Journal Title (Medline/Pubmed accepted abbreviation): Int J Sports Nutr Exerc Metab
Page numbers: 436-445
doi (if applicable):
Article type: Review
The author presents a comprehensive review of the clinical evidence for nutritional practices and requirements in the sport of synchronized swimming, as well as areas in which further research is necessary. Currently, Olympic competition is limited to females who typically enter high-level competition at approximately 13 to 15 years of age. The sport requires a broad range of athletic abilities that demand long hours of training (1,690 hr/yr) at a critical development period for young women; however, very little is known regarding nutritional practices or requirements among these young athletes.
Physiologically, blood lactate levels accumulate during a routine, and there are adaptions to breath holding (eg, total lung capacity, vital capacity, hypoxic ventilatory response) that are critical to performance. In addition, aerobic capacity and isokinetic muscle strength are associated with performance scores, although swimmers have only a moderate level of aerobic fitness. Optimal physique has not been established and is driven primarily by aesthetics. Eating disorders are associated with aesthetic sports, and among synchronized swimmers approximately 55% consider themselves overweight. The incidence of eating distrubances is 30% among synchronized swimmers vs. 5% in other sports. In addition, menstrual-cycle initiation and stability are affected in synchronized swimmers, which could contribute to osteoporosis. Clinical evidence suggests that lower leg bone strength is high but bone mineral density in the wrist is low compared with norms, possibly because the training is weight supported and not load bearing.
Energy expenditure evidence comes from 1 controlled study (2,739 kcal/day); however, energy intake was reported as lower than expended in the weight-stable Japanese swimmers. Micronutrient status data are also lacking. Two studies reported decreasing ferritin levels during training seasons, with 28% of athletes having borderline or low ferritin stores. Other nutrients examined included folate, vitamins B12 and D, and magnesium, with only magnesium being below normal in 26% of athletes. Sweat losses are minimal in this sport, although 50% of swimmers in 1 study were dehydrated before a training session. Fluid replacement occurred primarily during the land portion of the session. There are no studies evaluating supplement use in this sport.
Physiologic testing is needed to more precisely determine the demands and adaptions in synchronized swimming. Because physique is important in performance scores, full anthropometric profiles are necessary to understand the optimal characteristics for this sport. Energy requirements and nutritional practices are unknown and the only controlled study suggests that underreporting food intake may confound future studies. Opportunities for fluid replacement and intake of nutrients and/or supplements may be limited in this sport, both by the physical limitations of training and the drive to achieve a certain physique. Nutritional education is hampered by the lack of information.