Effects of Post-COVID-19 on Quadriceps Femoral Muscle-tendon Unit

Blood biomarkers

Blood biomarkers including metalloproteinase 9, interleukin-6, interleukin-8 and interleukin-10, interleukin 1 beta, tumor necrosis factor alpha type, nitric oxide, as well as creatine kinase will be collected in blood samples by venipuncture in the vein brachial, in heparinized tubes with separating gel using the vacutainer system with ethylenediaminetetraacetic acid (EDTA). The samples will be stored and later analyzed using appropriate techniques.

Time frame: Change from baseline 1 (days 21-30) to assessments 2 (days 31-90), 3 (days 91-180), and 4 (days 181 to 360) for groups composed of COVID-19 positive participants. The Control group will be assessed only at baseline.

Sit to stand test

To carry out the test will be used a stopwatch and a chair with the back against a wall, seat height 43 cm from the floor and without armrest. The test consists of measuring how many times the participant can get up and sit down from a chair (counting as a movement) in a period of 30 seconds.

Time frame: Change from baseline 1 (days 21-30) to assessments 2 (days 31-90), 3 (days 91-180), and 4 (days 181 to 360) for groups composed of COVID-19 positive participants. The Control group will be assessed only at baseline.

Electrodiagnostic stimulus test

The quadriceps femoris, gastrocnemius, soleus and tibialis anterior muscles will be evaluated. At the muscle motor point, the values of rheobase, chronaxia and accommodation will be investigated.

Time frame: Change from baseline 1 (days 21-30) to assessments 2 (days 31-90), 3 (days 91-180), and 4 (days 181 to 360) for groups composed of COVID-19 positive participants. The Control group will be assessed only at baseline.

Body composition

Body composition will be estimated using dual x-ray absorptiometry. Fat mass and fat-free mass will be expressed in absolute values.

Time frame: Change from baseline 1 (days 21-30) to assessments 2 (days 31-90), 3 (days 91-180), and 4 (days 181 to 360) for groups composed of COVID-19 positive participants. The Control group will be assessed only at baseline.

Muscle force

Muscle force will be assessed by muscle force changes, based on the torque generated during maximum voluntary contraction.

Time frame: Change from baseline 1 (days 21-30) to assessments 2 (days 31-90), 3 (days 91-180), and 4 (days 181 to 360) for groups composed of COVID-19 positive participants. The Control group will be assessed only at baseline.

Peripheral oxygen extraction

The assessment of peripheral oxygen extraction will be performed both in rest and during voluntary contraction. The evaluation will be carried out by means of near-infrared spectroscopy (NIRS or near infrared spectroscopy).

Time frame: Change from baseline 1 (days 21-30) to assessments 2 (days 31-90), 3 (days 91-180), and 4 (days 181 to 360) for groups composed of COVID-19 positive participants. The Control group will be assessed only at baseline.

Surface electromyographic activity

Electromyographic activity of each superficial component of the quadriceps muscle both in rest and during voluntary contraction.

Time frame: Change from baseline 1 (days 21-30) to assessments 2 (days 31-90), 3 (days 91-180), and 4 (days 181 to 360) for groups composed of COVID-19 positive participants. The Control group will be assessed only at baseline.

Muscle architecture

Muscle architecture analyzes will be performed using ultrasound at rest and during voluntary contraction. The muscle volume of the knee extensors, muscle thickness, pennation angle, fascicle length and muscle echogenicity will be evaluated.

Time frame: Change from baseline 1 (days 21-30) to assessments 2 (days 31-90), 3 (days 91-180), and 4 (days 181 to 360) for groups composed of COVID-19 positive participants. The Control group will be assessed only at baseline.

Properties of the patellar tendon

The morphological, material and mechanical properties will be evaluated based from the elongation of the patellar tendon during maximum voluntary contraction.

Time frame: Change from baseline 1 (days 21-30) to assessments 2 (days 31-90), 3 (days 91-180), and 4 (days 181 to 360) for groups composed of COVID-19 positive participants. The Control group will be assessed only at baseline.

Muscle fatigue

Quadriceps muscle fatigue will be assessed in each leg after consecutive maximal isometric voluntary contractions of the quadriceps muscle.

Time frame: Change from baseline 1 (days 21-30) to assessments 2 (days 31-90), 3 (days 91-180), and 4 (days 181 to 360) for groups composed of COVID-19 positive participants. The Control group will be assessed only at baseline.

Assessment of perceived exertion during the fatigue protocol

Assessment of perceived exertion will be analyzed before, during, and after the performance of maximum voluntary isometric contractions performed to analyze muscle fatigue using the BORG scale of perceived exertion.

Time frame: Change from baseline 1 (days 21-30) to assessments 2 (days 31-90), 3 (days 91-180), and 4 (days 181 to 360) for groups composed of COVID-19 positive participants. The Control group will be assessed only at baseline.

Fatigue severity analysis

Fatigue severity analysis will be assessed using the fatigue severity scale.

Time frame: Change from baseline 1 (days 21-30) to assessments 2 (days 31-90), 3 (days 91-180), and 4 (days 181 to 360) for groups composed of COVID-19 positive participants. The Control group will be assessed only at baseline.