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Abstract

This study examined the effects of a progressive resistance training program in addition to soccer training on the physical capacities of male adolescents. Eighteen soccer players (age: 12-15 years) were separated in a soccer (SOC; n = 9) and a strength-soccer (STR; n = 9) training group and 8 subjects of similar age constituted a control group. All players followed a soccer training program 5 times a week for the development of technical and tactical skills. In addition, the STR group followed a strength training program twice a week for 16 weeks. The program included 10 exercises, and at each exercise, 2-3 sets of 8-15 repetitions with a load 55-80% of 1 repetition maximum (1RM). Maximum strength ([1RM] leg press, bench-press), jumping ability (squat jump [SJ], countermovement jump [CMJ], repeated jumps for 30 seconds) running speed (30 m, 10 x 5-m shuttle run), flexibility (seat and reach), and soccer technique were measured at the beginning, after 8 weeks, and at the end of the training period. After 16 weeks of training, 1RM leg press, 10 x 5-m shuttle run speed, and performance in soccer technique were higher (p < 0.05) for the STR and the SOC groups than for the control group. One repetition maximum bench press and leg press, SJ and CMJ height, and 30-m speed were higher (p < 0.05) for the STR group compared with SOC and control groups. The above data show that soccer training alone improves more than normal growth maximum strength of the lower limps and agility. The addition of resistance training, however, improves more maximal strength of the upper and the lower body, vertical jump height, and 30-m speed. Thus, the combination of soccer and resistance training could be used for an overall development of the physical capacities of young boys.
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Journal of Strength and Conditioning Research, 2006, 20(4), 783–791
2006 National Strength & Conditioning Association
E
FFECTS OF
R
ESISTANCE
T
RAINING ON THE
P
HYSICAL
C
APACITIES OF
A
DOLESCENT
S
OCCER
P
LAYERS
M
ARIOS
C
HRISTOU
,
1,2
I
LIAS
S
MILIOS
,
1
K
ONSTANTINOS
S
OTIROPOULOS
,
1
K
ONSTANTINOS
V
OLAKLIS
,
1
T
HEOFILOS
P
ILIANIDIS
,
1
AND
S
AVVAS
P. T
OKMAKIDIS
1
1
Department of Physical Education & Sport Science, Democritus University of Thrace, Komotini, Greece;
2
Center
for Leisure, Tourism and Sports Research and Development, Intercollege, Nicosia, Cyprus.
A
BSTRACT
.Christou, M., I. Smilios, K. Sotiropoulos, K. Volaklis,
T. Pilianidis, and S.P. Tokmakidis. Effects of resistance training
on the physical capacities of adolescent soccer players. J.
Strength Cond. Res. 20(4):783–791. 2006.—This study examined
the effects of a progressive resistance training program in ad-
dition to soccer training on the physical capacities of male ado-
lescents. Eighteen soccer players (age: 12–15 years) were sepa-
rated in a soccer (SOC; n9) and a strength-soccer (STR; n
9) training group and 8 subjects of similar age constituted a
control group. All players followed a soccer training program 5
times a week for the development of technical and tactical skills.
In addition, the STR group followed a strength training program
twice a week for 16 weeks. The program included 10 exercises,
and at each exercise, 2–3 sets of 8–15 repetitions with a load
55–80% of 1 repetition maximum (1RM). Maximum strength
([1RM] leg press, bench-press), jumping ability (squat jump [SJ],
countermovement jump [CMJ], repeated jumps for 30 seconds)
running speed (30 m, 10 5-m shuttle run), flexibility (seat and
reach), and soccer technique were measured at the beginning,
after 8 weeks, and at the end of the training period. After 16
weeks of training, 1RM leg press, 10 5-m shuttle run speed,
and performance in soccer technique were higher (p0.05) for
the STR and the SOC groups than for the control group. One
repetition maximum bench press and leg press, SJ and CMJ
height, and 30-m speed were higher (p0.05) for the STR group
compared with SOC and control groups. The above data show
that soccer training alone improves more than normal growth
maximum strength of the lower limps and agility. The addition
of resistance training, however, improves more maximal
strength of the upper and the lower body, vertical jump height,
and 30-m speed. Thus, the combination of soccer and resistance
training could be used for an overall development of the physical
capacities of young boys.
K
EY
W
ORDS
. agility, flexibility, growth, running speed, strength,
vertical jump
I
NTRODUCTION
Resistance training is proven to be safe and ef-
fective for adolescents when it is properly de-
signed and supervised. Established scientific
organizations recommend resistance training
for young people to enhance muscular
strength, prevent sport injuries, improve performance in
sports and recreational activities, and affect health and
lifestyle in a positive way (1, 3, 26).
Several studies have shown that resistance training
increases muscular strength more than natural growth in
adolescents (14, 20, 21, 25). However, as far as the effect
of resistance training on motor performance is concerned,
some studies have shown a positive effect on some phys-
ical capacities, whereas other studies have not indicated
a similar effect. For example, after a resistance training
program, vertical jump performance was found to either
increase (21) or not show changes at all (20). When the
effect of resistance training on running speed was ex-
amined, resistance training failed to influence running
performance (20). Similarly, resistance training failed to
affect anaerobic capacity (15, 21). To our knowledge, no
study has examined the effects of resistance training on
flexibility and agility in young boys. Therefore, research
findings concerning the effects of resistance training on
motor performance are either limited or inconclusive, and
further studies of the potential role of resistance training
on physical capacities of adolescents are required to pro-
vide useful information to coaches.
After participating in resistance training programs,
sport performance of youths is expected to improve. An-
ecdotal comments on strength training suggested that
this is enhanced (18). Definitely, sports performance is
the outcome of multiple factors, and it would be difficult
to control and assess the net impact of resistance train-
ing. Nevertheless, Gorostiaga et al. (20) found that hand-
ball throwing velocity in adolescent players increased af-
ter resistance training. Thus, it would be interesting to
examine if strength training would have a positive impact
on specific tasks of soccer involving fast running and ef-
fective handling of the ball at the same time.
On the other hand, it is unknown whether a resistance
training program incorporated with regular soccer train-
ing would enhance the physical capacity of adolescent
players compared with soccer training alone. Soccer is a
sport that requires acceleration, rapid change of direc-
tion, and many powerful movements. Therefore, training
of the sport itself may enhance muscular performance es-
pecially during the developmental period. It would have
been interesting for physical educators and coaches to
recognize if soccer training would have an effect on motor
performance and if resistance training combined with soc-
cer training would have an extra effect on motor perfor-
mance. The purpose of this study was to investigate the
effects of soccer training combined with resistance train-
ing as well as the effects of regular soccer training alone
on physical capacities such as muscular strength, vertical
jump performance, running speed, agility, and flexibility,
and on soccer technique of male adolescent soccer players.
M
ETHODS
Experimental Approach to the Problem
The objectives of this study were to examine (a) the ef-
fects of soccer training on anthropometric characteristics,
784 C
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OTIROPOULOS ET AL
.
T
ABLE
1. Strength training program throughout the 16-week
training period.*
Week Session
Set
repetitions
Intensity
(%1RM)
11215 55–60
2215 55–60
23315 55–60
4215 55–60
35315 55–60
6315 55–60
47215 55–60
8215 55–60
59212 65–70
10 2 12 65–70
611312 65–70
12 2 12 65–70
713312 65–70
14 3 12 65–70
815212 65–70
16 2 12 65–70
917210 70–75
18 2 10 70–75
10 19 3 10 70–75
20 2 10 70–75
11 21 3 10 70–75
22 3 10 70–75
12 23 2 10 70–75
24 2 10 70–75
13 25 2 8 75–80
26 2 8 75–80
14 27 3 8 75–80
28 2 8 75–80
15 29 3 8 75–80
30 3 8 75–80
16 31 2 8 75–80
32 2 8 75–80
*1RM1 repetition maximum.
muscular strength, jumping ability, running speed, agil-
ity, flexibility, and specific technical skills of male ado-
lescent players, and (b) the effects of a combined soccer
and resistance training program for 16 weeks on the
above physical capacities. For these reasons, a team of
male regional soccer players was divided into a strength-
soccer training group (STR) and a soccer training group
(SOC). Soccer training (5 times per week) for the devel-
opment of technical and tactical skills was the same in
both groups. The STR group not only trained in soccer,
but in a strength training program as well, using free
weights and machines twice a week (Table 1). No boy had
regularly participated in any form of resistance training
before this study. To assess the effect of natural growth
on physical capacities, a control group (CON) was used
with boys of a similar age and physical characteristics.
The subjects of this group did not participate in any struc-
tured training program. Anthropometric characteristics,
maximum strength, vertical jump performance, running
speed, agility, flexibility, and soccer-specific technical
skills were measured at the beginning of the training pro-
gram and after 8 and 16 weeks of training.
Subjects
Eighteen soccer players with training experience of 4.3
1.9 years and ranging from 12 to 15 years of age volun-
teered to participate in this study. The boys were equally
divided into 2 groups: STR (13.8 0.4 years; n9) and
SOC (13.5 0.9 years; n9). In addition, 8 boys were
recruited as a CON group (13.3 0.7; n8). The mat-
uration status of the boys was determined according to
the development of pubic hair, based on the Tanner 5-
point scale (23), at the beginning, after 8 weeks, and after
16 weeks of strength training by the same investigator.
There were no significant differences between groups for
age or Tanner ratings. The physical characteristics of the
subjects are presented in Table 2.
All boys underwent medical evaluation before the be-
ginning of the study, and the following exclusion criteria
were used: (a) boys with a chronic pediatric disease; (b)
boys with an orthopedic limitation; and (c) boys who were
not classified as Tanner stage 3–5 at the beginning of the
study. Both the boys and their parents were informed
about the scope and the objectives of the study as well as
the risks associated with strength training. A written con-
sent was obtained from the parents. The experimental
protocol was approved by the Institutional Review Board
Committee.
Training Program
Weight-Training Program. The study was performed at
the beginning of the competitive season. The STR group
followed an introductory weight training program of 4
weeks (2 times per week), focusing on proper lifting tech-
niques with low volume and intensity (2 sets of 15 repi-
titions at 30–50% of 1 repetition maximum [1RM]). Af-
ter this period, players began the strength training pro-
gram, 2 times per week for 16 weeks with a total of 32
training sessions. Weight-training sessions were separat-
ed by at least 48 hours of rest. Each player performed the
exercises in order: leg press, bench press, leg extension,
peck-deck, leg flexion, overhead press, lat pull-downs, calf
raise, sit-ups, and upper-lower back extension. The spe-
cific configuration of the acute program variables during
the course of the 16-week training period is presented in
detail in Table 1. In summary, the intensity was 55% of
the 1RM at the beginning of the program and progres-
sively increased up to 80% of the 1RM. For each exercise,
2–3 sets of 8–15 repetitions with 2–3 minutes of rest be-
tween sets and 3–5 minutes between exercises were per-
formed. When a boy was able to complete the predeter-
mined number of repetitions with proper form and with-
out help, the load was increased by 5%. Subjects per-
formed up to 2–3 sets of 20–30 repetitions of the body
weight exercises.
Strength training was performed before soccer train-
ing, and the duration of each session lasted approximate-
ly 45 minutes. A warm-up period of 10 minutes, including
low to moderate intensity aerobic exercises and stretch-
ing, was carried out before strength training. In addition,
boys performed stretching exercises for about 1 minute
after each set of exercises and for 5 minutes after the end
of each session. A qualified instructor, who monitored
proper exercise techniques and made adjustments in
training load and repetitions, supervised strength train-
ing sessions. No injuries occurred during the training and
testing sessions.
Soccer Training Program. Both training groups fol-
lowed a soccer training program 5 times a week, with
each session lasting 90 minutes. In addition, both
groups participated in a 70-minute official game once a
week (two 35-minute halves). Soccer training focused on
the development of technical and tactical skills first and
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785
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ABLE
2. Anthropometric characteristics for the 3 groups for the 16-week training program (mean SE).*
Group Pretraining 8 weeks Adjusted means 16 weeks Adjusted means
Body mass (kg)
Strength-soccer (n9) 52.0 3.3 54.3 3.4† 56.3 0.4 55.6 3.5† 57.5 0.7
Soccer (n9) 54.1 2 54.3 2.0 54.2 0.4 55.3 2.0†‡ 55.1 0.7
Control (n8) 55.8 4.5 57.4 4.4 55.6 0.4 57.5 4.1 55.8 0.7
Pretraining (covariate) 54.0
Height (cm)
Strength-soccer (n9) 162.0 3.8 164 3.9† 164.7 0.3 165.2 3.9†‡ 165.9 0.4
Soccer (n9) 163.0 2.5 164 2.5† 163.7 0.3 165.3 2.5†‡ 165.0 0.4
Control (n8) 163.2 4.5 164.9 4.2† 164.5 0.4 165.6 4.0† 165.2 0.5
Pretraining (covariate) 162.8
Maturational status (Tanner 5-pt scale)
Strength-soccer (n9) 4.0 0.2 4.2 0.2 4.1 0.1 4.3 0.2 4.3 0.1
Soccer (n9) 3.9 0.3 4.0 0.2 4.0 0.1 4.2 0.1 4.2 0.1
Control (n8) 3.8 0.3 4.0 0.3 4.1 0.1 4.1 0.2 4.2 0.2
Pretraining (covariate) 3.9
Sum of 4 skinfolds (mm)
Strength-soccer (n9) 30.0 1.9 28.3 1.6 38.9 1.4 28.1 1.6 37.6 1.8
Soccer (n9) 40.0 3.5 38.4 3.5 40.4 1.2 37.5 3.3† 39.2 1.6
Control (n8) 58.7 6.6 55.4 5.7 41.2 1.6 47.2 5.5†‡ 34.4 2.1
Pretraining (covariate) 42.3
Body fat (%)
Strength-soccer (n9) 12.2 0.9 11.9 0.7 16.9 0.7 12.0 0.7 16.8 0.8
Soccer (n9) 16.6 1.5 15.8 1.6 16.9 0.6 15.8 1.5 16.9 0.6
Control (n8) 24.8 2.9 23.5 2.6 17.4 0.8 20.3 2.5†‡ 14.6 0.8
Pretraining (covariate) 17.8
Girth, midthigh (cm)
Strength-soccer (n9) 45.4 1.1 46.4 1.4† 48.0 0.3 48.1 1.4†‡ 49.4 0.6
Soccer (n9) 47.7 0.9 48.3 0.8 47.6 0.3 48.9 0.8† 48.3 0.6
Control (n8) 47.9 1.9 49.3 1.8 48.5 0.4 48.3 1.5 47.5 0.6§
Pretraining (covariate) 47.0
Girth, calf (cm)
Strength-soccer (n9) 32.9 0.8 33.1 0.9 34.0 0.2 33.6 0.9† 34.4 0.2
Soccer (n9) 33.9 0.4 34.1 0.6 34.0 0.2 34.4 0.6† 34.2 0.2
Control (n8) 34.5 1.2 34.7 1.2 34.0 0.2 34.2 1.1 33.5 0.2§
Pretraining (covariate) 33.8
Girth, upper arm (cm)
Strength-soccer (n9) 23.8 1.0 23.7 0.9 24.1 0.2 24.0 0.9 24.4 0.2
Soccer (n9) 23.4 0.4 23.0 0.4† 23.7 0.2 23.4 0.4‡ 24.1 0.2
Control (n8) 25.2 1.1 25.4 1.3 24.3 0.2 24.8 1.0 23.8 0.2
Pretraining (covariate) 24.1
Girth, midbiceps (flexed) (cm)
Strength-soccer (n9) 25.7 1261 26.7 0.3 26.4 1 26.9 0.3
Soccer (n9) 26.0 0.5 25.4 0.5 25.7 0.3 25.6 0.5 25.9 0.3
Control (n8) 27.0 1.2 26.9 1.3 26.1 0.3 26.2 1 25.5 0.3
Pretraining (covariate) 26.2
*p0.05.
† From pretraining.
‡ From 8 weeks.
§ Between strength soccer and control.
then on the improvement of physical capacities. Technical
skills, such as dribbling, passing, receiving, shooting, and
heading were performed for 40–50 minutes in at least 3
training sessions a week. In addition, soccer drills and
games were performed in small areas from squads with
a reduced number of players (1 vs. 1, 3 vs. 3, 4 vs. 4) to
work on offensive and defensive strategies and individual
tactics. High-intensity training for the development of
running speed and agility (with and without a ball) was
carried out twice a week, and 1 training session per week
included soccer games or interval training for the devel-
opment of aerobic capacity. A half-field game lasting 20–
30 minutes was played at the end of each training ses-
sion. Stretching exercises for the main muscle groups
were executed in the warm-up and cool-down periods.
Testing Procedures
A standardized 15- to 20-minute warm-up consisting of
submaximal aerobic exercises and stretching exercises
preceded each test.
Anthropometric Measurements. All boys were mea-
sured for height, weight, body fat, and selected girths.
786 C
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Body fat was measured using triceps and calf skinfolds
as described by Slaughter et al. (33). Girth measures of
the upper arm, midbiceps (flexed), midthigh, and calf
(maximum girth of calf muscle) were obtained with an
anthropometric tape measure as described by Callaway
et al. (11). All anthropometric and body composition mea-
sures were taken from the right side by the same inves-
tigator.
Maximum Strength. All boys were evaluated for 1RM
in the bench press and leg press. The 1RM was typically
determined within 6 trials using the protocol of Ramsey
et al. (29). All testing procedures were closely supervised
(an instructor-to-subject ratio was 1:1), and verbal en-
couragement was given to all boys. All measurements
were performed with a constant position of the body, us-
ing the same resistance equipment by the same test ad-
ministrator. The intraclass correlation coefficient (ICC)
and the coefficient of variation (CV) of the SEM for the
measurement of maximum strength were r0.975 and
2.81%, respectively.
Vertical Jump Performance. Vertical jump performance
was measured with 3 types of jumps: a squat jump (SJ;
initiated from a knee flexion of 90), a countermovement
jump (CMJ), and repeated jumps (RJ) for 30 seconds (9,
10). During the performance of the jumps, the hands of
the boys were placed on the waist. The jumps were exe-
cuted on a platform connected to a digital timer (Ergo-
jump, Psion CM; MAGICA, Rome, Italy) that measured
flight time and calculated jump height. For the SJ and
the CMJ, after 2–3 practice trials, 3 trials were carried
out for each type of jump (1–2 minutes of rest were al-
lowed between jumps), and the best trial was used for
further analysis. For the RJ test, the boys were instructed
to jump continuously using maximal effort. For every
jump, the position of takeoff and landing were the same.
To standardize knee angular displacement during the
contact phase, the boys were instructed to bend the knee
to about 90. Pilot testing revealed an ICC and a CV of
the SEM of r0.971 and 2.47% for the SJ, r0.957
and 3.42% for the CMJ, and r0.932 and 3.44% for the
RJ, respectively.
10- and 30-m Sprint Time. Sprint time was measured
using 3 electronic photo cells connected to a Lafayette
63501 timer (Lafayette Instrument Co. Systems, Lafay-
ette, IN). A photocell was placed at the start, at 10 m, and
at 30 m. The first photocell was positioned at a height of
50 cm from the ground and the photocells of 10 and 30 m
were placed at the height of the head of the boys, in an
attempt to standardize the part of the body breaking the
photocell (5). The boys started on a visual signal from a
standing position and ran the 30-m distance as fast as
possible on an indoor running track. After 1 practice trial,
2 sprints were performed, separated by a 5-minute recov-
ery period, and the fastest was used for subsequent anal-
ysis. All performance times were recorded with an accu-
racy of 0.001 seconds, and the time from 0 to 10 m and
total sprint time from 0 to 30 m was recorded. These
sprint distances were selected because they are the most
common during soccer games (6). The ICC and the CV of
the SEM for the 10-m sprint were r0.958 and 1.46%,
and for the 30-m sprint, r0.979 and 0.83%, respective-
ly.
Agility (10
5m).Agility was evaluated using a 10
5-m maximal shuttle run on an indoor running track
following the protocol of Eurofit (16). After 1 practice trial
and at least 5 minutes of rest, a maximum test was per-
formed. Performance time was recorded with an accuracy
of 0.01 seconds. The ICC and the CV of the SEM for the
10 5-m shuttle run test were r0.935 and 1.01%,
respectively.
Flexibility. Flexibility of the lower back and ham-
strings was measured using the sit and reach test as sug-
gested by the American Alliance of Health, Physical Ed-
ucation, Recreation, and Dance (2). Two trials were per-
formed, and the best one was used for further analysis.
The ICC and the CV of the SEM for the sit and reach
test were r0.979 and 2.71%, respectively.
Soccer Technique Test. Technical skills in soccer were
evaluated using a slalom dribble test (35). The boys per-
formed zigzag dribbling with the preferred leg around a
series of 9 cones with a distance of 1.5 m between them
(total distance, 14 m). After 2 practice trials, 2 maximum
efforts of zigzag dribbling were performed separated by a
2-minute rest. The fastest and most successful trial (with-
out losing possession of the ball) was recorded for further
analysis. All performance times were recorded with an
accuracy of 0.001 seconds, using an electronic timer (La-
fayette Instrument Co. Systems). Pilot testing revealed
an ICC and a CV of the SEM of r0.982 and 1.88%,
respectively.
Statistical Analyses
The effects of training on each group were tested using a
repeated-measures analysis of variance and the effect
size ([posttest mean pretest mean]/SD) for the magni-
tude of treatment effects was determined (12, 30). A two-
way analysis of covariance (ANCOVA), using initial val-
ues as covariate and
2
for effect size, was used to deter-
mine the differences between groups at the 8th and 16th
week of training. Statistical power (P) for the ANCOVA
was determined as suggested by Keppel (22). Significant
differences between means were located with the Tukey
honestly significant difference procedure. The statistical
significance level was set at p0.05.
R
ESULTS
Anthropometric Measurements
Significant main effects (p0.05) were observed for
height and weight, but no differences (p0.05) were
found between groups. No significant changes were ob-
served between groups for percentage of body fat and the
sum of 4 skinfolds. Analysis of covariance revealed that
midthigh and calf circumferences were larger (p0.05)
for the STR group compared with the CON after 16 weeks
of training (Table 2).
Maximal Strength
Leg Press (1RM). Training resulted in significant increas-
es (p0.01) in lower body strength for the STR (58.8%)
and SOC groups (33.8%). A significant increase (17.3%; p
0.05), indicative of growth, was also observed for the
control group (Table 3). For all groups, the greatest in-
crease was observed after the first 8 weeks of training
(37.7, 20.7, and 9% respectively). Further analysis (AN-
COVA) revealed significant differences between groups in
maximum strength (p0.01,
2
0.551, P1). Leg
press 1RM for the STR group was greater than that
achieved by the SOC and CON groups after 8 and 16
weeks of training. Maximum strength of the SOC group
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3. Physical performance and soccer technique scores for the three groups for the 16-week training program.*
Group
Pretraining
Means SE
8 weeks
Means SE
Effect
size
Adjusted
means
16 weeks
Means SE
Effect
size
Adjusted
means
Flexibility (cm)
Strength-Soccer (n9) 26.7 1.8 23.7 2.2† 0.5 20.1 1.2 24.6 1.9 0.37 21.2 1.1
Soccer (n9) 22.1 3.8 23.2 3.3 0.11 23.5 1.2 24.7 2.8 0.26 24.9 1.1
Control (n8) 18.3 2.9 18.7 1.2 0.05 22.1 1.2 18.4 2.8 0.01 21.5 1.2
Pretraining (covariate) 22.5
Sprint time 10 m (s)
Strength-soccer (n9) 2.16 0.06 2.18 0.07 0.14 2.14 0.04 2.09 0.04 0.41 2.06 0.03
Soccer (n9) 2.00 0.04 2.04 0.04 0.4 2.13 0.04 1.98 0.04 0.15 2.05 0.03
Control (n8) 2.18 0.05 2.20 0.06 0.12 2.15 0.04 2.11 0.04 0.48 2.07 0.03
Pretraining (covariate) 2.11
Sprint time 30 m (s)
Strength-Soccer (n9) 5.07 0.16 5.16 0.16 0.19 5.13 0.05 4.94 0.12†‡ 0.3 4.91 0.04
Soccer (n9) 4.85 0.09 4.88 0.10 0.1 5.04 0.05 4.85 0.10 0 5.00 0.04
Control (n8) 5.20 0.11 5.26 0.06 0.22 5.12 0.05 5.22 0.10 0.06 5.09 0.04‡
Pretraining (covariate) 5.04
Agility 10 5 m (s)
Strength-soccer (n9) 19.92 0.24 19.25 0.29† 0.83 19.43 0.16 18.84 0.16† 1.74 18.97 0.19
Soccer (n9) 19.78 0.21 19.07 0.22† 1.08 19.34 0.16 18.99 0.24† 1.13 19.19 0.20
Control (n8) 20.86 0.63 20.89 0.41 0.02 20.43 0.18‡§ 21.12 0.40 0.17 20.78 0.22‡§
Pretraining (covariate) 20.18
Mean height of repeated jumps for 30 s (cm)
Strength-soccer (n9) 21.6 1.4 22.4 1.3 0.2 21.4 0.5 24.8 1.4†‡ 0.76 23.7 0.7
Soccer (n9) 22.2 1.3 23.0 1.2 0.21 21.4 0.5 23.7 1.2† 0.41 22.0 0.8
Control (n8) 16.9 1.4 16.9 1.1 0 19.5 0.6 18.3 1.4 0.36 21.0 0.9
Pretraining (covariate) 20.21
Soccer technique test (s)
Strength-soccer (n9) 7.91 0.20 7.51 0.18 0.69 7.95 0.18 7.32 0.10 1.22 7.72 0.19
Soccer (n9) 7.40 0.24 7.21 0.24 0.25 8.08 0.20 7.10 0.26 0.39 7.90 0.22
Control (n8) 10.27 0.55 10.32 0.52 0.03 8.85 0.26§ 10.30 0.51 0.02 8.95 0.28‡§
Pre-training (covariate) 8.52
Squat jump (cm)
Strength-soccer (n9) 24.9 1.4 28.1 1.4† 0.76 27.9 1 32.4 1.6† 1.65 32.1 1
Soccer (n9) 23.8 1.2 25.2 1.2 0.4 25.7 1 25.9 1.1 0.62 26.6
Control (n8) 25 2 26.5 1.8 0.28 26.2 1.1 27 2.1 0.35 26.6
Pretraining (covariate) 24.5
Countermovement jump (cm)
Strength-soccer (n9) 29 1.6 32.9 1.4† 0.86 33.1 0.6 35.7 1.4† 1.49 35.9 0.8
Soccer (n9) 29.7 1.7 30.3 1.5 0.12 30 0.6¶ 31.1 1.3 0.3 30.8 0.8
Control (n8) 29 2 30.6 1.4 0.33 30.7 0.7¶ 31.2 1.5 0.44 31.3 0.9
Pretraining (covariate) 29.2
Leg press 1RM (kg)
Strength-soccer (n9) 102.8 2.5 142.8 8.5† 1.73 148.7 4.7 163.9 7.4† 2.77 170.1 4.4
Soccer (n9) 106.1 7 126.7 6.7† 1 118.9 4.8¶ 139.4 6† 1.7 132.5 4.6¶
Control (n8) 93.8 5.2 102.5 6.7† 0.52 108.3 110 6.8† 0.95 115.2 4.8§
Pretraining (covariate) 100.9
Bench press 1RM (kg)
Strength-soccer (n9) 36 1.6 45.9 2.5† 1.57 50.6 1.1 55 3.1† 2.54 60.6 1.5
Soccer (n9) 48.3 3.2 47.8 2.6 0.01 41.4 1.2¶ 45.8 3.4 0.25 38.2 1.5¶
Control (n8) 39.4 2.7 41 2.4 0.22 42.7 1.1§ 40.5 2.5 0.15 42.5 1.5§
Pretraining (covariate) 41.2
*p0.05.
† From pretraining.
‡ From 8 weeks.
§ Between strength-soccer and control.
Between soccer and control.
Between strength-soccer and soccer.
788 C
HRISTOU
,S
MILIOS
,S
OTIROPOULOS ET AL
.
F
IGURE
1. Differences between the strength-soccer (STR),
soccer (SOC), and control (CON) groups in 1RM leg press and
bench press. *p0.01 between STR and SOC, †p0.01 be-
tween STR and CON, ‡p0.05 between SOC and CON.
F
IGURE
2. Differences between the strength-soccer (STR),
soccer (SOC), and control (CON) groups in countermovement
jump (CMJ) and squat jump (SJ). *p0.05 between STR and
SOC, †p0.05 between STR and CON.
was greater compared with the CON group only at the
end of the 16-week training period (Figure 1).
Bench Press (1RM). After 8 and 16 weeks of training,
bench press 1RM was significantly higher (p0.01) for
the STR group than the SOC and CON groups (p0.01,
2
0.79, P1; Figure 1). In particular, upper body
strength increased only in the STR group (52.3%; p
0.01), whereas no significant differences (p0.05) were
observed for the SOC and CON groups (-5.4 and 3.3%
respectively; Table 3).
Vertical Jump Performance
Squat Jump. After 16 weeks of training, SJ height was
higher (p0.05,
2
0.33, P0.83) for the STR group
compared with the SOC and CON groups (Figure 2). SJ
height was significantly improved by 13.5 and 31% for the
STR after 8 and 16 weeks of training, respectively (p
0.05). The increases observed for the SOC (9.8%) and
CON (9.6%) groups were not significant (p0.05; Table
3).
Countermovement Jump. After 8 and 16 weeks of train-
ing, CMJ height was greater (p0.01,
2
0.49, P1)
for the STR group compared to the SOC and CON groups
(Figure 2). CMJ height improved by 14.4 and 24.6% for
the STR after 8 and 16 weeks of training, respectively (p
0.05). No significant changes were observed for the
SOC (6.3%) and CON (9.5%) groups (Table 3).
Repeated Jumps for 30 Seconds. After 16 weeks of
training, the STR and the SOC groups improved signifi-
cantly in average height during repeated jumps for 30
seconds (15.8 and 7.2%, respectively; p0.05), whereas
the CON group showed a nonsignificant improvement
(9.8%; p0.05). No significant differences were observed
between groups after the end of the training period (p
0.07,
2
0.21, P0.57; Table 3).
Sprint and Agility Times
Running Speed. There were no significant improvements
for 10-m acceleration speed in any group during the
study, although the STR group showed a higher speed
(3.1%) than the SOC (0.7%) and CON (2.7%) groups. No
differences were observed between groups (p0.99,
2
0.01, P0.07). Significant improvements in 30-m
sprint time (p0.05) occurred only with the STR group
R
ESISTANCE
T
RAINING IN
A
DOLESCENTS
789
(2.5%) after 16 weeks of strength training, whereas no
significant differences were found for the SOC (0.04%)
and CON (0.5%) groups. Sprint velocity was higher for
the STR group compared with the SOC and CON groups
at the end of the training period (p0.049,
2
0.24, P
0.65; Table 3).
Agility Time. Improvements were observed in the 10
5-m shuttle run for the STR and SOC groups after 8
(3.4 and 3.5%, respectively; p0.05), and 16 weeks (5.4
and 4%, respectively) of training, whereas no changes
were observed in the CON (1.6%) group. The ANCOVA
revealed significant differences between groups in agility
time (p0.01,
2
0.65, P1) with the STR and the
SOC groups being faster than the CON group (Table 3).
Flexibility
Sit and reach scores decreased significantly by 8.2% in
the STR group (p0.05), whereas they increased, but
not in a significant way, in the SOC and CON groups.
The 3 groups did not differ in flexibility scores throughout
the course of the study (p0.07,
2
0.22, P0.62;
Table 3).
Soccer Technique Test
The STR and SOC groups improved their performance
(6.8 and 4.0%, respectively) in the soccer technique test
after training, but this improvement was not significant
(p0.05). No changes were observed in the CON group
(0.4%; p0.05). The scores in the soccer technique test,
at the end of the training period, were better for both the
STR and SOC groups compared with the CON group,
whereas no differences were observed between them (p
0.05,
2
0.34, P0.83; Table 3).
D
ISCUSSION
The soccer training applied in this study improves agility,
flexibility, and strength of the lower extremities. Strength
training twice a week in addition to soccer training (5
times per week) caused greater increases in upper- and
lower-body strength and improved more vertical jump
performance compared with soccer training alone. Fur-
thermore, strength-soccer training improved agility time
and 30-m running speed compared with subjects who did
not get any structured training. Flexibility decreased
(8%), and 10-m acceleration time was not affected by
strength training.
All 3 groups increased their lower-body strength (leg
press). However, upper-body strength (bench press) im-
proved only in the STR group, whereas the SOC and CON
groups showed minor increases. These results, based on
the principle of specificity, confirm the findings of other
studies in children (29) and adolescents (20, 21). Lower-
body muscles are used more in daily physical activities
and are strengthened faster than the upper-body muscles
that may be used less frequently (29). Therefore, strength
training for the upper-body muscles of adolescents seems
to be necessary for an optimal growth of the whole body
and especially for participants in sports such as soccer,
where strength stimuli for the upper body are rare.
The high acceleration of sprint, the stopping move-
ments after a sprint, and the changes in direction are
actions that occur frequently in soccer. These activities
require the development and application of high forces
from the legs, causing a greater leg strength increase in
our soccer training group than natural growth. The spe-
cific effect that soccer has on leg strength is supported by
the fact that these adaptations are limited to the leg mus-
culature, because maximum strength of the arms, which
are not used in soccer, did not increase.
Specific neural adaptations, such as increased motor
unit recruitment and coordination, and improved coordi-
nation of the involved muscle groups have been reported
after resistance training programs in children and ado-
lescents (28, 29). The STR group improved significantly
in 1RM bench press without any increases in their flexed
midbiceps circumferences, indicating that strength in-
creases were mainly caused by neural adaptations. How-
ever, the possibility of muscular hypertrophy in adoles-
cents caused by strength training should not be over-
looked (8, 21, 25). The strength improvements of the low-
er body muscles (1RM leg press) for the STR group were
accompanied by an increase in midthigh and calf circum-
ferences, with minor changes in midthigh and calf skin-
fold sites. Although circumference increases may follow
natural growth and development (24), our data suggest
the possibility of muscular hypertrophy caused by
strength training. The use of advanced techniques, such
as magnetic resonance imaging, would provide better re-
sults on muscular hypertrophy in adolescents after
strength training.
Vertical jump performance (SJ and CMJ) increased
significantly only in the STR group. Our results confirm
previous studies with prepubescent active men (31, 36)
and pubescent athletes (21). It seems that the increase in
the maximal muscle force, as a result of strength training,
also improves muscular power, despite the absence of spe-
cific exercises for the improvement of jump performance.
To our knowledge this is the first study that shows sig-
nificant improvement in jumping ability as a result of
strength training in adolescent soccer players.
Strength training combined with soccer training or
soccer training alone had no effects on anaerobic capacity,
evaluated with the average height of repeated jumps for
30 seconds. Similarly, other studies using the Wingate
test in preadolescents and adolescent subjects did not find
changes in anaerobic capacity, after strength training (15,
21). In the STR group, SJ and CMJ performance in-
creased to a greater rate than in the SOC and CON
groups. Although no significant differences were observed
between groups for repeated jump performance, the STR
group showed higher performance than the SOC and
CON groups. The results may be caused by the different
neuromuscular and metabolic components of anaerobic
performance. Short-term power output (SJ and CMJ) de-
pends more on the degree of neuromuscular activation
than on energy provision from anaerobic metabolism (27).
Besides the need of high neuromuscular activation, the
30-second all-out test (intermediate anaerobic perfor-
mance) activates anaerobic glycolysis and causes lactate
production because of the length of the protocol. Thus,
when increasing their maximum strength, children and
adolescents can benefit to a greater degree on maximum
anaerobic power.
Running speed has been found to correlate with max-
imum strength and VJ performance (4, 21). However, an
improvement in maximum strength does not assure an
improvement in sprinting velocity as well (13, 37). In a
study concerning a similar age group with ours, Hetzler
et al. (21) did not find an improvement in a 40-yd sprint
in boys who followed strength training. In this study,
790 C
HRISTOU
,S
MILIOS
,S
OTIROPOULOS ET AL
.
however, where the STR group followed strength and
sprint training, a significant improvement in 30-m sprint
time was observed, along with an improvement in maxi-
mum strength and vertical jump performance. Soccer
training did not lead to an improvement in sprint despite
the fact that specific sprint training took place 2 days a
week. It seems that a combination of strength and speed
training may be more beneficial for speed development.
It should be noted, however, that based on the data of our
study, the transfer of strength gain to speed was rather
small (58.8% increase in leg strength vs. 2.5% in 30-m
speed), and a low correlation was observed between the
percent increase in leg strength and 30-m speed (r
0.24).
Agility was affected in a similar way in both the STR
and SOC groups, indicating the specificity of soccer train-
ing. Soccer training drills and games involved continuous
changes of direction. Thus, agility performance improved
with this type of training, without any further contribu-
tion from strength training. Furthermore, it is interesting
to note that the soccer training group improved only dur-
ing the agility test, which involved fast running with
changes in direction, and not in 30-m speed that involved
forward fast running. This probably reflects the specific-
ity of soccer training and the need for targeted speed
training for an overall improvement of soccer perfor-
mance. To our knowledge, the only study that examined
the effects of 12 weeks of strength training in agility in-
volving preadolescent boys was that of Falk and Mor (19)
and it is in agreement with our result. Despite these lim-
ited data, it seems that strength training has a minor
effect on agility performance of young people. There is a
minor transfer of the strength gain to agility, which prob-
ably involves a motor control pattern that is not strongly
influenced by the neural adaptations, which occur with
resistance training.
Flexibility increased in the soccer training group. Al-
though it was not significantly different from the control
group, it seems that the participation in soccer training
does not impair flexibility development when proper care
is taken to include stretching exercises in the training
program. Studies performed in adults reported that if
stretching exercises are part of the strength training pro-
gram, flexibility would not be impaired and it may even
increase (34). In this study, stretching exercises were per-
formed before, during, and after the strength training
sessions. However, flexibility of the hamstrings and the
lower back muscles decreased (8%) in the STR group. Pre-
vious studies involving children and prepubescents re-
ported either increases or no changes in flexibility after
strength training when using programs with low to mod-
erate volume and intensity (17–19, 32, 36). The high
volume and intensity of resistance training or the com-
bination of soccer and resistance training in our study
probably interfered with flexibility. More emphasis was
probably required on specific stretching exercises. Fur-
thermore, our subjects were adolescents and the phase of
their physical development might also interact with flex-
ibility levels. It should be noted that, even in the control
group, a slight decrease in flexibility was observed. Stud-
ies reported that inadequate flexibility might limit joint
mobility and predispose the muscles or the connective tis-
sue to injury and reduced performance (7, 34). However,
no injury was observed during the course of this study in
the STR group and other physical performance compo-
nents improved in this group. In any case, it seems that
additional stretching exercises or sessions for the main-
tenance or improvement of flexibility are necessary to
prevent muscles from becoming tight during strength
training. Further research is needed to determine which
factors might impede flexibility or not when adolescent
soccer players lift weights.
Resistance training had no effects on the soccer tech-
nique test used in this study. The nature of the test (drib-
bling with a ball between cones) is such that resistance
training would have a minor effect in comparison with a
training program focusing more on motor performance
development. This does not mean that resistance training
has no effect on any soccer-related action. If we had used
another soccer-specific test (e.g., speed of the ball after a
shot), we might have seen some sort of effect through the
increased leg force after strength training. For example,
Gorostiaga et al. (20) found that handball throwing ve-
locity in adolescent handball players increased after re-
sistance training. Furthermore, resistance training may
improve performance during a soccer game through a
greater speed and jumping ability, which help the player
to get control of the ball. In any case, it should be noted
that in this study we applied a low-frequency resistance
training program of moderate to submaximal intensity,
using basic core exercises and not sport specific strength
exercises, during the competition period. The aim was not
to maximize soccer performance but to develop the neu-
romuscular system of the athletes and help them to tol-
erate the mechanical stress of the various soccer actions
more and protect them from possible injuries. This might
be even more important than an improved performance
in the sport.
P
RACTICAL
A
PPLICATIONS
Soccer is a popular sport worldwide, and many youths
participate in soccer training programs. Soccer training
in adolescents provides a pleasant pastime and seems to
increase the parameters of physical capacity and soccer-
related skills. Soccer training alone improves maximal
strength of the lower-body muscles and agility, and when
stretching is included in the training program flexibility
also increases. The application of soccer training com-
bined with low frequency of moderate to submaximal in-
tensity resistance training offers an overall development
of physical capacities by improving in a greater degree
soccer-related abilities such as maximal strength of the
upper- and lower-body muscles, VJ performance, and 30-
m speed compared with regular soccer training. More em-
phasis should be given, however, to stretching exercises
when the soccer training program is combined with resis-
tance training. This may prevent any possible inconve-
nience caused after resistance training on flexibility dur-
ing the developmental period.
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Address correspondence to Savvas P. Tokmakidis,
stokmaki@phyed.duth.gr.
... Some of them demonstrated positive findings of general and soccer-specific performance and others not (Granacher et al., 2016). Among them, some studies applied resistance training additionally to soccer training (Christou et al., 2006), plyometric exercises into the regular soccer training (Negra et al., 2018), complex training (combining resistance and plyometric training) additionally to regular soccer training (Hammami et al., 2017) and only one study applied strength training by performing specific soccer movements with additional weight during regular soccer training (Bogiatzidis et al., 2022). In the above studies, some significant differences were observed between the experimental and control groups, specifically in maximal strength of the upper and/or the lower body (Christou et al., 2006;Bogiatzidis et al., 2022), in sprint times during 5-to 40-meters and in RSA (Hammami et al., 2017;Negra et al., 2018), in vertical jump height (CMJ, SJ or DJ) (Christou et al., 2006;Negra et al., 2018;Bogiatzidis et al., 2022) and in agility (Christou et al., 2006;Hammami et al., 2017). ...
... Among them, some studies applied resistance training additionally to soccer training (Christou et al., 2006), plyometric exercises into the regular soccer training (Negra et al., 2018), complex training (combining resistance and plyometric training) additionally to regular soccer training (Hammami et al., 2017) and only one study applied strength training by performing specific soccer movements with additional weight during regular soccer training (Bogiatzidis et al., 2022). In the above studies, some significant differences were observed between the experimental and control groups, specifically in maximal strength of the upper and/or the lower body (Christou et al., 2006;Bogiatzidis et al., 2022), in sprint times during 5-to 40-meters and in RSA (Hammami et al., 2017;Negra et al., 2018), in vertical jump height (CMJ, SJ or DJ) (Christou et al., 2006;Negra et al., 2018;Bogiatzidis et al., 2022) and in agility (Christou et al., 2006;Hammami et al., 2017). ...
... Among them, some studies applied resistance training additionally to soccer training (Christou et al., 2006), plyometric exercises into the regular soccer training (Negra et al., 2018), complex training (combining resistance and plyometric training) additionally to regular soccer training (Hammami et al., 2017) and only one study applied strength training by performing specific soccer movements with additional weight during regular soccer training (Bogiatzidis et al., 2022). In the above studies, some significant differences were observed between the experimental and control groups, specifically in maximal strength of the upper and/or the lower body (Christou et al., 2006;Bogiatzidis et al., 2022), in sprint times during 5-to 40-meters and in RSA (Hammami et al., 2017;Negra et al., 2018), in vertical jump height (CMJ, SJ or DJ) (Christou et al., 2006;Negra et al., 2018;Bogiatzidis et al., 2022) and in agility (Christou et al., 2006;Hammami et al., 2017). ...
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This study examined the effects of an on field combined strength/speed/soccer training program on the physical performance of 20 male adolescent (age: 14.0 ±0.7 years) soccer players, who were divided into an experimental and a control group (EG, CG). The EG players wore "weight shorts", with 300 gr of additional weight on each thigh and participated 2 times/ week in a 12-week training intervention program. The CG followed the same training program without wearing the "weight shorts". The physical abilities were evaluated the week before (pre) and two days after the 12-week intervention training period (post) and the follow-up evaluation was performed 4 weeks after the post measurement. The measured parameters were: a) sprint/repeated sprint ability (straight and with 180º turns, RSA-best/mean/total), b) RSA fatigue-index, c) vertical jump ability and d) lower body maximal strength. The EG improved significantly more (p < 0.05) compared to the CG on 10-m-straight, 30-, 35-, 40-m with 180º turns RSAbest-sprints, RSA fatigue-index, squat jump, leg curl (single right/left leg) and in split squat (single right/left leg) 5RM load. Using special shorts with additional weights on the thighs during soccer training improved speed/RSAbest-times and fatigue-index, jump ability and lower limbs maximal strength in youth soccer players.
... Adolescence is characterized by rapid physical development and the formation of unique motor skills, making it an ideal period for developing speed, strength, agility, endurance, balance and coordination. Early initiation of long-term, periodized strength conditioning is recommended for maximizing strength values in young athletes (Christou et al., 2006;Faigenbaum et al., 2009;Keiner et al., 2013). ...
... Prior studies have revealed that increased strength from training may enhance physical abilities such as long jump, vertical jump, 30-m dash, squat jump, and agility runs (Christou et al., 2006;Falk & Mor, 1996;Lillegard et al., 1997). Our findings are consistent with those of previous research. ...
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This study assessed the effect of routine chiropractic care combined with a three-month strength and conditioning program on the physical performance of adolescent basketball players. Thirty-one male athletes, aged 16-19, from elite Chinese national basketball camps, were divided into experimental and control groups. All subjects received cervical adjustment one time per week done by a team chiropractor. The program aimed to enhance agility, muscular strength, endurance, and speed through professional training. Measurements were taken at baseline, at six weeks, and after twelve weeks, using tests such as the ¾ court sprint, box agility, 1RM back squat, 1RM bench press, 65kg bench press for maximum reps, and 17-line shuttle run. The experimental group showed significant improvements in all metrics except the box agility test, while the control group exhibited fewer substantial changes. Results indicate that structured strength and conditioning programs combined with chiropractic adjustment significantly enhance adolescent athletes’ physical performance. The level of significance was set at p < 0.05. The study concludes that consistent chiropractic care and professionally supervised training are beneficial for adolescent athletes’ development, suggesting the integration of such programs into training routines for adolescent athletes to improve their physical capabilities and minimize injury risks.
... (24). Strength programs in soccer and in other sports that based on strength training have proved to be effective on development in sprint performance (22,40,44,46,49), vertical jump performance (1,6,14,28,32), change of direction performance (29,32), and overall athletic development (18). However, most of the studies were short-term interventions that were completed over 6-20 weeks (1,6,22,49). ...
... Strength programs in soccer and in other sports that based on strength training have proved to be effective on development in sprint performance (22,40,44,46,49), vertical jump performance (1,6,14,28,32), change of direction performance (29,32), and overall athletic development (18). However, most of the studies were short-term interventions that were completed over 6-20 weeks (1,6,22,49). It should be noted that short-term training programs may result in different physiological adaptations compared with long-term training programs. ...
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The aim of the study was to evaluate the effect of traditional strength training on maximum strength (1 repetition maximum in front squat and back squat), jump (squat and countermovement jump) and linear sprint performance (5m, 10m and 30m) in elite young soccer players. A 12-month longitudinal design was chosen, and 48 elite male youth soccer players (age: 12-15 years old) were included. The subjects were divided in two groups (a strength training group and a control group). The intervention group trained for one year over a competitive soccer season with additional sessions to their regular soccer practice (4 sessions per week), while the control group did not complete any additional sessions to the regular soccer training (4 sessions per week). The additional strength training (2 sessions per week [each about 30 minutes]) consisted of either parallel front squat or back squat. The squat variants switched in each session. Data were analyzed using a 2 x 3 (group x time) repeated measures ANOVA. The main findings of this study were that the strength training group resulted in significant pre- and post-test improvements in maximum strength (d = 3.75-5.58), jump (d = 0.84-1.14), and linear sprint performance (d = -0.25--0.44) while for the control group smaller increases/performance decreases were measured (maximum strength: d=1.64-2.7. jump: d=0.12-0.31, sprint d=0.00-025). A significant interaction effect in all variables indicated significant (p<0.05) stronger performance improvements compared to the control group. Traditional strength training in elite youth soccer players is recommended to increase strength and speed-strength (jump and sprint performance) and should be considered in long-term athletic development programs.
... The contribution of the SSC to performance is commonly assessed by differences in the vertical jumps: squat jump (SJ) and countermovement jump (CMJ) (120,243,245,252). These actions are widely used in soccer for the assessment of lower limb muscle strength (41,46,114), offering high test-retest reliability (92) and validity (156), and are easily implemented for assessments, monitoring, and training (43,61,200). Because of the SSC, performance on the CMJ is expected to be superior to that on the SJ (11,128). ...
Article
Santos, SCR, Oliveira, AR, Costa, RA, Nascimento, KSB, Alvares, PD, Medeiros, FB, Assumpç ã o, CO, Ramos, GP, Banja, T, Veneroso, CE, Claudino, JGO, and Cabido, CET. Stretch-shortening cycle utilization in female and male soccer players: A systematic review. J Strength Cond Res 38(10): e600-e625, 2024-The stretch-shortening cycle (SSC) enhances strength and power in soccer players. However, little consistent information is found on expected SSC utilization in soccer players. The aim of the present study was to provide information on SSC utilization in soccer players of different sexes, ages, and competitive levels through the calculation of the percent of prestretch augmentation (PPA ((CMJ 2 SJ)/SJ 3 100)). A systematic review was performed of studies involving soccer players. After screening 3,921 studies, 214 assessing a total of 11,941 players were considered eligible. Twenty studies involved females (747 subjects), 16 of which involved professionals (380 players), and 7 of which involved non-professionals (367 players). One hundred ninety-seven studies involved males (11,194 subjects), 56 of which involved professionals (2,508 players), 16 involved semiprofessionals (698 players), and 135 involved young athletes [67 involved postpubertal youths (2,439 players) and 85 involved youths (5,549 players)]. Prestretch augmentation was 9.35% (95% CI: 6.33-12.38%) for professional and 5.73% (95% CI: 3.06-8.40%) for nonprofessional female players. For males, PPA was 6.16% (95% CI: 5.03-7.29%) for professional players, 8.55% (95% CI: 5.76-11.33%) for semiprofessionals, 6.64% (95% CI: 5.76-7.53%) for postpubertal youths, and 7.00% (95% CI: 6.11-7.90%) for youths. Stretch-shortening cycle utilization measured based on PPA in the sample studied ranged from 3.06 to 12.38%. These values could serve as reference to indicate the appropriate use of SSC among soccer players according to competitive level and sex, which could help coaches and physical trainers develop appropriate training programs.
... Over the course of the season, the study's findings revealed improvements in jump performance and neuromuscular variables. (Christou et al., 2006) examined the effects of resistance training on adolescent soccer players. They found that a combined soccer and strength training programme resulted in improved physical abilities compared to soccer training alone. ...
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The study's goal was to examine or investigate the impact of resistance training on the anthropometric enhancement of tribal adolescence in Tirupattur District. The study's goal is to enhance anthropometric development through resistance training. There were 40 tribal high school volleyball players from Tirupattur district, Tamil Nadu, India. We randomly selected the players for this study. The age group ranged from 15 to 17 years. We divided the participants into two groups: the control group and the experimental group. Each group consists of 20 participants. The Lambert Adolphe Jacques Quetelet test evaluated the body mass index's anthropometric fitness component, while the Tom Venuto test assessed body fat. The experimental study's results show that resistance training produces significant improvements over anthropometric components like body mass index and body fat among tribal adolescents in Tirupattur District.
... As in other performance-based sports, it is known that vertical jumping abilities are closely related to the physical characteristics of soccer players (Wisloff et al., 2004). In the literature, it has been observed that anthropometric characteristics of athletes such as body composition, lower extremity strength, flexibility and jumping technique directly affect vertical jump performance (García-Pinillos et al., 2015;Chrıstou et al., 2006;Davis et al., 2003;Zanini et al., 2020;Blackburn & Morrissey, 1998). At the same time, many studies show that lower extremity strength levels of athletes have a positive relationship with vertical jump (CMJ) performance. ...
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The aim of this study was to investigate the relationship between lower extremity flexibility values and vertical jump performance of elite soccer players. Twenty-six young elite male soccer players voluntarily participated in the study. Age, height, and weight of the participants were determined as descriptive statistics. Lower extremity flexibility (.=ROM) test and vertical jump (counter movement jump=CMJ) performance determination test were applied to the participants. A goniometer was used for lower extremity flexibility measurement and My Jump 2 application, which has proven its validity and reliability, was used for CMJ performances. Descriptive characteristics of the participants included in the study were mean age: 16.23 ±.51 years, height: 172.96 ±7.56 cm, body weight: 63,15±7,69 kg. The mean values of CMJ performance of the participants were: 37,54±5,51; the mean value of lower extremity flexibility angles (ROM) was 115±4,99°. According to the data obtained, a statistically significant relationship was observed between ROM and CMJ performance characteristics of elite soccer players (p=.008) (p<0.05). According to the results obtained, a significant relationship was found between ROM and CMJ performances of soccer players. It can be said that teaching the importance of flexibility exercises to soccer players in soccer training programs and including them in training programs will positively affect the sudden power output performances of soccer players such as jumping.
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RESUMEN En el presente artículo presentamos un estudio que tiene por objeto analizar los efectos de un programa de entrenamiento combinado de Fuerza Explosiva (FEXp) y Sprints Repetidos (SR) en jugadores de tenis jóvenes de alto nivel. Nuestra hipótesis era que la combinación de los dos programas de entrenamiento tendría como resultado mejoras sustanciales en el rendimiento neuromuscular (es decir, los cambios en la potencia de salto y sprint) así como en la capacidad de repetir sprints (RSA). Los resultados mostraron que los sujetos objeto del estudio, mejoraron significativamente en prácticamente todas las variables de rendimiento analizadas, por lo que parece razonable pensar que una combinación de SR y FExp parece ser una herramienta eficiente de mejora del rendimiento neuromuscular así como de la RSA en jugadores de tenis.
Article
Wannouch, YJ, Leahey, SR, Whitworth-Turner, CM, Oliver, JL, YH, KC, Laffer, JC, and Leicht, AS. A comprehensive analysis of 10-yard sprint reliability in male and female youth athletes. J Strength Cond Res XX(X): 000-000, 2024-This study investigates the inter-week test-retest reliability of 10-yard sprint times in youth athletes. Although essential for assessing athletic ability and training efficacy, the critical and comprehensive examination of both relative and absolute reliability indices for short-distance sprints has been insufficient in youth contexts. One hundred ninety-eight youth athletes (128 males and 70 females) underwent 2 sprint attempts across 2 separate trials 24 hours apart and within 7 days of each other. The sprints were measured using dual-beam timing gates to capture split times for 0-5, 5-10, and 0-10 yards. The minimal mean difference between the best sprint times across trials was 0.02 6 0.13 seconds for males and 0.003 6 0.14 seconds for females. No significant mean differences were found between trials for either gender (males: p 5 0.0875; females: p 5 0.8752), suggesting no systematic bias in sprint times. The SEM was 0.092 seconds for males and 0.099 seconds for females, with a corresponding SEM CV% of 4.6 and 4.8%. The overall coefficient of variation was 9.8% for males and 8.9% for females. Intraclass correlation coefficient values suggested that the sprint times across trials were reliable (males: 0.80; females: 0.76). The minimal detectable change was 0.25 seconds for males, 0.27 seconds for females. Cohen's d indicated trivial effects (,0.2) for males (0.154) and females (0.021). Minimal mean differences, a low SEM, and consistent ICC values demonstrate that the 0-10-yard sprint is a reliable assessment in youth athletes.
Chapter
Plant breeding is a promising technique to create and exploit the genetic variations in plants. The current updates in genetic engineering (GE) are also to boost plant research and plant breeding programs for sustainable agriculture. The nearly magical advancement of GE offers plant varieties exhibiting traits of agricultural interest, such as insect resistance, herbicide tolerance, as well as outstanding agronomic properties and superior-quality values. With the advancements in genetically modified (GM) crops with improved nutritious qualities, some of the elements stalled its development for instance; regulatory approval, consumer and societal acceptance, non-government organization opposition, and economic value. All these factors contribute to the delayed commercialization of GE plants. Nevertheless, the new advancements in genetic engineering are constantly evolving government policy regarding the widespread adoption of some of these techniques. However, the morality of altering an organism’s genetic makeup and the possibility that doing so may have unfavorable consequences for those who ingest it remain open questions. To ascertain the possible future application of GE, it is essential to carefully consider its advantages and disadvantages. This chapter provides a detailed analysis of GE plants, exploring their merits and drawbacks from diverse angles. This comprehensive examination is indispensable for gauging their acceptance on a wider level. Consequently, additional research efforts are imperative to gain insight into the effects of GE plants within ecosystems. The widespread adoption of GM crops has led to the overuse of a small number of cultivars compared to wild varieties. Consequently, this study tackles numerous concerns regarding food safety, environmental impacts, and socioeconomic issues. In summary, based on this research, there is a potential for increased prominence of the GMO debate among the general population and a clear trend toward greater acceptance in the future.
Book
Bu kitap, Mehmet Söyler tarafından hazırlanan \"Bölgesel Amatör Lig Futbolcularında Mevkilerine Göre Bazı Fiziksel ve Teknik Parametlerinin Sezonsal Değişimlerinin İncelenmesi\" adlı tezden üretilmiştir. Kitap, bölgesel amatör lig futbolcularının mevkilerine göre fiziksel ve teknik parametrelerindeki sezonsal değişimleri incelemektedir. Tez, Gazi Üniversitesi Sağlık Bilimleri Enstitüsü'nde kabul edilmiş olup, danışmanlığını Prof.Dr. Mehmet Günay yapmıştır. Kitap, bölgesel amatör lig futbolcularının performanslarını etkileyen faktörleri ve bu faktörlerin mevsimsel değişimlerini ele almaktadır. Bu çalışma, futbolcuların fiziksel ve teknik özelliklerinin sezon boyunca nasıl değiştiğini anlamak için önemli bir kaynak olabilir. This book is derived from the thesis titled \"Investigation of Seasonal Changes in Physical and Technical Parameters of Regional Amateur League Football Players According to Their Positions\" prepared by Mehmet Söyler. The book examines the seasonal changes in the physical and technical parameters of regional amateur league football players according to their positions. The thesis was accepted at the Institute of Health Sciences at Gazi University and supervised by Prof. Dr. Mehmet Günay. The book addresses the factors that affect the performance of regional amateur league football players and the seasonal changes in these factors. This study can be an important source to understand how the physical and technical characteristics of football players change throughout the season.
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This study examined the effects of training frequency on strength maintenance in 21 trained pubescent male baseball players (mean age 13.25 +/- 1.26 yrs). The subjects completed 12 weeks of preseason, progressive strength training 3 days a week and were assigned to 1 of 3 experimental groups for an additional 12 weeks of in-season maintenance training. Group 1 (n = 7) lifted weights 1 day a week, Group 2 (n = 8) lifted weights 2 days a week, and a control group (n = 6) did not train during this 2nd 12 weeks. The preseason strength training program revealed significant increases (p < 0.05) for all groups in upper (bench press) and lower (leg press) body strength and dynamic upper body muscular endurance (pull-up). Following the 12-week in-season maintenance program, significant differences (p < 0.05) were observed between the control group and both training groups for the bench press. However, no significant differences were revealed between groups for the leg press or pull-up. It was concluded that for pubescent male athletes, a 1-day-a-week maintenance program is sufficient to retain strength during the competitive season. (C) 1996 National Strength and Conditioning Association
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The purpose of the present study was to determine the effect of a 12-week training program on the motor performance of 6- to 8-year-old prepubertal boys (n = 14). Each subject participated in a 40-min session twice a week, which included three sets of upper body strength exercises (1 to 15 repetitions/ set), unregimented lower body strength exercises, coordination, balance, and martial arts skills. The control group included 15 prepubertal boys in the same age range. All subjects were pre- and posttested on 20-s sit-ups, seated ball put, standing broad jump, sit-and-reach flexibility, 6 × 4-m shuttle run, and a coordination task. The experimental group improved significantly (p < .05) more than the control group in the sit-ups and in the long jump. Both groups improved (p < .05) in the coordination task. No significant changes were observed in body weight, seated ball put, flexibility, and shuttle run. A twice-weekly training program seems to improve performance in selected motor tasks in 6- to 8-year-old boys.
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The effectiveness of a twice-a-week strength training program on children was evaluated in 14 boys and girls (mean age 10.8 yrs) who participated in a biweekly training program for 8 weeks. Each subject performed three sets of 10 to 15 repetitions on five exercises with intensities ranging between 50 and 100% of a given 10-repetition maximum (RM). All subjects were pre- and posttested on the following measures: 10-RM strength, sit and reach flexibility, vertical jump, seated ball put, resting blood pressure, and body composition parameters. The subjects were compared to a similar group of boys and girls (n = 9; mean age 9.9 yrs) who were randomly selected to serve as controls. Following the training period, the experimental group made greater gains in strength (74.3%) as compared to the control group (13.0%) (p < 0.001), and differences in the sum of seven skinfolds were noted (−2.3% vs. +1.7%, respectively, p < 0.05). Training did not significantly affect other variables. These results suggest that parti...
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This abridged version of the "Anthropometric Standardisation Reference Manual" contains the heart of the original manual - complete procedures for 45 anthropometric measurements. Its style enables it to be used as a supplemental text for courses in fitness assessment and exercise prescription, kinanthropometry, body composition, nutrition, and exercise physiology. It can also be used as a reference for exercise scientists. For each of the 45 measurements included in this abridged edition, readers will find complete information on the recommended technique for making the measurement, the purpose and uses for the measurement, the literature on which the measurement technique is based, and the reliability of the measurement.
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The second edition of "Growth, Maturation, and Physical Activity" has been expanded with almost 300 new pages of material, making it the most comprehensive text on the biological growth, maturation, physical performance, and physical activity of children and adolescents. The new edition retains all the best features of the original text, including the helpful outlines at the beginning of each chapter that allow students to review major concepts. This edition features updates on basic content, expanded and modified chapters, and the latest research findings to meet the needs of upper undergraduate and graduate students as well as researchers and professionals working with children and young adults. The second edition also includes these new features: -10 lab activities that encourage students to investigate subject matter outside of class and save teachers time-A complete reference list at the end of each chapter -Chapter-ending summaries to make the review process easy for students-New chapters that contain updates on thermoregulation, methods for the assessment of physical activity, undernutrition, obesity, children with clinical conditions, and trends in growth and performance-Discussions that span current problems in public health, such as the quantification of physical activity and energy expenditure, persistent undernutrition in developing countries, and the obesity epidemic in developed countriesThe authors are three of the world's foremost authorities on children's growth and development. In 29 chapters, they address introductory concepts and prenatal growth, postnatal growth, functional development, biological maturation, influencing factors in growth, maturation and development, and specific applications to public health and sport. In addition, secular trends in growth, maturation, and performance over the past 150 years are considered. You'll be able to recognize risk factors that may affect young athletes; you'll also be able to make informed decisions about appropriate physical activities, program delivery, and performance expectations. "Growth, Maturation, and Physical Activity, Second Edition, " covers many additional topics, including new techniques for the assessment of body composition, the latest advances in the study of skeletal muscle, the human genome, the hormonal regulation of growth and maturation, clarification of dietary reference intakes, and the study of risk factors for several adult diseases. This is the only text to focus on the biological growth and maturation process of children and adolescents as it relates to physical activity and performance. With over 300 new pages of material, this text expertly builds on the successful first edition.