The effects of the zone-diet on training measures in recreational master athletes

• Published in: Journal of sports sciences Vol. 27; p. S23
• Main Authors: Piacentini, M F, Salvatori, G, Di Cesare, C, Filomena, P, Olivi, M, Meeusen, R, Capranica, L
• Format: Journal Article
• Language: English
• Published: Abingdon Taylor & Francis Ltd 01.01.2009
• Subjects: Athletes; Diet; Effects; Performance evaluation; Sports training; Studies
• ISSN: 0264-0414; 1466-447X

Master athletes do not have comparable technical support of elite athletes and often adopt ''word-of-mouth'' training and nutritional programmes to optimise their performance. The zone-diet (40% carbohydrate, 30% protein and 30% fat), claiming to improve performance, reduce body fat and increase muscle mass (Sears, 2000: Sports Medicine 29:289-294), might attract recreational athletes. Previous studies showed no positive effects on endurance performances and reported high drop-outs during the experiments because unable to train as usual (Jarvis, McNaughton, Seddon, & Thompson, 2002: Journal of Strength and Conditioning Research 16:50-57; Piacentini, Parisi, Bonanni, & Capranica, 2004: 9th Annual Congress of the European College of Sport Science, 2007; 12th Annual Congress of the European College of Sport Science). Therefore, the aim of this study was to evaluate the effects of a 2-week zone-diet period on performance and training parameters of endurance runners. Six master athletes (52 ± 4 years, 74 ± 6 kg, and 52 ± 3 ml - kg... - min...) filled in a 1-week food record and wore a sensor (Sensewear ARMBAND) that continuously gathered data (i.e. movement, heat flux, skin temperature, galvanic skin response) in order to design an iso-caloric zone-diet regimen, maintaining the protein-to-carbohydrate ratio within the required range of 0.60-0.75. Before (Pre) and after (Post) 15 days on the zone-diet, athletes performed two exercise tests to exhaustion with a 3-h interval. During the 4-week prior and the 2-week zone-diet period subjects filled a daily online training diary (BLITS...) and a POMS questionnaire for objective and subjective evaluations of training. Analysis of variance (P < 0.05) for repeated measures was applied for pre-post differences. Significant decreases in body mass (Pre: 73 ± 5, Post: 69 ± 5 kg), body fat (Pre: 10 ± 2, Post: 9 ± 2 kg) and free fat mass (Pre: 63 ± 6, Post: 60 ± 6 kg) were observed, while running performances showed no significant difference with the experimental treatment. During the 2-week on the zone-diet athletes reported a 26 and 8% increase in their perception of training intensity and monotony respectively. The POMS showed an increase in fatigue and depression scores with a decrease in vigour. One athlete dropped out of the study after 10 days on the zone-diet. The results of the present study do not support an enhancement in performance or an increase in FFM determined by the zone diet, confirming previous work. Because of its low carbohydrate content it cannot be recommended as a nutritional regimen for elite and recreational runners because training sessions might be compromised. (ProQuest: ... denotes formulae/symbols omitted.)