Black Ginger (Kaempferia parviflora) Extract Enhances Endurance Capacity by Improving Energy Metabolism and Substrate Utilization in Mice

1. Introduction

Kaempferia parviflora

, KP) is a member of the ginger family that grows naturally in Laos and Thailand. The rhizome of KP is widely used in traditional medicine to treat diseases and symptoms such as inflammation, ulcers, gout, colic, and abscesses [8,9,11,12,9,14,15,17,

Black ginger (, KP) is a member of the ginger family that grows naturally in Laos and Thailand. The rhizome of KP is widely used in traditional medicine to treat diseases and symptoms such as inflammation, ulcers, gout, colic, and abscesses [ 1 ]. The KP extract (KPE), which is extracted from the rhizome of KP, contains several polymethoxy flavonoids (PMFs) [ 2 ]. PMFs belong to flavonoids in natural polyphenols [ 3 ], and the PMFs rich in KPE have been reported for a variety of pharmacological activities, such as suppressing the ability of prostate hyperplasia [ 4 ] and anti-tumor [ 5 6 ] and hepatoprotective effects [ 7 ]. In addition, the cellular-metabolism-regulating activity of PMFs has been reported in recent years [ 2 10 ]. According to the reports, KPE and/or PMFs promote cell energy metabolism by improving glucose and lipid metabolism and stimulating mitochondrial biogenesis [ 10 13 ]. KPE enhanced glycogen synthase mRNA expression and the content of glycogen in C2C12 cells, and in mice soleus muscle it also had a tendency to increase the content of glycogen [ 11 ]. It can inhibit fat accumulation in the obesity and diabetes model by inhibiting fat cell hypertrophy and activating thermogenesis function in brown adipose tissue [ 8 16 ]. KPE can also enhance the activation of AMP-activated protein kinase (AMPK) and phosphatidylinositol 3 kinase (PI3K)/Akt pathways to regulate muscle protein synthesis, and significantly increase the size, volume, and quality of muscle fibers, thereby enhancing muscle functions such as exercise endurance and grip strength [ 12 18 ].

Health-related components of physical fitness can be categorized as endurance, flexibility, balance, agility, and coordination, and endurance is standardized as cardiorespiratory endurance, muscle endurance, and muscle strength [ 19 ]. Great efforts are made by athletes and trainers to earn better endurance capacity, while endurance capacity is also important to endurance athletes as well very important to common individuals. Therefore, improvement of the overall endurance will also benefit the physical fitness of common people.

2 max [2 max, carbohydrates take the lead of energy supply [

All movements of the human body require energy. Cells use material energy through adenosine triphosphate (ATP), which is called energy currency [ 20 ]. The continuous supply of ATP to the processes that support skeletal muscle contraction during exercise is critical to exercise performance lasting seconds to hours [ 21 22 ]. Intensity and duration of exercise are major determinants affecting the relative contributions of energy production pathways during exercise [ 21 22 ]. At lower exercise intensity, lipid oxidation dominates the energy supply, and the oxidation rate reaches a maximum when the exercise intensity is approximately 60–65% of VOmax [ 22 ]. However, as the exercise intensity further increases to 80–100% VOmax, carbohydrates take the lead of energy supply [ 21 ].

2 max) prolonged exercise, blood lactate oxidation (90% direct oxidation, 10% through gluconeogenesis) accounts for about 30% of total carbohydrate metabolism [

In long-term endurance exercise, the oxidative metabolism of carbohydrates and lipids provides almost all the adenosine triphosphate (ATP) that the body needs [ 22 ]. Carbohydrates used in endurance exercise are mainly produced by the decomposition of muscle glycogen, glucose, liver glycogen, and the cycle of gluconeogenesis [ 22 ]. The substrates for lipid oxidation are mainly derived from fatty acids from the breakdown of triglycerides (TG) in adipocytes and intramuscular triglycerides (IMTG) [ 23 ]. Lactate is regarded as an important substrate for oxidation and gluconeogenesis and plays an important role between glycolysis and oxidation [ 22 ]. In moderate- to high-intensity (70–75% VOmax) prolonged exercise, blood lactate oxidation (90% direct oxidation, 10% through gluconeogenesis) accounts for about 30% of total carbohydrate metabolism [ 24 25 ]. Therefore, the availability and utilization of carbohydrate, lipid, and lactate in muscles and tissues are essential for maintaining athletic performance in endurance exercise.

tabebuia avellanedae

enhanced endurance performance in mice or rats by increasing hepatic or/and muscle glycogen storage and promoting antioxidant capacity [28,

Intake of nutritional supplements is one of the effective ways to enhance endurance capacity [ 26 ]. In recent years, the effects of various plant extracts on endurance capacity have been extensively studied. In several studies of plant extracts, the extracts of amarkand tubers, okra, andenhanced endurance performance in mice or rats by increasing hepatic or/and muscle glycogen storage and promoting antioxidant capacity [ 27 29 ].

17,32,

Polyphenols, a large class of nutritional supplements, are ubiquitously produced in plants. The ability of polyphenols to upregulate exogenous antioxidants, enhance vascular function, and reduce oxidative damage during exercise [ 30 ] is believed to have potential benefits for exercise performance [ 31 ]. The polyphenolic compound PMF in KPE has also been reported to have potential benefits to exercise performance by enhancing mitochondria biogenesis, energy metabolism, or anti-inflammation [ 10 33 ]. However, all the subjects in the above experiment received long-term administration of KPE for at least one month. The effect of a single KPE administration on exercise performance has not been fully studied and whether the cellular energy metabolism regulation of KPE can be effective in a single administration remains to be verified. In a pharmacokinetic study of the main components of KPE, the concentration of KPE quickly reached a peak and was widely distributed in various organs within 1 to 2 h after oral administration and then slowly eliminated in rats [ 34 ]. Therefore, it is reasonable that KPE affects endurance performance by exerting its cellular metabolism regulation effects in 1–2 h after acute administration. It is necessary to study the effect of a single dose of KPE on the endurance of mice. The purpose of our study was to determine whether a single administration of KPE could affect endurance performance in mice and whether the effect was produced through a pro-cellular energy metabolic pathway. We designed this experiment and assumed that mice extend their exhaustive exercise time after a single KPE administration and evaluated the effect of KPE from the perspective of energy metabolism.