Exercise Physiology Driving force behind all types of work Conversion of stored energy to mechanical energy

What Influences Athletic Ability? Genetics Training Training methodology Environment Nutrition Track/Arena Surfaces Shoes Jockey Etc.

ATHLETIC ABILITY Heart size Skeletal muscle properties Anaerobic capacity Gas exchange Hemoglobin concentration Biomechanics

ENERGY Sources –Carbohydrates –Fats Effect on performance –↓ energy = ↓ performance –Must meet energy requirement –Monitor body condition ↓ body condition = negative energy balance

Energy Metabolism Aerobic –With oxygen –Carbohydrate & fat –CO 2, H 2 O & ATP Anaerobic –Without oxygen –Carbohydrate (glycolysis) –Lactate & ATP

Muscle Glycogen Blood Glucose Anaerobic Glycolysis Oxidative Metabolism Pyruvate Lactate ATP Free-Fatty Acids Creatine Phosphate Myokinase and CPK Reactions CO 2 and Water Lipolysis Oxygen Synthesis of ATP from aerobic and anaerobic metabolism.

Muscular System

Types of Muscle Fiber Type I – Slow contracting – ↓ glycolytic activity – Fatigue resistant – Aerobic metabolism – Long term/low stress work – Endurance Type II – Fast contracting – Fatigue quickly – ↑ Glycolytic activity – Quick energy bursts – Speed for longer distances – Primarily anaerobic

Breed Differences Type I fibers Type II fibers

Energy For Muscle Contraction Walking –Slow contractions –Primarily type I fibers –Fat primary energy source (very efficient)

Energy For Muscle Contraction Trot and Canter –Increased contractions Increased contractions require more ATP Type II fibers Fat cannot be metabolized anaerobically

Anaerobic Glycolysis Fastest way to produce ATP Less efficient than aerobic glycolysis –Less ATP –Lactic acid produced –Decrease muscle pH –Fatigue/tying up

Horses that can generate a higher proportion of energy aerobically will outperform horses with lower aerobic capacity

Estimated Types Of Energy Used EventPreformed Energy AnaerobicAerobic Racing QH80%18%2% Racing 1000 m25%70%5% Racing 1600 m10%80%10% Racing 2400 m5%70%25% Racing 3200 m5%55%40% Polo5%50%45%

Estimated Types Of Energy Used EventPreformed Energy AnaerobicAerobic Barrel Racing99%4%1% Cutting88%10%2% Show Jumping15%65%20% 3 Day (Cross Country) 10%40%50% Endurance Rides1%5%94% Pleasure/Equitati on 1%2%97%

Cardiovascular System Delivers blood to body –O 2 from lungs –Nutrients from GI tract

Cardiovascular System Heart rate (HR) –Resting –Exercising – 240 bpm max Stroke Volume (SV) –Volume of blood pumped per beat –800 – 900 mls HR X SV = Cardiac Output –Can pump > 250 li/min –Equivalent to 55 gal drum

Affect of Exercise On The Cardiovascular System ↑ metabolic activity in limbs = ↑ blood flow Three ways to increase blood flow –Increase cardiac output HR and CO proportional to running speed Cannot ↑ HR beyond max –Increase O2 carried in blood Splenic dumping can double O2 carrying capacity –Redistribute blood flow ↑ to locomotive muscle ↓ to kidneys and small intestines

Respiratory System Respiratory Rate –Resting breaths per min Exercise –↑ O2 consumption –↑ CO2 emission To increase air exchange –↑ Respiratory rate RR linked to stride freq. ↑ Tidal Volume (TV) –Air inhaled or exhaled in a breath

Locomotor- Respiratory Coupling (LRC) Galloping Horse –150 Breaths –12-15 liters of air Trotting Horse –70-85 Breaths –20-25 liters of air

Respiratory Problems Laryngeal hemiplegia –Partial paralysis of larynx –Inadequate gas exchange –Surgical treatment Chronic Obstructive Pulmonary Disease –Decreases respiratory rate –Hyperallerginc response to dust, mold, irritants –House outdoors Exercise Induced Pulmonary Hemorrhage –Bleeding in lungs –Speeds above 14 m/s –Variable effects –Furosemide (Lasix)

Thermoregulation Importance –Evaporative Cooling (Sweating) –Most important route of heat dissipation –Requires ample blood flow to carry heat from core to surface Thoroughbred (race) –2.5 gal Endurance horse ( miles) –6-12 gal Three day event (dressage/cross country) –5-6 gal

Thermoregulation ↑ Exercise intensity > ↑ heat load > ↑ need for heat dissipation Prevent dehydration to prevent thermal injury –Provision of adequate water –Normal diet –Salt & mineral supplement

Thermoregulation Dehydration –Electrolyte & pH disturbances –Fatigue –Gait incoordination (ataxia) –↑ risk of orthopedic injury –Muscle damage –Death Supplement electrolytes –Beginning training program –Adjusting to high temperature

Types of Training Endurance –Enhances aerobic system High intensity/Quick burst –Increases muscle mass –Strength training

Influence of Training ↑ heart size ↓ HR at given speed Quicker recovery to given heart rate ↑ Capillaries –↑ O2 delivered to muscles Increase aerobic capacity

Influence of Training ↑ Muscle Cell Mitochondria –↑ O2 utilization per unit of muscle Muscle has quickest adaptation to training of all body tissues

Conditioning Times of Body Structures Months Unfit Fit

Signs of Fatigue Respiration rate > heart rate –Inversion –Hyperventilating –Shallow breathing –Shock Muscle soreness (lactic acid buildup) Ataxia Deydration

Conditioning is A Process That Occurs Over Time