Ketogenic
diet does not affect strength performance in elite artistic gymnasts
Antonio
Paoli1,2*, Keith Grimaldi3,
Dominic D’Agostino4,
Lorenzo Cenci5, Tatiana Moro1,
Antonino Bianco6 and Antonio Palma6
- * Corresponding author: Antonio Paoli antonio.paoli@unipd.it
1 Physiological Laboratory –
Department of Biomedical Sciences, University of Padova, Padova, Italy
2 Human Movement Sciences
School, University of Padova, Padova, Italy
3 Biomedical Engineering
Laboratory, Institute of Communication and Computer Systems, National Technical
University of Athens, Athens, Greece
4 Department of Molecular
Pharmacology & Physiology College of Medicine, University of South Florida,
Tampa, FL, USA
5 Tisanoreica Study Center, Lonigo,
Vicenza, Italy
6 Department of Sports and
Exercise Science (DISMOT), University of Palermo, Palermo, Italy
For all author emails, please
Journal of the International Society of Sports
Nutrition 2012, 9:34 doi:10.1186/1550-2783-9-34
Abstract
Background
Despite the increasing use of
very low carbohydrate ketogenic diets (VLCKD) in weight control and management
of the metabolic syndrome there is a paucity of research about effects of VLCKD
on sport performance. Ketogenic diets may be useful in sports that include
weight class divisions and the aim of our study was to investigate the
influence of VLCKD on explosive strength performance.
Methods
8 athletes, elite artistic
gymnasts (age 20.9 ± 5.5 yrs) were recruited. We analyzed body composition and
various performance aspects (hanging straight leg raise, ground push up,
parallel bar dips, pull up, squat jump, countermovement jump, 30 sec continuous
jumps) before and after 30 days of a modified ketogenic diet. The diet was
based on green vegetables, olive oil, fish and meat plus dishes composed of
high quality protein and virtually zero carbohydrates, but which mimicked their
taste, with the addition of some herbal extracts. During the VLCKD the athletes
performed the normal training program. After three months the same protocol,
tests were performed before and after 30 days of the athletes’ usual diet (a
typically western diet, WD). A one-way Anova for repeated measurements was
used.
Results
No significant differences
were detected between VLCKD and WD in all strength tests. Significant
differences were found in body weight and body composition: after VLCKD there
was a decrease in body weight (from 69.6 ± 7.3 Kg to 68.0 ± 7.5 Kg) and fat
mass (from 5.3 ± 1.3 Kg to 3.4 ± 0.8 Kg p < 0.001) with a non-significant
increase in muscle mass.
Conclusions
Despite concerns of coaches
and doctors about the possible detrimental effects of low carbohydrate diets on
athletic performance and the well known importance of carbohydrates there are
no data about VLCKD and strength performance. The undeniable and sudden effect
of VLCKD on fat loss may be useful for those athletes who compete in sports
based on weight class. We have demonstrated that using VLCKD for a relatively
short time period (i.e. 30 days) can decrease body weight and body fat without
negative effects on strength performance in high level athletes.
Keywords:
Background
Many procedures used for body
weight reduction by athletes in sports that include weight categories lead to a
series of negative side effects which directly influence physiological
efficiency during sports performance. The practice of rapidly losing a
significant amount of weight, through low calorie diets, deliberate
dehydration, saunas etc., just before competition, is widespread . These traditional methods are often unsafe and typically impair health,
physiological function, water balance, electrolytes, glycogen and lean body
mass and are sometimes illegal as with the use of diuretics .
However for athletes competing
in sports divided into weight categories a safe method of weight loss that does
not impair performance can be a legitimate and important tool. For example,
bodybuilders regularly need to reduce fat and/or weight before competition preferably
without affecting muscle strength or muscle size [7] and a VLCKD (very low carbohydrate ketogenic diet) is commonly used to
achieve this. VLCKD is a diet in which the daily carbohydrate intake is below
30 g and this restriction limits glucose availability to tissues, stimulating
ketogenesis in the liver. The physiological function of ketosis is to supply
the heart and central nervous system (CNS) with a high energy metabolic
substrate during reduced glucose availability – by this mechanism ketones
allowed our ancestors to survive and remain efficient even when deprived of
food . On this basis the ketosis induced by a VLCKD may be defined as
“physiological ketosis” to distinguish it from the severe pathological ketosis
(or ketoacidosis) commonly seen in uncontrolled diabetes . The use of low carbohydrate ketogenic diets for weight loss, despite
their efficacy, has been an area of controversy. In the last few years though
an increasing amount of evidence has accumulated concerning the positive
effects on short term weight loss, metabolic profile with regards to insulin
sensitivity, glycemic control and serum lipid values . These effects appear potentially very attractive for athletes needing to
lose fat mass quickly but, curiously, despite the huge amount of scientific
literature about ketogenic diets, their influence on sport performance remains
poorly investigated. Recently Kreider and colleagues studied the effect of a
specific exercise program in overweight woman with a VLCKD or normal
carbohydrate content diet , but only few papers that focus specifically on the influence of VLCKD on
sports performance have been published, and with conflicting results: showing
benefits , no effect or impairment .
The present study set out to
investigate if a VLCKD could be useful for athletes, especially for those
engaged in sports involving weight categories where weight loss without
negative changes in the body composition (i.e. loss of muscle mass) and
performance is often needed. To the best of our knowledge no previous study has
investigated the influence of a VLCKD on strength performance and on explosive
strength performance in competitive athletes.
