Blood Acid-Base Status Response And Running Performance At Different Constant Loads
Medicine & Science in Sports & Exercise. 2012 44(5S): 938 Thiago F. Lourenço
The maintenance of blood acid-base status (ABSb) is primarily accomplished by adjusting the partial pressure of CO2 in the lungs. For exercise intensities above the respiratory compensation
point (RCP), the buffering limited capacity of blood and the hyperventilation controlled by the central nervous system are insufficient to control ABSb. Despite the importance of RCP in this
control, no study has investigated the ABSb response during constant load at or higher than RCP running speed (sRCP).PURPOSE: Analyze the runners ABSb response after 10-km running
performed at three different constant loads.
METHODS: With at least 72 hours rest between the tests, twenty-five amateur runners (34.6±5.7 yrs; 68.7±10.2 kg; 10-km performance 48.9±7.3 min e VO2max de 40.9±6.5 ml*kg/min)
performed a maximum effort protocol to determine the running speed related to VT (sVT), RCP (sRCP) and VO2max (sVO2max) and three 10-km races at constant load on the sVT, sRCP and
V1 (sRCP + [0.25*(sVO2max - sRCP)]).
RESULTS:All runners that ran at sVT and sRCP completed 10-km with no changes in blood pH (7.48±0.05 vs 7.51±0.02, p>0.05), even with increased in blood lactate (2.8±0.8 vs 5.5±4.2
mmol*L-1) and decreased in bicarbonate (25.4±2.8 vs 22.2±4.2 mmol*L-1, p<0.05). At V1 intensity, only three of sixteen runners completed 10-km. The others completed only 5.2±2.2 km
with a significant decrease in pH (7.48±0.02 vs 7.33±0.04, p<0.05) and bicarbonate (24.1±0.5 vs 14.6±1.0 mmol*L-1, p<0.05).
CONCLUSIONS:All runners that ran at sVT and sRCP completed 10-km with no changes in blood pH (7.48±0.05 vs 7.51±0.02, p>0.05), even with increased in blood lactate (2.8±0.8 vs
5.5±4.2 mmol*L-1) and decreased in bicarbonate (25.4±2.8 vs 22.2±4.2 mmol*L-1, p<0.05). At V1 intensity, only three of sixteen runners completed 10-km. The others completed only
5.2±2.2 km with a significant decrease in pH (7.48±0.02 vs 7.33±0.04, p<0.05) and bicarbonate (24.1±0.5 vs 14.6±1.0 mmol*L-1, p<0.05).
