Antifatigue (Mental and Physical) Activity

Some of the first studies of ginseng’s adaptogenic activities were performed during the late 1950s and early 1960s by Brekhman and Dardymov^7,8 in the Soviet Union and by Petkov^15–17 in Bulgaria.

In one of Brekhman’s experiments, Soviet soldiers given an extract of ginseng ran faster in a 3-km race than those given a placebo. In another, radio operators tested after administration of ginseng extract transmitted text significantly faster and with fewer mistakes than those given placebo. These and similar results reported by European researchers, who demonstrated improvement in human physical and mental performance after administration of ginseng extracts, prompted researchers to confirm the results in experimental models using mice.^2,7,8,15

In perhaps the best known of these experiments, mice were subjected to swimming in cold water or running up an apparently endless rope to determine whether ginseng could lengthen the time to exhaustion. The results indicated that ginseng possessed significant antifatigue activity, because a clearly dose-dependent increase in time to exhaustion was noted in mice receiving ginseng.^2,8,18–20 In one study, the time to exhaustion was lengthened by up to 183% in the mice given ginseng 30 minutes before exercising compared with controls.⁸

Experimental animal studies indicated that much of the antifatigue action of ginseng was due to the stimulant effect of ginseng on the central nervous system (CNS). Stress coupled with ginseng ingestion induced alterations in energy metabolism during prolonged exercise.^9,16–20

Ginseng has been shown to improve locomotor activity,²¹ modify electroencephalographic (EEG) tracings,¹⁶ improve metabolic activity in the CNS,²² and affect the hypothalamic-pituitary-adrenal axis (discussed later), all of which could be largely responsible for ginseng’s antifatigue activity in mental and physical performance. The CNS activity of ginseng is essentially different from that of usual stimulants. Although stimulants are active under most situations, ginseng reveals its stimulatory action only with the challenge of stress.²²

On the physical level, ginseng’s antifatigue properties appear to be closely related to its ability to spare glycogen utilization in exercising muscle.⁹ Exercise physiologists clearly established that during prolonged exercise, the development of fatigue is closely related to the depletion of glycogen stores and the buildup of lactic acid, both in skeletal muscle and in the liver. If an adequate supply of oxygen is available to the working muscle, nonesterified fatty acids are the preferential energy substrate, thus sparing utilization of muscle glycogen, blood glucose, and, consequently, liver glycogen. The greater the ability to conserve body carbohydrate stores through mobilization and oxidizing of fatty acids, the greater the amount of time to exhaustion. Ginseng enhances fatty acid oxidation during prolonged exercise, thereby sparing muscle glycogen stores.⁹

Mental and physical antifatigue activity effects were demonstrated in both animal studies and double-blind clinical trials in humans. In one double-blind clinical study, nurses who switched from day to night duty rated themselves for competence, mood, and general well-being, and were evaluated with an objective test of psychophysical performance, blood cell counts, and blood chemistry analysis. The group administered ginseng demonstrated higher scores in competence, mood parameters, and objective psychophysical performance than those who received a placebo.²³

From a clinical standpoint, ginseng’s antifatigue properties may be useful whenever fatigue or lack of vigilance is apparent. In particular, cancer patients who underwent chemotherapy, patients with chronic obstructive pulmonary disease (COPD), and athletes were all shown to benefit from ginseng use. In regards to COPD, in one double-blind study, 92 adults with COPD were randomly assigned to receive either ginseng or placebo.²⁴ Pulmonary function tests, maximum voluntary ventilation, maximum inspiratory pressure, and maximal oxygen consumption were studied before treatment and every 2 weeks for the 3-month study. In the ginseng group, but not in the control group, all parameters were significantly higher than baseline and higher than the parameters in the placebo group. Maximum increases, in comparison with baseline, were forced vital capacity 32.5%, forced expiratory volume_1.0 27.0%, maximum voluntary ventilation 40.4%, maximum inspiratory pressure 47.0%, and maximal oxygen consumption 37.5%. No side effects were observed.

In a large study in 290 cancer patients, subjects were randomized in a double-blind manner to receive American ginseng in doses of 750, 1000, or 2000 mg/day or placebo given in twice daily dosing over 8 weeks. Over twice as many patients on ginseng perceived a benefit and were satisfied with treatment over those on placebo.²⁵ In another double-blind trial, 53 cancer patients were randomly assigned to receive ginseng (3000 mg/day) or placebo for 12 weeks. Quality of life was assessed using the World Health Organization Quality of Life Assessment-BREF (WHOQOL-BREF) and the General Health Questionnaire-12.²⁶ After 12 weeks of therapy, the “psychological domain ” score of the WHOQOL-BREF was significantly improved in patients randomized to ginseng, compared with those randomized to placebo. There was a tendency for ginseng to improve the “physical health” and “environment” domain scores of the WHOQOL-BREF, compared with placebo. The General Health Questionnaire-12 total score was significantly improved in patients treated with ginseng than in those with placebo. These results from clinical trials indicate ginseng is of benefit in improving some aspects of mental and physical functioning in cancer patients.