Researchers examine performance, recovery effects of a prebiotic + protein food bar
Most commercially available carbohydrate-rich energy drinks, gels, and bars have a relatively high glycemic index, argued researchers from Texas A&M University, and therefore may not be not suitable for individuals who are glucose intolerant, diabetic, or susceptible to hypoglycemia during exercise.
Hence, the goal was to investigate whether replacing the carbohydrates found in traditional sports nutrition bars with a different composition (in this case whey protein and a plant-derived fiber called isomalto-oligosaccharide) might confer performance and recovery benefits.
According to the researchers, isomalto-oligosaccharides are a fiber that can be classified as a prebiotic—in other words, it is a carbohydrate that has been observed to stimulate activity of bacteria in the gut.
In their study of 12 men with experience in weight lifting, they found some evidence that the novel food bar of whey protein and the prebiotic can “positively affect glucose homeostasis, help maintain workout performance, and lessen perceptions of muscle soreness,” they reported in their paper, published yesterday in the Journal of the International Society of Sports Nutrition.
They came to this conclusion by comparing the participants’ exercise performance and questionnaire responses after ingesting the whey and prebiotic bar (Nutrabolt’s Fit Joy, which has since been reformulated) versus a carbohydrate-matched dextrose gel, which had the same amount of carbohydrates but a different overall nutritional profile.
“Research has shown that different types of carbohydrate and protein can have varying effects on substrate availability, exercise metabolism, performance, and/or recovery,” they wrote.
Building on previous research
The same team had previously examined the bar’s effects on glycemic and insulin response in a trial with four women and six men, and found that the bar increased insulin to a greater degree while maintaining blood glucose to a better degree than the control.
Building on this previous knowledge, the researchers hypothesized that ingestion of this whey protein food bar containing the prebiotic would promote a low to moderate glycemic response with a similar insulin response during exercise, help athletes maintain exercise performance capacity during an intense training session, and hasten recovery.
“Results revealed that ingestion of this food bar promoted a more favorable glucose and insulin profile in response to intense exercise,” they added.
In terms of performance and recovery, the researchers reported no significant interactions, but added that an analysis of changes from the beginning of the trial revealed that leg press and total lifting volume was maintained when participants consumed the protein and prebiotic bar compared to dextrose.
“While it is understandable that athletes/experienced lifters may not be able to maintain 70% of one repetition maximum for each exercise during an intense workout due to fatigue, this finding provides some evidence that ingestion of the food bar helped maintain the quality of the resistance-exercise training session.”
The study was a crossover trial, which means each participant ingested one type of food bar during one clinic visit, and after a seven-day ‘wash-out’ period, they ingest the other type of bar and perform the same exercises. Researchers collect and compare data from both visits.
The twelve men consumed either a carbohydrate matched dextrose comparito as a control or Nutrabolt’s FitJoy, containing 20 g of whey, 25 g of the prebiotic isomalto-oligosaccharide, and 7 g of fat.
The intervention food items were consumed 30-minutes before, mid-way, and following intense exercise, which consisted of 11 resistance exercises and agility and sprint conditioning drills.
Researchers collected blood to assess catabolic and inflammatory markers and rated perception of muscle soreness.
The study was open label, which meant that both participants and investigators knew which food intervention was being consumed, leaving the possibility of so-called placebo effect especially when rating muscle soreness.
“With that said, the major strengths of this study were the randomized and crossover experimental design and assessment of a typical intense training bout used in the strength and conditioning of athletes.”
Source: Journal of the International Society of Sports Nutrition
Published online, https://doi.org/10.1186/s12970-019-0301-z
“Comparison of ingesting a food bar containing whey protein and isomalto-oligosaccharides to carbohydrate on performance and recovery from an acute bout of resistance-exercise and sprint conditioning: an open label, randomized, counterbalanced, crossover pilot study”
Authors: Tyler J. Grubic, et al.