Nutrition for Physical Activity & Sport Readings: Chapter 14 Omit “Muscles & Muscle Fibers”, p. 559

What is Physical Fitness? Definition the ability to perform moderate to vigorous levels of physical activity without undue fatigue and the capability of maintaining this level of activity throughout life (ACSM) Components: Cardiorespiratory Fitness Muscular Strength Muscular Endurance Flexibility

Physical Activity vs. Exercise any body movement carried out by skeletal muscles and requiring energy Exercise a subset of physical activity that is planned, structured, repetitive movement of the body designed to improve or maintain physical fitness

Benefits of Regular Physical Activity Exercise is one of the most important things you can do to improve your wellness! sedentary individuals have 50% more health problems that active individuals including increased risk of: hypertension diabetes obesity hyperlipidemia osteoporosis

Benefits of Physical Fitness improved sleep nutritional health healthy body composition healthy bone mineral density improved immune function reduced risk of CVD, Type II diabetes, some cancers reduced stress and anxiety improved self-esteem and lowered risk of depression improved cognitive functioning, alertness and memory injury reduction and low back pain greater longevity and quality of life

* Recommendations from the WHO & the Institute of Medicine Becoming more active… How much is needed to reap health benefits? 60 minutes of moderately intense physical activity every day* Is Lifestyle Physical Activity enough? increased lifestyle physical activity promotes improved health and well-being but does not necessarily improve physical fitness exercise programs designed to improve physical fitness contribute to even greater improvements in quality of life and greater reductions in disease and mortality risk * Recommendations from the WHO & the Institute of Medicine

Canada’s Guide for Healthy Active Living

Reduce sitting for long periods Increase Endurance Activities days a week Continuous activities for your heart, lungs, and circulatory system. 4 - 7 Reduce sitting for long periods days a week Gentle reaching, bending, and stretching activities to keep your muscles relaxed and joints mobile 4 - 7 Increase Flexibility Activities days a week Activities against resistance to strengthen muscles and bones and improve posture 2 - 4 Increase Strength Activities http://www.phac-aspc.gc.ca/pau-uap/fitness/pdf/guideEng.pdf

Sources of Energy for Physical Activity physical activity increases the energy needs of working tissues including the muscles and the heart…where does this energy come from? ATP & CP Carbohydrate: Glucose/Glycogen Fat Protein

1. ATP & CP very small pool of ATP available in cells CP (creatine phosphate) can release phosphate which combines with ADP to form ATP supplies are limited, fuels activity for 3 - 15 seconds of maximal effort anaerobic exercise creatine phosphate + ADP creatine + ATP rest

ATP-CP Energy System

2. Carbohydrate: Glucose derived from muscle & liver glycogen stores fuels activities of extreme intensity (20 s to 3 minutes): oxygen needs of muscle exceed the ability of cardiovascular system to supply oxygen glucose is used anaerobically (without oxygen) to produce ATP by-product is lactate

Anaerobic Metabolism of Glucose

2. Carbohydrate: Glucose in activities of high intensity (3 to 20 minutes): glucose is used AEROBICALLY (with oxygen) to produce ATP in activities of moderate intensity (> 20 minutes): glucose oxidation is supplemented with fatty acid oxidation

3. Fat Metabolism initially during exercise blood [fatty acid] decreases after 20 minutes there is an increase in release of fatty acids from stores due to hormone epinephrine (adrenalin) endurance training produces adaptations that enhance the ability to burn fat ’d size & number of mitochondria in muscles ’d number of capillaries to supply oxygen & nutrients to muscles

increase use of protein as a fuel decrease use of protein as a fuel not a primary fuel for physical activity contributes about 5 - 10% to energy expenditure both during activity and at rest Factors that influence protein use during activity: high dietary protein increased duration of activity increased intensity of activity increased training (especially strength training) increase use of protein as a fuel decrease use of protein as a fuel

Effect of Intensity & Duration on Fuel Use

Effect of Intensity & Duration on Fuel Use increased duration, decreased intensity fatty acid oxidation glucose utilization decreased duration, increased intensity fatty acid oxidation glucose utilization

Summary…

Summary… Duration Intensity Preferred Fuel Source 8 – 10 seconds EXTREME 20 sec – 3 min VERY HIGH 3 – 20 minutes HIGH > 20 minutes MODERATE ATP - CP anaerobic glycolysis aerobic glycolysis fatty acid oxidation Note: all energy sources are used to some extent at all times

Effect of Diet on Physical Endurance Maximum Endurance Time fat and protein diet normal mixed diet high carbohydrate diet 57 min 114 min 167 min

Diet to Support Physical Activity Water nutrient required in largest amounts by the body needs increase during physical activity Body can lose water in four ways: urine feces sweat respiration * * * Loss increases during physical activity

Water & Temperature Regulation heat production increases 15-20x during exercise compared to rest body cools itself by sweating 1 L of sweat dissipates about 600 kcal of heat prevents an  in body temperature of about 10°C EVAPORATION of sweat cools the body blood is rerouted through capillary beds that lie just beneath surface of skin to cool the blood endurance athletes can lose 1.5 L of water or more during each hour of activity

Lance Armstrong said blistering temperatures and not drinking enough fluids gave him a challenging day in the saddle during the 2003 Tour de France's 12th-stage time trial, won by German rival Jan Ullrich. "Maybe it was too hot for me. I suffered," said Armstrong. "There was a moment where I felt like I was going backwards. I felt thirsty throughout the stage, and it was the thirstiest I've ever felt in a time trial. In the second half of the course there was a moment when I knew I had a problem. I'd run out of water and, well, maybe I didn't drink enough before the stage. " He lost about 6 kilograms of fluid weight between morning and the end of the stage-12 time trial, and also lost 1:36 to Jan Ullrich during that same time period. Losing 2 percent of your body weight due to dehydration leads to a 10-15 percent drop in performance, and Lance lost 8 percent of his body weight.

Water & Temperature Regulation in hot humid weather, need for water ’s even more dehydration not only decreases performance but can cause dizziness, cardiac arrhythmias, muscle spasms, delirium, and death Hydration Schedule 2 hrs before 400 – 600 ml 15 min before 250 – 500 ml every 15-20 min during 150 - 350 ml after exercise 500 ml for each lb body weight lost, or 1.5x body weight lost

Water & Temperature Regulation Too much water? leads to a condition called HYPONATREMIA symptoms include swelling, weight gain, nausea, and dizziness may occur in events where individuals replace more water than they lose and do not replace electrolytes causing dilution of sodium in the blood

Electrolytes in addition to contributing to water loss, sweat also results in loss of electrolytes electrically charged minerals Na+, K+, Cl-, and Mg2+ minerals are important for water balance losses normally replaced through diet for exercises lasting longer than 1 hour, replacement of fluids with water & electrolytes may provide a performance advantage more important for athletes in competitions lasting 4+ hours with heavy sweating

Replenishing Energy DURING activity… during endurance activities lasting longer than one hour, glycogen supplies risk depletion maintaining blood glucose levels can prolong time to exhaustion glucose replacement (200 kcal) useful in activities lasting longer than 1 hour sports drinks with 6 - 10% carbohydrates (50 - 100 kcal per cup) depends on goal of exercise!

Replenishing Energy AFTER activity… a high carbohydrate meal eaten within 15 minutes accelerates rate of glycogen storage by 300%, called “glycogen window” Are energy bars or drinks necessary?

Glycogen Depletion and Fatigue Sensation

Protein in the Athlete’s Diet athletes have increased need for protein due to need to repair and build muscles after activity (max 2.0 g/kg body weight) see Table 13.4 for recommended intakes protein intake after exercise helps replenish glycogen stores Too much protein? Risks of Supplements: dehydration displacement of carbohydrates from diet, insufficient replenishment of glycogen stores kidney problems

Fat Intake and the Athlete Fat intake should not be overly restricted. There is no performance benefit in consuming a diet with less than 15 percent of energy from fat. Extreme fat restriction limits food choices, especially sources of protein, iron, zinc, and essential fatty acids. Sports nutritionists recommend that any extra fat calories come from monounsaturated and polyunsaturated sources.

Vitamins and Minerals many vitamins and minerals are important for energy metabolism deficiencies impair performance extra from supplements DO NOT enhance physical performance Iron physically active young women prone to iron deficiency multiple contributing factors supplementation should be based on blood tests, not self-assessment