Creatine is a popular dietary supplement. Many people don’t realize it is also a naturally occurring food constituent that globally is eaten daily.
The two main dietary sources of creatine are red meat and fish (some types of fish are better sources than others). This means that people who eat meat or fish— heck, even both—are naturally getting creatine in their diet. The type of people who typically do not get dietary creatine are those who adhere to vegetarian or vegan diets. The human body can make creatine from amino acids ingested in the diet as well; however, the manufacture of endogenous (within the body) creatine is low.
As outlined in the 2018 exercise and sports nutrition research review (J Int Soc Sports Nutr. 15:38) from the International Society of Sports Nutrition (ISSN), the most promising strategies to augment gains in muscle size and strength appear to be consumption of protein-carbohydrate calories before and after resistance exercise, and creatine supplementation.
As a nutrient, creatine has probably made one of the biggest impacts on the sports nutrition landscape. To date, more than 500 studies have been published on this ergogenic aid; many of these studies are outlined in ISSN’s position stand on creatine (J Int Soc Sports Nutr. 2017;14:18), a detailed research review of the safety and efficacy of creatine that supports the statements below.
Creatine monohydrate is the most commonly studied form of creatine in the literature—and may also be the most popular form of creatine sold to companies and consumers. Other forms are on the market—creatine citrate, creatine pyruvate, creatine ethyl ester (EE) and creatine nitrate, for example. However, none have shown to be superior to creatine monohydrate, the first form of creatine on the global market (prior to Oct. 15, 1994, the date set by DSHEA as the dividing line between old and new dietary ingredients).
Short-term creatine supplementation (e.g., 20 g/d for 5-7 days) has typically been reported to increase total creatine content by 10-30% and phosphocreatine stores by 10-40%. Short-term creatine supplementation has been reported to improve maximal power/strength (5-15%), work performed during sets of maximal effort muscle contractions (5-15%), single-effort sprint performance (1-5%), and work performed during repetitive sprint performance (5-15%). No study to date has found an ergolytic (opposite of work-enhancing) effect of creatine.
Creatine supplementation during training has been reported to promote significantly greater gains in strength, fat-free (aka lean body) mass and performance, primarily of high-intensity exercise tasks. However, not all of the studies examining athletic uses have demonstrated an ergogenic effect; approximately 30% do not support the agent, although some report nonsignificant positive effects or influence of creatine monohydrate. Future research will determine what dose may be best for athletic uses. Also, as food science evolves, stabilized liquid forms of creatine for ease of use are expected to be developed.
Relative to creatine supplementation, the popular media often discusses adverse or potential side effects. The only universal (or common) side effect reported from clinical studies in preoperative and postoperative patients, untrained subjects and elite athletes has been weight gain. However, concerns about possible side effects of creatine monohydrate supplementation have been mentioned in lay publications, supplement advertisements and on the internet. Claims that creatine is “unsafe” have not been substantiated in any prospective creatine monohydrate study. Unfortunately, many of these concerns have recently received significant media coverage and, thus, are worthy of discussion.
As creatine is an amino acid (by structure), it has been suggested that creatine monohydrate supplementation may affect kidney and/or liver function. However, no studies have reported clinically significant elevations in kidney function markers or liver enzymes in response to creatine monohydrate supplementation. Nor has any study found that creatine monohydrate supplementation has any negative effects on athletes (medical markers of safety) who participate in outdoor summer-type sports. Contrarily, creatine usage has been associated with long-term health in athletes.
Some reports have indicated creatine monohydrate supplementation may promote a greater incidence of muscle strains, cramps or pulls; however, no studies have found this to be true. In fact, the data demonstrates a protection effect or a non-impact effect concerning creatine and these types of musculoskeletal injuries.
As reported in the ISSN position stand, creatine can serve as a workout or sport performance enhancer by enhancing and or supporting:
• Increased single and repetitive sprint performance.
• Increased work performed during sets of maximal effort muscle contractions.
• Increased muscle mass and strength adaptations during training.
• Enhanced glycogen synthesis.
• Increased anaerobic threshold.
• Possible enhancement of aerobic capacity via greater shuttling of adenosine triphosphate (ATP) from mitochondria.
• Increased work capacity.
• Enhanced recovery.
• Greater training tolerance.
The JISSN publication also includes an applications list, showing benefits relative to specific sports:
Increased muscle phosphocreatine (PCr) levels
• Track sprints: 60-200 m
• Swim sprints: 50 m
• Pursuit cycling
Increased PCr resynthesis
• Field hockey
• American football
• Ice hockey
Reduced muscle acidosis
• Downhill skiing
• Water sports (e.g., rowing, canoe, kayak, stand-up paddling)
• Swim events: 100, 200 m
• Track events: 400, 800 m
• Combat sports (e.g., mixed martial arts [MMA], wrestling, boxing, etc.)
• Team handball
• Interval training in endurance athletes
Increased body mass/muscle mass
• American football
• Combat sports (e.g., MMA, wrestling, boxing, etc.)
• Track/field events (shot put, javelin, discus, hammer throw)
• Olympic weightlifting
As a nutritional ingredient, creatine monohydrate has consistently shown ergogenic benefits in research. Additional health benefits have been reported from supplementation as well. The dietary supplement and medical industries are encouraged to continue to support life cycle research for potential health benefits related to creatine.
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