Table 1 Selected studies on the effects of ginseng, caffeine, ephedrine, combination of caffeine and ephedrine, and Eurycoma longifolia Jack in exercise and sports

Panax ginseng

Kim et al., 2005 [14]

Seven healthy males

2 g of Panax ginseng extract or placebo three times per day for 8 weeks

Exhaustive incremental exercise on treadmill

Increased exercise duration until exhaustion and facilitation of recovery from exhaustive exercise

Liang et al., 2005 [18]

29 untrained adults (ages 20 to 35 years old)

For 30 days: 1, 350 mg/day Panax ginseng or placebo

Endurance exercise on cycle ergometer at 65% to 70% VO₂ peak. Exercise intensity increased by 30 W at every 5-minute interval after first 35 minutes of exercise until exhaustion.

Improved endurance exercise time to exhaustion with Panax ginseng consumption

Caffeine

Ping et al., 2010 [31]

Nine male recreational runners

1 hour prior to exercise: 5 mg/kg body weight of caffeine or placebo

Running to exhaustion at 70% VO₂max on a motorised treadmill in the heat (31°C and 70% relative humidity)

Improved endurance running performance in the heat

Bell and McLellan, 2003 [24]

Nine males

1 hour before exercise: 5 or 2.5 mg/kg body mass of caffeine or placebo

Exercise rides to exhaustion on cycle ergometer at 80% VO₂max performed in the morning and 5 hours later on the same day

Increased exercise time to exhaustion

Cohen et al., 1996 [28]

Seven endurance-trained competitive road racers (ages 23 to 51 years old)

0, 5 or 9 mg/kg body mass of caffeine

Maximal effort of 21-km road racers outdoors in hot and humid conditions

Race performance in high heat stress not affected by caffeine supplementation

Collomp et al., 1992 [37]

Seven trained and seven untrained subjects

Single dose of 250 mg of caffeine or placebo

2 × 100-metre freestyle swims at maximal speed separated by 20 minutes of passive recovery

Trained subjects exhibited significant improvement in swimming velocity after caffeine supplementation

Costill et al., 1978 [25]

Nine competitive cyclists

Ingestion of coffee containing 339 mg of caffeine or exercise without caffeine

Exercise until exhaustion on a bicycle ergometer at 80% VO₂max

Cycling time with caffeine ingestion greater than non-caffeine fluid ingestion

Graham and Spriet, 1991 [27]

Seven trained competitive runners

1 hour before exercise: 9 mg/kg body mass of caffeine or placebo

Four exercise trials at approximately 85% VO₂max: two trials of running to exhaustion and two trials of cycling to exhaustion.

Endurance time increased with caffeine supplementation in both exercise modes

Schneiker et al., 2006 [23]

Ten male team sport athletes

6 mg/kg body mass of caffeine or placebo 1 hour before exercise

Two 36-minute halves, with each half composed of 18 × 4-second sprints and 2 minutes of active recovery at 35% VO₂ peak between each sprint

Total amount of sprint work performed and mean peak power score achieved during sprints were greater with caffeine ingestion in both exercise halves

Ephedrine

Sidney and Lefcoe, 1977 [46]

21 healthy males (ages 19 to 30 years old)

A single dose of ephedrine (24 mg) or placebo

Muscle strength, endurance and power exercise

No effect on any of the measurements of physical work capacity

Caffeine + ephedrine

Bell and Jacobs, 1999 [40]

Nine male recreational runners

2 hours before trials: combination of 375 mg of caffeine and 75 mg of ephedrine or placebo

Trials of the Canadian Forces Warrior Test (3.2-km run wearing 'fighting order' which weighed about 11 kg).

Run time significantly faster in the treatment group compared with placebo, and test performance was improved by caffeine and ephedrine

Bell et al., 2000 [49]

12 healthy untrained males

1.5 to 2 hours before exercise: 5 mg/kg body mass of caffeine plus 0.8 mg/kg body mass of ephedrine, 4 mg/kg body mass of caffeine plus 1 mg/kg body mass of ephedrine, 4 mg/kg body mass of caffeine plus 0.8 mg/kg body mass of ephedrine, or placebo

Cycling to exhaustion on a cycle ergometer at 85% VO₂ peak

Time to exhaustion in the treatment trial greater than placebo

Bell et al., 1998 [39]

Eight males

1.5 hours before exercise: 5 mg/kg body mass of caffeine, 1 mg/kg body mass of ephedrine, combination of both caffeine and ephedrine, or placebo

Exercise on a cycle ergometer at a maximal power output until exhaustion

Only the combination of caffeine and ephedrine led to a significantly longer time to exhaustion than placebo

Bell et al., 2002 [42]

12 subjects

4 mg/kg body mass of caffeine, 0.8 mg/kg body mass of ephedrine, combination of both caffeine and ephedrine, or placebo

10-km run in a climatic suite at 12°C to 13°C on treadmill while wearing a helmet and backpack weighing 11 kg. Speed was regulated by subjects.

Running time decreased in ephedrine and combination of ephedrine and caffeine trials.

Running pace increased in ephedrine compared with nonephedrine groups over the last 5 km of the run.

Williams et al., 2008 [43]

Nine resistance-trained male participants

45 minutes before exercise: 300 mg of caffeine, 300 mg of caffeine plus 60 mg of ephedrine, or 300 mg of glucose placebo

Maximal strength exercise of bench press (BP) at one repetition maximum (1 RM) and latissimus dorsi pull-down (LP) at 1 RM. Each subject also performed repeated repetitions at 80% of 1 RM on both BP and LP until exhaustion.

Increased alertness and enhanced mood after supplementation of combination of caffeine and ephedrine. No differences in muscle strength, endurance or peak aerobic power.

Eurycoma longifolia Jack

Muhamad et al., 2010 [64]

12 recreational male athletes (age 23.3 ± 3.7 years old SD)

Two capsules per day containing 75 mg of Eurycoma longifolia Jack or placebo for 7 days before and another two capsules 1 hour before exercise trial

60-minute run on treadmill at 60% VO₂max followed by 20-minute time trial

Running distance during time trial with Eurycoma longifolia Jack was not different from placebo. Physiological responses were also not different between trials.

Ooi et al., 2001 [62], 2003 [63]

Six male cyclists

Ingestion of herbal drink containing 0.1 mg of Eurycoma longifolia Jack per 100 ml of drink (about 0.67 mg of Eurycoma per trial) or placebo drink during exercise

Cycling at 70% VO₂max for the first hour and 80% VO₂max thereafter until exhaustion

No significant improvement in cycling performance or physiological responses