Leg muscle strength and power predict rating of perceived effort during cardiopulmonary exercise testing

The effort required to cycle progressively intensifies during an incremental exercise test. The determinants of the perceptions of leg cycling effort have not been assessed in large samples where sufficient response variation permits definitive characterization of relationships to better inform the use of ratings of perceived exertion. The perceived intensities of the effort required to cycle was rated during an incremental exercise test to symptom-limited capacity by 35,597 participants (53 ± 17 yrs, 60 % male) referred from 1988 to 2012 using a 0–10 scale (modified Borg scale). Height, weight, age, muscle strength, pulmonary function, hemoglobin, and arterialized capillary blood gases were measured and assessed for their predictive capacity for ratings of perceived exertion. In this sample, the perceived effort required to cycle was determined by cycling power (power) and the maximum cycling power output (P MAX ) according to the following equation: perceived leg cycling effort = power 2.12 • P MAX −1.86 (r = 0.8159). Forward stepwise linear regression revealed that there was additional predictive capacity with the addition of quadriceps strength to the equation while the additional inclusion of height, age and sex to the relationships contributed minimally. As the P MAX achieved was dependent on leg strength the findings of this study suggest that assessment of muscle-specific strength may be used to predict perceived leg cycling effort when completion of an incremental cycling test is not feasible. This is highly relevant knowing the technical and physiological limitations that present barriers to widespread use of incremental exercise testing.