What are the effects of caffeine and muscle development? Also, what is caffeine's response to muscle development?
One of the main ergogenic effects of caffeine is the stimulation of the central nervous system and hence the stimulation of lypolisis (break down of fatty acids). Studies in humans have shown that caffeine ingestion up to one hour before exercise can improve one's endurance during moderately/hard aerobic exercise (in a laboratory setting). For instance, French, C. et al demonstrated that elite distance runners were able to improve their running time by 1.9 percent when compared to a control group. The subjects ingested 10 mg of caffeine per kg of body weight immediately before their run to exhaustion.
One of the proposed mechanisms for improved endurance is that caffeine ingestion seems to increase the rate of lipolysis during sustained exercise. Thus, one of the benefits of aerobic exercise is the “glycogen sparing effect" due to the oxidation of fatty acids for energy. Simply, endurance athletes have a higher fatty acid oxidation during aerobic exercise. This glycogen sparing effect becomes critical during aerobic exercise as the body needs a minimal level of circulating glycogen (sugar) at all times in order to function properly. No matter how much fatty acids we have available for energy, it is the availability of glycogen that will determine how long the activity will last. Thus, even for fatty oxidation to occur, we need to have a minimal of glycogen/glucose available in the body.
Caffeine seems to affect brain tissue, which may aid in the stimulation of lipolysis. The anterior pituitary gland is responsible for growth hormone (GH) production and secretion. One of the functions of GH is to stimulate lipolysis. GH can increase fat acid oxidation.
Other possible effects of caffeine ingestion may occur directly on muscle during repetitive low frequency electrical stimulation before and after muscle fatigue. No effect has been found on maximal muscle force during voluntary or electrically stimulated muscle actions.
The IOC permits athletes to consume some caffeine as long as its concentration in urine does not exceed 12 µ grams ML. For instance, 2.5 cups of percolated coffee contains between 250 to 400 mg or generally between three and six mg per kg of body weight. This amount of coffee produces urinary caffeine concentrations below the IOC acceptable limit. The consumption of four to six cups of coffee consumed over a 30 minute period significantly raises the caffeine concentration in the urine, which may cause grounds for disqualification by IOC (600 to 800 mg). Also ingesting caffeine tablets/suppositories can cause a positive doping test.
Although caffeine appears to have positive effects on fat oxidation, one needs to be aware of its possible toxicity effects. Caffeine has been shown to increase blood pressure and heart rate. It also has a diuretic effect and can cause possible loose bowel movements and/or diarrhea. Also, keep in mind that an individual can develop caffeine tolerance where the discussed enhanced fat oxidation benefits may not occur.
- Jose Antonio and Jeffrey Stout: Sports Supplements (2001).
- McArdle, W.; Katch & Katch, ( 2001). Exercise Physiology: Energy, Nutrition, and Human Performance. 5th ed.
- Mohr, et. al 1998. Caffeine ingestion and metabolic responses of tetraplegic humans during electrical cycling. J applied physiologyl, 85, 979).
- French, C. et al ( 1991- Caffeine Ingestion during exercise to exhaustion in elite distance runners- Journal of Sports Medicine Physical Fitness, 31, 425
- Sottovia, Carla. Energy Substrate: Truths & Misconceptions (2006).