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. Hemoglobin concentration Biomechanics Gas exchange ATHLETIC ABILITY Anaerobic capacity Heart size Skeletal muscle properties 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 – CO2, H2O & ATP • Anaerobic – Without oxygen – Carbohydrate (glycolysis) – Lactate & ATP Synthesis of ATP from aerobic and anaerobic metabolism. Muscle Glycogen Blood Glucose Creatine Phosphate Anaerobic Glycolysis Lactate ATP Myokinase and CPK Reactions Lipolysis Free-Fatty Acids Pyruvate Oxidative Metabolism Oxygen CO2and Water 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 Event Preformed Energy Anaerobic Aerobic Racing QH 80% 18% 2% Racing 1000 m 25% 70% 5% Racing 1600 m 10% 80% 10% Racing 2400 m 5% 70% 25% Racing 3200 m 5% 55% 40% Polo 5% 50% 45% Estimated Types Of Energy Used Event Preformed Energy Anaerobic Aerobic Barrel Racing 99% 4% 1% Cutting 88% 10% 2% Show Jumping 15% 65% 20% 3 Day (Cross Country) 10% 40% 50% Endurance Rides 1% 5% 94% Pleasure/Equitati on 1% 2% 97% Cardiovascular System • Delivers blood to body – O2 from lungs – Nutrients from GI tract Cardiovascular System • Heart rate (HR) – Resting 30-45 – 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 - 8-20 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 LocomotorRespiratory 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 • Thoroughbred (race) – 2.5 gal • Endurance horse (50100 miles) – 6-12 gal • Three day event (dressage/cross country) – 5-6 gal • Importance – Evaporative Cooling (Sweating) – Most important route of heat dissipation – Requires ample blood flow to carry heat from core to surface 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 Fit 25 20 15 10 5 Unfit 0 Muscles Ligaments Bones 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