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Trial registered on ANZCTR

Trial ID
Ethics application status
Date submitted
Date registered
Date last updated
Type of registration
Retrospectively registered

Titles & IDs
Public title
Electrical stimulation in soccer players
Scientific title
The effect of NeuroMuscular Electrical Stimulation on quadriceps strength and knee function in professional soccer players: return to sport after anterior cruciate ligament reconstruction
Secondary ID [1] 283413 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
electrical stimulation on quadriceps and knee 290323 0
rehabilitation after anterior cruciate ligament replacement 290338 0
Condition category
Condition code
Physical Medicine / Rehabilitation 290724 290724 0 0

Study type
Description of intervention(s) / exposure
The objective of this study is to assess the efficacy and safety of NeuroMuscular Electrical Stimulation (NMES) program applied in soccer players - 6 months after anterior cruciate ligament (ACL) reconstruction - on the quadriceps muscle. The primary study endpoint is comparison of the change in muscle strength between the stimulated and control group. The secondary end point is the analysis between groups of the change of quadriceps muscle circumference and other measured parameters as predictors of safety (whether are any pathological changes in knee function) after NMES therapy.

NMES procedure is on both right and left quadriceps (two electrodes on the muscle attachment sites). A portable electrical stimulator delivers biphasic symmetric rectangular pulses (frequency of impulses 2500 Hz, train of pulses frequency 50 Hz). The stimulus output is interrupted every 10 ms to create “bursts” of stimulation every second. The 10 ms off period is not detectable by the subject. A total of 10 maximal contractions sustain for 10 seconds each, with a 50 second off time defined a treatment session. The intensity is between 55 to 67 mA. Stimulation is performed with a current which produced strong, visible motion effects. Electrodes are made of conductive carbon rubber (8 x 6 cm). Before application of electrodes the skin is cleaned in use of alcohol. The total time of single procedure is 30 minutes. Quadriceps is stimulated at 60 degree of knee flexion. The procedures are repeated three times daily (3 hours break between treatments), 3 days a week (Tuesdays, Thursdays and Saturdays), for one month. All procedures are administered by a physiotherapist in sports clinic.

The measurements:
1. Measurements of muscle strength is performed by a tensometer, composed of resistance lever, roller and electronic momentum meter. The spectrum of measurement is between 0 and 500 Newton meters [Nm]. The magnitudes of force moment are converted into Newtons [N]. The tested legs are at 60 degrees of knee flexion.
2. Change of muscle circumference is measured by a “tailor tape” 10 cm above the patella on the quadriceps. The measurements are performed before and after experiment (the measurements are in a supine position before first and after the last NMES procedure).
3. The goniometry pendulum test is composed of a peripheral device and a personal computer with software. The peripheral device consisted of a goniometry compass and an interface system – transducer cooperate with the computer. The goniometry compass is composed of two thin metal arms. One of the arms (immobile) is fixed in a special outlet that allowed for changing the angle and length. The mobile arm is connected to the athlete’s leg. The motion of the compass is measured by a mini – optoelectronic transducer. The position of the transducer is measured (with a resolution of 12 bytes [B] on one revolution) and coded in a range from 0 to 360 degrees (exact to 0.088) The signal is transmitted to the interface. The software allow readings of 100 positions of the compass per second. Using the pendulum test, the spectrum (range) and ease of motion in knee (whether the movement was smooth, physiological and free in examined axis) are measured and determined the following parameters:
n – number of oscillations,
t – whole time of oscillations,
T – period of oscillations (T=t/n),
lambda – logarithm decrement of suppression (lambda=ln X2/X4, where X2 is a second amplitude
during oscillations and X4 is a fourth amplitude during oscillations,
beta – suppression index (beta= lambda/T).
The number of oscillations (n) and whole time of oscillations (t) describe the ease of knee motion. The period of oscillations (T) and suppression parameters (lambda and beta) assess the spectrum of knee motion. The goniometry pendulum test is performed for analysis of NMES safety (to assess whether an increase in muscle mass and strength will change in the mechanics of the knee joint).
Intervention code [1] 288136 0
Comparator / control treatment
soccer players without NMES

during 1 month participants only continued the rehabilitation program from week 16-24 (continue strength, endurance, proprioception progression, double-leg hopping, jogging, agility drills)
Control group

Primary outcome [1] 290725 0
The primary outcome is comparison of the change in muscle strength between the stimulated and control groups.

Tests/methods: tensometry
Timepoint [1] 290725 0
Immediately after NMES procedures (after 1 month therapy), in control after 1 month (compared to the baseline).

Secondary outcome [1] 305100 0
The secondary outcome is analysis between groups of the change of quadriceps muscle circumference and other measured parameters as predictors of safety (whether are any pathological changes in knee function) after NMES therapy

Tests/methods: goniometry pendulum test, circumference and linear measurements in use of "tailor tape"
Timepoint [1] 305100 0
Immediately after treatment and follow up (1 and 3 months later)

Key inclusion criteria
(1) underwent arthroscopy surgery as follows: initially, an anteromedial incision was made on the proximal tibia and the gracilis and semitendinosus tendons were detached from their insertions on tibia. Subsequently, the tendons were removed to fashion the graft for ACL reconstruction. A tibial canal was established; through this canal, the femoral canal was created under arthroscopy guide. Finally, the graft was passed through the canals as a single bundle,
(2) 6 months after operation,
(3) received the same rehabilitation program before NMES procedures: Week 1 (CPM Machine - start at 0-30 degrees, increase no less than 10 degrees per day PROM Wall Slides Seated Active Assistive Knee Flexion Prone Dangle Passive resting extension with heel prop Patellar Mobilizations, SLR x3 Flexion, Adduction, Abduction, Hamstring/Calf Stretches, Ankle Pumps, Gait Training, Home Exercise Program-2 or 3 times per day). Week 2-4 (Scar Mobilization/Massage, Proprioceptive Neuromuscular Facilitation, Progressive Resistive Exercises, Manual/Machine resisted leg press, Balance/Proprioception, Isometric Knee extension 90-60 degrees, Stationary Bike, Mini-Squats progress up to 90 degrees, Step ups, Retro Treadmill/Stairmaster, Hip abduction/external rotation). Week 4-16 (Functional Strengthening, Proprioceptive Neuromuscular Facilitation, Progressive Resistive Exercises, Manual/Machine resisted leg press, Balance/Proprioception, Squats to 90 degrees, Single leg squats, Step ups, Retro Treadmill/Stairmaster, Review Home Exercise Program-2 times per day). Week 16-24 (Continue strength, endurance, proprioception progression, Begin double-leg hopping, jogging, agility drills).
(4) provided written informed consent to participate in the study
Minimum age
18 Years
Maximum age
30 Years
Can healthy volunteers participate?
Key exclusion criteria
(1) women,
(2) soccer practice less than 3 years (share of the league for at least three years),
(3) bone fracture in last 2 years,
(4) chronic sprain ankle,
(5) a history of Achilles tendon injury.

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Participants are randomly allocated to the groups. Computer-generated random numbers is sealed in sequentially numbered envelopes, and the group allocation is independent of the time and person delivering the treatment. The physician (research coordinator) who allocated the subjects to groups had envelopes, each containing a piece of paper marked with either group A (NMES) or B (control). The physician selects and opens an envelope in the presence of a physiotherapist to see the symbol and then direct the patient to the corresponding group.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Simple randomisation using computer and numbered envelopes
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?

Intervention assignment
Other design features
Not Applicable
Type of endpoint(s)
Statistical methods / analysis
Analysis and evaluation of the results will be based on the comparison of intra- and intergroup results. Statistical analysis of these results will be performed by means of the Statistica 10 software, manufactured by StatSoft (licence of Academy School of Physical Education). All analysed intergroup variables will be checked with respect to their similarity (uniformity; chi2 NW). A critical significance level a (alpha) = 0.05 or less will be considered statistically significant. For measurable variables (quantitative), arithmetic mean, standard deviations, medians and range of variability (extreme values) will be calculated. For qualitative variables, the frequency of occurrence (percentage) will be calculated. Comparison of intergroup results in order to determine the significance of the achieved differences, will be performed by means of parametric (Student's t-test, Welch's t test) or non-parametric (Mann-Whitney`s test) tests, depending on meeting criteria for the specific test. Correlation of variables in the examined groups will also be checked.

According to statistical estimation the population over 30-35 is needed for further analysis of normal distribution, the scientific team had to include at least 80 participants in two groups to this study and use the parametric tests. Analyzed distributions appeared normal and we received the Gauss decay in all comparisons. For earlier, pilot analyses (smaller groups) the team had to use non-parametric tests

Recruitment status
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment outside Australia
Country [1] 5523 0
State/province [1] 5523 0

Funding & Sponsors
Funding source category [1] 288139 0
Name [1] 288139 0
Academy School of Physical Education
Address [1] 288139 0
Mikolowska Street 72 40-065 Katowice
Country [1] 288139 0
Primary sponsor type
Academy School of Physical Education
Mikolowska Street 72 40-065 Katowice
Secondary sponsor category [1] 286856 0
Name [1] 286856 0
Address [1] 286856 0
Country [1] 286856 0

Ethics approval
Ethics application status
Ethics committee name [1] 290052 0
The Research Ethics Committee from the Medical University of Silesia in Katowice, Poland
Ethics committee address [1] 290052 0
Poniatowskiego Street 15 40-055 Katowice
Ethics committee country [1] 290052 0
Date submitted for ethics approval [1] 290052 0
Approval date [1] 290052 0
Ethics approval number [1] 290052 0

Brief summary
The goal of improving human performance in sport and exercise has been an extremely interesting topic for coaches, athletic trainers, physical therapists, exercise physiologists and athletes alike. Unfortunately, the utility of the NMES for sport application still remains controversial. For example, while many of research studies find muscle strength and recovery after physical effort significantly improved by NMES, a few do not. It is also unclear whether the NMES is completely safe. Some authors maintain that NMES could induce muscle damage or influence on function and biomechanics of the near articulations of the stimulated muscles. The aim of this study is to assess the clinical efficacy and safety of NMES program applied in male soccer players (after ACL reconstruction) on the quadriceps muscle.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 43718 0
Prof Jakub Taradaj
Address 43718 0
Department of Physiotherapy Basics
Academy School of Physical Education
Mikolowska 72 Street 40-065 Katowice, Poland
Country 43718 0
Phone 43718 0
Fax 43718 0
Email 43718 0
Contact person for public queries
Name 43719 0
Prof Jakub Taradaj
Address 43719 0
Department of Physiotherapy Basics
Academy School of Physical Education
Mikolowska 72 Street 40-065 Katowice, Poland
Country 43719 0
Phone 43719 0
Fax 43719 0
Email 43719 0
Contact person for scientific queries
Name 43720 0
Prof Jakub Taradaj
Address 43720 0
Department of Physiotherapy Basics
Academy School of Physical Education
Mikolowska 72 Street 40-065 Katowice, Poland
Country 43720 0
Phone 43720 0
Fax 43720 0
Email 43720 0