Author(s): DELL ANNA, S., AZZALI, G., BERNARDES, A.G., LIBERALI, G., LUCCIONI, L., SPARNERI, F., AMATORI, S., BALDARI, C., BUZZACHERA, C.F., Institution: LINK CAMPUS UNIVERSITY, Country: ITALY, Abstract-ID: 2749

INTRODUCTION:
The musculo-cardio-pulmonary exercise test (mCPET) is method for independently assessing neuromuscular, cardiovascular, and pulmonary systems during a cycle ramp-incremental test to the limit of tolerance. By quantifying maximal voluntary isokinetic efforts at baseline and at the limit of tolerance, mCPET determines the decline in neuromuscular performance from rest to peak exercise. Derived indices include the fatigue index (FI), reflecting performance reduction at exercise termination, the power reserve (PR), representing the percentage of baseline isokinetic power that can be generated above peak ramp power, and the aerobic power index (API), indicating the proportion of baseline isokinetic power supported by aerobic metabolism at peak exercise. Previous studies using mCPET report negligible PR at peak ramp exercise in healthy adults, suggesting that them are generally unable to augment neuromuscular performance beyond that required by the ramp-incremental test, thereby indicating neuromuscular limitation. Whether PR differs in endurance-trained athletes, in whom a larger PR could confer a performance advantage, remains uncertain and warrants further investigation.
METHODS:
Nineteen endurance cyclists (V̇O2peak: 64.0±5.0 mL∙kg⁻1∙min⁻1) and 12 recreationally trained adults (V̇O2peak: 45.0±4.5 mL∙kg⁻1∙min⁻1) participated in the study. All participants performed a cycle ramp-incremental exercise test. Following a warm-up, a single maximal voluntary isokinetic effort (Piso baseline) was performed with a cadence constrained at 80 rpm. After ~4 min of unloading pedalling, the ramp-incremental test commenced and continued to the limit of tolerance (LoT). A further maximal voluntary isokinetic effort was performed at exercise intolerance (Piso intolerance). The limit of tolerance was defined as when cadence fell below 55 rpm despite verbal encouragement. The FI, PR, and API were subsequently calculated and HD-EMG signals from the vastus lateralis muscle were recorded.
RESULTS:
Baseline Piso (875.9 W ± 136.4 W vs. 760.8 ± 132.8 W), Piso at intolerance (602.0 ± 96.7 W vs. 445.1 ± 128.1 W), and LoT (425.1 ± 37.3 W vs. 290.5 ± 62.7 W) were significantly higher in well-trained cyclists than in recreationally trained adults (P<0.01). The API was also greater in endurance cyclists (49.8±9.8 vs. 38.5 ±8.33%; P<0.01), while the FI was significantly lower (30.41±10.51 vs. 41.87±13.5%, P<0.05). Notably, PR did not differ between groups (19.7±7.7 vs. 19.6 ±13.0%; P>0.05). Vastus lateralis muscle activation differed at LoT (48.9±11.7 vs. 60.9 ± 15.6%; P<0.05), but not at Piso intolerance (65.5±12.0 vs. 68.4±15.6%; P>0.05).
CONCLUSION:
The present findings demonstrate that, despite substantial differences in absolute values of baseline Piso, Piso at intolerance, and LoT, both moderately trained adults and well-trained endurance cyclists exhibited a similar PR (~20%) at volitional exhaustion during a ramp-incremental exercise test.