Energy Systems

Energy Systems for Exercise

Energy Systems Immediate energy  ATP-PC Short-term energy  Lactic acid system Long-term energy  Aerobic system

ATP-PCr System ultra-short duration (< 6 seconds) high intensity require an immediate and rapid supply of energy  100-m sprint  25-m swim  Smashing a tennis serve  Thrusting a heavy weight upwards

Lactic Acid System During performances of short duration and high intensity that require rapid energy transfer that exceeds that supplied by phosphagens  400-m sprint  100-m swim  Multi-sprint sports Anything up to 3 minutes Lactate is the by product “Lactic acid system’

Lactate Shuttling Pyruvate  Acetyl CoA Citric acid cycle Oxidation = removal + energy

Lactic Acid System Blood lactate removal  Gluconeogenesis- conversion to glucose through Cori cycle in the liver  Oxidation to pyruvate Fuels citric acid cycle

Lactate Threshold The exercise intensity prior to the abrupt increase in blood lactate  A.k.a onset of blood lactate accumulation (OBLA)

Lactate / Lactic Acid Terms: LACTATE AND LACTIC ACID Lactate production and accumulation in muscle coincides with, rather than causing acidosis DOMS incorrectly attributed to lactate build- up Caused by damage to muscles  not the pain from damaged muscle cells, but from the reinforcement process- adding new sarcomeres (the segments in the muscle fibrils) sarcomeres  reinforcement process causes the cells to swell and put pressure on nerves and arteries, causing DOMS.

Aerobic Energy System Duration > 2/3 minutes Lipids  Lipolysis  Beta oxidation  Kreb’s cycle Carbs  Glycolysis  Pyruvate  Acetyl CoA  Krebs cycle (citric acid cycle or tricarboxylic acid cycle)  Electron transport chain

Energy requirements at rest Almost 100% energy comes from aerobic metabolism Therefore blood lactate levels are steady and low (<1.0 millimoles p/L) 7- kg young adult consumes 0.25 L O2 p/min

Transition to Exercise O2 consumption

Recovery O2 consumption remains elevated O2 Dept = payment for O2 deficit

Vo2 Max Determines cardiovascular fitness O2 uptake increases with intensity of exercise up until a certain point ml/kg/minute Factors influencing:  Delivery  uptake

Muscle Fibre Types Type 1 = Slow twitch  Generates energy aerobically  For endurance exercise Type 2 = fast twitch 2a- some aerobic power = anaerobic 2b-predominantly anaerobic  Generates energy anaerobically  For short intense exercise

Implications

Recovery from exercise Remove lactate Re-oxygenation muscle myoglobin Replace  Muscle glycogen  PCr  Lipid levels

Active recovery Movement at a lower intensity/ submax performed immediately after exercise Assists with oxidation of lactate (Lactate shuttling) But may impair glycogen synthesis

Passive recovery Lie down  complete inactivity Theory is that this ‘frees’ oxygen for the recovery process

Which is best? Research inconclusive Depends on exercise to recover from Steady rate exercise  PCr stores not depleted  Lactate levels not increased  Depends on post exercise glucose intake Intense/Non-Steady rate exercise  Large O2 deficit

Lactate Removal ExerciseRecovery Passive Active Passive

Training the Energy Systems

Training the ATP-PC system 4 to 7 seconds of high intensity work at near peak velocity are required e.g.  3 × 10 × 30 metres with recovery of 30 seconds/repetition and 5 minutes/set.  15 × 60 metres with 60 seconds recovery  20 × 20 metres shuttle runs with 45 seconds recovery

Training the anaerobic lactate system 5 to 8 × 300 metres fast - 45 seconds recovery - until pace significantly slows 150 metre intervals at 400 metre pace - 20 seconds recovery - until pace significantly slows 8 × 300 metres - 3 minutes recovery (lactate recovery training)

Training aerobic systems 4 to 6 × 2 to 5 minute runs - 2 to 5 minutes recovery 20 × 200m - 30 seconds recovery 10 × 400m - 60 to 90 seconds recovery 5 to 10 kilometre runs

Chronic Adaptations to Training

Summary Immediate energy  ATP-PC Short-term energy  Lactic acid system Long-term energy  Aerobic system Dynamic balance Training Recovery