Effect of fasting and exercise on physical performance and muscular oxidative metabolism

Recently, a program which combines fasting with exercise, has been developed.
This program is called Sport Fasting (www.sportvasten.nl) and consists of ten
days in which nutrient availability is slowly reduced (three days), maintained
low (three days), and increased again (four days). In addition to this diet
program, participants need to train 30 minutes each day and receive additional
amino acids, omega 3 and 6 fatty acids, minerals, and anti-oxidants. This
program claims a shift towards fat oxidation and an increased mitochondrial
density in the muscles, which are associated with long-term weight loss, an
improved health status, and an enhanced endurance capacity. Qualitative,
non-controlled results suggest positive effects of the Sport Fasting program on
body mass, and physical performance, in addition to a list of other health
benefits.
The experienced success of Sport Fasting is based on the hypothesis that
fasting in combination with exercise is more effective in establishing weight
loss and increasing endurance performance than fasting alone. This hypothesis
is based on the assumption that the combination of fasting and an exercise
program may enhance fat oxidation and oxidative capacity within the active
skeletal muscles. As yet, effects of fasting in combination with an exercise
program on these parameters and the underlying mechanisms are unknown. In
addition, not all subjects who completed the program do benefit from this
program. In order to improve this program, it is important to obtain insight in
the effects and mechanisms of a period of fasting in combination with an
exercise program. Furthermore it is important to explore whether fasting in
combination with exercise is more effective than fasting alone in establishing
weight loss, as well as improving endurance capacity, by increasing
mitochondrial density and fat oxidation within the skeletal muscles.

The main objective is to explore the effects of a 10-day fasting and exercise
program on body composition and physical performance (peak power, endurance
capacity, efficiency and resting VO2¬) of overweight, fit men and compare these
effects with those of fasting alone. The secondary objective is to investigate
the effects of a 10-day fasting and exercise program on the determinants of
physical performance at the molecular level and relate these to changes in
physical performance parameters (the exercise tests). For this purpose subjects
will be subjected to exercise tests and muscle biopsies. The muscle biopsies
will be analysed with respect to histological characteristics related to
oxidative and anaerobic metabolism (mitochondrial density, myoglobin
concentration, muscle fiber typing, muscle fiber size and capillary density,
GAPDH) in the vastus lateralis muscle of overweight, fit men in comparison with
fasting alone.

A randomized controlled (pilot) study using a longitudinal study design to
determine the effects of the proposed intervention.

One group will be subjected to a 10-day fasting protocol, which implies 3 days
of reducing food intake, 3 days of drinking fruit juices and 4 days of building
up food intake again (control group). The other group will be subjected to the
exact same fasting protocol, but with an addition of 30 minutes exercise each
day (intervention group).

The burden for the participants consists mainly of the number of hours that the
participants need to invest in the research project (measurements, meetings
etc.). The total number of hours that the participants need to present at the
Vrije Universiteit or at Medico Vision, is estimated to be about 25 hours. In
addition, the participants need to perform 30 minutes of intense exercise each
day during the 10 day program. However, 30 minutes exercise is part of the
program, so participants who take part in the Sport Fasting protocol but not in
the research also need to invest this amount of time. The burden of the muscle
biopsies is minor. The procedure does not take very long and the discomfort
afterwards is minimal. The risks of the additional measurements are negligible.
In contrast, the participants might benefit from taking part in this research
project. The possibility that they will lose weight and enhance their endurance
capacity is high. Furthermore, the program will be offered for free to
participants taking part in this research project and after the research
participants can take part in another free (complete) Sport Fasting program.
Besides that, this project will most likely increase our knowledge regarding
the effects and mechanisms of the program and will create the possibility to
optimize the program for further use.