Outcome
Type |
Measure |
Description |
Time frame |
Safety issue |
Primary |
Swimming time for 400 m |
Swimming time is recorded according to swimming and fin-swimming rules. Swimming time is measured by two qualified timekeepers. The longer time is the official time. |
Change between values before and after 7 days of crossover. |
|
Secondary |
Swimming time for 50 m |
Swimming time is recorded according to swimming and fin-swimming rules. Swimming time is measured by three qualified timekeepers. If two of the three watches record the same time and the third disagrees, the two identical times is the official time. If all three watches disagree, the watch recording the intermediate time is the official time. The 50-m swimming is repeated in 3 sets and 4 rounds, representing 12 measured times. |
Change between values before and after 7 days of crossover. |
|
Secondary |
Heart rate variability |
To determine heart rate variability variables, the ECG signal is measured at a sampling frequency of 1000 Hz using DiANS PF8 (DIMEA Group, Olomouc, Czech Republic). ECG sampling is performed during an orthoclinostatic maneuver (supine-standing-supine) in calm room without any acoustic or visual disturbances. Time domain variables (RMSSD and SDNN) and frequency domain variables (high and low frequency power) are calculated from the ECG. Variables are measured before and after the first training unit, before and after the second training unit, morning and evening of the following day. |
Change between values before and after 7 days of crossover. |
|
Secondary |
Lower limb explosive strength |
The subject performs 3 single maximum effort countermovement jumps with 30 seconds of rest between each jump. The starting position for the jump is an upright posture with the hands placed on the hips. Vertical ground reaction force is measured on 2 parallel force platforms (AMTI OR6-7-1000, Advanced Mechanical Technology, Watertown, USA) with a sampling frequency of 1000 Hz. The jump height is calculated from the measured force-time curve and the average of three jumps is considered for subsequent analysis. The jump height is measured before and after the first training unit, before and after the second training unit, morning and evening of the following day. |
Change between values before and after 7 days of crossover. |
|
Secondary |
Rating of perceived exertion |
The subject is asked to score subjective rating of perceived exertion using the scale developed by Borg. All subjects are familiar with the Borg scale before testing. We use modified scale ranged from 1 (no exertion at all) to 10 (maximum exertion). The rating is scored immediately after each set of 50-m swimming and after 400-m swimming. |
Change between values before and after 7 days of crossover. |
|
Secondary |
Subjective perceived muscle soreness |
Visual analogue scale (VAS) is used to assess lower limb muscle soreness. The VAS is a horizontal 100 mm length line, marked with 0, indicating "no pain" and 100 indicating the "worst imaginable pain". The VAS is assessed before and after the first training unit, before and after the second training unit, morning and evening of the following day. |
Change between values before and after 7 days of crossover. |
|
Secondary |
Creatine kinase |
Creatine kinase is evaluated based on blood samples taken from fingertip. An alcohol wipe is used to clean fingertip and the skin is punctured with lancet. First drop is wiped away and the second drop is used. A Reflotron applicator with a 32 µL disposable pipette tip is used to extract a 32 µL sample of blood and place it on a creatine kinase assay strip (Reflotron CK strips, Roche Diagnostics, Rotkreuz, Switzerland). The blood sample is analyzed using a spectrophotometer (Reflotron Plus, Roche Diagnostics, Rotkreuz, Switzerland) to set plasma creatine kinase concentration.The creatine kinase is evaluated before the first training unit, before the second training unit, morning and evening of the following day. |
Change between values before and after 7 days of crossover. |
|
Secondary |
Blood lactate |
Blood lactate concentration is evaluated based on blood samples taken from fingertip. An alcohol wipe is used to clean fingertip and the skin will be punctured with lancet. First drop is wiped away and the second drop is be used. For lactate sampling the analyzer Lactate Scout+ (EKF Diagnostics, Cardiff, United Kingdom) is used. The blood lactate is evaluated before the first training unit, after each set of 50-m swimming, after swim-up, before and after the second training unit, morning and evening of the following day. |
Change between values before and after 7 days of crossover. |
|
Secondary |
Protein carbonyls |
Protein carbonyls are detected from vein blood sample which is taken from the inside of the elbow by a healthcare specialist. The blood is taken into heparinized vacuum tubes. These is then centrifuged at 1000 g. Subsequently, the blood plasma is separated into cryotubes and frozen at -80 °C until biochemical analysis. Protein carbonyls concentration is measured by ELISA method in accordance with the manufacturer's manual (Protein carbonyl content assay kit, Sigma-Aldrich, Saint Louis, USA). The protein carbonyls is analyzed before the first training unit, before the second training unit, morning and evening of the following day. |
Change between values before and after 7 days of crossover. |
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