F-12F Free Communication/Slide Vo2 Max Measurement/Prediction
The absence of a plateau during VO2max testing has been interpreted to indicate VO2max is not centrally limited. One possible limitation in a cycle graded exercise test (GXT) test is leg power. To examine this possibility we tested college distance runners (DR), individuals biased toward high cardiovascular fitness/lower muscle power, and college football linemen (FL), individuals biased toward low cardiovascular fitness/high muscle power. We postulated that if muscle power limited the occurrence of a plateau in a cycle (GXT) we would find a lower plateau occurrence rate in DR than FL.
To determine the effect of muscle power on the plateau occurrence rate in a cycle GXT.
The subjects, 7 DR (67±3 kg) and 6 FL (120±13 kg), performed a 7 stage continuous/discontinuous cycle GXT protocol ranging in power output from 120–484 W. VO2 was averaged over 15 sec intervals during each stage. Each subject performed an initial continuous test consisting of 2 min stages until exhaustion. For the discontinuous phase the subject reported to the lab at 24 hr intervals and performed the next highest stage. The discontinuous phase continued until the subject could not complete the stage (defined as achieving a steady state VO2). Leg strength was assessed by 1RM leg press using a hip sled.
Plateau occurrence rate was not different between groups (6/7 DR and 6/6 FL; p = 0.54). Absolute VO2max was similar in DR and FL (4.36±0.1 vs. 4.63±0.2 L/min; p = 0.27), relative VO2max was greater in DR than FL (65.9±2.2 vs. 38.9±2.2 ml/kg·min; p < 0.01). Absolute leg strength was greater in FL than DR (342.0±14.6 vs. 158.1±12.0 kg; p <0.01), as was the leg strength to body mass ratio (2.85±0.1 vs. 2.38±0.1; p = 0.03). The cardiovascular fitness to leg strength ratio, expressed in (ml/min)/kg, was greater in DR than FL (28.5±2.3 vs. 13.8±1.0; p < 0.01).
The leg power bias between groups did not affect the occurrence rate of a plateau in the VO2/exercise intensity curve.