Enhancement of physical fitness by black ginger extract rich in polymethoxyflavones: a double-blind randomized crossover trial

Abstract

Background: Black ginger (Kaempferia parviflora) contains polymethoxyflavones, which are flavonoids that exhibit various bioactivities including improvements in muscular metabolism. We examined the effects of black ginger extract (KPE) rich in polymethoxyflavones on physical fitness and fatigue. Methods: 24 healthy volunteers were recruited. They were randomly divided into two groups: group A received KPE (30 mg/day) and then a placebo while group B received a placebo and then KPE in a crossover trial. Each volunteer took one capsule containing KPE or the placebo once a day for 4 weeks. A physical fitness test (PFT), questionnaire, and blood test were performed at 0, 4, 7, and 11 weeks (wash-out term for 3 weeks). Results: After a 4-week ingestion period, improvements in left hand grip strength (2.80 vs 0.03 kg), performance in the 30-second chair stand test (6.27 vs 1.71 times), 5-m tandem walking test (-3.17 vs -0.87 sec), and cycle ergometer test (8.54 vs 1.13 kcal) were significantly greater in the KPE group than in the placebo group. In a fatigue of subjects without an exercise habit, the mean reductions after ingestion of KPE in the daily VAS fatigue score (-9.87 vs +1.52%), post PFT VAS fatigue score (-10.2 vs -0.91%), and chronic fatigue syndrome (CFS) score (-3.93 vs -2.47) were greater than the placebo group. Conclusions: The ingestion of KPE was found to enhanced physical fitness, namely, grip strength, leg strength, balance, endurance, and locomotor activity. Furthermore, KPE intake slightly improved fatigue at the conventional state and post PFT state as well as CFS scores in subjects without an exercise habit List