PurposeAlthough maximal heart rate (HR<sub>max</sub>) is used widely to assess exercise intensity in training, there are limited data with regards to the validity of age-based prediction equations of HR<sub>max</sub> in volleyball players. Therefore, the aim of the present study was to compare the measured-HR<sub>max</sub> of two prediction equations (Fox-HR<sub>max</sub> = 220 − age and Tanaka-HR<sub>max</sub> = 208 − 0.7 × age) in young female volleyball players.MethodsThe study involved 47 volleyball players (age 13.39 ± 2.01 years, body mass 54.0 ± 10.8 kg, height 162.7 ± 10.2 cm) who performed a graded exercise field test (20 m shuttle run endurance test) to assess HR<sub>max</sub>. Measured-HR<sub>max</sub> values were compared with the Fox and Tanaka prediction equations.ResultsThe results showed that mean scores for HR<sub>max</sub> significantly differed between measured and predicted values (<i>p</i> < 0.001, <i>ŋ</i><sup>2</sup> = 0.49). Post-hoc tests revealed that Fox-HR<sub>max</sub> overestimated measured-HR<sub>max</sub> (mean difference 5.7 bpm; 95% CI [3.0, 8.5]), whereas Tanaka-HR<sub>max</sub> was similar to measured-HR<sub>max</sub> (-2.2 bpm; 95% CI [-4.9, 0.4]). HR<sub>max</sub> did not correlate with age (<i>r</i> = 0.16, <i>p</i> = 0.291).ConclusionsThe results of this study failed to validate the widely used ‘220−age’ formula in volleyball players. Coaches and fitness trainers should take into account that the overestimation of HR<sub>max</sub> by the Fox equation might lead to prescribing exercise at a higher intensity than what is targeted. Therefore, the Tanaka equation appears to offer a more accurate prediction equation of HR<sub>max</sub> than the Fox equation in young female volleyball players.