Correlation Between VO2max Estimates of the 30-15 Intermittent Fitness Test and the 20-m Shuttle Run Test in Professional Female Volleyball Players

Aerobic capacity is a crucial determinant of performance in volleyball, a sport characterized by intermittent high-intensity efforts. Field-based tests such as the 20-meter Shuttle Run Test (20 mSRT) and the 30-15 Intermittent Fitness Test (30-15 IFT) are commonly used to estimate maximal oxygen uptake (VO2max) in athletes. However, the degree of agreement between these tests in elite female volleyball players remains unclear. This study aimed to compare VO2max estimates obtained from the 20 mSRT and 30-15 IFT in professional female volleyball players and assess the level of agreement between the two tests. Eight professional female volleyball players (age: 23.3 ± 2.1 years; height: 182.1 ± 5.4 cm; body mass: 72.4 ± 4.8 kg) completed both the 20 mSRT and 30-15 IFT. A paired-sample t-test was used to compare VO2max values between tests, and intraclass correlation coefficient (ICC 3,1) was calculated to assess agreement. Pearson correlation analysis was also performed between the test results. VO2max values estimated from the 30-15 IFT (48.10 ± 5.03 ml·kg⁻¹·min⁻¹) were significantly higher than those from the 20 mSRT (35.49 ± 3.19 ml·kg⁻¹·min⁻¹) (p < 0.001, d = 2.80). A strong positive correlation was found between the two tests (r = 0.833, p = 0.010). However, the ICC (3,1) value of 0.754 (95% CI: 0.176–0.945) indicated only moderate agreement.