β-Alanine for Kickboxing Anaerobic Performance (BA-KAST)

Effects of β-Alanine Supplementation on Kickboxing-Specific Anaerobic Performance, Neuromuscular Power, and Strength Endurance: A Randomized, Double-Blind, Placebo-Controlled Trial

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.

Study Overview

• Status: Completed
• Conditions: Anaerobic Performance; Athletic Performance Enhancement (Kickboxing); Strength Endurance; Neuromuscular Power; Nutritional Supplementation (β-Alanine)
• Intervention / Treatment: Dietary supplement: β-Alanine; Dietary supplement: Rice Flour (Placebo)

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.

• Study Type: Interventional
• Enrollment (Actual): 28
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Turkey (Türkiye)
  • Yakutiye
    • Erzurum, Yakutiye, Turkey (Türkiye)
      • Erzurum Technical University, Sport Laboratory

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

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

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Quadruple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: 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.	Dietary supplement: 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.
Placebo Comparator: 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).	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.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Total Time on Kickboxing Anaerobic Speed Test (KASTtotal)	KASTtotal represents the cumulative time (in seconds) required to complete five consecutive sets of a standardized four-technique striking combination (jab-roundhouse-cross-roundhouse) performed at maximal intensity, with 10 seconds of passive recovery between sets. Timing begins at the first strike and ends at the completion of the final kick. This outcome reflects total anaerobic performance capacity under repeated high-intensity conditions specific to kickboxing.	Baseline (Pre-supplementation) and after 4 weeks of supplementation (Post-intervention).

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Best Single-Set Time (KASTbest)	Fastest time achieved across two maximal-effort sets of the KAST protocol, separated by 5 minutes of rest.	Baseline and Week 4
Countermovement Jump Height (CMJ)	Vertical jump height (cm) measured using the validated MyJump2 mobile application based on flight time, with hands on hips. Reflects lower-limb explosive power.	Baseline and Week 4
Squat Jump Height (SJ)	Vertical jump height (cm) measured from a static 90° knee flexion position held for 3 seconds prior to the jump, assessed using MyJump2.	Baseline and Week 4
Push-up Repetitions	Maximum number of continuous, correctly performed push-ups maintaining full elbow extension and rigid body alignment.	Baseline and Week 4
Pull-up Repetitions	Maximum number of continuous pull-ups performed with pronated grip, full arm extension at the start, and chin passing the bar at the top.	Baseline and Week 4

Collaborators and Investigators

• Sponsor: Salih ÇABUK

Study record dates

Study Major Dates

• Study Start (Actual): April 30, 2025
• Primary Completion (Actual): May 30, 2025
• Study Completion (Actual): June 4, 2025

Study Registration Dates

• First Submitted: December 21, 2025
• First Submitted That Met QC Criteria: December 21, 2025
• First Posted (Estimated): January 6, 2026

Study Record Updates

• Last Update Posted (Estimated): January 12, 2026
• Last Update Submitted That Met QC Criteria: January 8, 2026
• Last Verified: January 1, 2026

More Information

Terms related to this study

• Keywords: β-alanine; KAST; Kickboxing Anaerobic Speed Test; randomized double-blind placebo-controlled
• Additional Relevant MeSH Terms: Food; Diet, Food, and Nutrition; Physiological Phenomena; Food and Beverages; Flour
• Other Study ID Numbers: ETU-BETAALANINE-2025; 06/5/21.04.2025 (Other Identifier: Erzurum Technical University)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED
• IPD Plan Description: Individual participant data (IPD) will not be shared publicly, as this study involves a relatively small sample of competitive athletes whose anonymized data could still be indirectly identifiable due to performance metrics and demographic characteristics. Only aggregated and de-identified summary results will be reported in peer-reviewed publications and conference presentations. Upon reasonable request, group-level statistical data or analysis code may be shared with qualified researchers following institutional and ethical approval procedures.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No