PMC

Schematic overview of experimental design. This scheme shows the different stages of the 3‐day experimental protocol (first protocol execution). This complete experimental protocol was repeated after 1 week in exactly the same way (second protocol execution).

Effect of exercise and serum DPP4 activity on urine betacasomorphin‐7 (BCM7) levels. Urinary BCM7 levels (A) and serum DPP4 activity (B) (n = 10) are shown as mean ± SEM. Statistical comparisons are made for the first protocol execution (black) and the second protocol execution (striped) between the resting condition (rest) and the exercise condition. The * symbol depicts P < 0.05.

Effect of exercise and casein intake on serum urea levels. Data are shown as mean ± SEM. Serum levels during the first (black) and second (striped) protocol execution are compared between the resting condition (rest) and exercise condition in combination with 1 h casein intake (rest and Ex 1 h Cas). The * symbol depicts P < 0.05.

Effect of exercise on markers of intestinal permeability in urine and plasma. L/R ratio (A) and recoveries of lactulose (C), l‐rhamnose (E), and d‐xylose (G) in 5 h pooled urine are shown as mean ± SEM. L/R ratio (B) and levels of lactulose (D), l‐rhamnose (F), and d‐xylose (H) in 1 h plasma (n = 10 for first protocol execution) are shown as  ± SEM. Statistical comparisons are made between values during the resting condition (rest) and the exercise condition (Exercise and Exercise+ 1 h casein protein intake) within the first protocol execution (circles) and the second protocol execution (squares). The * symbol depicts P < 0.05 and the ** symbol depicts P < 0.01.

Effect of exercise on postprandial plasma amino acid levels. Plasma levels of total AAs (A), EAAs (B), nEAAs (C), citrulline (D), glutamine+ glutamate (GLX; E), arginine (F), alanine (G), and taurine (H) following casein bolus intake are shown as mean ± SEM. Comparisons are made for the first (open circles) and second (closed squares) protocol execution between the resting condition (line) versus exercise condition (dashed line). N = 10 for first protocol execution. Significant differences are depicted with * when different for both protocol executions and *¹ when different for the first protocol execution only.

Effect of exercise on markers of intestinal integrity, recovery and systemic inflammation. Levels of plasma FABP2 (A), serum calprotectin (B), serum prehaptoglobin 2 (preHP2) (C), and serum glucagon‐like peptide 2 (GLP2) (D) are shown as mean ± SEM. Statistical comparisons are made for the first protocol execution (black) and the second protocol execution (striped) between the resting condition (rest) and the exercise condition with or without 1 h casein intake (Ex 1 h Cas), and for plasma FABP2 also 24 h post exercise. For serum preHP2, 1 h casein sample in the resting condition was not analyzed. The * symbol depicts P < 0.05, **P < 0.01, and ****P < 0.0001. For plasma FABP2, bars with different symbols (#, & and $) are statistically different.

Schematic overview of blood sampling and analyses during one repetition of the experimental protocol. This scheme shows the blood sampling during rest, exercise, and 24 h post exercise. The resting condition started at 0800 h and finished around 1400 h with lunch. The exercise condition started around 2000 h in the evening of the same day (2 h after dinner), and continued at 0730 h the next morning, and sampling lasted till around 1400 h on that day. The 24 h post exercise blood sampling took place around 0900 h the next day. This complete experimental protocol with a dual exercise protocol was repeated in exactly the same way 1 week later. Samples taken at baseline were used as t = 0 for calculations. The different blood analyses are displayed at the different sampling time points. AA: amino acids; sugars: lactulose, l‐rhamnose, and d‐xylose.