In the review study, published in the Journal of the International Society of Sports Nutrition, researchers from Lindenwood University in Missouri, the University of Regina in Saskatchewan and the Human Performance Lab associated with a Mayo Clinic location in Wisconsin looked at the research backing a number of micronutrients and ergogenic aids.
The researchers said most of the research regarding nutrient delivery and its connection to performance boosts is associated with carbohydrate and protein intake. But there is a growing body of research related to other nutrients and ergogenic aids of interest to athletes as well.
The study looked at the data backing the timing of ergogenic aids (caffeine, creatine, nitrates, sodium bicarbonate, beta-alanine) and micronutrients (iron, calcium) on muscle adaptations and exercise performance.
Results mixed for caffeine, inconclusive for nitrates
In caffeine, the results were mixed, partly because of the different dosages studies and different delivery modes. In general, the studies included in the review backed the notion that caffeine can boost aerobic performance, but were less clear about whether caffeine taken all at once before a longer event or taken at intervals during the event was better.
In the case of nitrates supplementation, the researchers found that most studies with nitrates involve prophylactic supplementation for 3-5 days prior to an event. When ingested, dietary nitrate (NO3−) is reduced to nitrite (NO2−) by bacteria in the oral cavity and then to nitric oxide (NO) in the stomach. NO may improve exercise performance by enhancing blood flow and muscular contractility and reducing the oxygen cost associated with aerobic exercise. One study looked at timed delivery of beetroot juice during a complicated cycling time trial test setup did not yield definitive results.
Timing data solid for creatine
Creatine is one of the best researched sports ingredients on this list. “creatine supplementation has been repeatedly demonstrated to improve high-intensity exercise capacity and increase muscle mass and muscle performance in conjunction with resistance training, by influencing high-energy phosphate metabolism, cellular hydration status, muscle protein kinetics, satellite cells, anabolic growth factors, and inflammation,” the researchers wrote.
The studies looking at the timing of creatine (either morning and night, or immediately before and/or after hard workouts) were small scale and used different methodologies, the review study authors concluded that there was enough data to support the benefits of timed delivery of this popular nutrient
“It appears that pre-exercise and post-exercise creatine supplementation are effective strategies to increase muscle mass and strength, with potentially greater muscle accretion benefits from post-exercise creatine,” they wrote.
Iron is of interest in sports nutrition applications for its relationship to hemoglobin and oxygen transport in the blood. The researchers found little support for the timed delivery of this nutrient and significant increases in sports performance.
Little data on timed delivery of other nutrients
Sodium bicarbonate, commonly known as baking soda, is an ergogenic aid that is of interest in its ability to buffer the buildup of lactic acid in the muscles after anaerobic efforts. But it is unpleasant to ingest at therapeutic dosages, so the researchers concluding that much of the ‘timing’ data associated with this nutrient is in fact a result of taking it in small quantities over time to reduce GI distress.
Calcium is important for bone health, with some athletes, notably cyclists, being at risk for weakened bones. The data backing the timing of this nutrient is sketchy, but the researchers said they could identify a trend toward benefit.
“When viewed collectively, the evidence seems to indicate a benefit of timed calcium supplementation prior to exercise to mitigate exercise-induced disruption to calcium homeostasis,” they wrote.
The researchers said that beta alanine, while backed with significant research for its muscle building benefits, had really no data relating to the specific timing of ingestion.
Promising avenue for future research
Even though hard and fast rules for nutrient delivery cannot be put forward at this time, the researchers said it is a promising avenue for future research.
“At the current time, research involving the timing of micronutrients and non-nutrients is in its infancy but will likely be an area of future interest for researchers, coaches, athletes, and the general public. . . As the body of timing-related research evolves, a greater understanding in this space will help athletes to better refine feeding and supplementation regimens to avoid unnecessary dosing, minimize known side effects, and improve training adaptations and performance,” they concluded.
Source: Journal of the International Society of Sports Nutrition
16, Article number: 37 (2019)
Timing of ergogenic aids and micronutrients on muscle and exercise performance
Authors: Stecker RA, et al.