Energy Production conversion of chemical energy to mechanical energy stored in the form of ATP breakdown of ATP releases energy and produces heat –used by muscle sliding of myosin and actin –transport of molecules glucose, Ca++ and other ions across cell membranes for repair conduction of nervous system

rest –ATP synthesis and breakdown remain steady stored ATP only lasts a few seconds during contraction maximal exercise –ATP breakdown is 200 times faster than rest insufficient ATP to meet demand causes fatigue

Protein very little used for energy (<5%) proteins > AA some AA to glucose (gluconeogenesis), pyruvic acid or acetyl CoA –used in oxidative process nitrogen forms other AA –excess to urea uses energy

CHO (C 6 H 12 O 6 ) faster energy - short duration –stored as liver glycogen and muscle glycogen –blood glucose immediate energy 38 ATP (70% of energy for ATP, 30% lost as heat ) –muscle glycogen depleted 20-30% with short, high- intensity bout of exercise depletion rate of 18.8 umol/g per minute ? glycogen availability causes fatigue –moderate intensity exercise of 56 minutes depletion rate of 1.1 umol/g per minute prolonged exercise results in greatest depletion of muscle glycogen –glycogen concentration fell 50-60%

Fats triglycerides, phospholipids and cholesterol triglycerides – used for energy (69% for energy, 31% lost as heat) –stored in muscle and adipose tissue –1 glycerol and 3 FFA (lypolisis) –FFA in blood enter fibers by diffusion rate of entry regulated by it’s own concentration gradient increased FFA in blood drives FFA into muscle

Metabolic Pathways aerobic (oxidative phosphorylation) anaerobic alactic (ATP-PCr) anaerobic lactic (anaerobic glycolytic) all active at all times –% contribution varies with exercise intensity and duration –anaerobic used for high intensity, short duration exercise –aerobic used for low to moderate, longer duration exercise condition to most important pathway –“sport specific”

ATP-PCr start-up system simplest pathway, readily available energy phosphocreatine (PCr) rebuilds ATP –not used for direct cellular work creatine kinase releases Pi from PCr, binds to ADP O 2 not needed sprint for sec, majority of energy from PCr –> 20 sec, very little contribution to energy supply rapid depletion of PCr and ATP no toxic waste product replenish supply of PCr in 3 min at rest barrels, roping, ect.

Anaerobic Glycolytic ATP produced from breakdown of glucose via special enzymes; lactate dehydrogenase (LDH) no O 2 needed lactate produced duration of energy supply sec glucose - 99% of all sugars in blood –digestion of CHO –breakdown of liver glycogen glycogen  glucose-1-phosphate (glycogenolysis) breakdown of G-6-P to pyruvate (glycolysis)

Glycolysis early use with high intensity exercise –ATP-PCr system does not produce large amounts of ATP glycogen (anaerobic pathway) –3 ATP + 2 NADH = 9 ATP glucose (anaerobic pathway) –2 ATP + 2 NADH = 8 ATP glycogen produces pyruvate, O 2 determines fate of pyruvate –O 2 to Kreb’s cycle –no O 2, lactic acid

Oxidative Pathway most complex pathway disassembles fuels with O 2 O 2 production of ATP in mitochondria –next to myofibrils and in sarcoplasm high energy yield slow production of energy –oxidative production of ATP requires 3 processes glycolysis Kreb’s cycle electron transport chain

glycolysis  pyruvate –pyruvate + O 2  acetyl CoA Kreb’s cycle (per pyruvate:1/2 glucose) –complete oxidation of acetyl CoA –2 ATP + 1 FADH NADH –C + O 2  CO 2 expired electron transport chain –glycolysis produces H+ (too acidic) FADH 2 and NADH transport H+ to electron transport chain H+ split into protons and electrons phosphorylation produces ATP H+ + O 2  H 2 O expelled

Energy Stores

Lactic Acid lactate –lactic acid combined with Na+ or K+ to form salt regulated by feedback system –accumulation of lactate in muscle inhibits further glycogen breakdown acidity decreases pH of muscle and Cal-binding capacity slows reactions for energy production resulting in fatigue lactate concentration in muscle –production level –rate of removed from muscle by blood detoxified in liver –amount used as energy by aerobic metabolism

recovery at rest - 3 hours light exercise aids in removal of lactate additional increase in blood lactate concentration at end of work bout –> 5 min removal rate exceeds release from muscle –decreased blood lactate concentration measure of fitness –decrease level of lactate following conditioning for same work load