Energy intake and energy balance in male and female adolescent rowers in New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Nutrition and Dietetics, Massey University, Albany, New Zealand

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Background Adequate energy intake (EI) is essential for adolescent athletes to support health, performance, and growth. Rowing is a physically demanding sport where intense training begins in adolescence. Research is needed to assess whether current EI is sufficient to support healthy physiological functions and training in adolescent rowers. The aim of this study was to evaluate the energy status (energy availability (EA) or energy balance (EB)) including EI and exercise energy expenditure (EEE) of adolescent rowers in New Zealand. Methods A total of 35 rowers (23 females, 16.8 ± 1.9yrs; 12 males, 17.3 ± 1.6yrs) who had been rowing for at least one season participated. Energy balance for all participants was calculated using estimated body weight (23 females, weight 71.6 ± 9.7kg; 12 males, weight 72.6 ± 10.7kg). A bioimpedance analyser measured body composition in 11 participants (8 females, weight 63.0 ± 7.0kg, fat-free mass (FFM) 50.8 ± 6.5kg; 3 males, weight 78.5 ± 15.9kg, FFM 70.7 ± 12.2kg) enabling calculation of EA. All participants completed four days of food and training diaries, two ‘recovery’ and two ‘hard’ training days. EI was determined in FoodWorks10 software using the New Zealand Food Composition Database. For training, metabolic equivalent of tasks (MET) were assigned using body weight, heart rate and rating of perceived effort to estimate EEE. Paired sample t-tests or Wilcoxon Signed Rank test (non-parametric data) were used to determine differences between EI, EEE, EA and EB on the high and low training days for each gender. Significance was set at p< 0.05. Results The average EI for females on hard and recovery days was 2584.6 ± 678.3kcal and 2492.6 ± 618.7kcal respectively, and for males was 3655.1 ± 792.5kcal and 3183.3 ± 1078.2kcal respectively. No significant differences were found between EI on hard vs. recovery days in both genders. Significant differences between average EEE on hard vs. recovery days were found in both genders (females, hard day 1108.8 ± 541.6kcal, recovery day 757.3 ± 431.6kcal, p<0.001; males, hard day 1574.9 ± 686.0kcal, recovery day 794.9 ± 690.8kcal, p=0.001). The average EB across hard and recovery training days was 65.5 ± 524.0kcal for females and 236.4 ± 913.9kcal for males. Both genders had no significant difference in EB between hard and recovery training days (females p=0.341, males p=0.433). EA on hard and recovery training days was classified as subclinical for both genders at 35.8 ± 12.6kcal×FFMkg-¹×day-¹ and 38.2 ± 26.2kcal×FFMkg-¹ ×day-¹ for females and males respectively. No significant difference in EA between hard and recovery days was found in either gender (females p=0.934, males p=0.212). The average carbohydrate (CHO) intake ranged between 2.4-7.0g×kg- ¹ ×day-¹ for females and 2.2-8.7g×kg-¹×day-¹ for males, both beginning below sport nutrition recommendations. Conclusion The results suggest that adolescent rowers do not adjust their nutritional intake to match EEE. This may increase the risk of adolescent rowers presenting with suboptimal EB or EA.