Utility of heart rate (HR)-oxygen consumption (VO₂) method to estimate energy expenditure (EE) was studied for 5 main apple working days based on 24 hour HR recording and EE by this method partially was compared with RMR (relative metabolic rate) method currently used in Japan. Results were as follows:
1. Heart rate during the apple cultivating work were 90-110 beats per minute, that were ranked with moderate work classified by Rodahl.
2. The values of EE estimated by HR-VO₂ method in every apple working days were almost suited for that of previous reports by RMR method.
3. Comparing EE by HR-VO₂ and RMR method for an example in harvesting work, 2, 654 kcal in former was 376 kcal (16.5%) higher than latter. Correlation coefficient was 0.987 (p<0.001) between both method with EE estimated in every working contents.
4. The intense of activity in a working day from view point of daily activity index (1-EE/basal metabolism) followed the order of harvesting putting sack on≅pluking flower>thinning apple> pruning.
Consequently, estimation of EE by HR-VO₂ method was precisely reflected metabolic state in human by comparison in spite of some defects. After this it was expected to use the HR-VO₂ method instead of RMR method.