Energy- and nutritional requirements in professional soccer: The ProSoccer study.

Many elite athletes utilize periods of intensified exercise training to enhance
performance. When intensified training is not counterbalanced by sufficient
recovery, overuse injury and overtraining may develop. Adequate nutrition
intake is prerequisite to optimize recovery and to meet the energy demands of
intense exercise. Although the energy demands and dietary requirements of many
endurance sports have been well established, there is little information on the
energy demands and physical activity patterns in soccer players. In addition,
the dietary intake patterns of soccer players are largely unknown.

In the current study we aim to assess the energy requirements and physical
activity patterns in professional soccer players along with their nutritional
intake patterns. As such, this study will provide valuable information to
optimize the nutritional counseling and sport medical treatment of professional
soccer players.

This is a cross-sectional study design with parallel measurements of energy
requirements (doubly labelled water), physical activity patterns
(accelerometry), and dietary intake (digital 24h recall), and body composition
(DXA and anthropometry).

* During the baseline measurements, body composition will be assessed by DXA.
The measurement is painless, non-invasive and involves low radiation exposure
(<10 *Sv).
* For venous blood collection, a small needle will be inserted into the
antecubital vein and blood is 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 when donating blood.
* A wrist-worn accelerometer will be worn during a 2-week period for 24h/day.
This is 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. The 24-h recall will be
conducted thrice.
* Energy expenditure will be assessed by the doubly labelled water method.
Because the stable isotopes used in the doubly labelled water are
non-radioactive, and also non-toxic in the doses used, the doubly labelled
water method has been used extensively in human volunteers, and even in infants
and pregnant women. The doubly labelled water requires the collection of 7
urine samples over a period of 14 days.
Altogether, it can be concluded that the burden and risks associated with this
study are low. The study provides novel insight into the energy expenditure,
physical activity patterns, and dietary intake in professional soccer players.
As such, this study provides an important framework for dietary counselling in
professional soccer players.