Does Acute Caffeine Alter the Temporal Countermovement Jump Response Following Reactive Strength Index-Individualized Drop Jumps in Chinese Han Basketball Players with Different Habitual Caffeine Exposure? A Randomized, Double-Blind, Placebo-Controlled Crossover Trial.
This study did not obtain clear evidence that 3 mg·kg-1 caffeine provided additional CMJ improvement following this specific RSI-derived individualized DJ protocol, and habitual caffeine exposure did not systematically moderate the temporal response.
Key Findings
Results
Countermovement jump performance varied significantly across time but the primary Condition × Time interaction between caffeine and placebo was not significant.
CMJ varied across time (p < 0.001), indicating a post-conditioning temporal effect regardless of supplement condition.
The Condition × Time interaction was not significant (p = 0.305).
All 30 randomized Chinese Han male basketball players contributed data across 57 participant-period observations.
The study used a randomized, double-blind, placebo-controlled crossover design with CMJ assessed at 15 s, 3, 6, 9, and 12 min post-conditioning.
Results
CAF-PLA differences in countermovement jump height at all five post-conditioning time points were small and non-significant after Holm adjustment.
At 15 s: CAF-PLA difference was 0.89 cm (95% CI, -0.11 to 1.88).
At 3 min: 0.39 cm (95% CI, -0.61 to 1.38); at 6 min: 0.21 cm (95% CI, -0.79 to 1.21).
At 9 min: 0.84 cm (95% CI, -0.15 to 1.84); at 12 min: 0.71 cm (95% CI, -0.29 to 1.71).
All Holm-adjusted p-values were ≥ 0.399 across these five time points.
The dose used was 3 mg·kg⁻¹ caffeine administered 60 min prior to conditioning.
Results
Habitual caffeine exposure did not significantly moderate the temporal CMJ response to caffeine supplementation.
17 participants reported no habitual caffeine exposure and 13 reported exposure during the preceding 4 weeks.
Global moderation by habitual caffeine exposure was not significant either continuously (p = 0.158) or categorically (p = 0.116).
An isolated exploratory contrast at 9 min in participants reporting zero habitual caffeine exposure favored CAF by 1.83 cm (95% CI, 0.74–2.92; Holm-adjusted p = 0.031), but this was flagged as exploratory.
The authors noted this isolated signal should not be interpreted as confirmatory evidence of moderation.
Results
Ratings of perceived exertion showed no significant Condition × Time interaction, though a trend toward lower RPE with caffeine was observed at 15 seconds.
The RPE Condition × Time interaction was not significant (p = 0.253).
At 15 s post-conditioning, the CAF-PLA difference in RPE was -0.60 points (95% CI, -1.09 to -0.12; Holm-adjusted p = 0.088), indicating a trend toward lower perceived exertion with caffeine.
This difference did not survive Holm adjustment for multiple comparisons.
RPE was assessed alongside CMJ at the same temporal points following the drop-jump conditioning protocol.
Results
The reactive strength index (RSI)-derived individualized drop-jump protocol produced a significant post-activation potentiation temporal effect on CMJ regardless of caffeine supplementation.
The conditioning protocol consisted of 3 × 5 drop jumps with drop height individualized based on each participant's RSI.
CMJ height changed significantly across the post-conditioning measurement time points (p < 0.001).
Participants performed a post-supplement, pre-conditioning CMJ baseline assessment after a 60-min absorption period and warm-up.
Three participants did not complete Period 2 due to unmet readiness criteria, but their Period 1 data were retained, yielding 57 participant-period observations from 30 randomized participants.
Methods
The study was conducted in Chinese Han male basketball players with a median age of 22.0 years using a within-subject crossover design.
Median age was 22.0 years (IQR, 21.0–27.75).
All participants were male Chinese Han basketball players (n = 30).
The design was randomized, double-blind, placebo-controlled, and crossover.
The caffeine dose was 3 mg·kg⁻¹, which is at the lower end of the commonly studied ergogenic range.
What This Means
This research suggests that taking a moderate dose of caffeine (3 mg per kilogram of body weight) does not provide meaningful additional benefit for jump performance when it is added on top of an individualized plyometric warm-up protocol in basketball players. The study had 30 male Chinese Han basketball players complete jump tests at multiple time points after either caffeine or a placebo, followed by a set of individualized drop jumps. While jump performance did change over time after the conditioning exercise—a known effect called post-activation potentiation—caffeine did not meaningfully change the pattern or magnitude of this response compared to placebo at any of the five time points measured.
The study also investigated whether players' habitual caffeine consumption (whether they regularly drank coffee or other caffeinated beverages) affected how they responded to the caffeine supplement. No systematic difference was found between habitual caffeine consumers and non-consumers. One isolated statistical signal suggested that non-consumers might jump slightly higher at the 9-minute mark with caffeine, but the authors explicitly labeled this as exploratory and not a reliable finding, as it could easily be a chance result given the number of comparisons made.
This research matters because it adds to the growing body of evidence about when and how caffeine works as a sports supplement. It suggests that when athletes already perform an optimized, individually tailored plyometric warm-up, caffeine at this dose may not add further benefit for explosive jumping ability. The findings also provide data specifically from Chinese Han athletes, a population underrepresented in sports nutrition research, and highlight that habitual caffeine use did not clearly blunt or enhance the supplement's effects in this context.
Check Your Own Numbers
Upload your bloodwork. We'll cross-reference your results against this study and 4,700 others.
Sun J, Wang M, Chen L, Li J, Zhou Y, Li M, et al.. (2026). Does Acute Caffeine Alter the Temporal Countermovement Jump Response Following Reactive Strength Index-Individualized Drop Jumps in Chinese Han Basketball Players with Different Habitual Caffeine Exposure? A Randomized, Double-Blind, Placebo-Controlled Crossover Trial.. Nutrients. https://doi.org/10.3390/nu18172842