Athletes
Conditions
Keywords
dietary supplements, ergogenic aids, strength, caffeine
Brief summary
Weightlifting is a high-intensity strength-power sport where performance depends on maximal force, power output, and technical execution in the snatch and clean and jerk. Due to the sport's short-duration efforts, the ATP-PCr system predominates, with glycolysis supporting recovery between attempts. Given these demands, ergogenic aids are commonly used. While some supplements show limited or inconsistent evidence, caffeine stands out as one of the most well-supported for enhancing strength and power, mainly through central nervous system stimulation. Although its benefits are well documented in other strength sports, research specifically in Olympic weightlifting is scarce. Therefore, this study aimed to examine the effects of caffeine on neuromuscular and competition performance in elite weightlifters, hypothesizing a positive effect.
Detailed description
Olympic weightlifting is a strength-power sport in which athletes aim to lift maximal loads in two highly technical movements: the snatch and the clean and jerk. Performance is determined by the Olympic Total, which combines the best successful attempts in both lifts. These movements are executed in very short durations (2-5 seconds) and require exceptionally high levels of force, power, neuromuscular coordination, and technical proficiency. Because athletes compete within bodyweight categories, relative strength and power are more critical than absolute values. The strength sport is characterized by extremely high mechanical outputs, with barbell velocities exceeding \ 1.65 m/s in the snatch and \ 0.88 m/s in the clean and jerk. These conditions generate some of the highest power outputs recorded in sport science, particularly during the second pull phase. From a physiological perspective, the ATP-PCr system predominates due to the explosive and brief nature of the efforts, although the glycolytic system contributes to recovery between attempts and supports repeated efforts in training. Given these demands, ergogenic aids are often used to optimize performance. While some supplements such as pomegranate juice, BCAAs, and creatine have been associated with benefits in recovery, fatigue reduction, and strength, the supporting evidence is not always robust. In contrast, caffeine is one of the most evidence-based ergogenic aids, primarily acting through antagonism of adenosine receptors (A1 and A2A), which enhances neurotransmitter release (e.g., dopamine and acetylcholine) and improves central nervous system activation. Research has consistently shown that caffeine can enhance muscular strength, including improvements in one-repetition maximum, handgrip strength, and jump performance. Meta-analyses further support its role in increasing maximal strength and power output. Additionally, studies in related strength sports such as powerlifting have reported improvements in power output, movement velocity, velocity loss, and perceived exertion following caffeine ingestion. However, despite this strong body of evidence, research specifically focused on Olympic weightlifting remains limited, and there is a lack of direct evidence regarding both performance outcomes and potential side effects in this population. Therefore, this study was designed to address this gap by examining the effects of caffeine ingestion on neuromuscular performance and simulated competition outcomes in elite weightlifters. The authors hypothesized that caffeine would enhance both neuromuscular and competitive performance in this population.
Interventions
DIETARY_SUPPLEMENTPlacebo
Participants ingested an identical opaque capsule containing an inert substance (cellulose; Guinama, Valencia, Spain). The capsule was also consumed with 200 mL of water under researcher supervision. This condition served as a control to compare against the caffeine condition while maintaining blinding.
DIETARY_SUPPLEMENTCaffeine
Participants ingested an opaque capsule containing 3 mg·kg-¹ of anhydrous caffeine (HSN, Granada, Spain). The capsule was consumed with 200 mL of water under researcher supervision to ensure compliance. This condition was designed to evaluate the ergogenic effects of caffeine on neuromuscular and weightlifting performance.
Sponsors
Universidad Pontificia Comillas
Universidad Francisco de Vitoria
Universidad Rey Juan Carlos
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
TREATMENT
Masking
TRIPLE (Subject, Caregiver, Investigator)
Intervention model description
A randomized, double-blind, placebo-controlled crossover design was employed. Each participant completed two identical evaluation sessions separated by 7 days to ensure adequate recovery and washout of substances. Both sessions were conducted at the same time of day (10:00 a.m.) at the Spanish National Team Training Facility in Madrid. Participants were instructed to replicate their dietary intake prior to each session, avoid strenuous exercise for 24 hours, maintain proper hydration (500 mL of water before arrival), and refrain from consuming supplements or stimulants (e.g., caffeine) for 48 hours before each session and until completing the side-effects questionnaire the following day. In each session, participants ingested an opaque capsule containing either 3 mg·kg-¹ of anhydrous caffeine (HSN, Granada, Spain) or a placebo (cellulose; Guinama, Valencia, Spain), administered with 200 mL of water under researcher supervision. Following ingestion, participants completed their habitua
Eligibility
Sex/Gender
ALL
Age
16 Years to 35 Years
Healthy volunteers
Yes
Inclusion criteria
* Possession of a valid weightlifting federation license * At least two years of weightlifting experience * Free from injury or illness at the time of testing
Exclusion criteria
* Caffeine intolerance * Presence of any chronic disease or injury within the month preceding the study * Habitual caffeine consumption exceeding 100 mg/day * Use of medications or dietary supplements during the study period
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Weightlifting competition | Four weeks | The simulated competition was conducted under official weightlifting conditions, following the standard order of lifts (snatch followed by clean and jerk) and using certified competition equipment. Athletes were allowed three attempts per lift, with up to 5 minutes of rest between attempts and a 10-minute rest period between lifts. Two experienced Level II coaches independently judged each lift, and only those approved by both were considered valid. From this protocol, key variables were derived, including competition strategy (load selected per attempt), competition results (best valid snatch, clean and jerk, and Olympic total), and the number of valid attempts performed in each exercise. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Countermovement jump | 2 weeks | The countermovement jump (CMJ) was used to assess lower-body explosive performance. Participants started from an upright standing position with hands on hips to eliminate arm swing contribution. They then performed a rapid downward movement followed immediately by a maximal vertical jump, aiming to reach the highest possible height. The eccentric phase was self-selected, but participants were instructed to avoid any pause between the downward and upward phases. Multiple attempts were performed, and the best performance was retained for analysis. |
| Deep squat jump | 2 weeks | The deep squat jump (DSJ) was used to assess lower-body explosive performance from a static position. Participants began in a deep squat position (approximately 90° knee flexion or lower) with hands on hips to eliminate arm swing contribution. After holding the position briefly to remove any countermovement, they performed a maximal vertical jump, aiming to reach the highest possible height. This test isolates concentric force production by minimizing the contribution of the stretch-shortening cycle. Multiple attempts were performed, and the best performance was retained for analysis. |
| isometric start position pull | 2 weeks | The isometric start position pull was used to assess maximal isometric strength specific to weightlifting. Participants adopted the start position of the clean or snatch, with the bar fixed against an immovable structure at approximately mid-shin height. From this standardized position, they were instructed to pull maximally against the bar as quickly and forcefully as possible, maintaining proper lifting posture. Force output was recorded during the effort, and peak force was used for analysis. Multiple trials were performed, and the best result was retained. |
| Isometric handgrip strength | 2 weeks | The isometric handgrip strength test was used to assess maximal voluntary grip strength. Participants performed the test using a handgrip dynamometer, holding it in a standardized position with the arm extended alongside the body without touching the trunk. They were instructed to squeeze the dynamometer as forcefully as possible for a few seconds. Both dominant and non-dominant hands were tested, and multiple trials were performed. The highest value achieved for each hand was recorded for analysis. |
| Rating of perceived exertion (RPE) | 2 weeks | The rating of perceived exertion (RPE) was used to assess the subjective perception of effort during the session using scale 1-10 points. After each attempt in the simulated competition, participants reported their exertion using a standardized RPE scale. Additionally, a session-RPE was collected at the end of the protocol to reflect the overall perceived intensity of the entire session. |
| Side effects questionnarie | 2 weeks | The side-effects questionnaire was administered the morning after each experimental session to evaluate the presence and intensity of potential adverse effects associated with the intervention. The questionnaire assessed a range of subjective symptoms, including perceived energy levels, irritability, muscle pain or stiffness, headache, gastrointestinal discomfort, urine production, and sleep-related variables such as difficulty sleeping and overall sleep quality. Participants rated each item using a standardized scale to quantify their responses. |
Countries
Spain
Outcome results
None listed