The impact of milk protein glycation on muscle protein synthesis after resistance training in healthy young men

Protein intake is an essential stimulus for muscle protein anabolism. The
muscle protein synthetic response to protein ingestion is mainly determined by
the post-prandial plasma amino acid response. A study shows that glycation of
proteins during commonly applied milk processing procedures (Maillard
reaction), attenuates the digestibility of a dairy product, and the subsequent
appearance of amino acids in the circulation. The level of protein glycation in
processed dairy products might therefore be an important modulator of the
overall protein quality of a product, and its ability to stimulate protein
metabolism. However, it has not yet been investigated if the glycation level of
dietary protein modulates its capacity to stimulate muscle protein synthesis.

To compare the muscle protein synthetic response after ingestion of a milk
protein powder with different levels of protein glycation in healthy young men.

Randomized, parallel groups study design. The nutritional interventions will be
single blinded (researchers blinded).

All subjects will perform a single bout of whole-body resistance-type exercise.
Subsequently, subjects will ingest a beverage containing water, low glycated
milk protein (5% blocked lysine), or high glycated milk protein (50% blocked
lysine).

The burden and risks with participation are small. During the screening,
subjects will perform 1-repetition maximum tests to determine maximal strength
to calculate the workloads for the test day. A DEXA scan will be done to assess
body composition, where the level of radiation is very low compared to the
background radiation level in the Netherlands. Furthermore, we will ask the
participants to fill out a medical questionnaire. Insertion of the catheters
during the test day is comparable to a blood draw and could result in a small
hematoma. We will take 14 blood samples during the experimental period. The
total amount of blood we draw (140 mL) is much less than the amount of a blood
donation (500 mL) and will be completely restored in approximately 1 month.
Throughout the test day, a total of three muscle biopsies will be taken under
local anaesthesia by an experienced physician, but may cause some minor
discomfort only up to 24 h after completion. The discomfort is comparable to
muscle soreness or the pain one has after bumping into a table. Participants
will come to the university twice: 1 screening (~2h) and 1 experimental day
(~9h). On the experimental test day, the subjects will be asked to remain
fasted (with the exception of the experimental drinks). In addition, subjects
will be asked in the two days prior to the test day not to perform any type of
intense physical activity and to avoid consuming caffeine and alcohol in the
12h and 24h prior to the test day, respectively. Participants will be asked to
record their nutritional intake and daily activities in the two days prior to
the experimental test day. During the experimental test day, subjects will
perform a single bout of resistance-type exercise. There is no direct benefit
to the participant, only their contribution to the scientific knowledge on the
impact of protein glycation on stimulation of muscle protein synthesis.