Association between BOLT Score, aerobic fitness, and physical activity in active university students: a...

The Body Oxygen Level Test (BOLT), also known as the control pause in the Buteyko method, is a breath-hold test proposed to reflect CO2 tolerance and breathing efficiency. Although popularized as a fitness indicator, its relationship to aerobic capacity and physical activity in healthy adults remains unclear. This study examined associations between BOLT score, maximal oxygen uptake (VO2max), treadmill time to exhaustion (TTE), and weekly physical activity in active university students.

Twenty-eight healthy, physically active university students (15 men, 13 women; age 22.1±2.5 years) completed a graded treadmill test (Bruce protocol) with gas analysis to determine VO2max and TTE. BOLT was measured as comfortable breath-hold time after normal exhalation. Weekly physical activity was assessed using the Godin Leisure-Time Exercise Questionnaire (GLTEQ). Spearman correlations examined associations between BOLT, VO2max, TTE, and GLTEQ. A multiple linear regression tested whether VO2max, TTE, age, height, weight, and GLTEQ predicted BOLT.

BOLT times did not significantly differ between sexes. BOLT scores showed no strong correlation with VO2max (ρ=0.31, P=0.10), TTE (ρ=0.27, P=0.16), or GLTEQ (ρ=0.05, P=0.59). Regression analysis (R²=0.22, P=0.46) identified no significant predictors of BOLT.

In active young adults, the BOLT breath-hold test was not significantly associated with VO2max, endurance time, or self-reported exercise levels. These findings suggest that BOLT - a measure of breathing function and CO2 tolerance - does not serve as a surrogate indicator of aerobic capacity or habitual physical activity in this population. BOLT should be interpreted with caution if used for fitness assessment, as it appears to reflect a distinct aspect of physiological function not captured by standard aerobic performance tests.