Fenugreek and Its Effects on Muscle Performance: A Systematic Review

Fenugreek extracts possess promising physiological and pharmacological properties in human and animal models. This review aims to provide a scientific and comprehensive analysis of the literature on the effects of fenugreek extracts on muscle performance. An extensive online search was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement guidelines. The main medical and scientific engines were searched for articles from May 1981 to May 2021 to capture all scientific studies focused on the effect of fenugreek on muscle and exercise or sport. Out of 81 studies acquired, six eligible randomized controlled trials (RCTs) were included in the qualitative analysis. Four RCTs observed that fenugreek supplementation had significantly improved muscle strength, repetitions to failure (muscle endurance), submaximal performance index, lean body mass, and reduced body fat. Among the remaining two trials, one reported the significant effect of fenugreek extracts on the rate of muscle glycogen resynthesis during post-exercise recovery; however, the other failed to do so. Those two trials were weak, with a minimal sample size (<10). Further, fenugreek glycoside supplementation with sapogenins and saponins reported substantial anabolic and androgenic activity, influencing testosterone levels and muscle performance. It was useful during eight weeks of resistance training without any clinical side effects. Fenugreek with creatine supplementation improved creatine uptake without the necessity of high carbohydrate intake. Hence, fenugreek extracts can be a helpful natural supplement and ergogenic aid for athletes. However, it is better to be aware of doping and liver and kidney damage before using the fenugreek supplement.

The genus Trigonella, "little triangle" in Latin, is named after the triangular flowers [3]. It is among the most promising traditional plants, cultivated widely in many parts of Africa, Europe, and Asia as an indigenous medicine, spice, and herbal food [2]. The seeds and leaves of fenugreek are formulated in powder and extract forms for medical purposes [4]. The macroscopic picture of fenugreek is provided in Figure 1. The physiological and pharmacological features of fenugreek are described in Figure 2.
The evidence showed that proper nutritional consumption is essential for achieving training adaptations, improving exercise performance, and recovering muscle function  A broad spectrum of systematic reviews and scientific data demonstrated that fenugreek and its extracts improve glycemic and lipid profiles [5]. Fenugreek is known to have antioxidant [6], anti-carcinogenic [7], gastroprotective [8], anti-inflammatory [9], antimicrobial [10], immunological [11], antiobesity [12], and hepatoprotective [13] effects, and are beneficial to women's health [14]. Further, previous studies reported that fenugreek improved cognitive functions and Parkinson's symptoms and showed antianxiety, antidepressant, and neuroprotective properties [15,16]. A recent study has reported the beneficial effects of fenugreek and its extract on hormonal-related statuses, such as galactagogue in lactating women and male impotence [17].
The evidence showed that proper nutritional consumption is essential for achieving training adaptations, improving exercise performance, and recovering muscle function The evidence showed that proper nutritional consumption is essential for achieving training adaptations, improving exercise performance, and recovering muscle function [18,19]. Specifically, high athletic performance requires well-controlled nutritional composition and timing (before, during, and after an exercise session) to optimize exercise performance and hasten recovery following exercise [19,20]. Many researchers have identified nutritional supplements that enhance muscle performance and facilitate optimal post-exercise recovery. Therefore, this review aims to provide an update on the recent findings of fenugreek's muscular, metabolic, and exercise-enhancing effects.

Study Design
For this review, an extensive online search was conducted according to the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement [21]. The PRISMA flow diagram is shown in Figure 3. Further, this systematic review has been registered in the INPLASY, an international platform of registered systematic review and meta-analysis protocols (Registration number: INPLASY202320089). [18,19]. Specifically, high athletic performance requires well-controlled nutritional composition and timing (before, during, and after an exercise session) to optimize exercise performance and hasten recovery following exercise [19,20]. Many researchers have identified nutritional supplements that enhance muscle performance and facilitate optimal post-exercise recovery. Therefore, this review aims to provide an update on the recent findings of fenugreek's muscular, metabolic, and exercise-enhancing effects.

Study Design
For this review, an extensive online search was conducted according to the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement [21]. The PRISMA flow diagram is shown in Figure 3. Further, this systematic review has been registered in the INPLASY, an international platform of registered systematic review and meta-analysis protocols (Registration number: INPLASY202320089).

Search Strategy
This study searched Google Scholar and MEDLINE/PubMed for articles from May 1981 to May 2021 to capture recent scientific studies about fenugreek and its effects on muscles, exercise, or sport. The keywords used to identify the studies were (((Fenugreek) OR (Trigonella foenum)) AND ((((Sport) OR (Exercise)) OR (Muscle)) OR (Physical activity))) AND (("1981/05/30"[Date -Publication]: "3000"[Date -Publication])). Further manual screening through Scopus and ISI websites yielded no additional articles.

Search Strategy
This study searched Google Scholar and MEDLINE/PubMed for articles from May 1981 to May 2021 to capture recent scientific studies about fenugreek and its effects on muscles, exercise, or sport. The keywords used to identify the studies were (((Fenugreek) OR (Trigonella foenum)) AND ((((Sport) OR (Exercise)) OR (Muscle)) OR (Physical activity))) AND (("1981/05/30"[Date -Publication]: "3000"[Date -Publication])). Further manual screening through Scopus and ISI websites yielded no additional articles. The search was limited to papers written in English. The references retrieved were imported into Mendeley.

Selection Criteria
The systematic review included publications that met the following inclusion criteria: (1) a randomized controlled trial (RCT) with a cross-over or parallel design; (2) assessed the effects of fenugreek on sports, muscle performance, and post-exercise recovery; and (3) reported values at baseline and at the end of follow-up in each group, or the net change data. The exclusion criteria were (1) in vitro, in situ, animal, pregnant women's, and children's studies; (2) trials that studied the effect of fenugreek extracts in combination with other herbs; (3) articles that were not peer-reviewed, with no available abstracts, or not written in English. After the preliminary eligibility screening evaluation, only the most complete studies were included.

Data Extraction
A standardized form was used to obtain the following data from each study: (1) general characteristics "first author, publication date, country," (2) study characteristics "mean age, sample size, sex, study design, daily dose, type of fenugreek/control, duration of the study, conclusion, and limitation" and (3) quality score. As such, the author collected and reviewed the data and recorded it in tabular form.

Quality Assessment
The six-point scale criteria by Hayden et al. [22] was applied to assess the quality of the included studies. The criteria are (1) study participation (the sample is large enough and represents the population of interest); (2) control for confounding factors; (3) determination of the factor of interest (clear definition and description of the factor of interest are provided); (4) study attrition (full explanation of the sample drop out); (5) appropriateness of statistical analysis; and (6) outcome measurement (full explanation of the method used for outcome measurement in such a way that reduces measurement bias). A single-point score was given for each criterion; "the score of 0-3 points indicated low-quality studies, while the score above 3-6 was considered as high-quality studies".

Results
Eighty-one studies were obtained from the advanced search. Out of them, 75 were eliminated after thoroughly reviewing the title and abstracts using PICOS criteria. Those excluded studies were (1) in situ study (n = 1); (2) review (n = 2); (3) animal studies (n = 2); (4) combination with other herbs or unrelated titles (n = 70). Finally, six eligible RCTs were included in the qualitative analysis ( Figure 3).

Findings
Based on the findings, one trial used fenugreek seed power as an intervention, with daily doses of 500 mg/day for eight weeks (4). Three trials chose fenugreek seed extracts at doses of 2-900 mg/day [24][25][26]. The glycoside fraction of fenugreek seeds was used daily (300 mg) for eight weeks [27]. On the other hand, fenugreek soluble fibers were administered at a daily dosage of 300 mg for 28 days [23].
Four trials reported positive effects of fenugreek on muscle performance and postexercise recovery [4,23,24,27]. While reviewing those trials, one trial found that fenugreek extract (500mg) had positively affected the upper (1 repetition maximum [RM] bench press) and lower (1 RM leg press) body strength compared to the placebo, without any reported side effects, in eight weeks of resistance training for male participants. It also showed a significant improvement in lean body mass and body fat reduction, thereby augmenting body composition compared to the placebo group [4]. Further, another trial concluded that creatine (3.5 g) plus fenugreek extract (900 mg) for eight weeks, along with a structured resistance training program, could significantly affect muscle strength (1 RM bench press; 1 RM leg press) among resistance-trained males as effectively as creatine (5 g) plus dextrose (70 g). Fenugreek with creatine supplementation might be a new method for improving creatine uptake while eliminating the necessity for high quantities of simple carbohydrates [24]. In contrast, the glycoside fraction of fenugreek (Trigonella foenum-graecum) seeds (Fenu-FG) failed to increase muscle strength significantly compared to the placebo group. However, Fenu-FG had more substantial anabolic and androgenic activity and significantly showed more repetitions to failure (muscle endurance) during resistance training than the placebo group. It was beneficial during eight weeks of resistance training, without any clinical side effects [27]. Moreover, an increase in one submaximal fatigue threshold was observed in both the fenugreek soluble fiber (FEN) and the CurQfen (CUR, i.e., curcumin plus fenugreek supplementation) groups, without alterations in maximal endurance performance (VO2 peak). The presence of fenugreek improved the submaximal performance index for both FEN and CUR groups [23].
Additionally, two controversial trials on muscle glycogen resynthesis were reported. However, both trials were weak, with a minimal sample size (<10) [25,26]. Among those trials, one trial inferred that a fenugreek extract supplement with dextrose could promote and accelerate the rate of glycogen resynthesis levels following a glycogen-depleting cycle exercise test in trained male cyclists. Grounded on the similarity in blood glucose and insulin between trials, fenugreek extract supplement with dextrose improves muscle glycogen resynthesis without altering circulating insulin [26]. In contrast, another trial concluded that adding fenugreek to post-exercise feeding does not affect muscle glycogen synthesis or subsequent exercise performance (cycling) among normoglycemic male endurance athletes [25].

Body Composition and Muscle Performance
Testosterone is an essential hormone for muscle homeostasis in both men and women. An earlier study has found elevated body fat mass and decreased protein synthesis, muscle strength, and mass in males with testosterone hormone deficiency [28]. Furthermore, it is an essential hormone for sports performance and athletic success because of its anabolic properties. It causes a positive nitrogen balance by decreasing protein breakdown and increasing protein synthesis, resulting in muscle hypertrophy with improved muscle strength and performance [29]. Additionally, exercise, especially resistance training, directly affects protein synthesis and improves muscle mass and development, resulting in increased basal metabolic rate, exercise performance, and fat oxidation [30]. Notably, fenugreek extracts augmented muscle growth and overall rat weight compared to the control groups [31]. In a human trial, fenugreek extract (500 mg) showed a significant improvement in upper and lower body strength, lean body mass, and body fat reduction, thus enhancing overall body composition over the placebo over an eight-week duration without any side effects. The mechanisms accountable for the observed changes must be clarified due to inadequate research concerning fenugreek's competence in affecting anaerobic exercise output and hormonal alterations in humans and animals. Moreover, no variations were observed within or between fenugreek extract (500 mg) and the placebo group for any measured serum hormone variables-namely, leptin, estradiol, cortisol, and dihydrotestosterone-excluding free testosterone. Additionally, this fenugreek supplement failed to significantly influence hematological variables (i.e., kidney function or muscle damage markers, liver enzymes, cholesterol, proteins, triglycerides, white and red blood cell count) and muscular endurance on leg and bench press. Further research can be warranted to examine various extractions and doses of fenugreek on trained subjects to conclude whether anabolic hormones can be changed and discover the possibility of additional strength and power output adaptations, which could eventually improve exercise performance [4]. Also, Taylor et al. concluded that fenugreek extract (900 mg) with creatine (3.5 g) during an 8-week resistance program significantly influenced muscle strength and body composition in resistance-trained males as similarly as creatine (5 g) with dextrose (70 g). Both groups significantly increased 1 RM bench press, 1 RM leg press, and lean body mass. Notably, the fenugreek and creatine combination increased 1 RM bench press and lean mass after four weeks of resistance training more than the creatine and dextrose combination. This observation might be due to increased creatine absorption and retention resulting from fenugreek intake, which sets earlier training adaptations. Fenugreek might transport creatine into the skeletal muscle similarly to carbohydrates [24].
Furthermore, a clinical trial found positive effects of fenugreek extract in enhancing body composition, endurance capacity, muscle strength, testosterone levels, and mass (hypertrophy) from baseline when used with an eight-week calisthenic regimen for males [32]. An earlier study confirmed that a six-week dietary supplement comprising chitosan, fenugreek, glucomannan, vitamin C, and gymnema sylvestre significantly reduced body weight and fat in obese adults [33]. Fenu-FG supplementation significantly decreased body fat and thigh and triceps skinfold thickness. These observations can be attributed to marker compounds (i.e., furostanol glycosides) of Fenu-FG supplementation. This furostanol glycoside (i.e., diosgenin) plays a role in hormone-interceded activity pathways. The glycoside fraction of fenugreek also demonstrated fat-burning and anabolic activity in animals [27].
Additionally, a previous study reported that Fenu-FG supplementation significantly increased the repetitions to failure (muscle endurance) during eight weeks of resistance training in males compared to the placebo group. However, Fenu-FG supplementation failed to increase muscle strength significantly [27]. Further, subjects who received fenugreek extracts (300 mg/kg) exhibited improved aerobic capacity after four weeks of treatment [34]. In a randomized, double-blind, placebo-controlled, parallel-design trial including 45 untrained women and men, the ingestion of FEN (300 mg/day) improved aerobic performance and delayed fatigue in healthy participants. However, the study did not cover "very poor" and "high" fitness individuals. It recommended that the variation between the curcumin and fenugreek supplementation on the ventilatory threshold can be revealed in future studies. Also, the effects of fenugreek fiber alone and curcumin with other ingredients (i.e., piperine) on submaximal endurance performance indices can be explored [23].

Ergogenic Aid
Athletes often seek natural formulations to enhance stamina, aerobic capacity, muscle growth, and overall performance [35]. Creatine monohydrate is widely investigated as a sport and consumable supplement. It is a predominant component of ergogenic aids and sports nutrition [24]. Moreover, it is an important energy source for muscles and is usually consumed by gymnasts and athletes during high-intensity, short-duration regimens [36]. It is phosphorylated into energy-generating substrates (e.g., phosphocreatine), replenishing adenosine triphosphate in active skeletal muscle [36].
Nearly half of the creatine is produced endogenously from amino acids; the remainder is obtained via supplementation or dietary protein consumption [37]. At the molecular level, in situ research demonstrated that fenugreek extracts resulted in greater insulinstimulated intracellular creatine content in mock-transfected L6 (clone L6C11) skeletal myoblasts [38], which may offer an extra advantage for exercise performance.
In addition, several studies stated that consuming carbohydrates and creatine simultaneously improves body composition and muscle strength [39,40]. Meanwhile, chronic consumption of high amounts of carbohydrates provides large amounts of calories and can have harmful health outcomes, such as changes in body composition and hyperglycemia [41]. A clinical trial using a structured resistance training program found that combining 3.5 g of creatine with 900 mg of a fenugreek extract for eight weeks had the same effect on male body composition and strength as combining 5 g creatine with 70 g dextrose, which indicates that fenugreek extracts have increased muscle creatine uptake without requiring excessive amounts of creatine or carbohydrates. Such alternative creatine supplementation might be helpful for those with the adverse effects of consumption of vast amounts of simple carbohydrates. In the future, fenugreek plus conventional creatine supplements can be analyzed to evaluate the ability of fenugreek to deliver and retain creatine within skeletal muscle compared to creatine-carbohydrate supplements. Further research can be conducted to ascertain the effect of fenugreek extract on androgen levels since alterations in hormone levels could influence resistance training adaptions [24].
In light of the established role of testosterone in androgen-regulating physiological activity and improving muscle strength and energy, marketed formulations focus on testosterone enhancer products [42]. Due to the unfavorable side effects of anabolic steroids, pharmaceutical companies are now trying to produce natural nutritional products containing ergogenic components. Importantly, fenugreek extracts have previously been shown to increase free testosterone hormone levels in older men with androgen decline and reduce physical symptoms associated with hypogonadism [43]. Similarly, 600 mg fenugreek extracts increased testosterone hormone levels from the baseline value [32].
Moreover, during an eight-week resistance training program, Fenu-FG supplementation demonstrated substantial anabolic and androgenic activity in males. It enhanced the serum-free testosterone without reduction in total testosterone [27]. The androgenic activity is supposed to have interceded through the 5-alpha-reductase and aromatase inhibition pathways. Also, the glycoside-rich fractions of fenugreek seeds, such as sapogenins and saponins, have shown anabolic and androgenic activities [27]. Notably, saponins, the compound protodioscin, influence the anabolic and testosterone status [44]. Furthermore, Fenu-FG supplementation significantly reduced serum creatinine and blood urea nitrogen levels, which are likely pointers of anabolic activity [27].

Post-Exercise Recovery
During physical activity, liver and muscle glycogen stores are the primary energy source, making them vital for success. When the muscle glycogen level is depleted, it must be resynthesized during recovery to achieve the highest level during subsequent exercise bouts [26]. Optimal post-exercise glycogen store repletion is a critical factor in achieving optimal performance, especially in athletes who train multiple times per day [45]. An earlier trial has shown that a fenugreek extract supplement with dextrose can promote and accelerate the glycogen resynthesis rate after the glycogen-depleting cycle exercise test [26].
However, another trial could not prove the positive effect of fenugreek extract on the muscle glycogen resynthesis rate [25]. Those trials were confined to minimal sample size and female subjects [25,26]. Further research is required to recognize fenugreek interactions in normoglycemic exercise in humans, and the conditions must provoke physiological effects [25]. Research is also required into the basic mechanisms of the unique amino acid (fenugreek seeds) and its effect on muscle glycogen recovery and subsequent exercise output during multiple days of laborious exercise if glycogen concentrations are reliably confronted [26]. These points might give rise to new research questions for future studies.
Additionally, ingesting amino acids or protein with carbohydrates in post-exercise sessions has been proposed to promote the glycogen synthase pathway [46,47]. Macronutrients, especially proteins, are associated with nutritional support to enhance recovery and return to competition and training after exercise-induced injuries and those involving immobilization [48]. Inadequate protein consumption can lead to health problems, impair wound healing, and likely increase inflammation and cytokines to a harmful level [49]. The reduction in protein (myofibrillar) synthesis affects muscle metabolism and results in muscle loss. Accordingly, the healing process mainly depends on collagen and other protein syntheses [50].
On the other hand, fenugreek containing 4-hydroxyisoclucine (nonproteinergic amino acid), apigenins, saponins, and alkaloids has notable anti-inflammatory activity [3]. This effect could help treat exercise-induced injuries due to the anti-inflammatory properties. Besides, the growth of fenugreek products intends to enhance their therapeutic efficacy through implementing techniques like nano-formulation and liposomal drug delivery. Nevertheless, future studies must reveal how fenugreek products inhibit inflammatory signals [3].

Health Benefits of Fenugreek
The health benefits of fenugreek seeds are feasible since those seeds contain fenugreek glycosides, namely, sapogenins (e.g., diosgenin), saponins, savsalpogenin, yuccagenin, and similagenin [27]. Among those glycosides, sapogenins and saponins have demonstrated anabolic and androgenic activities [27]. Moreover, an increase in serum testosterone level might be because fenugreek inhibits the enzymes like aromatase and 5-alpha-reductase and limits the metabolism of serum testosterone [27]. Diosgenin, a glycoside constituent of fenugreek, influences cholesterol metabolism. The fenugreek saponins do not interact directly with cholesterol; however, they have a robust inhibitory effect on bile salt absorption [27]. Fenugreek intake has elevated creatine absorption and retention, which results in earlier training adaptations. Also, it might influx creatine into the skeletal muscle like carbohydrates [24].
Based on the studies analyzed for review, it is suggested that fenugreek extracts are a natural plant supplement that positively affects muscle performance and recovery. The hypothesized mechanisms for enhancing muscle performance include increased anabolic and androgenic activity and rate of glycogen resynthesis following glycogen depletion. In line with these statements, fenugreek is a rich source of several nitrogen-containing amino acids, carbohydrates, and other bionutrient compounds, which improve exercise performance and muscle function recovery and delay fatigue (Figure 4). Additional studies are required to attain the potential doses and effects of fenugreek extracts as an efficacious nutraceutical or over-the-counter sports supplement. ence allergic reactions to fenugreek despite its safety and usefulness. Those allergic reactions include dyspepsia, abdominal distention, diarrhea, flatulence, and hypoglycemia [35]. Previous literature has intensively investigated stress-related disorders and chronic pain conditions with various objectives [52][53][54][55][56]. However, some studies focused on revealing fenugreek's role in managing pain and stress-related conditions in animals and humans [57][58][59][60][61]. Future studies can explore the effect of fenugreek in alleviating pain and mental stress, especially among athletes. Moreover, a recent study revealed the antihyperglycemic effect of fenugreek and ginger in type 2 diabetes mellitus (T2DM) cases. It is reported that the oral intake of 1 g of fenugreek capsules three times a day for eight weeks significantly reduced fasting blood sugar and glycosylated hemoglobin compared to ginger capsules. Both fenugreek and ginger capsules significantly reduced serum creatinine and triglyceride levels in T2DM cases [62]. The precise mechanism behind these observations is still being determined. However, the possible hypoglycemic and lipidreducing mechanism of fenugreek comprise late gastric emptying, inhibition of glucose transport, raised oxidative stress, low fat, and glucose absorption, enhanced modulation of glucagon-like peptide-1, augmented insulin sensitivity, and stimulation of insulin secretion [63]. Furthermore, combining fenugreek seed extracts and swimming training significantly decreased plasma glucose and enhanced cardiac antioxidant enzyme activity. However, those changes were observed in diabetic rats, not humans [64].

Conclusions
This review reported that fenugreek extracts positively reduced body fat, increased lean body mass, improved muscle strength and endurance, and accelerated the rate of glycogen resynthesis during post-exercise recovery. Their anabolic and androgenic activity is responsible for enhanced muscle performance. Further, those extracts act as an ergogenic aid and increase muscle creatine uptake to provide energy for the muscles during sports activities. However, the effects of various fenugreek extractions and doses on anabolic hormones influencing additional strength and power output adaptations can be discovered in future studies. Also, the impact of fenugreek fiber alone, and curcumin combined with piperine, on submaximal endurance performance indices can be revealed. Further research is warranted to cover a larger sample size while revealing the role of fenugreek extracts on the rate of glycogen resynthesis. Most included RCTs covered only male subjects, which insists the researchers should include both genders in the future. Though fenugreek supplementation is valuable during resistance training and deprived of clinical side effects, doping should be considered before using it for sports Notably, all performance-improving supplements are regulated by the world antidoping code as demarcated by the word anti-doping agency. Several conventional herbal medicines are being examined as safer substitutes for their nutritional aids and performance improvement. However, their safety and effectiveness must be scientifically investigated [27]. Though natural supplements in markets improve health and physical performance, it is sensible to be aware that some herbs might possess doping substances in their composition, and some products of herbal extracts might be adulterated by agents prohibited in sports activities [35]. Fenugreek supplementation is beneficial during resistance training without any clinical side effects; however, doping aspects should also be confirmed before using it for sports events. At the same time, Wankhede et al. showed that fenugreek supplementation positively affects free testosterone levels, serum creatinine, and body fat without causing changes in kidney profile enzymes [27]. However, more protein or amino acid intake might lead to severe liver damage and metabolic diseases [51]. It is advised to be cautious while consuming fenugreek as a sports supplement rich in nitrogen-containing amino acids, to prevent liver and kidney damage. Hence, further investigations are warranted to reveal the effect of fenugreek intake on liver and kidney functions. Also, it is noteworthy that some individuals might experience allergic reactions to fenugreek despite its safety and usefulness. Those allergic reactions include dyspepsia, abdominal distention, diarrhea, flatulence, and hypoglycemia [35].
Previous literature has intensively investigated stress-related disorders and chronic pain conditions with various objectives [52][53][54][55][56]. However, some studies focused on revealing fenugreek's role in managing pain and stress-related conditions in animals and humans [57][58][59][60][61]. Future studies can explore the effect of fenugreek in alleviating pain and mental stress, especially among athletes. Moreover, a recent study revealed the antihyperglycemic effect of fenugreek and ginger in type 2 diabetes mellitus (T2DM) cases. It is reported that the oral intake of 1 g of fenugreek capsules three times a day for eight weeks significantly reduced fasting blood sugar and glycosylated hemoglobin compared to ginger capsules. Both fenugreek and ginger capsules significantly reduced serum creatinine and triglyceride levels in T2DM cases [62]. The precise mechanism behind these observations is still being determined. However, the possible hypoglycemic and lipid-reducing mechanism of fenugreek comprise late gastric emptying, inhibition of glucose transport, raised oxidative stress, low fat, and glucose absorption, enhanced modulation of glucagon-like peptide-1, augmented insulin sensitivity, and stimulation of insulin secretion [63]. Furthermore, combining fenugreek seed extracts and swimming training significantly decreased plasma glucose and enhanced cardiac antioxidant enzyme activity. However, those changes were observed in diabetic rats, not humans [64].

Conclusions
This review reported that fenugreek extracts positively reduced body fat, increased lean body mass, improved muscle strength and endurance, and accelerated the rate of glycogen resynthesis during post-exercise recovery. Their anabolic and androgenic activity is responsible for enhanced muscle performance. Further, those extracts act as an ergogenic aid and increase muscle creatine uptake to provide energy for the muscles during sports activities. However, the effects of various fenugreek extractions and doses on anabolic hormones influencing additional strength and power output adaptations can be discovered in future studies. Also, the impact of fenugreek fiber alone, and curcumin combined with piperine, on submaximal endurance performance indices can be revealed. Further research is warranted to cover a larger sample size while revealing the role of fenugreek extracts on the rate of glycogen resynthesis. Most included RCTs covered only male subjects, which insists the researchers should include both genders in the future. Though fenugreek supplementation is valuable during resistance training and deprived of clinical side effects, doping should be considered before using it for sports activities. It is necessary to ensure awareness of protecting liver and kidney function while consuming fenugreek as a sports supplement.
Author Contributions: Waleed I Albaker (W.I.A.) performed the systematic review and drafted the manuscript. W.I.A. is responsible for reviewing and approving the final manuscript.
Funding: The author reports that there is no funding associated with the work featured in this article.
Institutional Review Board Statement: Not applicable.