Effects of a low-volume plyometric training in anaerobic performance of adolescent athletes

Abstract

Background:
Parameters related to the anaerobic capacity and power may be important for the performance of many sports whose skills are related to high-intensity and short- duration efforts. Although plyometric training (PT) has been widely used in the regular strength and conditioning programs of young athletes, its effects on anaerobic performance are still controversial. Therefore, the purpose of the present study was to evaluate the effects of PT in anaerobic performance in young athletes.

Methods:
Twenty-nine adolescent athletes participated in this 10-week study. Baseline and post intervention testing included flying start 30 m sprint test (F30), 1600m, and Running-based Anaerobic Sprint Test (RAST). Subjects were divided in two groups: one completed only their regular training sessions, thus serving as the control (CON, n = 15), whereas the other performed the regular training plus twice-weekly low-volume plyometric training (PLYO, n = 14).

Results:
PLYO groups had significant increases in all variables analyzed. The novel findings were the increase in F30 performance (4.22% for PLYO vs. 1.08% for CON), the decreases in fatigue index (9.9% for PLYO vs. 1.53% for CON), and increases in minimum (19.41% for PLYO vs. 0.29 for CON), mean (14.7% for PLYO vs. 0.16% for CON) and peak power (10.88% for PLYO vs. 0.81% for CON) during the RAST test.

Conclusions:
Considering that anaerobic performance is an important feature in many sports, our results suggests that coaches involved with strength and conditioning of youth athletes should consider the inclusion PT in their training periodization.

Full text

Effects of a low-volume plyometric training in anaerobic performance of adolescent
athletes
Ari Rodrigo Assunção1,2, Martim Bottaro1, Euler Alves Cardoso1,2, Daiane Priscilla
Dantas da Silva2, Marcelo Ferraz2, Carlos Alexandre Vieira3, Paulo Gentil3
1 College of Physical Education, University of Brasilia, Brasilia, Brazil
2 Integrated Center of Physical Activity, Brasília, Brazil
3 College of Physical Education and Dance, Federal University of Goias, Goiânia, Brasil

Corresponding author:
Paulo Gentil
Address: Faculdade de Educação Física e Dança, Universidade Federal de Goias -
Avenida Esperança s/n, Campus Samambaia-
ZIP code: 74.690-900
Email: paulogentil@hotmail.com

Abstract
Background: Parameters related to the anaerobic capacity and power may be important
for the performance of many sports whose skills are related to high-intensity and short-
duration efforts. Although plyometric training (PT) has been widely used in the regular
strength and conditioning programs of young athletes, its effects on anaerobic
performance are still controversial. Therefore, the purpose of the present study was to
evaluate the effects of PT in anaerobic performance in young athletes.
Methods: Twenty-nine adolescent athletes participated in this 10-week study. Baseline
and post intervention testing included flying start 30 m sprint test (F30), 1600m, and
Running-based Anaerobic Sprint Test (RAST). Subjects were divided in two groups:
one completed only their regular training sessions, thus serving as the control (CON, n
= 15), whereas the other performed the regular training plus twice-weekly low-volume
plyometric training (PLYO, n = 14).
Results: PLYO groups had significant increases in all variables analyzed. The novel
findings were the increase in F30 performance (4.22% for PLYO vs. 1.08% for CON),
the decreases in fatigue index (9.9% for PLYO vs. 1.53% for CON), and increases in
minimum (19.41% for PLYO vs. 0.29 for CON), mean (14.7% for PLYO vs. 0.16% for
CON) and peak power (10.88% for PLYO vs. 0.81% for CON) during the RAST test.
Conclusions: Considering that anaerobic performance is an important feature in many
sports, our results suggests that coaches involved with strength and conditioning of
youth athletes should consider the inclusion PT in their training periodization.
Key words: explosive actions, stretch-shortening cycle, young athlete, adolescence,
strength and conditioning

Introduction
Plyometric training (PT) involves the rapid stretch of a muscle followed by a
rapid shortening, using the stretch-shortening cycle (SSC) muscle action to enable a
muscle to reach maximal force in the shortest possible time 1, 2. This type of training is
usually performed to increase the power of subsequent movements by using both
natural elastic components of muscle and tendon and the stretch reflex 2, 3. PT is seen as
a bridge between strength and speed, and is been used to improve performance in both
explosive and endurance athletic events 1. PT is also a useful training tool for athletes
involved in dynamic explosive types of sports.
PT has been shown to be beneficial in youth athletes when age-appropriate
training guidelines are followed 4, 5. In addition, a recent review suggested that the
performance of jumping/plyometric exercises by child and adolescent athletes resulted
in a significant better injury preventive effect 6. The benefits of PT in the young include
increased neuromuscular function 1, 4, 7, power production 2, 8, 9, running speed and
jumping ability 10, muscle strength 11, bone mineral density 12, improved cardiovascular
risk profile, facilitated weight control, enhanced psychosocial well-being, and decreased
risk for injury in sports 1, 4, 5.
However, the effects of plyometric training in some outcomes are poorly
understood. Decisive skills in many sports are related to high-intensity and short-
duration efforts, which places high demands on the anaerobic systems. Thus, parameters
related to the anaerobic capacity (i.e., the total amount of energy that can be
resynthesized by anaerobic metabolism) and anaerobic power (i.e., maximum amount of

anaerobic energy produced per unit of time) may be important for athletic performance
13. However, the effects of PT on anaerobic performance are controversial. One
previous study showed that plyometric training stresses the energy system similar to a
400m running protocol and also increase lactate production 14, suggesting that it may
promote positive adaptations in anaerobic performance. However, Piernar et al. 15 and
Michailidis et al. 16 found no improvements in peak or mean power during the Wingate
Anaerobic test (WAnT) in young athletes after performing PT.
This lack of results may be related to the testing procedures. Although the
WAnT is the most commonly used test to evaluate anaerobic capacity 17, 18, it may not
be a good procedure to mimic the exercise pattern performed in running-base activities
19. In this regard, it is important to respect the test specificity when we consider the
sports modalities that have running as the principal form of locomotion, such as soccer,
athletics and basketball 19, 20. Therefore, the purpose of the present study was to evaluate
the effects of plyometric training on anaerobic power of young athletes.

Materials and methods
Experimental approach to the problem
In the present study, a randomized 2-group repeated-measures experimental
design was used to compare the effect of 10 weeks of low-volume plyometric training
performed two times a week with traditional training programs on performance
variables. Baseline and post intervention testing included speed (flying start 30 m sprint
test – F30), aerobic capacity (1600m) and anaerobic power (RAST). Subjects were
divided in two groups: one completed only their regular training sessions, thus serving
as the control (CON, n = 15), whereas the other performed the regular training plus
twice-weekly plyometric training (PLYO, n = 14). Participants of both groups had
similar characteristics and participated in the same activities; therefore, we assumed the
participants were nearly equal in ability, experience, and training level.
Participants
All participants were from the same institution, the Integrated Center of Physical
Activity, a public institution were children and adolescents are introduced and trained in
different sport modalities. None of the participants had any experience with formalized
PT before participating in the study. The participants of the study were adolescents
engaged in different sports (track and field, volleyball, basketball and soccer) and were
studied during their preseason. Participants were separated into groups in pairs,
according to the modality they practiced, so the groups were balanced. All of them were

oriented to keep their current practices to ensure that the only change was the inclusion
of PT in the PLYO group.
Thirty-four adolescents initiated the study; however, the data of three from the
PLYO were excluded due to attendance lower than 80%, and two were excluded from
CON based on their absence from one or more testing sessions. Therefore, the data of
29 participants, 15 in CON (16.85 ± 0.68 years; 68.38 ± 8.10 kg) and 14 in PLYO
(16.79 ± 0.7 years; 65.24 ± 6.93 kg), were included in the analysis. Exclusion
criteria included potential medical problems, lower extremity reconstructive surgery in
the past year, unresolved musculoskeletal disorders or a history of ankle, knee, or back
injury that could compromise participation in the study. All participants and their
guardians were informed in detail about the testing and training procedures, and written
consent form were provided before participating in the study. The study was undertaken
in compliance with the Helsinki Declaration regarding research in human subjects and
was approved by the local University Ethic Committee.
Experimental procedures
Testing
All volunteers took part of an introductory session where they received
orientations about the correct procedures and detailed explanations about each test.
After explanation, participants practiced the tests and were individually instructed in
order to ensure adequate performance and safety. Participants were orientated not to
perform any type of physical activity in the two days preceding the tests. The order of
the tests was: anthropometric measures, RAST, F30 and 1.600 m aerobic test. Each test

was separated by 20-30 minutes intervals. The tests were performed in the same order
and accompanied by the same experienced investigators, at the same place, at the same
time of the day and using the same equipment, before and after the intervention.
Baseline tests were performed 5 to 7 days after the familiarization session and post-
training tests were performed 5 to 7 days after the last training session.
Running Anaerobic Sprint Test (RAST).
Initially, body mass of each participant was measured with the same clothes used
in the RAST test. Two lines taped to the floor marked a sprinting trace of 35 meters and
cones were placed at the end of each of the line. Participants were instructed to
complete six 35-meter sprints at maximum pace and to be sure to cross each line.
Participants were verbally encouraged to sprint as fast as possible during each run to
ensure a maximal effort. Between each run, participants were allowed to rest for 10
seconds before turning around, in order to allow them to prepare for the subsequent
sprint. Each 10- second interval between the sprints was also timed manually. An
experienced exercise physiologist, blinded to the intervention, administered all RAST
tests. For the first sprint, the instructions given were “ready, 3, 2, 1, go”. For the other
five sprints, a countdown from 6 to 1 and the start signal “go” proved to be sufficient.
Power, expressed in Watts (W), in each sprint was then calculated by the formula Power
= (Body Mass/*Distance2)/Time3 21. Peak Power (PP) was defined as the highest
calculated power and Minimum Power (MNP) as the lowest, while Mean Power (MP)
was defined as the average power over the six sprints. The fatigue index (FI) was
calculates as FI = (peak power – minimum power/peak power) X 100. All measures

were normalized for body mass by respectively dividing them by the participant’s body
mass.
Flying start 30 m sprint test (F30)
This test assessed the sprinting ability over a short distance, which is of
particular importance for many sports 22, 23 and has been associated with the
performance of different activities 23, 24. F30 was performed on a straight track marked
with cones and lines at 30 and 60m after the starting point. The participants waited for
the signal at the starting point and then ran at maximum speed. Participants performed
two trials separated by 5 minutes and the best time was used in the analysis.
1600m Time Trial.
After a warm-up of two laps at self-select velocity and 5 minutes of rest,
participants were oriented to perform 4 laps of a 400-m track in the minimal time
possible.
Training
The protocol was based on the recommendation of a meta-analysis and reviews
that analyzed the role of various factors on the effects of plyometric training25, 26 and the
exercises were selected based on its accessibility. As one of the possible factors
associated with increased injury risk during PT is excessive training volume, we opted
to perform a low volume of exercise 25, but maintaining volume of more than 50 jumps

per session, performed two times a week, as previously suggested 25. CON was oriented
not to perform any kind of additional training besides their regular training sessions.
PLYO performed plyometric exercises in addition to their regular training. The program
was divided in two phases, each lasting 5 weeks as shown in table 1. PT was performed
two times a week in nonconsecutive days (Tuesdays and Thursdays) under strict
supervision and control. Every session began with a 10 minutes warmup that included
jogging at a self-selected pace and calisthenics. The plyometric sessions took ~25
minutes and were followed by a 5 minutes calm down.
Table 1 about here
Statistical procedures
All values are reported by means ± standard deviation. Data normality was
verified by the Kolmogorov-Sminov test. Paired samples t-tests were used to compare
pre and post training values. An analysis of covariance (ANCOVA) was used to
compare post training values between PLYO and CON, using baseline values as
covariates. The probability level of statistical significance was set at P < 0.05 in all
comparisons. Data were analyzed using the statistical software package SPSS 17.0
(SPSS Inc., Chicago, IL, USA).

Results
Pre and post training results of both groups are presented in table 2. According
to the results, there were significant increases in the results of 1600m (from 7.11 ± 1.00
s to 6.57 ± 0.80 s) and F30 (from 520.43 ± 85.31 s to 577.06 ± 100.78 s) in the PLYO
group (p<0.05), but not in CON. The results of ANCOVA revealed that changes in
PLYO were significantly higher than CON for all variables analyzed (p<0.05).
Results of RAST test revealed significant increases for PLYO in MP (394.85 ±
76.62 W/kg to 452.88 ± 81.09 W/kg), PP (520.43 ± 85.31 W/kg to 577.06 ± 100.78
W/kg) and MNP (287.58 ± 65.23 W/kg to 343.4 ± 68.71 W/kg) and decreases in FI
from pre to post training (p<0.05). Again, the results of CON group were not significant
(p<0.05) in any variable and the comparison between groups revealed that post training
values for PLYO were higher than CON (p<0.05).
Table 2 about here

Discussion
The present study aimed to test if PT would promote increases in anaerobic
performance in young athletes. We found that only the PLYO group showed
improvements in all variables analyzed, and changes were greater than CON. The lack
of difference in CON suggests that the participants’ regular training program did not
provide sufficient stimuli to improve performance, which reinforces the importance of
implementing an adequate periodization program.
Previously, Brown et al. 14 showed that plyometric training increases lactate
levels above resting values and stresses the energy system similar to running 400m 14.
These results may explain the positive adaptations in anaerobic performance seen with
PLYO. A complementary explanation may be related to the running economy
associated to PT 27-29 , which may have retarded fatigue and allowed the athletes to
maintain a higher velocity during the tests. This is supported by the finding that fatigue
index decreased by 10% in PLYO after the training period. Another interesting
observation is that the increases in MP and MNP were 14.7 and 19.41% while the
increase in PP was 10.88%. By analyzing these data, it is possible to suggest that the
improvements in the ability to sustain effort was higher than the ability to reach higher
levels of muscle power. This outcome can be interesting in sports that demands the
repetition and/or sustainment of high levels of muscle work, such as team sports like
soccer and basketball.
Our results are contrary to Pienaar & Coetzee 15 that studied the effects of 4
weeks of PT on university-level rugby players and found no differences in MP and PP
between groups. Similarly, Michailidis et al. 16 found no increases in MP and PP in

preadolescent soccer athletes after 12 weeks of PT performed twice a week. This
discrepancy is possibly derived from the fact that the studies used WAnT to evaluate
anaerobic performance. The absence of SSC during cycling may have limited the
transference of the adaptations derived from PT to the WAnT test.
The improvement in aerobic capacity, reflected in the 7.58% decrease in the
time to perform the 1600m test, is not novel. Ramırez-Campillo et al 30 reported a
significant 1.9% decrease in the 2400m time test in young soccer players after 7 weeks
of PT. Maybe the smaller changes, compared to the present study, occurred because the
authors substituted specific soccer drills by PT, which might have diminished the
overall aerobic stimuli provided by training. Moreover, the use of a longer distance
(2400 vs 1600m) might have increased the participation of the aerobic system in the
test31, diminishing the influence of PT.
Short sprints are performed regularly in many sports, and typically begin while
the athlete is already in motion, so it is important to evaluate both static and flying starts
for linear sprinting. Therefore, our results add relevant information for the current
literature as it shows a 4.22% decrease in F30 time after PT. Although previous studies
suggested that sprinting from a static start relies on different variables than flying start
sprints 23, 32, our results are in agreement with previous studies that evaluated 30m sprint
time starting from a static position. Michailidis et al 16 reported a significant decrease in
30m sprint time in preadolescents soccer player after 12 weeks of PT, and Sohnlein 33
found improvements in 30m time after 16 weeks of PT in elite young soccer players.
However, our results conflicts with Ramırez-Campillo et al 30, who reported no
significant changes in 20m sprint time in young soccer players after 7 weeks of PT
performed twice a week. Simlarly, Granacher et al. 34 did not find decreases in 30m time
after 8 weeks of PT in adolescent sub-elite soccer players. A possible explanation for

the differences is that, contrary to Michailidis et al 16, Sohnlein 33 and the present study,
both Ramırez-Campillo et al 30 and Granacher et al. 34 protocols involved only vertical
jumps. Ramirez-Campillo et al. 35 reported that the performance in the 30m sprint test
increased significantly only in the groups that trained with horizontal jumps.
No musculoskeletal injuries occurred during the implementation of PT, as
previously reported for adolescents16, 30, 36, suggesting that supervised and properly
designed PT represents a safe training modality for this group. According to Bedoya et
al. 26 misconceptions about the potential danger of incorporating PT with youth athletes
may result in fewer coaches using plyometrics with youth athletes than expected.
However, it is important to note that some degree of low-impact plyometrics is part of
daily and sportive activities of children and adolescents (i.e. jumping, skipping,
hopping…). Therefore, the type of training program used in the present study would
hardly bring a harmful physical stress. Moreover, PT has been shown to be have
innumerous benefits in young athletes like injury prevention6, increased neuromuscular
function 1, 4, 7, power production 2, 8, 9, running speed and jumping ability 10, muscle
strength 11, bone mineral density 12, improved cardiovascular risk profile, facilitated
weight control, enhanced psychosocial well-being, and decreased risk for injury in
sports 1, 4, 5.
In conclusion, the present study shows that 10 weeks of low volume PT
improved the performance in F30, 1600 test and anaerobic capacity in young athletes.
The novelty of the study is in the use of RAST test to evaluate anaerobic capacity. The
decision to use this test was based on its proximity to sports that use running as the
predominant form of locomotion. It is important to note that decisive skills in many
sports are related to high-intensity and short-duration efforts that places high demands
on the anaerobic systems. Thus, the improvements in parameters related to the

anaerobic capacity and anaerobic power may bring important benefits for athletic
performance 13. It is interesting to note that the benefits of PT were obtained by adding
only two weekly sessions of low volume PT, which suggests that it is a viable and time
efficient option for young athletes.

Conclusions
The present results suggest that two weekly sessions of low volume PT
improved aerobic capacity, speed and anaerobic power in young athletes. Although
some of these outcomes have been previously studied, our results may provide
additional information to address some controversy in the literature. A novelty find was
the increase in anaerobic performance. Considering that anaerobic performance is an
important feature in many sports, our results suggests that coaches involved with the
preparation of youth athletes should consider including PT in their periodization with
the purpose to improve performance in many different variables. Moreover, the present
results showed that the benefits can be obtained with a low-volume training program,
which can be feasible in the training schedules of young athletes.

Acknowledgements
The authors would like to thank the participants and their coaches sincerely for
their valuable cooperation and participation in this study.

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List of tables
Table 1: Plyometric training program
Table 2: Pre and post training results of both groups (mean ± standard deviation)