Repository of DUTH

Μεταβολές της φυσικής απόδοσης και της μυικής οξυγόνωσης κατά τη διάρκεια της άσκησης και της αποκατάστασης μετά από επαναλαμβανόμενα σπριντ διαφορετικής διάρκειας. (Bachelor thesis)

Πολυμενάκου, Ειρήνη

The purpose of the study was to examine the change in power output and muscle oxygenation during the execution and the recovery phases of repeated sprints performed with different durations. Twelve males (age: 21.3 ± 2.1 years, height: 180.5 ± 6.2 cm, body mass: 78.3 ± 7.6 kg) performed two protocols of repeated sprints at a cycle ergometer. The first protocol included the execution of 12 sprints of 5 sec duration with 50 sec recovery and the second protocol 3 sprints of 20 sec duration with 200 sec recovery. During the exercise and the first 30 sec of recovery the oxygenation status of the VL was recorded through the changes of oxyhemoglobin (O2Hb), deoxyhemoglobin (HHb), total haemoglobin (tHb) and Hb difference (Hbdiff) which were monitored continuously by near infrared spectroscopy (NIRS). Power output was also measured during the execution of two additional 10 sec sprints, performed five minutes before and two minutes after the execution of the repeated sprint sessions. Mechanical power during the execution of 12 sprints of 5 sec decreased by 11,2  8,2% and during the 3 sprints of 20 sec by 16  4,9%. Power output during the 10 sec sprint was reduced after the execution of the repeated sprint sessions, with larger (p< 0.05) declines observed after the 20 sec protocol (23.5 ± 5.1%) compared to the 5 sec protocol (6 ± 4,7%). During the 12 x 5 sec sprints protocol, the range of decrease of tHb was increased (p= 0,003) and the range of increase of HHb was reduced (p= 0,04) while there were no significant changes at the range of decrease of O2Hb (p= 0,1) and Hbdiff (p= 0,92). During the 3 x 20 sec sprints of protocol, the range of decrease of O2Hb, tHb (p= 0,001) and Hbdiff was increased (p= 0,001), while there was no significant change at the range of increase (p= 0,62) of HHb. During the first 30 sec of recovery during the 12 x 5 sec protocol there was a decline at the increase of O2Hb (p= 0,01) and Hbdiff (p= 0,001), no change in the increase of tHb (p= 0,56), while HHb reduction was reduced (p= 0,001). At recovery phases among the sprints of the 3 x 20 sec protocol, the range of increase of tHb was reduced (p= 0,03), of O2Hb was increased (p= 0,03) while the range of increase of Hbdiff (p= 0,13) and the range of decrease of HHb (p= 0,69) remained stable. In conclusion, during repeated sprints of short duration (5 sec), muscle oxygenation remains stable despite the decrease in blood volume, whereas during repeated sprints of long duration (20 sec) muscle oxygenation and blood volume decreases. During recovery phases of short duration repeated sprints performance, blood volume remains stable but muscle re-oxygenation decreases, whereas with the execution of long duration repeated sprints blood volume decreases but muscle reoxygenation does not change. It appears that sprint duration differentiates the means human body uses to respond to the metabolic demands of exercise.