(2) ENERGY PRODUCTION IN EXERCISEKUORMITUKSESSA
1.Immediate energy stores 2.Anaerobic glykolysis 3.Aerobic energy production
= Hi-energy phosphates adenocine-triphosphate (ATP) and creatinephosphate (CP) –stores IMMEDIATE ENERGY STORES ATP:storage in cells g (in muscles about 50%, enough for max. work of 2-3 s ) CP (PCr): stores 4-6 x that of ATP- stores (sufficient for maximal work for 10 s ) -reactions dont reguire oxygen
ATP and CP-stores in exercise
Recovery of hi-energy phosphates is very quick!
Creatine loading (creatiinimonohydrate, CrH 2 O) has been shown to enhance performance in short maximal bouts, adds also body weight
1. Under 30 s ATP ja KP 2. 30s – 1½ min ATP, CP ja anaero- bic glykolysis 3. 1½-3 min Anaer. ja aer. glykol. 4. Over 3 min Aerobic energy production Maximal bouts of action:
ANAEROBIC GLYCOLYSIS Glucose/glycogen pyruvic acid lactic acid - no oxygen needed (anaerobic) - 10 steps - occurs in watery medium of cell - only 2/3 molecules of ATP is formed/glucose/glycogen molecule,also hydrogen is produced to electron transfer chain - activity of glycolysis depends on the amount/activity of regulatory enzymes, amount of oxygen and availability of glucose -end-product is pyruvic acid which is sent to aerobic process Krebs cycle -some of the pyruvic acid is turned into lactic acid
2 ATP:tä kuluu - FT-cells contain more PCK (most important regulatory enzyme) - breakdown of muscle glycogen more economical (net result 3 ATP molecules) Glucose from blood into cell In very heavy work all 6 hydrogen ions cannot be transformed with oxygen in electron transfer chain - acidosis
-Lactic acid is split into lactate and hydrogen ions -Lactate is moved into bloodstream - even at rest there is some lactate in blood (red blood cells and FT-cells) - used in energy production in muscles,especially heart - gluconeogenesis (Cori cycle in liver) transforms lactate into glucose when enough oxygen is available in less powerful work
Cori cycle
On the other hand: - lactate is produced in muscles even when there is no lack of oxygen - lactate is also produced in liver,skin and heart - lactate is the most important energy source of heart in heavy work
- use of immediate energy sources and anaerobic glycolysis are parallel energy sources -lactate starts to accumulate in working muscles before hi-energy phosphates are fully used
- transfer of lactate from blood is fastest at work rates of % VO 2 max in cycle ergometer work - on treadmill power should be % VO 2 max
- muscular exhaustion is not equal to amount of lactate in muscle - Lactate accumulation and lowering of muscle pH both play a role in muscular exhaustion - diminishing muscle glycogen stores and hi-energy phosphates are also important factors in exhaustion - other apparent reasons are at central nervous system level and in neuromuscular junctions
Minutes