84
Journal of Exercise Physiologyonline
October 2014
Volume 17 Number 5
Editor-in-Chief
Official Research
Tommy
Journal
Boone,
of thePhD,
American
MBA
Review
Board
Society
of Exercise
Todd Astorino,
Physiologists
PhD
Julien Baker, PhD
Steve Brock,
ISSN 1097-9751
PhD
Lance Dalleck, PhD
Eric Goulet, PhD
Robert Gotshall, PhD
Alexander Hutchison, PhD
M. Knight-Maloney, PhD
Len Kravitz, PhD
James Laskin, PhD
Yit Aun Lim, PhD
Lonnie Lowery, PhD
Derek Marks, PhD
Cristine Mermier, PhD
Robert Robergs, PhD
Chantal Vella, PhD
Dale Wagner, PhD
Frank Wyatt, PhD
Ben Zhou, PhD
Official Research Journal
of the American Society of
Exercise Physiologists
ISSN 1097-9751
JEPonline
Effects of Pre-Exercise Activities on Progressive
Cycling Test Performance and Autonomic Response
Raoni da Conceição Dos-Santos1, César Rafael Marins Costa1,
Fabrizio di Masi 1, Anderson Luiz Bezerra da Silveira1
1Laboratório
de Fisiologia e Desempenho Humano/Universidade
Federal Rural do Rio de Janeiro, Seropédica, Rio de Janeiro, Brazil
ABSTRACT
Dos-Santos RC, Costa CRM, Di Masi F, Silveira ALB. Effects of
Pre-Exercise Activities on Progressive Cycling Test Performance
and Autonomic Responses. JEPonline 2014;17(5):84-94. Recent
reviews have shown detrimental effects of muscle stretching before
sports activity. In addition, controversial results have been presented
on the benefits of warming up. This purpose of this study was to
evaluate the influence of a pre-exercise warm-up and ballistic
stretching on performance and heart rate variability during an
incremental cycle ergometer test. The subjects were untrained
physically active men who were familiarized with the cycle test on
day 1, which was followed by three protocols (Control, Warm-Up,
and Ballistic Stretching) separated by at least 48 hrs. After each
protocol, the subjects performed a maximal incremental cycle
ergometer test. The warm-up did not have any influence on the test
performance compared to the control (P>0.05). Both the total test
time and maximal sustained load decreased after the ballistic stretch
protocol (P<0.05). The cardiovascular and autonomic variables did
not show any statistical difference between protocols. Thus, the
results indicate that ballistic stretch impaired performance and warmup did not show any beneficial effect. Both pre-exercise activities
should be used carefully just prior to an athletic performance.
Key Words: Heart Rate Variability, Ballistic Stretch, Warm-Up
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INTRODUCTION
Since a difference of just a few seconds in a sports competition may mean the loss of a gold medal,
it is important to understand the influence of pre-exercise activities such as a warm-up. While it is
believed that a warm-up is necessary to improve performance, the effects of a warm-up on the
physiology of exercise are still unclear (7,17,18). In fact, despite being part of the recommended
guidelines for a safe exercise prescription (19) the beneficial effects of this activity are regularly
based on the coach’s personal experience rather than scientific studies (18).
In general, a warm-up consists of low-intensity aerobic exercise, a stretching session, and sportsspecific movements (18). Although there is little evidence to indicate that a warm-up is harmful,
there are reports (6,7,52) of particularly long and intense warm-ups causing fatigue and impaired
performance (46). In order to understand the effects of a warm-up on sports performance, each
component should be studied separately (18).
Muscle stretching can impair performance in power or strength-dependent activities when used prior
to exercise (33,39,43,44). However, ballistic stretching routines are becoming more common prior to
exercise due to a reduced impairment of performance in various activities (5,40). Additionally,
Bacurau et al. (3) stated that ballistic stretching could be more appropriate because a decrease in
muscle strength seems less probable. Nonetheless, there are discrepancies whether ballistic
stretching improves, impairs or has no effect on performance (37,42). There are no studies, to our
knowledge, that report ballistic stretch-induced impairments to subsequent performance on
endurance-dominant activities.
Optimal endurance exercise performance correlates with autonomic activity through a higher
parasympathetic activity at rest (8,9). Efferent autonomic activity may be measured by the indirect
method of heart rate variability (HRV), which assesses autonomic control over the heart (14). Also,
HRV has been shown to be effective in both physiological and pathological conditions (48). Previous
work from our laboratory has shown that when ballistic stretching was used as prior sprint running,
the vagal modulation was higher than warm-up during a high intensity running exercise (13). Yet,
there is a gap of knowledge regarding the effects of ballistic stretching on autonomic modulation
during an incremental cycling exercise.
The purpose of the present study was to evaluate for the first time the effectiveness of different
components of a warm-up session as low intensity aerobic exercise and ballistic muscle stretching
on autonomic activity and performance in an incremental maximal cycling test. The experimental
protocol was designed to evaluate each warm-up component separately, to avoid any interference
on results between them. The primary hypothesis was that the inclusion of a low-intensity aerobic
exercise component to the warm-up would impair performance and reduce parasympathetic
modulation. The secondary hypothesis was that the dynamic stretching component would improve
subsequent performance and parasympathetic modulation compared to the low-intensity aerobic
exercise.
METHODS
Subjects
The sample size was established in accordance with studies with similar methods that produced
clear results (26). Nine untrained males (age = 22 ± 1 yrs; height = 174 ± 2.6 cm; weight = 74.2 ±
2.6 kg; body fat = 8.6 ± 2.8%) were selected to participate in this study.
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Each subject read, filled out, and signed a consent form, which was approved by the Institutional
Ethics Committee under protocol 23083.010576/2011-79 in accordance with Resolution 196/96 from
National Health Council. In the consent form, a complete explanation of all experimental steps was
presented. The subjects were instructed to avoid: (a) strenuous exercise for 24 hrs prior to the
cycling test; (b) alcohol and caffeine consumption; and (c) taking drugs with autonomic effects.
Test Validity
We used a maximal incremental cycle ergometer test similar to the test proposed by Ozcelik and
Kelestimur (36). The test consisted of a cycle ergometer challenge (ERGO-FIT® – Ergo 167 Cycle,
Pirmasens, Germany) of which the load was started at 100 watts (W) that was then increased
progressively by 5 W/20 sec. In accordance to Grazzi et al (23), when hyperventilation was evident
the load increment shifted to 10 W/20 sec until exertion. In order to assess the measurement
stability of the test, each subject performed the maximal incremental cycle test for three consecutive
days without any pre-exercise activity. The measure was stable with a coefficient of variation equal
to 3.82%.
Experimental Protocols
The experimental protocols had a randomized crossover design that consisted of three procedures
separated by at least 48 hrs. One week before the exercise tests, the subjects underwent
anthropometric measurements and a familiarization session for each procedure used in this study.
During the control protocol (CTRL), the subjects rested for 3 min. During the warm-up protocol
(WU), the subjects cycled at a 70 W load while maintaining 60 rev·min-1 for 3 min, as described by
Bishop (7). During the ballistic stretch protocol (BS), the subjects performed 6 sets of 30 sec of
ballistic stretching related to cycling movements. The muscles that were stretched throughout the 3
min of ballistic stretching included the abdominal region, lower back, hamstrings, gluteals, hip
adductors, quadriceps femoris, gastrocnemius, and soleus muscles.
In order to discriminate the effects of aerobic warm-up or stretching on performance, the subjects in
the control protocol performed a maximal test without any pre-exercise activity despite the
recommendations of current guidelines (1,24,27,32). To maintain the same rhythm between the
ballistic stretch and the warm-up protocols, a metronome was used at 60 beats·min-1 in accordance
with previous work (13,53). After each experimental protocol, the subjects performed the maximal
incremental cycling test in a controlled environment (temperature ~23°C, humidity ~50%). Total time
was determined using a Timex Marathon Stopwatch - t5g811 (Connecticut, EUA).
Heart Rate Analysis
The subjects’ HR was recorded during the entire experiment by a Polar RS800CX (Polar Electro
OY, Kempele, Finland), which was validated in previous studies (28,35,38). After R wave peak
detection, tachograms were generated during each protocol and exercise tests, containing all heart
period fluctuations within this time segment. In the time-domain, the following indexes were
obtained: (a) mean interval between R wave peaks (RR); and (b) square root of the mean squared
differences of successive RR intervals (RMSSD). For spectral analysis (frequency-domain) of HRV,
tachograms were resampled to equal intervals at 4 Hz and the linear trend was removed. The power
spectrum was obtained with a fast Fourier transform based method (Welch’s periodogram: 256
points, 50% overlap, and Hanning window). Three frequency bands were determined: (a) very low
frequency (VLF: 0.0 – 0.04 Hz); (b) low frequency (LF: 0.04 – 0.15 Hz); and (c) high frequency (HF:
0.15 – 0.4 Hz). Low frequency and HF were normalized by the equations LF(n.u.) = LF ÷ (LF + HF)
or HF(n.u.) = HF ÷ (LF + HF) (10). All HRV analyses were performed by Kubios HRV software
(version 2.1; Biomedical Signaling and Medical Imaging Group, Kuopio, Finland).
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Statistical Analysis
The Shapiro-Wilk test was used to determine the normality of the variables. All normal variables
were compared using one-way ANOVA with repeated measures and Tukey’s post-hoc test. For
variables with non-Gaussian distributions, the Friedman test and Dunn’s post-hoc test were used.
All statistical procedures were performed using Graphpad Prism (Version 6.0; Graphpad Software
Inc., California, USA).
RESULTS
All data is described as mean ± standard deviation. In order to reduce the high data variation found
on total time and maximal load, both variables were normalized. The results demonstrated that total
time on incremental cycling exercise was significantly impaired after ballistic stretching when
compared to the control and warm-up protocols, with no differences between control and warm-up
(CTRL = 1 ± 0; WU = 1 ± 0.12; BS 0.9 ± 0.07, p < 0.05) (Figure 1A). Similarly, the maximum load
decreased after ballistic stretching when compared to the control and warm-up protocols, but also
with no significant change between the control and warm-up (CTRL = 1 ± 0 W; WU = 1.048 ± 0.038
W; BS = 0.91 ± 0.068, P≤0.05) (Figure 1B). Ballistic stretching impaired performance by decreasing
total time and maximal cycle load while the warm-up did not influence total time and maximal
workload.
Figure 1. Performance on Maximal Cycling Test after Different Pre-Exercise Protocols. Total time (A)
and maximal load (B) sustained to exhaustion in cycling incremental exercise expressed in normalized units
(n.u.). CTRL (control), WU (warm-up), BS (ballistic stretching). *Represents a significant difference compared
with controls (*P≤0.05; ***P<0.001); #Represents a significant difference compared with WU (#P≤0.05).
Values expressed as mean ± standard deviation.
Addressing HRV during each pre-exercise protocol, all variables in time (HR, RR, and RMSSD) and
frequency domain (LF, HF, and LF/HF) were different from the control protocol (P≤0.05) with no
difference between them (Table 1). However, no statistical differences were observed in both time
and frequency domain (P>0.05) during the maximal incremental exercise test (Table 2). Therefore,
the differences found in total time and maximal workload seem to be independent of autonomic
modulation.
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Table 1. Heart Rate Variability Responses in Time and Frequency Domain during the Pre-Test
Protocols.
Ballistic
Control
Warm-Up
P
Stretching
Heart Rate (beats·min-1)
73.6 ± 7.7
121.4 ± 20.9*
127.2 ± 12.4*
<0.001
829.7 ± 96.5
507.6 ± 85.3*
483 ± 48.1*
<0.001
RMSSD (ms)
53.7 ± 18.9
7.1 ± 5.6*
9.7 ± 4.5*
<0.001
LF (n.u.)
0.66 ± 0.12
0.84 ± 0.06*
0.84 ± 0.10*
0.03
HF (n.u.)
0.33 ± 0.11
0.16 ± 0.06*
0.15 ± 0.11*
0.03
6.5 ± 3.7*
0.02
R-R interval (ms)
LF/HF
2.5 ± 1.3
5 ± 1.5*
RMSSD (Root Mean Square of the Successive Differences); LF (Low-Frequency); HF (High-Frequency); n.u.
(normalized units); *Statistically significant difference vs. the control group (P≤0.05). Values expressed as mean ±
standard deviation.
Table 2. Heart Rate Variability Responses in Time and Frequency Domain during the Maximal
Cycle Ergometer Test.
Ballistic
Control
Warm-Up
P
Stretching
Heart Rate (beats·min-1)
153.9 ± 11.6
158.7 ± 15.5
157.8 ± 16.1
0.4657
R-R interval (ms)
399.2 ± 32.2
388.2 ± 40.1
389.3 ± 42.2
0.5395
RMSSD (ms)
4.2 ± 1.4
4.6 ± 2.2
4.2 ± 1.4
0.5469
LF (n.u.)
0.9 ± 0.04
0.8 ± 0.15
0.9 ± 0.14
0.5690
HF (n.u.)
0.2 ± 0.12
0.2 ± 0.15
0.2 ± 0.14
0.5690
LF/HF
7.7 ± 4.4
6.7 ± 2.9
9.0 ± 5.1
0.2872
RMSSD (Root Mean Square of the Successive Differences); LF (Low-Frequency); HF (High-Frequency); n.u.
(normalized units); Values expressed as mean ± standard deviation.
DISCUSSION
Following the recommendations of Fradkin et al. (18), the purpose of this study was to evaluate the
effects of two different pre-exercise activities (i.e., the warm-up and the ballistic stretch exercise) on
an incremental cycle ergometer test. The findings indicate that the warm-up did not have an
influence on the subjects’ total time or maximal workload. These results are in accordance with
previous studies (1,13,18,33,39,41,43,44,50) that found no alterations in performance due to the low
intensity short protocol as a pre-exercise activity. Hence, the activity itself was designed to avoid
fatigue, bearing in mind the intrinsic relationship of fatigue and the decrements caused by a warmup (15,46). Ballistic stretching was addressed in this work because it was considered less likely to
decrease performance in comparison with other stretching protocols (5,40).
89
Possibly, the low intensity short protocol failed to induce changes in physiological factors that are
generally thought to influence the warm-up effects (e.g., muscle temperature, nerve conduction
velocity, and muscle enzymatic cycling along with a decrease in muscle viscosity) (7). Moreover,
Wittekind and colleagues (51) demonstrated that different intensities of a warm-up alter some
metabolic variables and yet, the effects often disappear during maximal exercise. Gray and Nimmo
(22) found similar results when comparing active, passive, and no warm-up protocols. The changes
induced by the experimental protocol also disappeared during maximal exercise. Thus, in the
present study the responses achieved by warm-up were rapidly counterbalanced during maximal
exercise, which explains the absence of alterations on performance.
Several studies (2,3,16,29) have demonstrated that the ballistic stretch protocol results in a better
performance compared to the static stretch protocol. However, fewer studies have compared the
ballistic stretch protocol to a no-stretch protocol. This is an important point, as indicated by Behm
and Chaouachi (5) and Turki et al. (47), especially since the dynamic stretches may induce postactivation potentiation (PAP) and may increase cross bridge cycling via an increase in myosin
phosphorylation of the regulatory light chains (45). There may also be neural potentiation that
results in a decrease of fast twitch motor unit thresholds, which is related to an increase in motor
unit recruitment and firing frequency (30). The increase in firing frequency may relate to an increase
rate of force development (34).
Interestingly, the present study found that the ballistic stretch protocol resulted in a decrease in total
time and maximal workload in the progressive cycling test. This resulted in an impaired performance
compared to the warm-up and the control protocols. This finding is in agreement with the findings of
two studies (4,31). It is possible that the ballistic stretch protocol reduced high-energy phosphates
(7,40), which has a minimal influence on sprint exercises (21,40). But, it is reasonable to think the
reduction in high-energy phosphates has a greater effect on activities that involve repetitive highintensity contractions to failure (25), as in the exercise used in the present study. Also, the ballistic
stretch may have decreased muscle blood flow and increased metabolite accumulation in the
exercised muscles (4).
Perhaps, as a result of the negative physiological responses related to ballistic stretch, the protocol
culminated with a PAP impairment that promoted a premature fatigue. The end result translated in a
reduced total time and a decrease in muscle strength as indicated in the reduced maximal workload
during the test. It should be highlighted that other studies (11,49) have also used ballistic stretching
as a pre-exercise activity and found conflicting results compared to this study. But, none of the
earlier studies used an incremental graded cycle exercise test.
It could be argued that a slight significant impairment in total time and workload is not clinically
meaningful and, therefore, is inconsequential for a recreational athlete. Yet, on the other hand, the
slight impairment might prove to be very substantial to an elite athlete.
While HR was significantly higher in both the warm-up and ballistic stretch pre-exercise protocols
versus the control condition, HR was not statistically different between the two. This change was
accompanied by HRV variables in time domain, in which all variables related to R-R interval
decreased during both protocols. This change was expected since the subjects remained at rest
during the control condition, but did in fact engage in some activity during both the warm-up and the
ballistic stretch conditions. Nonetheless, no changes were found during the incremental graded
cycle test. Thus, none of the protocols modified the dynamics of the cardiovascular response to
strenuous exercise.
90
Gladwell and colleagues (20) reported that a lower high-frequency (HF) response during exercise is
associated with a higher risk of cardiac arrhythmias. Hence, neither the warm-up HF response nor
the ballistic stretch HF response in the present study would suggests a greater cardiovascular
protection since there was a significant decrease in HF after both pre-exercise protocols during
incremental exercise test. These results are contrary to those of our previous study that showed a
higher HF after a ballistic stretch protocol during a high intensity short duration running test (13).
The likely explanation is that the exercise applied in this study was a cycle test, which lasted longer
and allowed the subjects to reach steady state that influenced the autonomic responses during the
exercise.
CONCLUSIONS
The ballistic stretch protocol prior to sports activities should be carefully analyzed, especially since it
may impair performance during a graded cycle exercise. While the changes found in this study may
seem small, they are very important in the context of competitive sports. Meanwhile, the warm-up
did not change any of the variables that were analyzed and seems to be unnecessary as a preexercise practice to improve performance. Also, the pre-exercise activities did not influence
autonomic modulation. More research is necessary to shed additional light on the physiological
responses with and without the traditionally accepted pre-exercise activities and the role each may
play in general sports practice.
Address for correspondence: Anderson Luiz Bezerra da Silveira, Department of Physical
Education and Sports, Federal Rural University of Rio de Janeiro, Seropédica, Rio de Janeiro,
Brazil, zip-code: 23890-00, Email: andersonsilveira@ufrrj.br
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