Daytime and nighttime casein supplements similarly increase muscle size and strength in response to resistance training earlier in the day: a preliminary investigation

Abstract

Background

Casein protein consumed before sleep has been suggested to offer an overnight supply of exogenous amino acids for anabolic processes. The purpose of this study was to compare supplemental casein consumed earlier in the day (DayTime, DT) versus shortly before bed (NightTime, NT) on body composition, strength, and muscle hypertrophy in response to supervised resistance training.

Methods

Thirteen males participated in a 10-week exercise and dietary intervention while receiving 35 g casein daily. Isocaloric diets provided 1.8 g protein/kg body weight.

Results

Both groups increased (p < 0.05) in lean soft tissue (DT Pre: 58.3 ± 10.3 kg; DT Post: 61.1 ± 11.1 kg; NT Pre: 58.3 ± 8.6 kg; NT Post: 60.3 ± 8.2 kg), cross-sectional area (CSA, DT Pre: 3.4 ± 1.5 cm2; DT Post: 4.1 ± 1.7 cm2; NT Pre: 3.3 ± 1.6 cm2; NT Post: 3.7 ± 1.6 cm2) and strength in the leg press (DT Pre: 341 ± 87.3 kg; DT Post: 421.1 ± 94.0 kg; NT Pre: 450.0 ± 180.3 kg; NT Post: 533.9 ± 155.4 kg) and bench press (DT Pre: 89.0 ± 27.0 kg; DT Post: 101.0 ± 24.0 kg; NT Pre 100.8 ± 32.4 kg; NT Post: 109.1 ± 30.4 kg) with no difference between groups in any variable (p > 0.05).

Conclusions

Both NT and DT protein consumption as part of a 24-h nutrition approach are effective for increasing strength and hypertrophy. The results support the strategy of achieving specific daily protein levels versus specific timing of protein ingestion for increasing muscle mass and performance.

Trial registration

ClinicalTrials.gov Identifier: NCT03352583.

Keywords:

• Protein
• Timing
• Hypertrophy
• Supplements
• Resistance training
• Window of opportunity
• Anabolic window

Acknowledgements

The authors would like to thank those participants who made the present study possible.

Funding

The present study was funded by Dymatize Active Nutrition Institute (Dallas, TX) and Friesland Campina (Amersfoort, The Netherlands). This article was published with support from Texas Woman’s University Libraries’ Open Access Fund.

Availability of data and materials

The datasets obtained during the current study are not publicly available due to ongoing analyses but are available from the corresponding author on reasonable request.

Authors’ contributions

The study was designed by JMJ, RMV, KSB, UK, RECW, and NMD. JMJ, RMV, NYK, and JMD implemented the study, conducted testing, and collected data. Data were analyzed by JMJ and interpreted by JMJ, RMV, RECW, and NMD. All authors approve of, and contributed to writing, the manuscript.

Ethics approval and consent to participate

The present study was approved by the Texas Woman’s University IRB, and all subjects provided their written informed consent prior to participation.

Competing interests

RECW actively serves as Chief Science Officer for Post Active Nutrition (St. Louis, MO), parent company of Dymatize, a funding source. UK is an employee of Friesland Campina, a funding source. JMJ has received payment from Dymatize Enterprises LLC for consulting. RMV is currently a sports nutritionist for GU Energy Labs, a supplement company, but was not at the time of the research. The authors declare no other competing of interests.

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