Protein supplementation to augment the training adaptations to endurance-type exercise training.

Although many studies support the importance of protein supplementation in
relation to resistance-type, the role of protein supplementation in relation to
adaptations to endurance exercise training has been less well studied. In this
regard, it has been shown that supplementation of protein following endurance
exercise accelerates skeletal muscle recovery. Moreover, the results from two
small studies suggested that protein supplementation augments the training
adaptations to longer term endurance exercise training. More research is
required to firmly establish the impact of protein supplementation during
long-term endurance exercise training on VO2max and related exercise
performance outcomes.

Primary Objective: The primary objective of the current study is to assess the
impact protein supplementation during long-term endurance-type exercise
training on VO2max.

Secondary Objective(s): The secondary objective of the current study is to
assess the impact protein supplementation during long-term endurance-type
exercise training on endurance exercise performance (time trial) and muscle
function (isokinetic dynamometry).

Double blind, randomized, placebo-controlled intervention trial. The study
involves 12 weeks of endurance-type exercise training with pre- and
post-measurements of exercise capacity and performance. During the 12-week
exercise programs, participants will be randomly assigned to a protein or
placebo supplement group.

Exercise training: During the 12-week exercise training program participants
will complete three exercise sessions weekly. In the training programs
continuous endurance exercise sessions will be alternated with interval
exercise sessions.

Protein supplementation: All participants will be randomly assigned to the
protein or placebo (isocaloric carbohydrate) group. The protein or placebo
supplements will be ingested after each training session and each day before
sleep.

During a 12-week periods, subjects perform three endurance exercise sessions
per week. The time investment associated with the endurance exercise training
is approximately 3 hours per week. The protein supplements and placebos are
almost identical to commercially available dairy products. Moreover, the
applied doses for the protein supplement and carbohydrate placebo fit within a
healthy diet. The protein and placebo supplements will be produced by
FrieslandCampina under strict food safety regulations.

The study comprises various measurements with a low risk for complications:
-Participants will perform various exercise tests (VO2max, time trial,
isokinetic dynamometry) before and after the 12-week exercise training program.
Although the exercise test can be considered as strenuous exercise, the burden
is limited to temporary discomfort and muscle soreness.
-Body composition will be assessed twice by DXA. The measurement is painless,
non-invasive and involves only low radiation exposure (<10 *Sv).
-Venous blood will be collected twice. For this procedure, a small needle will
be inserted into the antecubital vein and blood (25 mL) will be collected
through a closed system attached to the needle. The discomfort of this
procedure is transient and is comparable to having an injection by a needle, or
donating blood.
-A wrist-worn physical activity monitor will be worn twice for period of 7
days period for 24h/day. This measurement is comparable with wearing a watch.
-The 24-hour dietary recalls will collected by the *Compl-eat** software
program. This program developed by Wageningen University guides participants
through foods and drinks consumed during the previous day. A single 24-h recall
takes approximately 30 to 45 minutes to complete. Three 24-h recalls will be
conducted before, during and at the end of the 12-week intervention period.

Despite the time investment associated with the exercise training and
measurements, this study will give us novel information on the potential impact
of protein supplementation on training adaptation to long-term endurance-type
exercise training, including VO2-max, exercise performance, and muscle
function. As such, this study may identify a novel nutritional strategy to
enhance endurance exercise capacity and performance. As we include relatively
young and untrained male volunteers, the results will be primarily applicable
to this population. Nevertheless, this study may provide a proof-of-principle
for populations aiming to maximize the benefit from endurance-type exercise
programs, such patients revalidating form myocardial infarction, COPD patients,
elite athletes or athletes recovering from injury.