A New Personalized Heart Rate Zone Test For Estimating VO₂max: A Pilot Study

PURPOSE: The purpose of this study is to develop a new and more accurate cardiorespiratory fitness (CRF) measurement test estimating maximal oxygen uptake (VO2max) for supplementing the existing field tests. METHODS: For the study, a personalized heart rate zone test (PHRZT), modified the 1-mile walk/run test was designed. During PHRZT, subjects walked or ran 1,600 meters, divided into 5 stages (320 m in each stage, named as zone 1 to 5). In each stage, subjects exercised to reach a target heart rate (HR) corresponding from 50-60% of an individual maximal HR in zone 1 to 90-100% in zone 5. At zone 1, starting at 5 km/h, the treadmill speed was increased by 0.2 km/h every 8 seconds to reach the target HR. When the target HR was reached, the speed was fixed until the completion of 320 m. This procedure of incremental work load was continued in the subsequent zones until voluntary exhaustion. A total of 20 (10 men, 10 women) aged 18 to 39 years old participated in the PHRZT, and they were tested for the conventional graded exercise test. RESULTS: The measured VO2max showed a high correlation with the run-time (RT) of zone 1 thru 5 at r equal to -0.738, -0.708, -0.708, -0.764, and -0.802, respectively (p < 0.01). The average zone RT (r = -0.762), and total RT (r = -0.761) during PHRZT was also correlated (p < 0.01). When a stepwise regression was performed inserting variables of sex, age, body mass index, HR, and RT of each zone as predictors, only the sex and RT for each zone were finally selected. Because the measured VO2max was highly correlated with RT of all zones, 5 formulas could be developed. This formulas can be used even for the person who stopped at any zone. VO2max (ml/kg/min) can be estimated in zone 1 = 78.805 - (0.195 × RT of zone 1) - (5.330 × S) [R = 0.820, SEE = 4.62]; in zone 2 = 74.584 - (0.186 × RT of zone 2) - (5.468 × S) [R = 0.798, SEE = 4.86]; in zone 3 = 65.148 - (0.192 × RT of zone 3) [R = 0.708, SEE = 5.54]; in zone 4 = 70.191 - (0.201 × RT of zone 4) - (4.530 × S) [R = 0.822, SEE = 4.60]; and in zone 5 = 70.037 - (0.219 × RT of zone 5) - (5.104 × S) [R = 0.872, SEE = 3.94], where RT in sec and S as sex 1 for man and 2 for woman. CONCLUSIONS: The PHRZT and its corresponding five equations seem to estimate VO2max accurately with only two variables; sex and time. The equations can be utilized by the exercise experts for evaluating CRF of healthy adults in fields.