Effects of 8-week sprint interval training on cardiorespiratory fitness, blood lactate responses, stroke performance, and neuromuscular function in collegiate male tennis players

Background Tennis requires repeated high-intensity movement, rapid recovery, and stable stroke execution. This study compared court-based sprint interval training (SIT) with continuous endurance training (CT) for cardiorespiratory fitness, blood lactate responses, stroke performance, and neuromuscular ability in collegiate male tennis players. Methods In this single-blind trial, forty-eight collegiate male tennis players were randomly allocated to SIT or CT (n = 24 per group) for 8 weeks, with three supervised conditioning sessions per week in addition to regular tennis training. Both groups attended regular tennis classes twice weekly for 45 min per session under the same course schedule. SIT consisted of court-based 110-m shuttle sprints (3 sets × 3 repetitions; 20 s between repetitions and 5 min between sets), whereas CT was treadmill running at 65% of baseline VO 2 max, progressing from 30 to 60 min per session. Cardiorespiratory fitness, blood lactate, standardized stroke performance, jumping and reactive-strength measures, 20-m sprint time, and 5-0–5 change-of-direction time were assessed before and after training. Interaction tests were adjusted using Holm’s method within six outcome families, with secondary outcomes interpreted exploratorily. Results VO 2 max increased from 50.41 ± 1.62 to 53.24 ± 2.05 mL·kg −1 ·min −1 in SIT and from 49.83 ± 1.98 to 51.58 ± 2.44 mL·kg −1 ·min −1 in CT. VT2 increased from 2530.08 ± 136.72 to 2744.79 ± 205.49 mL·min −1 in SIT and from 2490.94 ± 189.47 to 2597.70 ± 222.72 mL·min −1 in CT. The group × time interactions remained significant after within-family Holm adjustment for VO 2 max (adjusted P = 0.023) and VT2 (adjusted P = 0.005). Exploratory interactions also remained significant within their respective families for stroke accuracy (adjusted P < 0.001), unforced-error rate (adjusted P = 0.009), RSI (adjusted P < 0.001), 20-m sprint time (adjusted P = 0.020), and 5-0–5 change-of-direction time (adjusted P = 0.007). BLa-15 and BLa-R15 estimates favored SIT, but neither interaction remained significant after adjustment (both adjusted P = .0.054). Conclusions Court-based SIT produced greater improvements than CT in VO 2 max and VT2. Domain-adjusted exploratory findings also supported greater improvements in stroke performance, RSI, sprint performance, and change-of-direction performance, whereas recovery-phase blood lactate differences remained uncertain after adjustment.