Relationship between force exertion of lower body and energy expenditure during bicycle exercise

PURPOSE: To investigate the influence of force exerted of lower body on estimation of EE during an incremental bicycle exercise. METHODS: 21 healthy, nontrained males (age: 25.0±2.1, range 24-33yr) participated in this study. Bicycle exercise protocol consists of four stages : resting for 5 min, warm-up for 5 min, an incremental exercise(increase 10 RPM and 1 friction) for every 3min and cool-down for 5min. Both acceleration and force devices were designed and fabricated. Force of lower body exerted by pedaling is measured using loadcell. Acceleration and loadcell sensor were put inside the pedal of bicycle. Acceleration(x, y, z) and force(f) data were sampled at 100Hz and transmitted to PC program. Acceleration, force data and EE value using respiratory gas analysis were collected at the same time. To evaluate developed device, our result was compared with estimated value from accelerometer attached on waist. 'SVM' and 'FORCE' parameters calculated each from acceleration and force data. Pearson correlation and multiple regression analysis were used as statistical method. The significance level was p<0.05. RESULTS: Waist.SVM(r=0.720, p<0.001), pedal.SVM(r=0.741, p<0.001) and pedal.FORCE(r=0.712, p<0.001) variables were significant relationship with EE value. As the predictor of multiple regression equation, SVM, FORCE, exercise time(r=0.613, p<0.001), height(r=0.073, p<0.001), weight(r=0.159, p<0.001) and BMI(r=0.144, p<0.001) variables were selected. Multiple linear regression of EE estimation using acceleration sensor on waist and using both acceleration and force sensors inside the pedal generated the following result, R2=0.660, SEE=274.54 and R2=0.723, SEE=247.78, respectively. CONCLUSIONS: Aside from acceleration sensor attached on upper body such as waist, chest and so on, sensors on lower body are necessary during bicycle exercise because it is more likely to be lower body workout compared to the treadmill exercise. Thus, we tested using the module which was combination of acceleration and force sensor and was placed inside the pedal to represent lower body workout. In conclusion, findings from this study indicate that the estimation of EE considered the acceleration and the force exerted of lower body by pedaling is more accurate and efficient during bicycle exercise.