β-Alanine for Kickboxing Anaerobic Performance

NCT ID: NCT07319052

Last Updated: 2026-01-12

Basic Information

• Recruitment Status: COMPLETED
• Clinical Phase: NA
• Total Enrollment: 28 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2025-04-30
• Study Completion Date: 2025-06-04

Brief Summary

This randomized, double-blind, placebo-controlled parallel-group trial will evaluate whether four weeks of β-alanine (BA) supplementation improves sport-specific anaerobic performance, neuromuscular power, and strength endurance in trained male kickboxers. β-Alanine is the rate-limiting precursor for skeletal muscle carnosine, an intramuscular buffer that can attenuate exercise-induced acidosis during repeated high-intensity efforts. Because kickboxing involves brief, repeated striking sequences with high glycolytic demand, BA may represent a practical, legal ergogenic aid for this population.

Twenty-eight adult male kickboxers will be randomized (stratified) to BA (6.4 g·day-¹) or placebo for 4 weeks while maintaining habitual training and diet. Assessments will occur at baseline and post-intervention under standardized laboratory conditions and time-of-day control. The primary outcome is the total time on the Kickboxing Anaerobic Speed Test (KASTtotal; five consecutive sets of a validated four-technique striking combination with 10-s passive recovery). Secondary outcomes include best single-set time (KASTbest), individual set times (KAST₁-₅), Performance Decrement Index (PDI), countermovement jump (CMJ) and squat jump (SJ) height, and upper-body strength endurance (maximal push-ups and pull-ups performed to strict standards). Timing is determined from 25-fps video with frame-level analysis; jump height is derived via a validated smartphone application.

Adverse events-particularly transient paresthesia-will be monitored throughout. The main analysis will use two-way repeated-measures ANOVA (group × time) with partial eta-squared to quantify effects; assumption checks and correction procedures will be applied as appropriate. BA will yield greater improvements than placebo in KASTtotal and upper-body strength endurance, with limited changes expected for jump performance.

Detailed Description

Rationale and Background: β-Alanine supplementation increases intramuscular carnosine, enhancing intracellular buffering capacity and potentially preserving excitation-contraction coupling during high-intensity, repeated efforts. Kickboxing competition is characterized by short striking bouts, rapid direction changes, and high glycolytic contribution-conditions under which increased buffering may translate to meaningful performance benefits. Prior work in combat sports has reported ergogenic effects of BA; however, evidence in kickboxing using a validated sport-specific test remains limited. This trial addresses that gap using the Kickboxing Anaerobic Speed Test (KAST), which offers strong ecological validity for combat athletes.

Design and Setting: Randomized, double-blind, placebo-controlled, parallel-group clinical trial with two assessment time points (pre, post). Participants continue usual training under coach supervision and are instructed to avoid other ergogenic aids and caffeine for 24 h before testing. All testing is performed under standardized environmental conditions (temperature and humidity controlled) and at the same time of day (±1 h) to minimize circadian and residual fatigue effects.

Participants: Twenty-eight healthy adult male kickboxers with ≥5 years of systematic training and active competition in the prior year. Key exclusions include musculoskeletal injury limiting high-intensity exercise, cardiometabolic or respiratory disease, β-alanine intolerance, and recent use of overlapping supplements. Written informed consent is obtained. The protocol complies with the Declaration of Helsinki and local ethics approval.

Interventions Experimental: β-alanine, 6.4 g·day-¹ for 4 weeks (e.g., divided doses). Comparator: Appearance-matched placebo (rice flour), same schedule. Products are dispensed in coded containers to preserve blinding of participants, investigators, and outcome assessors.

Outcome Measures Primary: KASTtotal (s), computed as the sum of five consecutive sets of a standardized four-technique combination performed at maximal effort with 10-s passive recovery. Timing starts at first bag contact and ends after the final kick; performance is video-recorded at 25 fps and analyzed frame-by-frame.

Secondary: KASTbest (best of two maximal sets separated by 5-min recovery), individual set times KAST₁-₅, PDI (%) = KASTtotal/(KASTbest × 5) × 100, CMJ and SJ height (hands on hips; validated smartphone app), and maximal push-ups and pull-ups (strict form criteria). Adverse events and tolerability-especially paresthesia-are recorded throughout.

Procedures and Standardization: A familiarization session precedes baseline testing. Warm-up includes light aerobic activity, dynamic drills, plyometrics, mobility work, and shadowboxing following a scripted sequence. Standardized verbal encouragement and rest intervals are used. Technique order for KAST is fixed; any deviation leads to trial termination and repeat after enforced rest.

Sample Size and Statistical Analysis: An a priori power analysis for a medium within-between interaction (α=0.05, power 0.80) indicated a minimum sample of 24; the target enrollment of 28 provides adequate sensitivity. Baseline between-group differences are assessed by independent t-tests (effect size: Hedges' g). The primary inferential model is a two-way repeated-measures ANOVA (group × time) for each outcome, reporting F(1,26), p values, and partial eta-squared (ηp²) with conventional magnitude thresholds. Assumptions are tested (Shapiro-Wilk, Levene, Mauchly); Greenhouse-Geisser corrections are applied as needed. When interactions are significant, simple-effects tests with Bonferroni adjustment localize differences.

Safety and Monitoring: This is a low-risk nutrition study in trained athletes. The most common expected adverse effect is transient paresthesia, which will be monitored via spontaneous reports and direct questioning. Any unexpected or serious events will be evaluated and reported per institutional policy; supplementation may be paused or discontinued at investigator discretion.

Expected Impact and Limitations: BA to reduce KASTtotal and improve push-up and pull-up performance versus placebo, with minimal changes in CMJ/SJ. Limitations include the absence of direct physiological verification of carnosine accrual (e.g., muscle biopsy) and lack of concurrent lactate or pH measures, which constrain mechanistic inference. Nonetheless, by deploying a validated, sport-specific performance test with rigorous control of confounders and blinded assessment, this trial aims to provide clinically relevant, ecologically valid evidence for practitioners working with combat sport athletes.

Conditions

Athletic Performance Enhancement (Kickboxing); Anaerobic Performance; Strength Endurance; Neuromuscular Power; Nutritional Supplementation (β-Alanine)

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: PARALLEL
• Primary Study Purpose: TREATMENT
• Blinding Strategy: QUADRUPLE

Study Groups

β-Alanine Supplementation

Participants receive 6.4 g of β-alanine per day for 4 weeks (e.g., 4 × 1.6 g divided doses). The supplement is provided as Hardline β-Alanine (Hardline Nutrition, Türkiye), standardized for active ingredient content.

Group Type: EXPERIMENTAL

β-Alanine

Intervention Type: DIETARY_SUPPLEMENT

Participants in the experimental group will receive 6.4 grams of β-alanine per day for 4 weeks, administered orally in four divided doses (1.6 g each). The supplement used is a commercially available β-alanine formulation (Hardline Nutrition, Türkiye), standardized for purity and active ingredient content. The dosing protocol follows established guidelines from prior ergogenic studies in athletes. Supplementation is supervised by the research team, and adherence is monitored weekly.

Rice Flour

Participants receive a visually identical, flavor-matched placebo composed of rice flour, dosed equivalently to the experimental group (6.4 g·day-¹ for 4 weeks).

Group Type: PLACEBO_COMPARATOR

Rice Flour (Placebo)

Intervention Type: DIETARY_SUPPLEMENT

Participants in the placebo group will receive 6.4 grams of rice flour per day for 4 weeks, divided into four equal doses (1.6 g each) and identical in appearance, packaging, and flavor to the β-alanine supplement. The placebo is prepared and coded by an independent staff member to maintain double-blind conditions. All participants consume their assigned supplement orally each day under the same schedule, maintaining their normal training and diet routines.

Interventions

β-Alanine

Participants in the experimental group will receive 6.4 grams of β-alanine per day for 4 weeks, administered orally in four divided doses (1.6 g each). The supplement used is a commercially available β-alanine formulation (Hardline Nutrition, Türkiye), standardized for purity and active ingredient content. The dosing protocol follows established guidelines from prior ergogenic studies in athletes. Supplementation is supervised by the research team, and adherence is monitored weekly.

Intervention Type: DIETARY_SUPPLEMENT

Rice Flour (Placebo)

Participants in the placebo group will receive 6.4 grams of rice flour per day for 4 weeks, divided into four equal doses (1.6 g each) and identical in appearance, packaging, and flavor to the β-alanine supplement. The placebo is prepared and coded by an independent staff member to maintain double-blind conditions. All participants consume their assigned supplement orally each day under the same schedule, maintaining their normal training and diet routines.

Intervention Type: DIETARY_SUPPLEMENT

Eligibility Criteria

Inclusion Criteria

• Healthy male kickboxers aged 18-35 years
• Minimum 5 years of systematic kickboxing training experience
• Actively engaged in competition or structured training within the last 12 months
• Free from any musculoskeletal injuries, metabolic, cardiovascular, or respiratory disorders that could affect high-intensity exercise performance
• Not currently taking any ergogenic aids, nutritional supplements, or medications known to influence performance or recovery
• Willing to maintain habitual diet and training routines throughout the study period
• Provided written informed consent before participation

Exclusion Criteria

• Current or recent (<6 months) musculoskeletal injury preventing maximal effort performance
• Metabolic, cardiovascular, or respiratory conditions that may increase risk during high-intensity activity
• Known allergy or intolerance to β-alanine
• Use of performance-enhancing supplements (e.g., creatine, caffeine, sodium bicarbonate, beta-alanine) in the past 4 weeks
• Any neurological, psychiatric, or endocrine disorder affecting physical performance or adherence
• Inability or unwillingness to comply with supplementation protocol or testing procedures

• Minimum Eligible Age: 18 Years
• Maximum Eligible Age: 35 Years
• Eligible Sex: MALE
• Accepts Healthy Volunteers: Yes

Sponsors

Salih ÇABUK

OTHER

Sponsor Role: lead

Responsible Party

Salih ÇABUK

Research Assistant

Responsibility Role: SPONSOR_INVESTIGATOR

Locations

Erzurum Technical University, Sport Laboratory

Erzurum, Yakutiye, Turkey (Türkiye)

Countries

Turkey (Türkiye)

Other Identifiers

06/5/21.04.2025

Identifier Type: OTHER

Identifier Source: secondary_id

ETU-BETAALANINE-2025

Identifier Type: -

Identifier Source: org_study_id