The impact of whey versus collagen protein ingestion on post-exercise myofibrillar and connective tissue protein synthesis rates

Protein ingestion stimulates muscle protein synthesis and augments the muscle
protein synthetic response to a single exercise session. In support, protein
supplementation has been shown to augment the gains in muscle mass and strength
following resistance exercise training. The force generated by contracting
muscle is transferred through a network of collagenous connective tissue
proteins to articulate the bone. Therefore, the remodelling of skeletal muscle
connective tissue represents an essential component of muscle adaptation to
exercise. A single exercise session increases muscle connective tissue protein
synthesis rates. However, the impact of protein ingestion to augment
post-exercise connective tissue protein synthesis rate remains to be
established. Whey protein is considered the preferred protein source to
maximize myofibrillar protein synthesis rates. However, whey protein contains
insufficient glycine and proline to support the post-exercise increase in
connective tissue protein synthesis rates. In contrast, dietary collagen
protein is rich in glycine and proline and has, therefore, been proposed as a
preferred protein source to support connective tissue remodelling. We
hypothesize that whey protein ingestion will stimulate greater myofibrillar
protein synthesis rates and collagen protein ingestion will stimulate greater
collagen protein synthesis rates in skeletal muscle tissue during post-exercise
recovery in young men and women.

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

double-blind, placebo-controlled intervention study.

All subjects will perform an exercise bout consisting of 6 sets of barbell
squats at a workload of 60% 1RM with 15, 12, 10, 10, 8, 8 repetitions per set,
respectively. Immediately following exercise, subjects will be randomly
assigned to ingest a beverage (500 mL) containing either 30 g whey protein, 30
g collagen protein or non-caloric flavoured water (n=15 per group). Muscle
biopsies will be collected to assess myofibrillar and connective tissue protein
synthesis rates. Blood samples will be collected to assess post-prandial plasma
amino acid availability.

The burden and risks associated with participation are low. Participants will
come to the university twice: 1 screening (3 hours) and 1 experimental trial (9
hours). During the screening visit, we will perform a BIA and determine 1RM for
the squat exercise. For 3 days prior to the experimental trial, participants
will be asked to keep their diets as consistent as possible and to refrain from
consuming alcohol or performing any type of intense physical exercise. We will
ask the participants to fill out a medical questionnaire and record their food
intake and physical activity for the last 2 days prior to the experimental
trial. For the experimental trial, participants will be fasted and will need to
refrain from eating or drinking (except for water) from 22h00 the evening
before. During the experimental trial, participants will complete an exercise
session, additionally one group will consume a milk-based protein beverage and
one group will consume a collagen protein beverage (both commercially available
food products) while the researchers involved will collect muscle and blood
samples. For blood collection, insertion of the catheters is comparable to a
blood draw and could result in a small hematoma. We will take 11 blood samples
(10 mL) during the experimental trial. The total amount of blood drawn (110 mL)
is less than a third the amount of a blood donation (500 mL) and will be
completely restored in approximately 1 month. We will collect 2 muscle biopsies
from the vastus lateralis during the experimental trial. Muscle biopsies will
be taken under local anaesthesia by an experienced physician, but may cause
some minor discomfort up to 24 h after completion. The discomfort is comparable
to muscle soreness or the pain one has after bumping into a table. There is no
direct benefit for the participants except for their contribution to the
scientific knowledge and this will provide the basis for novel nutritional
interventions to improve health and functional capacity in older and more
clinically compromised populations, which will be obtained from this study and
used in the future.