Author(s): ADACHI, T., FUJITA, K., YOKOYAMA, T., MARUTANI, Y., Institution: OSAKA UNIVERSITY OF HEALTH AND SPORT SCIENCES, Country: JAPAN, Abstract-ID: 1909

INTRODUCTION:
The UKK Walk Test was developed in Finland and has not been validated for Japanese individuals. Users have indicated an underestimation in predicted VO2 max. This study aimed to examine the validity of the UKK Walk Test (UKKWT) in Japanese individuals.
METHODS:
The participants were 40 healthy adult men and 42 women between the ages of 20 and 65. The physical profile of the subjects was male, height 170.3 ± 7.3 cm, weight 66.9 ± 11.4 kg, and BMI 23.0 ± 3.1 kg/m2. In females, height was 156.9 ± 5.5 cm, weight was 53.1 ± 8.3 kg, and BMI was 21.5 ± 3.0 kg/m2.
VO2 max was determined during uphill walking on a treadmill. The test protocol followed the method of Laukkanen et al. Respiratory gases were analyzed using the Aero Monitor AE-310S (Minato Medical Science Co., Ltd., Japan). Heart rate was recorded with a Polar H10 (Polar Electro, Finland) on the chest and a Polar M430 (Polar Electro, Finland) on the arm. The UKKWT was conducted according to the UKK Walk Test Testers Guide. UKKWT walked at 80% HRR. Predicted VO2 max was calculated from the formula of Oja et al.
All data are presented as means and standard deviations. The validity of predicted and measured VO2 max values was compared using Bland-Altman analysis.
RESULTS:
The measured VO2 max was 43.3 ± 6.7 ml/kg/min for men and 33.5 ± 5.8 ml/kg/min for women. The performance time in walking during UKKWT was 16.3 ± 1.0 min for men and 18.2 ± 1.3 min for women. The heart rate at the end of UKKWT was 156 ± 13 beats/min for men and 155 ± 10 beats/min for women. Predicted VO2 max was 40.4 ± 7.8 ml/kg/min for men and 30.3 ± 5.0 ml/kg/min for women. The mean difference between predicted and measured VO2 max by Bland-Altman analysis was -2.9 ml/kg/min for men and -3.2 ml/kg/min for women. The 95% limits of agreement were within the range of -4.3 to -1.5 ml/kg/min for males and -4.6 to -1.9 ml/kg/min for females, excluding zero. Bland-Altman analysis showed significant differences (p<0.001) only for fixed errors for both sexes.
CONCLUSION:
Bland-Altman analysis showed a bias in the negative direction for both men and women, suggesting that the VO2 max predicted by the UKKWT was lower than the measured value, indicating the presence of a fixed error. The Japanese are shorter in stature than the Finns, which may have resulted in a shorter stride length during walking, which may have affected the performance time in walking on the UKKWT. The standard BMI of the Japanese is 22 kg/m2, which tends to be lower than that of the Finnish. Thus, racial differences in body size may have influenced the predicted VO2 max. These results suggest that the VO2 max prediction formula developed in Finland by UKKWT is probably underestimating VO2 max for the Japanese.

References：
Oja P et al. (1991). Int J Sports Med, 12(4), 356-362.
Laukkanen RMT et al. (1999). Int J Sports Med, 20, 113-116.