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- Ashwagandha (Withania somnifera, Solanaceae)
- Ergogenic Aid
- Muscle Strength and Recovery
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Date:
02-15-2016 | HC# 011651-538
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Re: Ashwagandha Improves Muscle Strength and Recovery in Men Performing Resistance Training
Wankhede
S, Langade D, Joshi K, Sinha SR, Bhattacharyya S. Examining the effect of Withania somnifera supplementation on
muscle strength and recovery: a randomized controlled trial. J Int Soc Sports Nutr. November 25, 2015;12:43.
doi: 10.1186/s12970-015-0104-9.
Ashwagandha
(Withania somnifera, Solanaceae) root
is an adaptogen, helping the body adapt to stress. Although it has been shown
to have a wide range of beneficial effects, studies of ashwagandha as an
ergogenic aid are lacking. The authors hypothesize that ashwagandha supplementation
may enhance the physiological adaptation of the body in response to the stress
of weight resistance training. Hence, the purpose of this 8-week, randomized,
double-blind, placebo-controlled study was to evaluate the effects of
ashwagandha on healthy men performing resistance training.
Healthy
men (n = 57, aged 18-50 years) with little experience in resistance training were
recruited at a gymnasium in Kolkata, India. Subjects were excluded if they were
taking any medication or steroids to enhance physical performance; had weight
loss of > 5 kg in the previous 3 months; had history of drug abuse, smoking >
10 cigarettes day, or consuming > 14 grams of alcohol/day; were hypersensitive
to ashwagandha; had orthopedic injury or surgery within the previous 6 months; had
participated in other clinical studies during the previous 3 months; or had any
other condition which the investigators judged problematic. Subjects were
instructed not to take anti-inflammatory agents, drink alcohol, or smoke
tobacco (Nicotiana tabacum,
Solanaceae) during the study.
Subjects
received either placebo (starch) or 600 mg/day ashwagandha root extract (KSM-66®;
Ixoreal Biomed; Los Angeles, California) for 8 weeks. The extract was produced
using a water-based process and was standardized to contain 5% withanolides. During
the 8-week study period, subjects participated in a structured resistance
training program based on the publications of the National Strength and Conditioning
Association (NSCA); Colorado Springs, Colorado. Subjects trained every other
day (3x/week), exercising the major muscle groups in both the upper body and
lower body. During the first 2-week acclimatization phase, each exercise set
consisted of 15 repetitions at a lower load to allow the subject's body and
neurological system to adjust to the training. The subsequent 6 weeks of
training consisted of varying numbers of higher-load repetitions.
The
primary endpoints were upper body and lower body muscle strength. The secondary
endpoints were muscle size, muscle recovery, serum testosterone level, and body
fat percentage. Muscle size was measured at the arm, chest, and upper thigh. Creatine
kinase levels were assessed as a measure of muscle recovery (reduction in
exercise-induced muscle damage over time). Assessments were made 1-2 days after
the first day of training, and 2 days after the end of the 8-week training
period.
As
expected, the resistance training resulted in improvements in all of the
measured parameters in both groups. However, the ashwagandha group had a
significantly greater increase in upper body (P = 0.001) and lower body (P =
0.04) strength compared with placebo; it also had significantly better muscle recovery
(P = 0.03). Compared with placebo, the ashwagandha group had a significantly
greater increase in the muscle size of the arm (P = 0.01) and chest (P <
0.001), but there was no significant difference in the size of the upper thigh.
The ashwagandha group had a significantly greater increase in serum
testosterone (P = 0.004) and a significantly greater decrease in body fat
percentage (P = 0.03), compared to placebo. Ashwagandha was well tolerated, and
there were no serious adverse effects.
The
focal question of this study was whether ashwagandha supplementation would
increase the adaptations to resistance training. At a P value of 0.05, the
adaptations as measured by muscle strength, muscle size, testosterone level,
and body fat percentage were found to be significantly greater with ashwagandha
compared to placebo. The authors conclude that "ashwagandha
supplementation is associated with significant increases in muscle mass and
strength and suggests that ashwagandha supplementation may be useful in
conjunction with a resistance training program." Acknowledged limitations were
that only untrained subjects ≤ 50 years were included, the relatively small
sample size, and short duration of the study. The authors recommend further
studies evaluate the potential benefit of ashwagandha over longer periods of
time and for different populations, including females and older adults of both
genders.
—Heather S. Oliff,
PhD
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