VALIDITY OF BREATHING FREQUENCY TO MONITOR EXERCISE INTENSITY IN TRAINED CYCLISTS

This study compared breathing frequency (f(B)) during a ventilation threshold (VT) test with f(B) during a simulated 40 km time trial (40TT) to assess whether f(B) can be used to monitor exercise intensity. Twenty-six male cyclists (X+/-SD VO(2)max = 4.42+/-0274 l . min(-1)) performed an incremental VT ergometer test and a simulated 40TT on a set of wind-loaded rollers. During the 40TT, expired gas was collected for 3 min using open circuit spirometry at 10 km intervals. A significant correlation (r = 0.89; p less than or equal to 0.05) was found between the f(B) threshold (VTf) and the gas exchange VT (VTg) (3.42+/-0.08 and 3.31+/-0.09 l . min(-1), respectively). No differences were found in VO2 at the VTf vs. X VO2 (3.48+/-0.08 l . min(-1)) during the simulated 40TT. However, when f(B) in br . min(-1) calculated from the VT test (32.5 br . min(-1)), was compared with f(B) during the 40TT (45.6 br . min(-1)), there was a significant difference. Ventilation, heart rate and the respiratory exchange ratio were all significantly higher during the 40TT. Although a significant relationship was found between the VT test and the 40TT for VTf measured in l . min(-1) of VO2 (r = 0.66; p less than or equal to 0.05), f(B) in br . min(-1) obtained from the incremental test should not be used to identify exercise training intensity. These data suggest that during competition, trained athletes exercise at a higher f(B) than that determined when being tested, implying that f(B) in br . min(-1) may not be a Valid measurement of exercise intensity.