Objective: 

The heart rate in response to exercise test is a widely used criteria for determination of subject's aerobic fitness and establishing optimal training work protocol. We aimed to determine the effects of anaerobic threshold (AT) on work rate to heart rate (WR-HR) ratio during incremental exercise. Thus, WR-HR ratio was comparatively evaluated in the aerobic and anaerobic region of incremental exercise.

Methods: 

Twenty one sedentary females (age: 20±0.2 yr, weight: 54.9±1.4 kg) were participated to the study after giving a signed written informed contents which were approved by the local ethical committee. Each subjects performed an incremental exercise test (15 W/min) using an electromagnetically braked cycle ergometer. Ventilatory parameters were estimated using spirometry. The heart rate was recorded as beat-by-beat. WR-HR ratio was averaged in aerobic and anaerobic region of the AT. During exercise, AT estimated using ventilation to work rate relationships. A paired t- test was used to evaluate values (P<0.05).

Results: 

The work rate at maximal exercise capacity was 128.3±3 W. The WR-HR ratio in response to the incremental exercise was not linear and the WR-Hr break point associated with AT: 78.1±2 W vs 77.8±2 W (R=0.92191, P<0.0001). The WR-HR ratio was similar below and above the AT: 1.895±0.07 W/beat and 1.743±0.11 W/beat, respectively. However, averaged WR-HR ratio was 0.349±0.01 W/beat in aerobic region and 0.591±0.01 W/beat in anaerobic region (p<0.05).

Conclusions: 

The work production capacity for each heart beat was significantly affected with metabolic activity. Thus, determination of averaged HRWR ratio for aerobic and anaerobic exercise test could be a useful index when evaluating subject's with different aerobic fitness level.