Writing in the Journal of the International Society of Sports Nutrition, the authors also call for a more complete guide to better understand the beneficial and harmful effects of some products.
“We have identified the plants Ginseng, alkaloids, and other purported herbal ergogenics such as Tribulus Terrestris, Cordyceps Sinensis,” said the review’s authors, led by Dr Maha Sellami, sports scientist based at the National Center of Medicine and Science in Sports, Tunis, Tunisia.
“We found that most herbal supplement effects are likely due to activation of the central nervous system via stimulation of catecholamines.
“Ginseng was used as an endurance performance enhancer, while alkaloids supplementation resulted in improvements in sprint and cycling intense exercises. Despite it is prohibited use, small amounts of ephedrine in combination with caffeine may enhance muscle strength in trained individuals.”
Supplement irregularities
The review also highlights a lack of watertight regulation, which has resulted in a number of products coming onto the market that contain banned or undeclared ingredients.
Only last month, The Trade Inspection Authority performing quality control duties on commercially available dietary supplements in Poland found the caffeine content of energy supplements to be 166 milligrams (mg)/3 tablets and 27 mg/ 100 millilitres (ml) of prepared liquid.
The figures were some way off the claimed 192 mg/3 tablets and 32 mg/100 ml of liquid prepared in accordance with the instructions.
The Food Safety Authority of Ireland (FSAI) recently recalled a range of branded sports supplements that they believed were tainted with illegal steroids and stimulants.
Reports of products that fall short of standards have overshadowed the purported efficacy of some of these extracts, which research has supported in its effects on reducing oxidative stress and enhancing muscle strength.
The mental aspect of sport has not been neglected with some products containing guarana, pepper and ginger root, believed to increase mental vigilance and concentration.
The study presents a comprehensive review of studies that look into ginseng, herbal sources of caffeine and ephedrine and other purported herbal ergogenic plants such as Tribulus Terrestris, Ginkgo biloba, and Rhodiola Rosea.
Ginseng evidence
Ginseng in particular is popular amongst athletes for its apparent effects on cardio respiratory function and lower blood lactate concentrations, in addition to the central nervous system (CNS).
Other studies reported that ginseng improves alertness, and fatigue resistance through cortisol stimulation.
Caffeine’s effect on mental alertness has been well documented with ingestion of 1-2 mg/kg caffeine at breakfast found to decrease reaction time during exercise and improves mental alertness.
Its effect on physical performance is amongst the most studied with one study finding small quantities of caffeine (around 2 to 9 milligrams per kilogram (mg/kg) body mass) taken at least 1 hour prior to exercise or competition stimulated greater improvements in strength.
The study also noted increases in serum catecholamine levels and immune responses in runner and cyclist.
Ginkgo biloba efficacy
The review pointed to Ginkgo biloba’s (GB) flavonoid and terpenoid content as most likely responsible for observed enhancements to endurance performance.
One study found that 7-week of GB ingestion combined with another extract Rhodiola Rosea (RR) improved the endurance performance (higher VO2max) and time to exhaustion in healthy young athletes.
“Ginseng and caffeine had greater effect on central nervous system and appear to increase alertness and reaction time, while other herbs seem to stimulate steroids hormone production such as Tribulus Terrestris (TT),” the review concluded.
“Despite their positive effects, these herbs should be used with precaution because high doses may cause harmful side effects on kidney and stomach in particular.”
Source: Journal of the International Society of Sports Nutrition
Published online ahead of print: doi.org/10.1186/s12970-018-0218-y
“Herbal medicine for sports: a review.”
Authors: Maha Sellami, Olfa Slimeni, Andrzej Pokrywka, Goran Kuvačić, Lawrence D Hayes, Mirjana Milic and Johnny Padulo