The study will be conducted on a group of healthy individuals aged 18 - 35 years. After
an interview confirming that the subject does not have exclusion criteria and written
consent to participate in the study, anthropometric measurements will be taken of height
and weight using a scale and tape measure. The subjects will be informed in detail about
the procedure and the form of the measurements, the way in which they are to be taken,
and will be familiarised with the the measuring instruments and their principles of
operation. Then, in accordance with the study protocol, specific measurements will be
taken of the rectus femoris, medial vastus and lateral vastus muscles using surface EMG
of a non-invasive nature.
Study participants will undergo the following measurements:
Measurement of the MVC (maximum voluntary contraction) of the quadriceps of the
thigh, in a sitting position with the lower leg flexed to 90 degrees.
Measurement of muscle activity during elevation of the straightened lower limb in a
supine position without an orthosis.
Measurement of muscle activity during straight leg raise in supine position with
knee brace.
Ad.a. Measurement of quadriceps excitability of the dominant lower limb using surface EMG
in a seated position with the trunk stabilised and the lower leg flexed to 90 degrees,
stabilised in the distal part (without taking the foot) against a stationary object so as
to execute maximal volitional isometric quadriceps muscle tension. Upper limbs crossed
over the chest.
Ad.b. Measurement of right quadriceps excitability using surface EMG in supine position
without orthosis. The subject raises the test limb by touching the anterior surface of
the tibia to a pole set at 20 cm at the command 'raise leg', then lowers the limb at the
command 'lower leg'. During the task there is a 1 second moment of holding the leg
straight as the tibia touches the pole. This action is repeated three times.
Ad.c. Measurement of quadriceps excitability of the dominant lower limb using surface EMG
in supine position with knee extension brace on. Measurement performed in three variants:
The test subject raises the test limb by touching the front surface of the tibia to
a pole set at a height of 20 cm on the command 'raise leg', then lowers the limb on
the command 'lower leg'. During the task there is a 1 second moment of holding the
leg straight as the tibia touches the pole. This action is repeated three times.
The test subject is asked to apply maximum tension to the quadriceps (thigh muscle)
(command 'press the knee against the ground, bring the toes together, straighten the
foot and flex the quadriceps maximally"), then maintaining the tension he/she raises
the limb touching the front surface of the tibia to the pole placed at the height of
20 cm on the command "raise the leg", then lowers the limb on the command "lower the
leg". During the task there is a 1 second moment of holding the leg straight as the
tibia touches the pole. This action is repeated three times.
Before the test, the test subject is verbally instructed to 'Try, despite the
orthosis holding you upright, to bend the knee and raise the leg so that the
quadriceps do not tense'. Then, on the command 'raise leg', the test subject raises
the limb by touching the front surface of the tibia to a pole set at 20 cm, on the
command 'lower leg' he lowers the limb. During the task there is a 1 second moment
of keeping the leg straight as the tibia touches the pole. This activity is repeated
three times.
The time for the full test is approximately 15-20 minutes per participant. Statistical
analysis will be performed using Statistica and/or JASP software. The study will be
carried out with a minimum of 20 adults aged 18 - 35 years. The exact number of
participants in the study, will be determined after performing an a-priori sample size
estimation after collecting data from the first 10 people examined. Eligibility of
subjects will include a subject and physical examination by a physiotherapist.
Inclusion criteria: age between 18-35 years, no contraindications to physical exercise,
ability to perform the required commands without pain or discomfort, full range of motion
of the knee joint.
Exclusion criteria: those with a history of knee and/or hip surgery, damage to
ligamentous structures of the knee joint in the past treated conservatively or meniscus
treated conservatively, muscle and tendon injury of the knee joint area in the past 3
months.