The effect of ingesting a whey and collagen protein blend on myofibrillar and connective tissue protein synthesis rates at rest and during recovery from exercise

The preservation of skeletal muscle mass is of great importance for maintaining
metabolic health and functional capacity. Skeletal muscle mass maintenance is
regulated via changes in both muscle protein synthesis and muscle protein
breakdown. Of the two, the stimulation of muscle protein synthesis is assumed
to be the primary variable responsible for regulating the maintenance or gain
in skeletal muscle mass. The two main anabolic stimuli that augment muscle
protein synthesis are food intake, in particular dietary protein ingestion, and
physical activity. Protein ingestion stimulates muscle protein synthesis and
augments the muscle protein synthetic response to a single exercise session. In
support, protein supplementation during recovery from exercise has been shown
to augment the gains in muscle mass and strength following more prolonged,
resistance-type exercise training. The force generated by contracting muscle is
transferred through a network of connective tissue proteins towards the bone .
Consequently, remodeling of skeletal muscle connective tissue represents an
essential component of skeletal muscle adaptation to exercise. A single bout of
exercise has been shown to stimulate muscle connective tissue protein synthesis
rates. However, the impact of protein ingestion to further augment connective
tissue (i.e. collagen) protein synthesis rates remains to be established .
Whey protein is considered the preferred protein source to maximize
myofibrillar (i.e. myofiber contractile components) protein synthesis rates.
However, whey protein contains relatively little glycine and proline and may,
therefore, be ineffective to support the post-exercise increase in collagen
protein synthesis rates. Recently, we demonstrated that milk protein ingestion
actually lowers plasma glycine availability below baseline concentrations,
implying that collagen tissue remodeling during recovery from exercise may be
compromised by low plasma glycine availability. In contrast to whey protein,
collagen protein is rich in glycine and proline and has, therefore, been
proposed as a preferred protein source to support collagen tissue remodeling.
While the impact of collagen protein ingestion on collagen tissue protein
synthesis rates in skeletal muscle tissue remains to be established, recent
studies have shown that collagen protein supplementation can strongly increase
both skeletal muscle mass as well as strength gains following more prolonged
resistance-type exercise training. Consequently, we hypothesize that the
combined ingestion of whey plus collagen protein increases both myofibrillar
and connective tissue protein synthesis rates in skeletal muscle tissue. The
most ideal protein supplement for stimulating both myofibrillar and collagen
protein synthesis is one that gives a rapid initial rise in plasma amino acid
concentrations including proline and glycine concentrations. Data from a
previous study conducted in this lab (not published yet; METC20-044) showed
that a combination of whey and collagen protein with 25 g of whey protein and 5
g of collagen protein ingested during recovery from exercise resulted in the
greatest increase in plasma essential amino acids without compromising
post-prandial plasma glycine and proline availability. Therefore, the present
study will assess the impact of the combined ingestion of 25 g whey and 5 g
collagen protein on myofibrillar and connective tissue protein synthesis rates
in muscle tissue obtained at rest and during recovery from exercise in vivo in
humans.

To assess the impact of the combined ingestion of whey and collagen protein on
myofibrillar and connective tissue protein synthesis rates in muscle tissue
obtained at rest and during recovery from exercise in vivo in humans.

This study utilizes a double-blind, parallel-group, placebo-controlled
intervention with two groups. In total, 28 healthy recreationally active male
subjects (age: 18-35 y) will be included in the study. Subjects will perform a
single unilateral resistance exercise session (leg press and leg extension) and
will be randomly assigned to consume a beverage containing either a blend of 25
g whey and 5 g collagen protein or a placebo with non nitrogenous, non-caloric
flavored water. Blood and muscle biopsies will be collected while a primed
continuous infusion of L-[ring-13C6] phenylalanine infusion will be
administered. The duration of the entire study will be approximately 24 months.
This period includes screening, testing and data analysis of all 28 subjects.

Participants will perform unilateral resistance exercise followed by the
ingestion of either 30 g of a protein blend or a non-caloric placebo (flavored
water). Continuous intravenous tracer infusion will be applied, and plasma and
muscle samples will be collected in order to assess the muscle protein
synthetic response.

The burden and risks involved in participating in this experiment are small.
Insertion of the catheters in a vein is comparable to a normal blood draw and
the only risk is a small local hematoma. Muscle biopsies will be obtained under
local anesthesia by an experienced physician. The muscle biopsy may cause some
minor discomfort, which is comparable to muscle soreness or the pain one has
after bumping into the corner of a table. During the experimental trial 12
blood samples (~120 mL in total) will be obtained. The total amount of blood
collected is less than half the amount of a blood donation and will be
completely restored in approximately 1 month. The stable isotope amino acid
tracers that will be infused intravenously during the experimental trial are
produced according to GMP standards and are safe for human use. Participants
will be instructed on proper utilization of the exercise equipment by the
researcher to prevent injury. Participants will visit the University two times.
The first visit will involve a screening visit (~3 h), during which the
eligibility of the participant will be assessed and a bioelectrical impedance
analysis (BIA) will be performed. Additionally, participants will be
familiarized with single leg exercise on the leg press and leg extension
machine. The single leg one repetition maximum will be determined on the same
machines. For the second visit (experimental trial) participants are required
to come to the University in a fasted state, not having consumed any food or
beverages (except for water) as from 22:00 the evening before. Also, 2 days
prior to the experimental trial participants need to record their food intake
and activities performed. During these 2 days* participants are not allowed to
perform heavy physical exercise or drink alcohol. Filling out the food and
activity log properly will take the participant 30-45 min each day. There is no
direct benefit for the participants, except from their contribution to
scientific knowledge.