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.
ATHLETICABILITY
Heart sizeSkeletal muscle
properties
Anaerobic capacity
Gas exchange
Hemoglobinconcentration
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– CO2, H2O & ATP
• Anaerobic– Without oxygen– Carbohydrate
(glycolysis)– Lactate & ATP
Muscle GlycogenBlood Glucose
Anaerobic Glycolysis
OxidativeMetabolism
Pyruvate Lactate
ATP
Free-Fatty Acids
CreatinePhosphate
Myokinaseand CPKReactions
CO2and 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
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/Equitation
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
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 (50-100 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
0
5
10
15
20
25
Muscles Ligaments Bones
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