These results came from a 12-week study conducted by researchers from Lindenwood University’s Exercise and Performance Nutrition Laboratory, as well as the Center for Applied Health Sciences, a contract research organization.
The investigated ingredient was Sensoril, a patented, aqueous extract of the roots and leaves of ashwagandha (Withania somnifera) manufactured and distributed by Natreon, the study’s funder.
Ashwagandha, also known as Indian ginseng, has been used in the South Asian botanical medical tradition Ayurveda for centuries.
In the US market, ashwagandha has enjoyed an upward sales trajectory. Sales data compiled by HerbalGram, which compiles sales analysis of botanical products annually, revealed a 25% year-over-year increase for ashwagandha in the natural retail channel. This is boosted mainly by the rise of adaptogenic consumer products with general health claims, from supplements to tonics to functional beverages, according to market research firm Nielsen.
But according to Dr. Tim Ziegenfuss, CEO of The Center for Applied Health Sciences and one of the lead authors of this current study, these latest results “help establish an evidence base for this impressive Ayurvedic herb in sports nutrition.”
The results were published recently in the journal Nutrients.
Thirty-eight recreationally active men completed the study. The primary outcomes the researchers wanted to explore included changes in muscle strength, body composition, muscle endurance, power and recovery.
Because previous studies on ashwagandha have linked it to anti-inflammatory, anabolic, and antioxidant effects, the researchers hypothesized that the herb may also benefit physical performance and muscle recovery in a sports context.
Participants first were matched based on training experience and baseline body weight before researchers divided them into two groups—19 were assigned capsules containing 500 mg of ashwagandha extract, while another 19 participants were assigned capsules containing rice flour. Both capsules were similar in size, color, and smell.
Throughout the study period, participants were instructed to take one capsule in the morning with 12 fluid ounces of cold tap water.
Participants visited a clinic four times during the period, in which they went through several exercise protocols, such as bench presses and squats. Researchers measured how many sets a participant could complete and for how long, as well as their power output using specialized equipment.
Body measurements and blood analysis were also collected throughout the study.
“Ashwagandha extract from the planst and leaves (Sensoril), in combination with a progressive, heavy resistance-training program, resulted in singinificant improvements in maximal lower-body and upper-body strength,” the researchers wrote.
Researchers also observed that participants who ingested the placebo reported more muscle soreness post-training than the ashwagandha group.
Potential limitations of the study included the fact that workouts were not strictly supervides by study personnel, and that the participants’ diets were not closely controlled. “The subjects’ total energy and protein intakes may have undermined their ability to attain more pronounced changes in muscle mass,” the authors wrote.
“Future studies should attempt to more thoroughly control diet, and then include measurements of appetite.”
"Effects of an Aqueous Extract of Withania somnifera on Strength Training Adaptations and Recovery: The STAR Trial"
Authors: Tim. N Ziegenfuss, et al.
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