Author(s): ADACHI, T., ADACHI, H., FUJITA, K., MARUTANI, Y., YOKOYAMA, T., Institution: OSAKA UNIVERSITY OF HEALTH AND SPORT SCIENCES, Country: JAPAN, Abstract-ID: 1367

INTRODUCTION:
The UKK Walk Test (UKKWT) is a cardiorespiratory fitness test developed in Finland; however, its validity in Japanese adults has not been sufficiently evaluated. This study aimed to compare measured VO₂max with values estimated by the UKKWT in Japanese adult men and women to assess its validity and clarify age-related characteristics of estimation accuracy.
METHODS:
A total of 145 healthy adult men and women aged 20–73 years participated. Participants were classified into six age groups: 20–24 (20s), 25–34 (30s), and subsequent decades up to the 70s. VO₂max was measured using a treadmill protocol based on Laukkanen et al. The UKKWT was conducted at 80% of heart rate reserve, following the UKK Walk Test Tester’s Guide. One-way ANOVA followed by Tukey’s post-hoc test was used for statistical analyses. Significance was set at p < 0.05.
RESULTS:
Significant differences between estimated and measured VO₂max values were observed across age groups. In men, significant differences were found from the 40s onward (moderate to large effect sizes), while in women, differences were observed in the 20s, 50s, and 60s. In middle-aged and older adults, VO₂max estimated by the UKKWT tended to be lower than measured values. During maximal exercise testing, VO₂max, maximal ventilation, respiratory rate, and maximal heart rate (HRmax) decreased with age. HRmax showed a significant negative correlation with age and declined more gradually than predicted by the “220 − age” formula. Comparisons of UKKWT-estimated VO₂max among age groups revealed significant differences mainly between younger and older adults, particularly men aged ≥70 years and women aged ≥50 years.
CONCLUSION:
Discrepancies between VO₂max estimated by the UKKWT and measured VO₂max varied by age group and were greater in middle-aged and older adults. This suggests that the estimation accuracy of the UKKWT is influenced by age. Physiological responses during maximal exercise decline with age, and age-related changes in cardiovascular and respiratory function may contribute to reductions in VO₂max. Since the UKKWT evaluates cardiorespiratory endurance based on heart rate response, age-related changes in maximal heart rate and estimation errors may affect the determination of relative exercise intensity, resulting in age-related differences in estimated VO₂max.
The UKK Walk Test is a useful field test for evaluating cardiorespiratory endurance in Japanese adults; however, its estimation accuracy is influenced by age. Discrepancies between estimated and measured VO₂max values are greater in middle-aged and older adults. The estimation accuracy may be improved by developing evaluation standards that account for age-related changes and heart rate response characteristics specific to Japanese adults.