Supplementation of Kaempferia parviflora Extract Enhances Physical Fitness and Modulates Parameters of Heart Rate Variability in Adolescent Student-Athletes: A Randomized, Double-Blind, Placebo-Controlled Clinical Study

Abstract

This randomized double-blind controlled study aimed to investigate the effects of a standardized Kaempferia parviflora (KP) extract on the physical fitness and heart rate variability (HRV) parameters in adolescent sport school students. 194 male students were recruited and randomized into two groups (n = 97), matched by age and sports. The KP-treated group received KP extract capsules at a dose of 360 mg/day and the control group received placebo capsules, continuously for 12 weeks. Physical fitness performance and HRV parameters were monitored with blood biochemical analysis for product safety. KP extract significantly increased the right-hand grip strength, the back-leg strength and maximal oxygen consumption (VO₂ max) and decreased the time used for 50-meter sprint test without changing the sit-and-reach test and the 40 yard technical test. For HRV parameters, KP extract significantly increased standard deviation of normal to normal intervals (SDNN), square root of the mean of square of successive normal to normal interval differences (RMSSD) and high frequency (HF) norm, without changing low frequency (LF) norm and LF/HF ratio. The increase in stress resistance and decrease in stress index were found in the KP-treated group, without changing the autonomic nervous system (ANS) activity and balance. Blood biochemical analysis showed normal values of all participants. This data indicates the safety and positive effects of KP on muscle strength, endurance and speed, but not on the flexibility and agility. The modulatory effects of KP extract on HRV parameters suggest its anti-stress effects and would encourage the application in a sport training and exercise.

Keywords:

• Kaempferia parviflora
• sport supplement
• physical fitness
• heart rate variability
• anti-stress
• pressure pain threshold

Acknowledgments

The authors would like to thank all the participants, the sport schools at Khon Kaen and Srisaket provinces for the support in this study.

Declaration of interest

The authors declare no conflicts of interest in the study.

Additional information

Funding

The research was supported by the Agricultural Research and Development Agency (ARDA) of Thailand under the grant number CRP5705021720.

Notes on contributors

Bungorn Sripanidkulchai

Bungorn Sripanidkulchai earned BSc (Pharmacy), MSc(Biochemistry) and PhD (Cell Biology) degrees with affiliation at the Center for Research and Development of Herbal Health Products, Faculty of Pharmaceutical Sciences, Khon Kaen University, Khon Kaen, Thailand. Her research interest is the integrated aspects for the development of herbal health products.

Kreeta Promthep

Kreeta Promthep earned the BSc (Physical Education), MSc (Physical Education) and PhD (Exercise and Sport Sciences) degrees with the affiliation at the Faculty of Education, Udon Thani Rajabhat University, Udon Thani, Thailand. His research interests are Physical fitness and Athletic.

Sarunya Tuntiyasawasdikul

Sarunya Tuntiyasawasdikul earned BSc (Pharmacy) and PhD (Research and development of pharmaceutical product) degrees with affiliation at the Center for Research and Development of Herbal Health Products, Faculty of Pharmaceutical Sciences, Khon Kaen University, Khon Kaen, Thailand. Her research interests are Traditional medicines, Phytochemistry of herbal medicines, Natural products, Transdermal delivery.

Peera Tabboon

Peera Tabboon earned BSc (Pharmacy), MSc (Pharmaceuticals), PhD (Research and development of pharmaceutical product) degrees with affiliation at the Center for Research and Development of Herbal Health Products, Faculty of Pharmaceutical Sciences, Khon Kaen University, Khon Kaen, Thailand. His research interests are Traditional medicine, Phytochemistry of herbal medicines, Natural products, Product development.

Rosawan Areemit

Rosawan Areemit, MD MMSc (MedEd) is a pediatrician, adolescent medicine specialist and medical educator at the Faculty of Medicine, Khon Kaen University, Thailand. She works in advocacy and providing health care to adolescents and children in the North-East region of Thailand. She is passionate about teaching medical students and residents as well as providing faculty development and shaping a culture of communication and feedback at her institution. Her research interests include: Pediatrics, Adolescent Medicine, Child Health Supervision, Medical Education, Faculty Development.