Seminar for CUHK Marathon Team 19-12-2015 The Science of Endurance Running 長跑運動之運動科學 Stephen H. Wong Department of Sports Science and Physical Education The Chinese University of Hong Kong 1
What Determines Performance? Talent Motivation Training Trainability A good diet will not make a mediocre athlete into a champion, but poor food choices can turn a champion into a mediocre athlete Avoiding injury Nutrition Supplements 2
Factors Affecting Exercise Performance 3
Energy Source for Running 4
Energy Expenditure During Long Distance Running EE Carbohydrate Kcal/min Kcal Amount (g) % 10 KM 17.5 700 150-170 86-97 Marathon 15.0 2800 500-550 71-78 (For a 70kg athlete) Reference values for Daily Energy Intake are 2350 for men and 1850 for women ages 30-60 yrs (Centre for Food Safety, HKSAR) 5
Thermoregulation of Marathon Running Metabolic heat gain > environmental heat loss Competing at the fastest speeds and drink the least sweat loss > fluid intake Effects on T re observed in phase III include 5 possibilities: (1) Poor hydration, fast finish; (2) poor hydration, steady finish; (3) adequate hydration, fast finish; (4) adequate hydration, steady finish; (5) adequate hydration, slow finish (cool weather only). 6
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Impact of Weather on Marathon Running Performance Ely et al., MSSE, 2007 環境溫度越高成績越低, 尤其能力較低者受影響較大 Marathon race results were obtained from 7 different races. All marathon races evaluated were run in a WBGT range of 2.5 to 28.0 and were sorted by 5 increments in WBGT (5.1 10, 10.1 15, 15.1 20, and 20.1 25 ) 8
1 Monitoring Hydration Status Urine color test for dehydration Lemonade The good Apple juice The bad Tea The ugly 2 3 4 5 6 7 8 9 9
Keys to Endurance Performance Maximize and maintain fuel (glycogen) supplies Maintain and optimize hydration and electrolyte balance Prevent protein breakdown and maximize synthesis Efficient and timely recovery from prior bout of exercise 10
Let s Talk Carbohydrates CHO converted to glycogen and stored in muscles and liver Glycogen is #1 fuel source for endurance events of moderate to high intensity Glycogen repletion is slow and recovery time is directly related to ability to replenish Maintaining and restoring glycogen is key to performance 11
Carbohydrate Oxidation During Long Distance Running Energy Expenditure Carbohydrate Oxidation kcal/min Total (kcal) (g) (%) 10 km 17.5 700 150-170 86-97 Marathon 15.0 2800 500-550 71-78 (For a 70kg athlete) Eg. of foods supplying 50 grams CHO:500 ml juice or 3 medium pieces of fruit 12
Carbohydrates For Training Nutrition for athletes, a practical guide to eating for health and performance by Nutrition Working Group of the IOC, based on an International Consensus Conference held at the IOC in Lausanne in October 2010 13
Diets Strategy Three Days Before Race CHO Loading 9-10 g kg -1 d -1 CHO 65%CHO (Source: http://www.hkmarathon.com/default.aspx?lang=en-us) 14
Diets Strategy Three Days Before Race CHO loading Old school: One week low CHO (deplete) with 1-3 day high CHO prior New school: 3 days of high CHO diet before race or long distance training session Events longer than 60-90 minutes Goal: Pre-training/race build up glycogen stores to prevent hitting the wall 15
(By courtesy of Susan Chung, HKSI) 16
Do s and Don ts 比賽前一晚及當天準備 Do s 賽前一晚不應飲用酒精和咖啡等刺激性飲品 賽前進食時間應最遲於賽前 2 小時完成 Don ts 賽前不可不吃, 不可多吃 不應在比賽前一日或當天嘗試新食物或者改變飲食習慣 食物不可太油膩 檢查尿液顔色 (1-3) 賽前 1.5-2 小時飲用 8-24 安士水 (1-3 杯 ) 17
Do s and Don ts 比賽中 Do s 每隔 5 公里的水站可補充半杯飲品以防脫水 ( 約 150ml) 半馬和全馬跑手可適量進食能量棒以補充能量並減輕饑餓感 為達最佳補充效果, 應爭取飲用大會提供的運動飲品 Don ts 不應待感到口渴才飲水 每小時不要飲用多於 1 L 無需跟隨他人的飲水習慣 One size does not fit all! 15 21ºC 6-8% CHO drinks, 600-1200 ml/h 高水平跑手可根據個人經驗補充能量和水份 18
Sport Bars Developed to provide an easily accessible source of CHO Many bars provide complex proteins and may be high in fat Vary in type and amount of energy, CHO, protein and fat Some provide only 150 kcal and others up to 340 kcal Many contain other agents, herbs, etc READ LABELS CLOSELY! *average sports bar provides about 40-60 grams of CHO 19
Sport Gels Designed to deliver large amount of CHO in compact and easily consumed form Very slowly absorbed by body and must have adequate amounts of water to dilute and lower osmolality Gels may be effective source of energy, but challenge is taking in enough fluid About 100 calories per package (25 grams CHO) 20
Concerns with Sport Gels High cost alternative Some brands also contain other compounds Gastrointestinal intolerance Should be used during training to assess tolerance for use during race May lead to over consumption/over-reliance on low-nutrient CHO sources 21
賽後可能出現的身體不適及對策 Open Window Theory 開窗 理論 Exercise (3--72h) Immunosuppression 免疫抑制 最好在運動結束 2 小時內補充, 以恢復肌肉失去的碳水化合物, 增強免疫力 補充碳水化合物 電解質 ( 鈉鹽 ) 以及水份 鈉鹽流失 觀察尿量和尿色來調控水份補充 (150%body loss) 22
(By courtesy of Susan Chung, HKSI) 23
其他注意的事項 天橋和隧道路段多暗斜, 要注意控制速度 隧道內空氣翦悶 後來者食物及飲料不足, 可自攜補充 空曠位置當風, 速度太慢者體溫可能難以維持 重要提示 : 應在日常訓練中摸索及練習適合個人的補液及營養方案, 切勿在比賽當日改變習慣 24
Guidelines International Olympic Committee Nutrition for Athletes (April 2012) based on the International Consensus Conference, Oct 2010 25
Research Group for Physical Activity & Sport Nutrition Department of Sports Science and Physical Education The Chinese University of Hong Kong Contact: 3943 6085 Email: hsswong@cuhk.edu.hk Venue: Exercise Physiology Lab, Kwok Sports Building 26
Thank You! 27
Carbohydrates IOC Consensus Conference on Nutrition in Sport, Lausanne, Switzerland, 25-27 October, 2010 Journal of Sports Science, 2011, 29: 1 During high-intensity training, particularly of long duration, athletes should aim to achieve carbohydrate intakes that meet the needs of their training programs and also adequately replace carbohydrate stores during recovery between training sessions and competitions. 28
Carbohydrate Snacks Foods supplying 50 grams CHO 500 ml juice 3 medium pieces of fruit 1 honey sandwich 2 breakfast bars 1 sports bar (check label) 1.3 bagels 1/2 cup dried fruit 1 cup white rice 1 baked potato 29
Training and Game/Race Day Training and race day diet should consist of: CHO: 55-70 % (6-10 grams per kilogram of body weight or 8-10 kcals per kilogram) Fats: 25-30% (no benefit to extra) Protein: 12-15% (1.0-1.5 grams per kilogram) of high quality protein 30
訓練 / 比賽應注意的事項 衣著及器材水份補充訓練策略高碳水化合物的早餐 / 小食 / 晚餐在陰涼的地方進行熱身 訓練期間的水份補充 ( 水樽 ) 體重控制 / 尿液的顏色注意訓練 / 比賽後有足夠的恢復 31