; body mass 61.4 ± 7.1 kg; and percent body fat 21.0 ± 3.8%) volunteered. Anthropometric variables, peak oxygen uptake ((Formula presented.)), ventilatory threshold (VT), anaerobic peak power output (PPO), and mean power output (MPO) were determined. Results: (Formula presented.) was 40.88 ± 4.0 ml kg⁻¹ min⁻¹ or 2.50 ± 0.29 l min⁻¹, VT was 79.1 ± 8.6 (Formula presented.), PPO was 348.7 ± 32.1 W, 5.66 ± 0.64 W kg⁻¹, and MPO was 266.5 ± 29.4 W, 4.37 ± 0.56 W kg⁻¹. CHDFs and FDFs had significantly (p < 0.05) greater relative (Formula presented.) (19.5 and 15.0%, respectively) compared to GKs. GKs were significantly (p < 0.05) taller than CHDFs (6.3%) and FDFs (4.8%). Conclusions: Elite female canoe polo players have well-developed oxidative and non-oxidative energy systems, as well as low percent body fat. Positional differences demonstrated that CHDFs and FDFs had significantly higher aerobic power compared to GKs; however, GKs were significantly taller. These results may assist the coach or sport scientist to construct and implement tailored training programs and may be beneficial for talent identification.
  • Article
    Full-text available
    High-intensity interval training (HIIT) improves peak power output (PPO) in sedentary aging men but has not been examined in masters endurance athletes. Therefore, we investigated whether a six-week program of low-volume HIIT would (i) improve PPO in masters athletes and (ii) whether any change in PPO would be associated with steroid hormone perturbations. Seventeen male masters athletes (60 ± 5 years) completed the intervention, which comprised nine HIIT sessions over six weeks. HIIT sessions involved six 30-s sprints at 40% PPO, interspersed with 3 min active recovery. Absolute PPO (799 ± 205 W and 865 ± 211 W) and relative PPO (10.2 ± 2.0 W/kg and 11.0 ± 2.2 W/kg) increased from pre- to post-HIIT respectively (P < 0.001, Cohen’s d = 0.32−0.38). No significant change was observed for total testosterone (15.2 ± 4.2 nmol/L to 16.4 ± 3.3 nmol/L (P = 0.061, Cohen’s d = 0.32)), while a small increase in free testosterone occurred following HIIT (7.0 ± 1.2 ng/dL to 7.5 ± 1.1 ng/dL pre- to post-HIIT (P = 0.050, Cohen’s d = 0.40)). Six weeks’ HIIT improves PPO in masters athletes and increases free testosterone. Taken together, these data indicate there is a place for carefully timed HIIT epochs in regimes of masters athletes.
  • Thesis
    Full-text available
    Introduction: Specialized literature provides compelling evidence attesting the efficiency of HIIT. However, it is important to identify gender-specific differences to provide suitable intensity levels, in order to maximize results and minimize the likelihood of injuries. Starting by taking an extensive review of the most up to date literature (published in the last 5 years), this research defined as its primary goal the assessment of HIIT’s effect in healthy and physically active individuals. Goals: To delineate a literature-based HIIT training plan with no recourse to ergometers, and that is up to the challenge of monitoring the intensity of the protocol and assess its effect. The effect of the aforementioned protocol was measured in practitioners of this type of training in a recreational context, prescribed according to a progressive maximal effort test. Materials and Methods: A search algorithm was performed in PUBMED [(hint) OR ((((((High-Intensity Interval) AND Title/Abstract OR High Intensity Interval) AND Title/Abstract OR High-Intensity Intermittent) AND Title/Abstract OR high intensity intermittent[Title/Abstract])))], resulting in the following protocol: four series of seven holistic calisthenic exercises (4 x 7 x 30’’ with 15’’ pause among them), with 45’’ pause. Eleven women (35.4 ± 8.3 years) and nine men (36.6 ± 8.0 years), all HIIT practitioners, underwent a 3 times a week exercise plan, for 4 weeks. Results: If compared with existing literature, the results of the HIIT protocols implemented in this research reveal a fundamental heterogeneity. Previous studies, the majority of which with recourse to ergometers, suggest an optical work-to-rest ratio of 2:1. Concerning the effect of the protocol, only women followed it (p = .017). Subjects that sustained heart rates above 90% of HRVO2max for longer periods of time showed the largest increase in cardiorespiratory aptitude (r = .478, p < .05). Only women improved their aerobic aptitude capacity (p = .002 for relative VO2max; z = -2.491 and p = .005 for absolute VO2max ). Only men displayed a statistically significant drop (p = .046). Conclusion: Given the absence of external loads, and having opted for a holistic and polyarticular protocol, quantifying the intensity of the work ascribed to each individual became a challenge. It was thus decided to adopt an all-out bouts approach, which entailed the greatest possible number of repetitions of each proposed exercised while monitoring the cardiac response (% HRVO2max). HIIT’s effect was different between genders. The significant results obtained show a certain polarity between genders concerning the main variables at stake and also present differences in volitional intensity.
  • Article
    Full-text available
    Purpose: The purpose of this study was to examine the influence of three different high-intensity interval training (HIT) regimens on endurance performance in highly trained endurance athletes. Methods: Before, and after 2 and 4 wk of training, 38 cyclists and triathletes (mean +/- SD; age = 25 +/- 6 yr; mass = 75 +/- 7 kg; (V)over dot O-2peak = 64.5 +/- 5.2 mL.kg(-1).min(-1)) performed: 1) a progressive cycle test to measure peak oxygen consumption ((V)over dotO(2peak)) and peak aerobic power output (PPO), 2) a time to exhaustion test (T-max) at their (V)over dotO(2peak) power output (P-max), as well as 3) a 40-kin time-trial (TT40). Subjects were matched and assigned to one of four training groups (G(1), N = 8, 8 X 60% T-max P-max, 1:2 work:recovery ratio; G(2), N = 9, 8 X 60% T-max at P-max, recovery at 65% HRmax; G(3), N = 10, 12 X 30 s at 175% PPO, 4.5-min recovery; G(CON), N = 11). In addition to G(1) G(2), and G(3) performing HIT twice per week, all athletes maintained their regular low-intensity training throughout the experimental period. Results: All HIT groups improved TT40 performance (+4.4 to +5.8%) and PPO (+3.0 to +6.2%) significantly more than G(CON) (-0.9 to + 1.1 %; P < 0.05). Furthermore, G(1) (+5.4%) and G(2) (+8.1%) improved their (V)over dot O-2peak significantly more than G(CON) (+ 1.0%; P < 0.05). Conclusion: The present study has shown that when HIT incorporates P-max as the interval intensity and 60% of T-max as the interval duration, already highly trained cyclists can significantly improve their 40-km time trial performance. Moreover, the present data confirm prior research, in that repeated supramaximal HIT can significantly improve 40-km time trial performance.
  • Article
    Full-text available
    While the physiological adaptations that occur following endurance training in previously sedentary and recreationally active individuals are relatively well understood, the adaptations to training in already highly trained endurance athletes remain unclear. While significant improvements in endurance performance and corresponding physiological markers are evident following submaximal endurance training in sedentary and recreationally active groups, an additional increase in submaximal training (i.e. volume) in highly trained individuals does not appear to further enhance either endurance performance or associated physiological variables [e.g. peak oxygen uptake (V̇O2peak), oxidative enzyme activity]. It seems that, for athletes who are already trained, improvements in endurance performance can be achieved only through high-intensity interval training (HIT). The limited research which has examined changes in muscle enzyme activity in highly trained athletes, following HIT, has revealed no change in oxidative or glycolytic enzyme activity, despite significant improvements in endurance performance (p 2max is achieved (Vmax) as the interval intensity, and fractions (50 to 75%) of the time to exhaustion at Vmax (Tmax) as the interval duration has been successful in eliciting improvements in performance in long-distance runners. However, Vmax and Tmax have not been used with cyclists. Instead, HIT programme optimisation research in cyclists has revealed that repeated supramaximal sprinting may be equally effective as more traditional HIT programmes for eliciting improvements in endurance performance. Further examination of the biochemical and physiological adaptations which accompany different HIT programmes, as well as investigation into the optimal HIT programme for eliciting performance enhancements in highly trained athletes is required.
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    Full-text available
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    Purpose: Peak power (PP) and mean power (MP) attained in upper body sprint performance test are considered important factors for competitive success in wrestling. This study aimed to determine whether acute caffeine ingestion would better maintain PP and MP across a simulated competition day in wrestling. Methods: In a double-blind, counterbalanced, crossover study, 14 trained wrestlers ingested either placebo or 5 mg/kg caffeine and completed four 6-min upper body intermittent sprint performance tests with 30-min recovery periods between consecutive tests. PP and MP were recorded during and blood lactate concentration was measured before and after each test. Ratings of perceived fatigue (RPF) and exertion (RPE) were recorded before and after each test, respectively. Heart rate (HR) was monitored across the whole testing period. Results: Mean power decreased across four tests in both trials (p < .05), but the reduction in PP (from 277.2 ± 34.6 W to 257.3 ± 45.1 W; p < .05) only occurred in caffeine trial. Both pretest blood lactate concentration and HR were higher in caffeine than in placebo trial (p < .05) in the third and fourth tests. No between-trial differences occurred in RPF or RPE. Conclusions: Under simulated competition day conditions mimicking four consecutive wrestling matches, acute caffeine ingestion has a partially detrimental effect on upper body intermittent sprint performance in trained wrestlers. Elevated HR and blood lactate levels observed between tests after caffeine ingestion suggest that caffeine may impair recovery between consecutive maximal efforts.
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    PURPOSE:: To evaluate the time international canoe polo players spend performing various game activities, measure heart rate (HR) responses during games, and describe the physiological profile of elite players. METHODS:: Eight national canoe polo players were videotaped and wore HR monitors during 3 games at a World Championship and underwent fitness testing. The mean age, height, and weight was 25 ± 1 y, 1.82 ± 0.04 m, and 81.9 ± 10.9 kg, respectively. RESULTS:: Time motion analysis of 3 games indicated that the players spent 29 ± 3% of the game slow/moderate forward paddling, 28 ± 5% contesting, 27 ± 5% resting and gliding, 7 ± 1% turning, 5 ± 1% backwards paddling, 2 ± 1% sprinting, and 2 ± 1% dribbling. Sixty nine (± 20)% of the game time was played at a HR intensity above the HR which corresponded to ventilatory threshold (VT), that was determined during the peak VO2 test. Peak oxygen uptake and VT was 3.3 ± 0.3 and 2.2 ± 0.3 L·min, respectively, on a modified Monark arm crank ergometer. Arm crank peak 5 s anaerobic power was 379 W. CONCLUSION:: The majority of the time spent during international canoe polo games involved slow to moderate forward paddling, contesting for the ball, and resting and gliding. Canoe polo games are played at a high intensity indicated by the HR responses, and the physiological characteristics suggest that these athletes had high levels of upper body aerobic and anaerobic fitness levels.
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    The aim of this study was to evaluate the changes in aerobic and anaerobic metabolism produced by a newly devised short training programme. Five young male volunteers trained daily for 2 weeks on a cycle ergometer. Sessions consisted of 15-s all-out repetitions with 45-s rest periods, plus 30-s all-out repetitions with 12-min rest periods. The number of repetitions was gradually increased up to a maximum of seven. Biopsy samples of the vastus lateralis muscle were taken before and after training. Performance changes were evaluated by two tests, a 30-s all-out test and a maximal progressive test. Significant increases in phosphocreatine (31%) and glycogen (32%) were found at the end of training. In addition, a significant increase was observed in the muscle activity of creatine kinase (44%), phosphofructokinase (106%), lactate dehydrogenase (45%), 3-hydroxy-acyl-CoA dehydrogenase (60%) and citrate synthase (38%). After training, performance of the 30-s all-out test did not increase significantly, while in the maximal progressive test, the maximum oxygen consumption increased from mean (SD) 57.3 (2.6) ml · min−1 · kg−1 to 63.8 (3.0) ml · min−1 · kg−1, and the maximum load from 300 (11) W to 330 (21) W; all changes were significant. In conclusion, this new protocol, which utilises short durations, high loads and long recovery periods, seems to be an effective programme for improving the enzymatic activities of the energetic pathways in a short period of time.
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    Increasing the level of physical fitness for competition is the primary goal of any conditioning program for wrestlers. Wrestlers often need to peak for competitions several times over an annual training cycle. Additionally, the scheduling of these competitions does not always match an ideal periodization plan and may require a modified training program to achieve a high level of competitive fitness in a short-time frame. The purpose of this study was to examine the effects of 4 weeks of sprint-interval training (SIT) program, on selected aerobic and anaerobic performance indices, and hormonal and hematological adaptations, when added to the traditional Iranian training of wrestlers in their preseason phase. Fifteen trained wrestlers were assigned to either an experimental (EXP) or a control (CON) group. Both groups followed a traditional preparation phase consisting of learning and drilling technique, live wrestling and weight training for 4 weeks. In addition, the EXP group performed a running-based SIT protocol. The SIT consisted of 6 35-m sprints at maximum effort with a 10-second recovery between each sprint. The SIT protocol was performed in 2 sessions per week, for the 4 weeks of the study. Before and after the 4-week training program, pre and posttesting was performed on each subject on the following: a graded exercise test (GXT) to determine VO(2)max, the velocity associated with V(2)max (νVO(2)max), maximal ventilation, and peak oxygen pulse; a time to exhaustion test (T(max)) at their νVO(2)max; and 4 successive Wingate tests with a 4-minute recovery between each trial for the determination of peak and mean power output (PPO, MPO). Resting blood samples were also collected at the beginning of each pre and posttesting period, before and after the 4-week training program. The EXP group showed significant improvements in VO(2)max (+5.4%), peak oxygen pulse (+7.7%) and T(max) (+32.2%) compared with pretesting. The EXP group produced significant increases in PPO and MPO during the Wingate testing compared with pretesting (p < 0.05). After the 4-week training program, total testosterone and the total testosterone/cortisol ratio increased significantly in the EXP group, whereas cortisol tended to decrease (p = 0.06). The current findings indicate that the addition of an SIT program with short recovery can improve both aerobic and anaerobic performances in trained wrestlers during the preseason phase. The hormonal changes seen suggest training-induced anabolic adaptations.
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    Performance in intense exercise events, such as Olympic rowing, swimming, kayak, track running and track cycling events, involves energy contribution from aerobic and anaerobic sources. As aerobic energy supply dominates the total energy requirements after ∼75s of near maximal effort, and has the greatest potential for improvement with training, the majority of training for these events is generally aimed at increasing aerobic metabolic capacity. A short-term period (six to eight sessions over 2-4 weeks) of high-intensity interval training (consisting of repeated exercise bouts performed close to or well above the maximal oxygen uptake intensity, interspersed with low-intensity exercise or complete rest) can elicit increases in intense exercise performance of 2-4% in well-trained athletes. The influence of high-volume training is less discussed, but its importance should not be downplayed, as high-volume training also induces important metabolic adaptations. While the metabolic adaptations that occur with high-volume training and high-intensity training show considerable overlap, the molecular events that signal for these adaptations may be different. A polarized approach to training, whereby ∼75% of total training volume is performed at low intensities, and 10-15% is performed at very high intensities, has been suggested as an optimal training intensity distribution for elite athletes who perform intense exercise events.