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. 2025 Sep 5:12:1653559.
doi: 10.3389/fmed.2025.1653559. eCollection 2025.

Effect of Pinus koraiensis leaf extract on fatigue reduction and exercise performance: study protocol for a randomized, double-blind, placebo-controlled clinical trial

Yujin Choi  1 , Changsop Yang  1 , Ji Soo Yoon  2 , Sunhoo Kim  2 , Sang-Yoon Kim  2 , Mi Young Lee  3
Affiliations

Effect of Pinus koraiensis leaf extract on fatigue reduction and exercise performance: study protocol for a randomized, double-blind, placebo-controlled clinical trial

Yujin Choi et al. Front Med (Lausanne). .

Abstract

Background: Previous research has shown that Pinus koraiensis leaf (PKL) extract exhibits promising anti-fatigue potential in mice, showing improved exercise endurance, decreased stress-related biochemical markers, and enhanced antioxidant activity. Based on this previous animal study, the present study aims to evaluate the efficacy of PKL extract on fatigue reduction and exercise performance in healthy adults with moderate to severe fatigue.

Method and analysis: This randomized, double-blind, placebo-controlled clinical trial will enroll volunteers who meet the eligibility criteria, specifically those with a Fatigue Severity Scale (FSS) score of 27 or higher, indicating clinically significant fatigue. Eligible participants will be randomly assigned to either the PKL extract or placebo group. The intervention will consist of daily consumption of the assigned investigational product for 8 weeks, with evaluations conducted at 4-weeks intervals. Primary outcome measures include the Fatigue Severity Scale (FSS) and time to exhaustion during a treadmill exercise test. Secondary outcomes include blood fatigue markers, exercise performance parameters, rating of perceived exertion, visual analogue scale for fatigue, and grip strength.

Discussion: This clinical trial aims to develop PKL extract as a functional health food ingredient for fatigue improvement. The findings will provide evidence regarding the efficacy of PKL extract for alleviating fatigue and enhancing exercise performance in humans.

Keywords: Pinus koraiensis; clinical trial protocol; dietary supplements; exercise performance; fatigue; functional food; pine leaf extract.

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Conflict of interest statement

ML holds a patent for Pinus koraiensis leaf extract related fatigue. S-YK, JY, and SK are employed by Huons Dongam R&D Center, Huons N. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

Study timeline chart detailing activities during various phases: enrolment (-3 to 0 weeks), allocation (0 week), post-allocation (4 weeks 7 days), and close-out (8 weeks 7 days). Activities before enrollment include informed consent, physical examination, vital signs, and laboratory tests. Interventions are PKL extract or placebo (randomly allocated). Assessments involve scales for fatigue severity, treadmill exercise tests, perceived exertion, subjective fatigue (VAS), hand grip strength, blood fatigue markers, dietary intake, physical activity, and adherence monitoring. Activities are marked with Xs in corresponding phases. PKL refers to Pinus koraiensis leaf; VAS is visual analogue scale.
FIGURE 1
Schedule of enrollment, interventions, and assessments.
See this image and copyright information in PMC

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