Aerial Duel Performance in Soccer Players
Conditions
Keywords
Caffeine, Rhodiola rosea, Combined Supplementation, Soccer Performance, Neuromuscular Fatigue, Countermovement Jump (CMJ), Early Impulse (Impulse₀-₂₀₀), Aerial Duel
Brief summary
This study will examine whether caffeine (CAF) and Rhodiola rosea (RHO) supplementation, taken alone or in combination, can improve explosive performance and soccer-specific aerial duel performance in trained male soccer players. In a randomized, double-blind, placebo-controlled, parallel design, participants will be assigned to placebo, RHO, CAF, or RHO+CAF for 4 weeks. Performance outcomes will be assessed before and after the intervention using countermovement jump measures (including early take-off impulse) and standardized heading tests (heading reach height, ball exit velocity, and heading duel success rate), with additional measures of neck isometric strength and perceived exertion.
Interventions
DIETARY_SUPPLEMENTCaffeine
Anhydrous caffeine capsules administered at a dose of 3 mg/kg body weight. Taken as a single dose 30 minutes prior to the physical performance tests.
DIETARY_SUPPLEMENTRhodiola rosea extract
Standardized Rhodiola rosea extract capsules. Daily total dosage of 2.4 g (containing approx. 12 mg salidroside), taken twice daily (before breakfast and lunch) for 30 days.
DIETARY_SUPPLEMENTPlacebo
Appearance-matched capsules containing inert ingredients (starch or rice flour).
Sponsors
Beijing Sport University
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
OTHER
Masking
TRIPLE (Subject, Investigator, Outcomes Assessor)
Masking description
Participants, outcome assessors, and data analysts are blinded to group allocation. Supplement distribution and group coding are managed by an independent researcher not involved in data collection or statistical analysis. All capsules are identical in appearance to maintain blinding throughout the study period.
Intervention model description
This is a 4-week, randomized, double-blind, placebo-controlled, parallel-group trial with four arms (placebo, Rhodiola rosea, caffeine, and Rhodiola rosea plus caffeine; n=24 per arm). Participants complete identical pre- and post-intervention testing sessions. Rhodiola rosea is administered daily throughout the intervention period, while caffeine is administered acutely prior to the test sessions; matching placebo capsules are used to maintain blinding across all groups.
Eligibility
Sex/Gender
MALE
Age
18 Years to 30 Years
Healthy volunteers
Yes
Inclusion criteria
* Healthy male soccer players from the Beijing Sport University team. Systematic soccer-specific training background and stable competitive level. Suitable for high-intensity physical testing based on the Physical Activity Readiness Questionnaire (PAR-Q).
Exclusion criteria
* History of neuromuscular or musculoskeletal system diseases. Intake of caffeine (coffee/tea), other supplements, ergogenic aids, or alcohol within the last 3 months. Current use of antidepressants or central nervous system stimulants. Smokers.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Early takeoff impulse (Impulse₀-₂₀₀) | Baseline (Day 0) and Post-intervention (Day 30), measured under both non-fatigued and fatigued conditions. | Calculated as the integration of vertical force over the first 200 ms of the countermovement jump (CMJ) takeoff phase, relative to body mass (N·s·kg-¹). This measures the capacity for rapid force production. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Heading contact height | Baseline (Pre-test) and 4 weeks (Post-test), including measurements under both non-fatigued and fatigued conditions at each time point. | Participants perform a header and touch a football suspended on a vertical jump tester with their forehead. The highest touch height from three trials is recorded to reflect aerial reach capacity. |
| Heading Ball Velocity | Baseline (Pre-test) and 4 weeks (Post-test), including measurements under both non-fatigued and fatigued conditions at each time point. | The maximum velocity of the ball after heading is measured using a speed device. A ball machine is used to ensure consistent delivery direction and speed. This measures momentum transfer efficiency and technical execution. |
| Aerial Duel Success Rate | Baseline (Pre-test) and 4 weeks (Post-test), including measurements under both non-fatigued and fatigued conditions at each time point. | Calculated as the percentage of successful duels out of a fixed number of trials in a standardized head-to-head setting. Success is defined as effectively contacting the ball first and directing it toward a target area. |
| Neck Isometric Strength | Baseline (Pre-test) and 4 weeks (Post-test). | Maximum isometric force measured in neck flexion and extension using a handheld dynamometer. Values are normalized to body mass ($N \\cdot kg\^{-1}$) to assess the stability of the head-trunk system. |
| Rate of Perceived Exertion (RPE) | Immediately after the fatigue-induction protocol and post-fatigue testing at Baseline and 4 weeks. | Subjective effort level reported by participants on a scale of 1 to 10 (1 = nearly no effort, 10 = extreme effort) immediately following the fatigue protocol and post-fatigue tests. |
Countries
China
Outcome results
None listed