Relationship between Oxygen Uptake Reserve and Heart Rate Reserve in Young Male Tennis Players: Implications for Physical Fitness Monitoring

The aims of this study were to (i) verify the relationship between reserve oxygen uptake (VO(reserve)) and reserve heart rate (HR(reserve)) in young male tennis players, and (ii) understand the relationship between oxygen uptake (VO(2)) measured at the end of a tennis drill and recovery heart rate (HR(recovery)) after the tennis drill. Ten young male tennis players (16.64 ± 1.69 years; 62.36 ± 6.53 kg of body mass; 175.91 ± 5.26 cm of height) were recruited from the National Tennis Association. Players were instructed to perform a tennis drill based on an incremental intensity protocol. Afterward, three levels of intensity were used based on VO(2reserve) and HR(reserve). A significant variance was observed between levels (VO(2reserve) and HR(reserve) = p < 0.001). VO(2reserve) presented a significant and high agreement with HR(reserve). The mean data revealed non-significant differences (p > 0.05), a very high relationship of linear regression (R(2) = 82.4%, p < 0.001), and high agreement in Bland Altman plots. VO(2,) at the highest level of intensity (>93%), presented a significant correlation with HR(recovery) during the immediate 30 s after the drill (r(s) = 0.468, p = 0.028). Tennis coaches or instructors must be aware of the differences between monitoring or prescribing training intensities based on HR(reserve) or HR(max). They can also use HR(recovery) for 30 s immediately after exercise to verify and understand the variation in their players’ cardiorespiratory capacities.