Dietary supplementation with creatine has, for many years, been one of the most widely used forms of supplement for athletes. In particular, the integration with creatine (in all its various forms) is favored by athletes who perform short-term activities. Being a reserve molecule forfeited in the fibrous muscle cells, which serves to quickly recharge the ATP (Adenosin Tri Phosphate) during muscle contraction, creatine should be useful for: increased short-term recovery of very intense muscle contractions, resulting in an increase of the potential of stimulating training force (maximal, fast, resistant short) and muscular hypertrophy.
However, hundreds of studies have been carried out on creatine which, to varying degrees, have given blandly positive or unsuccessful results. For this reason, a research group recently (2015) produced a review summarizing the most significant experiments concerning integration in relation to the development of muscular strength on the lower limbs.
The title is: " Creatine Supplementation and Lower Limb Strength Performance: A Systematic Review and Meta-Analyzes ". Below we will cite the key points of this very interesting work in a more concise and comprehensive way.
Although creatine is the molecule most affected by dietary supplementation on strength, the meta-analyzes that concern it are few, dated (more than 10 years) and are considered unreliable for: the absence of randomization and use of placebo, diversity inclusion criteria (aerobic / resistance, anaerobic / strength), no assessment of individual muscles or specific muscle groups and the considerable amount of conflicting results.
The objective of this systematic review was to evaluate the effects of the meta-analysis on creatine supplementation in strength performance with reference to the lower limbs.
The systematic review and meta-analysis involved all randomized controlled trials that looked at creatine supplement compared to a placebo, measuring strength performance in exercises lasting about 3 minutes.
The search strategy was to use the keywords "creatine supplement" and "performance". The dependent variables were: creatine load, total dose, duration, time intervals between baseline (T0) and at the end of the supplement (T1), as well as any training during the supplement. The independent variables were: age, sex and the level of physical activity at baseline. A meta-analysis was performed at T1 and on the changes between T0 and T1. Each meta-analysis was limited to lower limb muscle groups and exercise tests.
60 studies were included (646 individuals in the supplement group and 651 control). At T1, the magnitude of effect (ES) on the squat and leg press were 0.336 (95% CI 0.047-0.625, p = 0.023) and 0.297 respectively (95% CI 0.098-0.496, p = 0.003). The quadriceps ES (average) was 0.266 (95% CI 0.150-0.381, p <0.001). The ES of the global lower limb was 0.235 (95% CI 0.125-0.346, p <0.001). The meta-regression showed no correlation with the characteristics of the research group or supplement, demonstrating the effect of creatine efficacy regardless of all the conditions listed.
The creatine supplement is therefore effective in increasing the performance of the lower limbs when performing exercises with a duration of less than 3 minutes, regardless of the characteristics of the population, training protocols and doses as well as treatment duration.
