Lactate product + peripheral fatigue Flashcards
List all 3 energy systems
ATP-PC: breakdown of phosphocreatine
Glycolysis: breakdown of glucose or glycogen: Anaerobic
Oxidative formation: using carbohydrate, fat and protein: aerobic
how is glucose transported to the cells
passed into the cell membrane using the GLUT 4 transporter
occurs in the presence of insulin
once insulin is accepted by its own receptor
signals GLUT 4 to move to the cell membrane to allow passage of glucose into the cell
what are the 3 main steps in glycolysis
Phosphorylation: 2 phosphates released from the 2 ATP molecules, attached to glucose=hexose bisphosphate
Lysis: destabilases, 2 x triose phosphate
Phosphorylation: another phosphate group is added= 2 x triose BIphosphate, phosphate comes from free inorganic phosphate present in the cytoplasm
Dehydrogenation and formation of ATP: oxidised by the removal of hydrogen atoms to form 2 x pyruvate. NAD coenzymes accept the removed hydrogens
2x ATP
2 X reduced NAD
What happens when their is insufficient o2 available
pyruvate act as a hydrogen acceptor taking the hydrogen from reduced NAD catalysed by enzyme lactate dehydrogenase
pyruvate converted to lactate and NAD is regenerated
Explain how accumulation of hydrogen ions during high intensity exercise causes peripheral fatigue
hydrogen ions are produced when lactate accumulates during glycolysis, accumulation of hydrogen ions reduces the pH of the muscle, muscle becomes increasingly acidic known as acidosis.
Acidosis interferes with enzymatic activity within the muscle. Reduces the calcium release from the sarcoplasmic reticulum which limits cross- bridge cycling and ultimately force production
what are the benefits of lactate
allows the production of NAD + used for ATP production
required to start the gluconeogenesis energy pathway
can be a major fuel source
Define OBLA: onset blood lactate accumulation
first blood lactate increase above resting values
above 0.5-1 mmol/l
Define MLSS: maximum lactate accumulation
highetst blood lactate concentration and work load that can b maintained without continual blood lactate accumulation
found at 60-80% VO2 max
List the path an action potential takes
Brain command
Spinal Cord
Peripheral Nerve
Neuromuscular Junction
Exciation-Contraction Coupling
Muscle Contraction
Define peripheral fatigue
reduction in force generating capacity induced by skeletal muscle work. Occurring at or below NM junction.
Fatigue caused by changes to the chemical/ metabolic environment within a muscle
what areas are influenced by peripheral fatigue
Reduction of synapse across NM to the muscle fiber
Reduction of excitation across muscle membrane
Impaired cross-bridge cycling within the sarcomere
what factors determine the influence of fatigue
Exercise intensity, type, age, buffering capacity
how does increase of inorganic phosphate affect force production
Resting Pi = 5mm
accumulation of Pi entering sarcoplasmic reticulum increases, Pi binds with calcium in the SR, reduction of calcium during cross bridge cycling
reduction in actin binding site availability
how does hydrogen ions affect force production
reduces muscle pH, Interferes with enzymatic activity, acidosis, affects calcium release from SR
how does potassium cause fatigue
The decreases in intracellular K+, and increases in interstitial K+ contribute to fatigue by decreasing the sarcolemma ( cell membrane) potential
Therefore, smaller action potentials travel along the T-tubules
Leading to reduced force capacity
