M.E.T. Willems, S.D. Myers, S.D. Blacker, M.D. Cook
Effects of new zealand blackcurrant extract on metabolic responses during cycling
University of Chichester Department of Sport & Exercise Sciences, College Lane Chichester, United Kingdom
M.E.T. Виллемс, С.Д. Майерс, С.Д. Блэккер, М.Д. Кук
Эффекты новозеландского экстракта черной смородины на метаболические реакции в течение цикличного приема антибиотиков
Университет Чичестера, отделение спорта и тренировок, Колледж Лейн Чичестер, Великобритания
Blackcurrant intake increases peripheral blood flow, potentially by anthocyanin-induced vasodilation which may affect substrate delivery. We showed with New Zealand blackcurrant (NZBC) intake a rightward shift of the blood lactate curve during an incremental cycling protocol, which may be partly explained by changes in substrate use. Here, we examined the effects of NZBC extract on intensity-dependent metabolic responses during steady-state cycling in trained cyclists. An intermittent incremental cycling protocol and a maximum oxygen uptake (VO2max) test were performed on a SRM ergometer to establish power at 45, 55 and 65% of VO2max. Following a randomized, doubleblind, crossover design, fourteen healthy men (age: 38±13 years, height: 178±4 cm, body mass: 77±9 kg, VO2max: 53±6 ml·kg-1·min-1, mean±SD) ingested NZBC extract (300 mg·day-1 CurraNZ™, ~105 mg anthocyanin) or placebo for 7-days (washout 14-days). On day 7, participants cycled at 45, 55 and 65% VO2max for 10 min. Wholebody carbohydrate and fat oxidation (i.e. CHox and FATox, respectively) were calculated. For each intensity, there were no differences in VO2, VCO2, heart rate, plasma lactate and energy expenditure indicating cyclists were experiencing similar relative exercise intensities between treatments. However, there were trends with NZBC for FATox rates to be 15 and 13% higher at 45% (p=0.08) and 55% VO2max (p=0.10), but these were not matched by a lower CHox rate (p>0.05). At 65% VO2max, FATox was 27% higher following NZBC supplementation (p=0.04) with a strong trend for lower CHox (p=0.06). Correspondingly, the RER had a trend to be lower at 45% VO2max (p=0.07) and 55% VO2max (p=0.12). At 65% VO2max RER was lower (p=0.04). It was concluded that seven days intake of New Zealand blackcurrant extract increases fat oxidation during moderate intensity cycling. These findings may implications for endurance performance.
G. Dubnov-Raz, Y. Mashiach-Arazi, A. Nouriel, R. Raz, N.W. Constantini
Can height categories replace weight categories in striking martial arts competitions?
Exercise, Nutrition and Lifestyle Clinic, The Edmond and Lily Safra Children’s Hospital, Sheba Medical Center, Tel Hashomer, Israel
Г. Дубнов-Рац, Ю. Машиач-Араци, А. Нуриэль, Р. Рац, Н.В. Константини
Могут ли категории роста быть заменой весовым категориям в соревнованиях боевых искусств?
Клиника спорта, питания и здорового образа жизни, Детская больница Эдмонда и Лили Сафра, Медицинский центр Шиба, Тель ха-Шомер, Израиль
In most combat sports and martial arts, athletes compete within weight categories. High rates of disordered eating behaviors and pre-competition weight loss are seen in this population, attributed to this weight categorization.
We examined if height categories can be used as an alternative to weight categories for competition, in order to protect the health of athletes.
Height and weight of 169 child and adolescent competitive karate athletes who competed in a national karate championship were measured. Participants were divided to eleven hypothetical weight categories of 5kg increments, and eleven hypothetical height categories of 5cm increments. We calculated the coefficient of variation of height and weight by each division method. We also calculated how many participants fit into corresponding categories of both height and weight, and how many would shift a category if divided by height.
There was a high correlation between height and weight in young karate athletes (r=0.91, p<0.001). The mean range of heights seen within current weight categories was reduced by 83% when participants were divided by height. When allocating athletes by height categories, 74% of athletes would shift up or down one weight category at most, compared with the current categorization method.
We conclude that dividing young karate athletes by height categories significantly reduced the range of heights of competitors within the category. Such categorization would not cause athletes to compete against much heavier opponents in most cases. Using height categories as a means to reduce eating disorders in combat sports should be further examined.
G. Dubnov-Raz, Y. Mashiach-Arazi, R. Arieli, R. Raz, N.W. Constantini
Eating attitudes and pre-competition rapid weight loss in young taekwondo fighters
Exercise, Nutrition and Lifestyle Clinic, The Edmond and Lily Safra Children’s Hospital, Sheba Medical Center, Tel Hashomer, Israel
Г. Дубнов-Рац, Ю. Машиач-Араци, Р. Ариэли, Р.Рац, Н.В. Константини
Соотношение компонентов пищи для предсоревновательного снижения массы тела у юных спортсменов-тхэквондо
Клиника спорта, питания и здорового образа жизни, Детская больница Эдмонда и Лили Сафра, Медицинский центр Шиба, Тель ха-Шомер, Израиль
Taekwondo is a martial art and a combat Olympic sport. Similar to other types of combat sports, Taekwondo fights are conducted between opponents grouped by sex, age and weight classes. Disordered eating behaviors are common in combat sports with weight classes, attributed to the athletes’ need to remain within a specific weight range. Pre-competition rapid weight loss (RWL) is also common, and carries a health risk. The aim of this study was to assess the eating attitudes and the prevalence and techniques of RWL among young Taekwondo fighters. 112 competitive Taekwondo fighters in national championships and regional competitions aged 12-21.5 years filled out questionnaires inquiring eating attitudes (EAT-26) and RWL techniques. 38% of respondents reported pre-competition RWL, with no significant between-sex difference. Common practices were training harder and eating less, but several potentially dangerous techniques were also described. 70% of those reporting RWL were not assisted by another person, and the degree of RWL reached -5.5kg. 23-40% or participants reporting RWL felt an improvement in some physical measure, yet 16% reported a decrease in subjective sport performance. 2.7% had abnormal scores on the EAT-26 questionnaire. There is a high rate of pre-competition RWL in young Taekwondo fighters, even in lower levels of competition. Most athletes performing RWL were unassisted, and some utilized potentially dangerous techniques. Most athletes did not feel that RWL affected their sport performance, yet a significant proportion felt decreased performance. Weight-class athletes should be consulted by personnel trained in sports nutrition, in both training and competition states.