Journal of Strength and Conditioning Research, 2007, 21(2), 431–437
䉷2007 National Strength & Conditioning Association
Faculty of Sport Science, Marc Bloch University, Strasbourg, France;
Performance Expertise Center, Faculty of
Sport Science, University of Burgundy, Dijon, France;
French Rugby Federation, Paris, France;
207 Motricity-Plasticity, Faculty of Sport Science, University of Burgundy, Dijon, France;
Physiology, St-Etienne, France.
.Babault, N., G. Cometti, M. Bernardin, M. Pousson,
and J.-C. Chatard. Effects of electromyostimulation training on
muscle strength and power of elite rugby players. J. Strength
Cond. Res. 21(2):431–437. 2007.—The present study investigat-
ed the inﬂuence of a 12-week electromyostimulation (EMS)
training program performed by elite rugby players. Twenty-ﬁve
rugby players participated in the study, 15 in an electrostimu-
lated group and the remaining 10 in a control group. EMS was
conducted on the knee extensor, plantar ﬂexor, and gluteus mus-
cles. During the ﬁrst 6 weeks, training sessions were carried out
3 times a week and during the last 6 weeks, once a week. Iso-
kinetic torque of the knee extensors was determined at different
eccentric and concentric angular velocities ranging from ⫺120
. Scrummaging and full squat strength, vertical jump
height and sprint-running times were also evaluated. After the
ﬁrst 6 weeks of EMS, only the squat strength was signiﬁcantly
improved (⫹8.3 ⫾6.5%; p⬍0.01). After the 12th week, the
maximal eccentric, 120 and 240⬚·s
tric torque (p⬍0.05), squat strength (⫹15.0 ⫾8.0%; p⬍0.001),
squat jump (⫹10.0 ⫾9.5%; p⬍0.01), and drop jump from a 40-
cm height (⫹6.6 ⫾6.1%; p⬍0.05) were signiﬁcantly improved.
No signiﬁcant change was observed for the control group. A 12-
week EMS training program demonstrated beneﬁcial effects on
muscle strength and power in elite rugby players on particular
tests. However, rugby skills such as scrummaging and sprinting
were not enhanced.
. isokinetic torque, scrum, sprint, vertical jump
Rugby competition is typically characterized by
high-intensity activities (15% of the game
time) interspersed with low-intensity activities
(11). On average, 70% of the high-intensity ac-
tions last from 4 to 10 seconds with the major-
ity of rest periods being shorter than 40 seconds (26).
Therefore, in addition to equally essential technical skills
and aerobic endurance (required for low-intensity activi-
ties), rugby players must have sufﬁcient anaerobic capac-
ities to produce high levels of muscular strength, power,
and speed (4, 8) required for heavy physical body contacts
and sprints with or without the ball. As a matter of fact,
professionals appear stronger and more powerful than
younger players for both the upper and lower body (3).
Consequently, before and during the rugby season, play-
ers participate in resistance training programs designed
to improve and maintain their anaerobic parameters at
high levels during the entire competition season (2).
Various training modalities can be used for improving
muscular strength. More particularly, electromyostimu-
lation (EMS) has been previously employed as a means
of strength training in healthy humans (18, 31, 33). Many
authors have reported increases in maximal voluntary
torque during isometric actions for joint angles close to
the training angle (20) and during isokinetic solicitations
for a wide range of concentric and eccentric angular ve-
locities (10, 20). Nevertheless, while monoarticular per-
formance enhancements are well established, the EMS
training effects during complex and speciﬁc polyarticular
abilities remain unclear. Indeed, immediate signiﬁcant
improvements of the vertical jump height have been re-
corded (21, 38) but remain debated (9, 24). For example,
Malatesta et al. (24) only registered vertical jump im-
provements 10 days after the end of the EMS training.
Performance improvements, induced by EMS, may origi-
nate from neural factors (10, 13, 22) as well as changes
in the muscle itself (15, 32) but seem to be closely related
to training durations. Neural adaptations, revealed by
both muscular activation and electromyographic activity
increases, are mainly obtained after short EMS training
periods (⬍4 weeks) (15, 22), whereas longer training du-
rations (e.g., 8 weeks) are accompanied by signiﬁcant
muscular hypertrophy (15, 32).
Recently, some studies have examined the training-
induced adaptations following short-term EMS programs
on speciﬁc athlete performance of various team sports (9,
20, 21). However, no study has attempted to investigate
EMS training effects in rugby players. Therefore, the
main purpose of the present investigation was to deter-
mine the inﬂuence of an EMS training program on mus-
cle strength and power of elite rugby players. Studies re-
lated with EMS predominantly considered short periods
(⬍4 weeks). Therefore, long-term effects were investigat-
ed here while performing 12 weeks of EMS training. Be-
cause highly skilled rugby players were considered, this
12-week training duration seems more appropriate for
neuromuscular adaptations and for neuromuscular per-
formance improvements during complex and speciﬁc abil-
ities. The training program was divided into two 6-week
intervals to simulate a taper period. We, therefore, hy-
pothesized that 12 weeks of EMS training was beneﬁcial
for elite rugby players and that reducing training sessions
during the last 6 weeks was associated with additional
physical performance improvements.
Experimental Approach to the Problem
This study was designed to determine whether a long-
term EMS training program (12 weeks) has beneﬁcial ef-
ERNARDIN ET AL
1. Illustration of the training procedure for both elec-
trostimulated (ES) and control groups (C). During the experi-
mental procedure, both groups performed rugby trainings with
the same coach (5 sessions a week). In addition, the ES group
underwent a 12-week electromyostimulation (EMS) training.
Tests at week 6 and 12 were the same as those performed be-
fore training. MVC ⫽maximal voluntary contraction; 1RM ⫽
1 repetition maximum; SJ ⫽squat jump; CMJ ⫽counter
movement jump; DJ ⫽drop jump; 15J ⫽15 consecutive CMJ.
fects in elite rugby players. Muscular adaptations were
investigated by measuring the isokinetic torque during
maximal voluntary eccentric and concentric knee exten-
sions, scrummaging, and full squat strength, vertical
jump performance, and sprint-running times. These var-
iables were tested on 3 occasions: pretraining (week 0,
beginning of the EMS training), mid-training (week 6),
and posttraining (week 12). Two groups of elite rugby
players were considered. During the 12-week period, the
ﬁrst group (control, C) only followed rugby trainings. The
second group (electrostimulated, ES), in addition to the
same rugby training, underwent a 12-week EMS training
on the knee extensor, plantar ﬂexor, and gluteus muscles.
During the ﬁrst 6 weeks, the EMS training program con-
sisted of 3 sessions a week. Only 1 session per week was
applied during the remaining 6 weeks to simulate a taper
period (Figure 1). Statistical analyses of pretraining, mid-
training, and posttraining values allowed us to evaluate
the effect of 12-week EMS training on physical perfor-
mances of elite rugby players. Independent variables
were time (pretraining, midtraining, and posttraining)
and group (ES and C). Values obtained for the different
tests were used as dependent variables.
A group of 25 highly skilled rugby players competing in
the ﬁrst or second division of the French Rugby league
(with 3 players also competing in the national French
team) participated in this study. All were members of the
national French military team and were trained by the
same coach. They were randomly divided into 2 groups.
Fifteen subjects were assigned to the electrostimulation
group (ES) and the remaining 10 served as controls (C).
Mean age, height, and mass were 22 ⫾1 year, 187.0 ⫾
8.5 cm, 93.2 ⫾13.0 kg and 22 ⫾1 year, 180.5 ⫾3.2 cm,
85.9 ⫾10.6 kg, respectively, for ES and C groups. After
being informed about the nature of the experiment, sub-
jects agreed to take part in the study on a voluntary basis
and provided their written informed consent for partici-
pation. The experimental procedure was performed in ac-
cordance with the declaration of Helsinki and was ap-
proved by the local committee of human research.
Training. The present experiment started about 2 weeks
after the end of the midwinter break. During this period,
all athletes (i.e., ES and C group) took part in speciﬁc
rugby workouts supervised by the national French mili-
tary team coach (5 sessions a week including, e.g., defen-
sive and attacking fundamentals). Special attention was
given to reduce any training difference depending on
player positions, and none of the subjects completed ad-
ditional weight training. In addition to this rugby train-
ing, the ES group performed an EMS training program
lasting 12 weeks. The EMS program was divided into 2
periods. The ﬁrst 6 weeks consisted of 18 EMS sessions
(12 minutes for each muscle group) with 3 sessions a
week. During the remaining 6-week period, EMS training
was composed of only 1 EMS session per week (Figure 1).
EMS sessions were performed at the same time of the day
and same days of the week.
EMS was delivered bilaterally on knee extensor, then
plantar-ﬂexor, and ﬁnally gluteus muscles using a por-
table battery-powered stimulator (Compex Medical SA,
Ecublens, Switzerland). Rectangular-wave pulsed cur-
rents (100 Hz) lasting 400 s were used as previously
recommended (16, 36). Indeed, rectangular waves asso-
ciated with long pulse durations (300 to 400 s) appear
to produce the most powerful contraction of the quadri-
ceps muscle group (7); 100 Hz stimulation frequencies
were used because 50 to 120 Hz frequencies have been
shown to be the most efﬁcient for strength training (16).
During the 12-minute EMS sessions, contractions, lasting
5 seconds, were followed by 15 seconds of rest. During
each session and for each muscle group, 36 contractions
were completed. These stimulation characteristics were
selected among the Compex commercially available
strength programs. Because elite athletes were consid-
ered, the most difﬁcult strength program was chosen and
slightly modiﬁed (i.e., contraction number, rest time) to
reduce EMS sessions durations. The stimulation intensity
(range 0–100 mA) was monitored on-line and determined
by the subject at the start of each EMS session according
to his pain threshold and so as to produce a force corre-
sponding to at least 60% of the pretest maximal voluntary
contraction (MVC) score. This level was measured and
veriﬁed by the examiner on the knee extensor muscles
with a myostatic type dynamometer (Allegro, Sallanches,
France). No subject reported serious discomfort from this
current. Each session was preceded by a standardized
warm-up, consisting of 5 minutes of submaximal EMS (5
Hz pulses; pulses lasting 200 s).
The EMS was delivered using 2-mm thick self-adhe-
sive electrodes. Pairs of positive electrodes (each measur-
ing 25 cm
;5cm⫻5 cm), which have the property of
depolarizing the membrane, were placed as close as pos-
sible to the motor point of the vastus lateralis, vastus me-
dialis, medial and lateral gastrocnemius, and gluteus
maximus muscles. Rectangular negative electrodes, each
measuring 50 cm
(10 cm ⫻5 cm), were placed over the
femoral triangle of each leg (1–3 cm below the inguinal
ligament), over the proximal aspect of the gastrocnemii
and gluteus, i.e., close to the proximal insertion of the
respective muscle. During EMS of the knee extensor mus-
cles, subjects were seated on a leg extension machine
(Multiform, La Roque D’Anthe´ ron, France) with the knee
ﬂexed and ﬁxed at a 60⬚joint angle (0⬚corresponding to
complete knee extension). For plantar ﬂexor muscles
EMS, subjects were seated on a calf machine (Multiform)
with joint angles at the hip, knee and ankle maintained
at ⬃90⬚. The subjects lay in the prone position during
EMS of the gluteus muscles.
Tests were carried out in both groups before (week 0), in
the middle (week 6), and immediately after the end of the
training period (week 12) (Figure 1). Tests, conducted in
a single session, consisted in the evaluation of (a) mus-
cular strength by measuring the maximal voluntary iso-
kinetic eccentric and concentric torque production capac-
ity, scrimmaging, and squat strength and (b) power with
the determination of vertical jump heights and power and
Isokinetic Tests. The maximal voluntary torque of the
right knee extensor muscles was measured using a Biod-
ex isokinetic dynamometer (Biodex, Shirley, NY) validat-
ed by Taylor et al. (35). Subjects were seated upright on
the dynamometer chair with a 95⬚hip angle. Velcro
straps were applied tightly across the thorax and pelvis;
the leg being ﬁxed to the dynamometer lever-arm. The
axis of rotation of the dynamometer was aligned to the
lateral femoral condyle, indicating the anatomical joint
axis of the knee. Arms were positioned across the chest
with each hand clasping the opposite shoulder. After a
standardized warm-up session including submaximal
concentric and eccentric knee extensions with progres-
sively increasing intensity until the MVC, subjects per-
formed maximal voluntary leg extensions at 8 different
angular velocities. Two eccentric (⫺60 and ⫺120⬚·s
6 concentric (60, 120, 180, 240, 300 and 360⬚·s
velocities were considered. Three consecutive contrac-
tions were achieved for each angular velocity and only the
best peak voluntary torque was retained for analysis. An-
gular velocities were randomly presented and a 4-minute
rest period was allowed between each velocity to avoid
fatigue effects. Leg extensions were conducted within a
90⬚range of motion (from 90 to 0⬚;0⬚corresponding to the
complete knee extension). Appropriate corrections were
made for the gravitational effect of the leg for all torque
measurements. Whatever the contraction, subjects were
strongly encouraged by the same investigator to push as
hard as possible to perform all actions maximally, i.e.,
throughout the whole range of motion for concentric and
Scrum Test. Speciﬁc rugby strength was measured us-
ing a scrum machine (Multiform). The isometric scrum-
maging force was assessed by means of strain gauge force
transducers (Captels, St. Mathieu de Tre´ viers, France).
The scrum machine was ﬁxed in a horizontal position
with height adjusted according to each subject’s position.
Subjects were free to choose their scrummaging position.
Knee ﬂexion angles and feet positions were determined
individually and ﬁxed using wedges. Positions were re-
corded so as to be identical for all test sessions. Each play-
er was allowed to perform three 5-second trials, in which
he attempted to push as hard as possible against the 2
central pads of the machine. Four-minute rest periods
were allowed between trials. Force, measured at stabili-
zation after impact, was evaluated for all trials and only
the best performance was retained for analysis.
Squat Test. Subjects were evaluated during concentric
strength tests while performing full squats (starting po-
sition ⫽complete knee ﬂexion). Players were tested for 1
repetition maximum (1RM) using standard Olympic style
bar and weights. Players were familiar with squats since
all have previously performed such movements during
their training program. Each subject performed submax-
imal repetitions at low weights for warm-up before grad-
ually increasing the load (10-kg increments, then 5-kg in-
crements near maximum) until the maximum. Four-
minute rest periods were allowed between trials.
Vertical Jump Tests. Jumping ability was evaluated
with a contact mat (Ergo tests, Globus, Codogne, Italy)
measuring the ﬂight time of the jumps. Squat jumps (SJ),
counter movement jumps (CMJ), drop jumps (DJ), and 15
repetitive CMJ (15J) were randomly performed. For each
test, subjects were asked to jump as high as possible with
their hands kept on the hips to minimize the contribution
of the upper body. The SJ started from a static semis-
quatting position (⬃90⬚knee ﬂexion), maintained ⬃1 sec-
ond; subjects were instructed to jump without any prelim-
inary movement. The CMJ started from a standing posi-
tion. Subjects were instructed to squat down until a 90⬚
knee ﬂexion angle and to extend the knee in 1 continuous
movement. The DJ started from a standing position at a
40-cm height above the ﬂoor. Subjects then dropped on
the contact mat, squatted down until 90⬚knee ﬂexion and
extended the knee in 1 continuous movement. Three tri-
als were performed for SJ, CMJ, and DJ, with a 2-minute
rest period between trials, and the best performance was
recorded. For 15J, 15 consecutive CMJ were performed
without any rest between jumps. Only 1 trial was
achieved for this jump test. The average height and power
were then calculated according to single jump ﬂight and
Sprint Test. Because, high-intensity rugby actions are
shorter than 10 seconds (21), running times were evalu-
ated during 20- and 50-m maximal running tracks using
infrared photoelectric cells (TT Sport, Dogana, San Ma-
rino). Cells, positioned at a 1.15-m height, were placed 20
and 50 m from the start line. Subjects started in a stand-
ing position and ran the 50-m distance as fast as possible.
During this maximal run, both the 20- and 50-m times
ERNARDIN ET AL
2. Torque-angular velocity relationships of the knee
extensors for electrostimulated (ES, upper graph) and control
groups (C, lower graph) before and after a 6-week and 12-week
period. Values are mean (⫾SE). * Differences between values
obtained before and after the 12-week training period (p⬍
3. Squat performance (kg) for electrostimulated and
control groups before and after a 6-week and 12-week period.
Values are mean (⫾SE). Differences between before, week 6,
and week 12 are shown (* p⬍0.05, ** p⬍0.01, and *** p⬍
4. Scrummaging performance (kg) for electrostimu-
lated and control groups before and after a 6-week and 12-
week period. Values are mean (⫾SE). The electrostimulated
(ES) group showed signiﬁcantly higher values than the control
(C) group. Whatever the group, no difference was obtained
with time (before vs. week 6 vs. week 12).
were measured. These performances did not include the
reaction time. Three trials were performed with a 4-min-
ute rest period, and the best performance was retained
for subsequent statistical analysis.
Mean values ⫾SD were calculated for all dependent var-
iables (i.e., knee extension torque, scrum and squat
strength, vertical jump height or power, and running
times). Figures are presented as mean value ⫾SE for
more clarity. Values were analyzed using a 2-way anal-
ysis of variance to test differences between groups (ES or
C) and time (before, after week 6, or after week 12). Time
factor was analyzed as repeated measures. Fratio was
considered signiﬁcant at a plevel less than 0.05. A New-
man-Keuls post hoc test was conducted if signiﬁcant main
effects or interactions were present. Statistical analyses
were undertaken using Statistica software for Windows
(StatSoft, Version 5, Tulsa, OK).
At midtraining, the ES group did not exhibit any modi-
ﬁcation of the torque-angular velocity relationship (Fig-
ure 2). After 12 weeks of training, the ES group exhibited
signiﬁcant voluntary torque improvements (p⬍0.05) un-
der eccentric (⫹18.0 ⫾26.3% at ⫺120⬚·s
) and concentric
conditions (⫹19.4 ⫾28.9% at 120⬚·s
and ⫹10.0 ⫾21.5%
) compared with pretraining. In the same way,
the squat strength enhancement was ⫹8.3 ⫾6.5% and
⫹15.0 ⫾8.0%, respectively after a 6- (p⬍0.01) and 12-
week (p⬍0.01) EMS training period (Figure 3). A sig-
niﬁcant squat improvement was also recorded between
mid- and posttraining (⫹6.2 ⫾4.9%; p⬍0.05). The
scrummaging strength did not demonstrate any time ef-
fect (Figure 4).
A signiﬁcant improvement in vertical jump height (p
⬍0.05) was obtained after 12 weeks of EMS training for
SJ and DJ (Table 1). For these 2 tests (SJ and DJ), no
difference was recorded when comparing values regis-
tered before and after 6 weeks of EMS training. After the
12th week, the performance enhancement was ⫹10.0 ⫾
9.5% (p⬍0.01) and ⫹11.8 ⫾9.9% (p⬍0.001) for SJ and
⫹6.6 ⫾6.1% (p⬍0.05) and ⫹7.6 ⫾5.7% (p⬍0.05) for
DJ when respectively compared with pre- and midtrain-
1. Vertical jump performances (mean value ⫾SD)on
electrostimulated (ES) and control (C) groups before and after a
6-week and 12-week training period.*
Group Before Week 6 Week 12
SJ (cm) ES 33.5 ⫾3.5 33.0 ⫾4.0 36.7 ⫾3.6 ‡㛳
C 37.9 ⫾4.8 36.8 ⫾3.7 38.1 ⫾4.1
CMJ (cm) ES 39.0 ⫾3.9 37.2 ⫾3.6 40.1 ⫾4.3
C 42.8 ⫾5.0 42.3 ⫾4.7 43.3 ⫾4.3
DJ (cm) ES 34.6 ⫾2.5 34.3 ⫾2.9 36.7 ⫾2.2 †§
C 41.6 ⫾4.3 40.5 ⫾6.3 43.8 ⫾3.1
15J height (cm) ES 30.7 ⫾3.1 29.8 ⫾2.9 30.8 ⫾3.3
C 35.7 ⫾2.9 33.2 ⫾3.6 34.6 ⫾3.6
15J power (W) ES 37.3 ⫾6.2 38.1 ⫾5.8 40.0 ⫾6.8
C 42.3 ⫾5.7 41.0 ⫾8.3 42.7 ⫾7.1
*SJ ⫽squat jump; CMJ ⫽counter movement jump; DJ ⫽
drop jump; 15J ⫽15 repetitive CMJ. Differences between before
and week 12 training are shown († p⬍0.05 and ‡ p⬍0.01).
Differences between week 6 and 12 are also shown (§ p⬍0.05
and 㛳p⬍0.001). Except for 15J power and SJ after week 12,
group C exhibited signiﬁcantly higher values than group ES.
2. Running times for electrostimulated (ES) and con-
trol (C) groups over 20 and 50 m before and after a 6-week and
12-week training period. Values are mean ⫾SD.*
Group Before Week 6 Week 12
20 m (s) ES 3.17 ⫾0.11 3.24 ⫾0.14 3.18 ⫾0.11
C 3.01 ⫾0.10 3.14 ⫾0.19 3.05 ⫾0.11
50 m (s) ES 6.82 ⫾0.29 6.92 ⫾0.33 6.82 ⫾0.26
C 6.31 ⫾0.19 6.46 ⫾0.19 6.38 ⫾0.17
* Group C exhibited signiﬁcantly lower values than ES. What-
ever the group, no difference was obtained with time (before vs.
week 6 vs. week 12).
ing tests. No difference was obtained with time for ES
when considering the 2 other jump tests (i.e., CMJ and
15J) and running times (Table 2).
At baseline, the ES group exhibited signiﬁcantly high-
er scrummaging values and lower vertical jump and
sprint performances than the C group. No difference was
obtained for the torque-angular velocity relationship and
squat strength. After the 6-week and 12-week periods, the
C group did not demonstrate any signiﬁcant changes for
EMS is largely employed for strength training but no
study has established its effect in rugby players. The
present study demonstrated that a 12-week EMS training
program has positive effects on muscle strength and pow-
er of highly skilled rugby players. Moreover, reduction of
the training session number from 3 to once a week during
the last 6 weeks, like in a taper period, was beneﬁcial for
physical performance improvements.
After a 12-week training period, EMS produced im-
provements in (a) muscle strength as revealed by maxi-
mal voluntary torque and squat strength measurements
and (b) power (i.e., SJ and DJ height). Although per-
formed isometrically, gains were primarily registered
during dynamic and more particularly concentric actions.
Moreover, the stimulation of the main extensor muscles
of the lower limb yield to improvements in both single-
joint and multi-joint performances.
Posttraining, rugby players exhibited increases in
squat strength and maximal voluntary torque during iso-
kinetic tests performed under eccentric (⫺120⬚·s
concentric conditions (120 and 240⬚·s
). Magnitudes of
the relative strength increases (on average ⫹16%) were
consistent with previous EMS studies (9, 20, 29) but ap-
peared larger than reported by others (10, 25). Gains
were obtained after the 12th week, whereas the previous
experiments consisted in shorter training programs (e.g.,
3 weeks for ref. 29). For example, after a 4-week EMS
training period, Mafﬁuletti et al. (20) registered a 29%
torque increase under eccentric condition at ⫺120⬚·s
Using slightly longer training duration (7 weeks) Colson
et al. (10) registered only ⬃10% torque increases at a
eccentric angular velocity. Differences between
the present experiment and these studies could be partly
attributed to differing stimulation modes (e.g., stimula-
tion frequencies), muscle group (knee extensors vs. elbow
ﬂexors), and training status of the subjects considered.
Indeed, in the present study, subjects were all highly
skilled rugby players. It is generally accepted that
strength gains, consecutive to training, are usually lower
for highly skilled than for sedentary subjects (1). There-
fore, long-term EMS seems to be more appropriate for
elite rugby players to improve muscle strength.
Paradoxically, the present study showed performance
improvements for squat strength and not for scrummag-
ing. High muscle strength of the whole lower body
(trained here with EMS) is needed to obtain elevated per-
formances for these 2 tests. The lack of gain in the scrum
test could be partly explained by factors such as tech-
nique or motivation. Quarrie and Wilson (30) demonstrat-
ed that the scrum force was primarily related to anthro-
pometric characteristics and physical factors such as an-
aerobic power attained on a cycle ergometer and to a less-
er extent to isokinetic knee extension torque. Therefore,
it may be postulated that isokinetic torque increases, ob-
served in the present study, were not sufﬁcient to induce
enhancements of scrummaging performance. Further-
more, both forward and back players participated in this
experiment. Backs, uninvolved and unfamiliar with
scrummaging, were technically less skilled for strength
transfer for this type of exercise. Quarrie and Wilson (30)
noted that technique and coordination may be the most
important parameters for maximal scrum force. There-
fore, association of technique and EMS training might
lead to performance improvements and might also mini-
mize the risk of potential injury during the rugby union
Muscular strength, enhanced with EMS, is an essen-
tial anaerobic characteristic for rugby players. Power, as
well as important for rugby players, was also improved
as revealed by SJ and DJ height increases. However, both
repetitive jumps (15J) and running times remained un-
changed after the 12-week training period. The lack of
change, in disagreement with previous investigations (9,
24), was unexpected since EMS was performed on the
main lower limb extensor muscles. According to Wisloff
et al. (37), gains of maximal quadriceps femoris isokinetic
torque and squat strength should have been associated
with decreased sprint times. However, Wisloff et al. (37)
suggested emphasizing concentric movements during
strength training for a better sprint improvement. Her-
rero et al. (17) also concluded that EMS training alone
did not result in any improvement in jumping height or
even interfered in sprint run. Likewise, as suggested by
Bobbert and Van Soest (5), strength-training programs
should be associated with speciﬁc exercises to improve
jumping ability by an optimization of the control of neu-
romuscular properties. Therefore, EMS training, con-
ERNARDIN ET AL
ducted under isometric conditions, should be accompa-
nied with speciﬁc dynamic exercises (e.g., jumping and
sprinting) for a better power improvement.
Like in a taper period, EMS training consisted of 3
sessions a week during the ﬁrst 6 weeks and only 1 ses-
sion from the sixth to the 12th week. Midtraining, our
results revealed only squat strength increases (⫹8.3%).
Despite the reduction in the number of EMS sessions, a
squat strength improvement was also obtained between
the sixth and 12th week (⫹6.2%). Besides, most increases
in muscle strength and power were obtained during the
second part of the training program. Indeed, voluntary
isokinetic torque and vertical jump height predominantly
increased after week 6. These results demonstrated that
reducing EMS volume (sessions per week) was beneﬁcial
for physical performance enhancements. Quite similarly,
the reduction of heavy-resistance training session num-
ber previously exhibited strength increases but for elderly
subjects (19). With EMS, no study demonstrated the pos-
itive effects of training volume reduction. Nevertheless,
stopping EMS trainings produced persisting results (25)
or delayed positive effects (20, 24). Indeed, Malatesta et
al. (24) obtained SJ and CMJ increases 10 days after the
end of EMS training while no gain was obtained imme-
diately after the 4 weeks of training.
Except for squat strength, the absence of performance
improvements at midtraining was surprising. Indeed,
studies dealing with EMS generally registered voluntary
torque (9, 20, 29) and vertical jump height (21, 24) gains
for short training durations (⬍4 weeks). As stated above,
this result could partly be explained by the elite training
status of our subjects. Moreover, the lack of signiﬁcant
vertical jump gain at week 6 could be attributed to the
fact that subjects tested in the present study were not
speciﬁcally trained for vertical jumps. Combination of
EMS with speciﬁc exercises such as scrummaging or ver-
tical jumps might favor physical performance improve-
ments. Indeed, no gain was observed midtraining for ver-
tical jumps, whereas Mafﬁuletti et al. (21) registered ⬃7
cm increases for SJ after only 4 weeks EMS combined
with plyometric exercises. More recently, Brocherie et al.
(9) suggested that EMS training programs should be of
longer duration when performed alone to achieve beneﬁ-
cial effects in vertical jump height. Present results sup-
port this hypothesis since vertical jump improvements
(⬃3 cm for SJ) were obtained with training duration 4
times longer than the last cited study (12 vs. 3 weeks).
Therefore, it can be concluded that long-term EMS pro-
grams (⬎6 weeks) conducted alone or short-term pro-
grams accompanied by jump exercises are required to ob-
tain signiﬁcant improvements in vertical jump height.
Mechanisms, related with muscle strength and power
increases after EMS training, may originate from central
neural drive adaptations (13, 22) and/or from peripheral
modiﬁcations, i.e., hypertrophy (12). Most authors favor
the neural drive hypothesis because EMS training is gen-
erally not long enough (⬍5 weeks) to induce modiﬁcations
at the muscle level (15). The observed increased EMG ac-
tivity (10) and higher activation level (22) corroborate this
enhanced volitional drive originating from spinal as well
as supraspinal centers. However, the absence of reﬂex
modiﬁcation after 4 weeks of EMS training suggests that
neural adaptations were primarily supraspinal (23). This
suggestion is reinforced by Smith et al. (34). Despite the
fairly long training period used in the present study (12
weeks), we think that performance improvements more
likely resulted from neural processes than peripheral
muscular adaptations. Peripheral adaptations would ef-
fectively produce uniform torque gains among velocities
while gains were obtained for only 3 angular velocities
and in particular under eccentric conditions (⫺120⬚·s
Part of this increase in eccentric torque may originate
from preferential adaptations of fast twitch ﬁbers (22).
Indeed, EMS (14) and eccentric actions (28) have been
shown to preferentially recruit fast twitch ﬁbers. Al-
though peripheral adaptations cannot be excluded, the in-
creased neural drive or preferential activation of fast
muscle ﬁbers, may additionally explain the improvement
in explosive-type actions (e.g., vertical jumps) (6) by an
optimization of neuromuscular properties control during
complex dynamic tasks (24).
Muscle strength and power appear to be important pa-
rameters for rugby players’ careers. On the basis of the
present investigation, it appears that EMS can be used
on rugby players, even with highly skilled athletes, for
strength and jumping ability improvements. However,
speciﬁc rugby skills such as scrummaging and sprint-run-
ning were not improved with EMS. In the practical set-
ting, it is suggested to combine technical and more spe-
ciﬁc rugby exercises with EMS so as to optimize strength
gains. Furthermore, reducing EMS sessions during the
second half of our training program (from week 6 to week
12) demonstrated persistent physical performance en-
hancements. This result is of interest for the rugby play-
ers’ conditioning periodization. Indeed, EMS could be con-
ducted during the preseason conditioning and prolonged
during the in-season conditioning with a lower volume.
The in-season EMS volume reduction could, therefore, be
helpful for performance maintenance across the whole
season (essential for successful rugby competition). EMS
training volume should, therefore, be carefully periodized
and sequenced with complementary exercises for optimal
gains and performance preservation in elite rugby play-
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The authors gratefully acknowledge Dr. Nicola A. Mafﬁuletti
and Dr. Gerald G. Pope for carefully reviewing the manuscript
and English corrections.
Address correspondence to Nicolas Babault, nicolas.