The researchers were exploring the concept of hyperaminoacidemia—excess of amino acids in the bloodstream—in the nighttime. “The potential role of nighttime nutrition in muscle adaptation to training is often overlooked,” the researchers from Texas Woman’s University wrote in a report.
Results from their 10-week long pilot study was published this week in the Journal of the International Society of Sports Nutrition. It was funded partially by Dutch dairy giant Friesland Campina, of which one of the authors was affiliated with, as well as sports nutrition manufacturer Dymatize Active Nutrition Institute.
“It was hypothesized that the nighttime [casein] supplemented group would experience greater benefit to resistance-training induced physiological changes,” wrote the authors.
But at the study’s conclusion, they found that participants who supplemented 35 g of casein at night time experienced changes in muscle hypertrophy and strength the same way as participants who took the 35 g of casein earlier in the day and in closer proximity to the workout timing.
“Therefore, night time consumption of protein may not be a special time period for protein consumption, but it may be treated as an equally effective time to consume protein to meet protein intake goals,” they added.
Participant recruitment, supplementation, and study design
The study design was a randomized, double-blind, placebo-controlled clinical trial. Thirteen recreationally active 18-25 year old males completed the 10-week study.
Their diets and exercise routines were controlled. Participants were divided into two groups—the ‘nighttime group’ was supplemented with 35 g calcium caseinate from Friesland Campina at night immediately before going to sleep while their day-time supplementation was 35 g of maltodextrin. The other group, the ‘daytime group,’ was given the opposite.
They also ingested 25 g of whey protein daily, the ISO100 brand by Dymatize. During the day, they performed exercise routines ranging from bicep curls to leg curls, abdominal cable crunches to box squats.
Daytime casein may create ‘elevated baseline’ for amino acid levels in bloodstream
The researchers did not notice a significant difference in muscle enlargement and strength between the two groups, hinting that what time of day casein is ingested may not matter.
“The results support the strategy of achieving specific daily protein levels versus specific timing of protein ingestion for increasing muscle mass and performance,” they argued.
However, the small sample size of participants meant “it is possible that potential differences would be undetectable without more participants,” they added.
One area of future exploration would be the effects of daytime supplementation of casein. They argued that the sterile nature of the study—with diet and total protein control—limited total protein intake to around 50 g per day.
“Therefore, another hypothesis is that it could be possible for day-time casein consumption to create an ‘elevated baseline’ for hyperaminoacidemia, thereby reducing the absolute amount of dietary protein necessary to maximize protein synthesis in meals consumed during the 6–7 hours [post-meal] period following casein supplementation.”
Source: Journal of the International Society of Sports Nutrition
Published online, https://doi.org/10.1186/s12970-018-0228-9
“Daytime and nighttime casein supplements similarly increase muscle size and strength in response to resistance training earlier in the day: a preliminary investigation”
Authors: Jordan M. Joy, et al.
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