Caffeine is one of the most widely consumed supplements due to its availability, safety and energy stimulating effects. Caffeine is also popular in the weight lifting world and has been a known performance enhancer for decades. Until recently, caffeine was even listed as a banned supplement by the Olympic Committee (1). While caffeine has been shown to have many performance enhancing abilities (all of which will be covered in later articles), this article will focus only on the relationship between caffeine intake and increased strength.
Caffeine and increased strength in men
A study of 37 resistance-trained men found that ingesting caffeine one hour before a workout can increase bench press 1 rep maximum (BP 1RM) (1). Subjects either consumed 201 mg of caffeine before the workout or a placebo. Interestingly, the study found that caffeine intake increased upper body strength (bench press) but not lower body strength (leg extensions).
Another study examined the relationship between caffeine intake and anaerobic exercise in 18 male athletes (2). Subjects were given caffeine (5 mg/kg of body weight) or a placebo and then asked to perform a leg press, chest press and Wingate test (test used to measure peak anaerobic power and anaerobic capacity, usually performed on a cycle ergometer).
Total amount of weight lifted in the chest press was significantly higher in the caffeine group, with 67% of participants in the caffeine group showing improvements. Although there was no significant difference between the placebo and caffeine group in the leg press amount, 78% of participants in the caffeine group showed improvements. For the Wingate test, those taking caffeine had greater peak power than those taking a placebo.
Caffeine and increased strength in women
It appears that men are not the only ones that can benefit from taking a caffeine supplement before strength training. A study looked at the relationship between caffeine intake and 1RM bench press in 15 resistance-trained women (3). Women were either given caffeine (6 mg/kg BW) or a placebo and asked to perform a 1RM bench press an hour after taking the caffeine. The women taking caffeine had a significantly increased 1RM bench press compared to those taking a placebo.
Calculating caffeine intake
Many of the studies looking at caffeine intake and increased performance use a caffeine intake that is related to the weight of a person, or mg of caffeine per kg of body weight. Since we do not use the metric system we have to first convert our body weight to kg to find out how much caffeine to take.
First, convert your weight in pounds to kg by multiplying your weight by 0.45. This will give you your weight in kg. Most studies use around 5-6 mg of caffeine per kg of body weight. Take your weight in kg and multiply it by 5 or 6. This will give you the amount of caffeine to take before the workout.
Here is an example. If someone weighs 200 lbs, they would weigh (200 X 0.45) 90 kg. Multiplying 90 by 5 or 6 would give you 450 mg and 540 mg of caffeine, respectively.
Words of caution
Although usually safe, high intakes of caffeine can cause heart palpitations. Check with your doctor before taking large doses of caffeine and engaging in physical activity, especially if you have underlying heart conditions.
Most studies have found that caffeine taken an hour before exercise can increase 1RM (1 rep maximum) bench press but not leg extension strength. It seems that taking caffeine produces increases in upper body strength but not lower body and that the results are similar between men and women. More studies need to be done to assess whether caffeine increases whole body strength in exercises like squats or dead lifts. The majority of studies investigating the relationship between caffeine intake and enhanced performance have used between 3 to 10 mg/kg of body weight (4).
- Beck, T. W., Housh, T. J., Malek, M. H., Mielke, M., & Hendrix, R. (2008). The acute effects of a caffeine-containing supplement on bench press strength and time to running exhaustion.The Journal of Strength & Conditioning Research, 22(5), 1654-1658.
- Woolf, K., Bidwell, W. K., & Carlson, A. G. (2008). The effect of caffeine as an ergogenic aid in anaerobic exercise.International journal of sport nutrition and exercise metabolism, 18(4), 412-429.
- Goldstein, E., Jacobs, P. L., Whitehurst, M., Penhollow, T., & Antonio, J. (2010). Caffeine enhances upper body strength in resistance-trained women.Journal of the International Society of Sports Nutrition, 7(1), 18.
- Doherty, M., & Smith, P. M. (2004). Effects of caffeine ingestion on exercise testing: a meta-analysis.International journal of sport nutrition and exercise metabolism, 14(6), 626-646.