Oxygen uptake, acid-base balance and hormonal responses in maximal 300 - 400 m running in child, adolescent and adult athletes

Vilmi, Nikke (2013). Oxygen uptake, acid-base balance and hormonal responses in maximal 300 400 m running in child, adolescent and adult athletes. Department of Biology of Physical Activity, University of Jyvaskyla, Master's thesis, Science of Sport Coaching and Fitness Testing, 55 pp. The 400 m sprint demands both aerobic and anaerobic energy systems. During the race the acidbase balance of the body is disturbed and that has effects on the oxygen uptake. The purpose of this study was to investigate the oxygen uptake and acid-base balance during and after the maximal anaerobic running test in child (300 m), adolescent (350 m) and adult (400 m) athletes. Furthermore, the aim was also to determine aerobic and anaerobic energy contributions during the test for the different age groups. Eight adult male 400 m runners (age 21 ± 2 years), eight male adolescent athletes (age 15 ± 1 years) and eight male child athletes (age 13 ± 1 years) volunteered for the study. Participants performed two running tests on the same 200 m indoor track. The first test was a maximal running test (MRT) and the second test was a VO2max running test. In both running tests oxygen uptake (VO2) was recorded with a portable gas exchange analyser. In MRT adult athletes ran 400 m, adolescent athletes 350 m and child athletes 300 m. VO2max running test included three different aerobic running speeds. Adults and adolescents ran three times 800 m and children ran three times 600 m. After these three runs the speed was increased by 0.3 m/s every 200 m until exhaustion. Blood samples to analyse lactate (La) and pH were taken in the morning, before and after warm-up, just before and 3, 6, 9, 12, 15, 30 and 60 minutes after MRT and before and 3, 6, 9, 12, 15 and 30 minutes after VO2max running test. Countermovement jumps (CMJ) were performed before and after MRT. Energy system contributions were estimated using accumulated oxygen deficit (AOD) method. Maximal oxygen uptake (VO2max) as the greatest 30 s average during the VO2max running test was 60.4 ± 6.0 ml/kg/min for adults, 58.7 ± 6.3 ml/kg/min for adolescents and 55.6 ± 5.1 ml/kg/min for children. Performance times in MRT were 52.1 ± 2.1 s in adults, 53.3 ± 2.3 s in adolescents and 53.6 ± 5.7 s in children. In CMJ the jumping height decreased after MRT in every group, but significantly only in adolescents (P < 0.01). VO2max during MRT using 30 s averages was 50.3 ± 3.9 ml/kg/min for children, 55.8 ± 4.7 ml/kg/min for adolescents and 57.7 ± 3.0 for adults. Difference in oxygen uptake between children and adults was significant (P < 0.05). These results were 91 ± 11 %, 96 ± 7 % and 96 ± 9 % from VO2max measured in VO2max running test. Peak oxygen uptake (VO2peak) during MRT using 5 s averages was significantly lowest in children (53.1 ± 4.6 ml/kg/min) compared to adolescents (59.9 ± 3.7 ml/kg/min, P < 0.01) and to adults (60.7 ± 2.4 ml/kg/min, P < 0.01) during MRT. After MRT La was greatest in adults (17.4 ± 1.8 mmol/l) compared to adolescents (13.3 ± 3.7 mmol/l, P < 0.05) and children (10.2 ± 1.1 mmol/l, P < 0.01). Blood pH was lowest in adults (6.97 ± 0.06) compared to adolescents (7.14 ± 0.07, P < 0.05) and to children (7.18 ± 0.03, P < 0.001). The estimated anaerobic energy percentage during MRT calculated using AOD method was greatest in adults (53 ± 5 %) compared to adolescents (44 ± 7 %, P < 0.05) and to children (45 ± 5 %, P < 0.05). The present data demonstrated that all age groups could achieve over 90 % of their real maximal oxygen uptake during maximal anaerobic 52 54 s run and adult male athletes used mainly anaerobic energy and achieve greater acidosis than adolescents and children who used mainly aerobic energy. This study suggests that training for pre-pubertal children should focus on skill, speed and endurance and for post-pubertal the focus should transfer more to anaerobic training.