Acute Responses to Sprint Exercise Flashcards
What is the concentration of ATP in a single cell? (mmol/kg)
5 mmol/kg
What is the rate of ATP breakdown during maximal intensity sprinting, in mmol/kg/s?
2.5 mmol/kg/s
How long would maximal sprint be able to be maintained if we only had the ATP available in the muscles before the sprint?
2 seconds
What are the three main energy systems for maintaining ATP levels?
- ATP/PCR
- Lactic/Glycolytic
- Aerobic
What is the ‘fatigue index’ and how is it measured?
Anaerobic Capacity/Endurance, measured in a wingate test.
[(PPO-EPO)/PPO]*100
What are the general features of a Type I muscle fibre?
- Many mitochondria
- High fatigue resistance
- High efficiency
- Fuelled mostly Aerobically
- Max velocity is very low
What are the general features of a Type IIx muscle fibre?
- Few Mitochondria
- Low resistance to fatigue
- Poor efficiency
- Fuelled mostly anaerobically
- Max velocity is high
In order from highest to lowest, how much ATP is produced by the three energy systems in the first 6s of a sprint according to Parolin et al. 1999?
- PCR produces about half
- Glycolysis produces slightly less than half
- Oxidative Phosphorylation produces some but very little
In order from highest to lowest, according to Parolin et al 1999, how much ATP is produced by the three energy systems from 6 to 15s of a sprint?
- Glycolysis produces about half of the energy
- Oxidative system produces about a quarter of the energy
- PCR produces the rest (not much)
In order from highest to lowest, according to Parolin et al 1999, how much ATP is produced by the three energy systems from 15 to 30s of a sprint?
- Oxidative produces about half
- Glycolysis produces a little more than a quarter
- PCR produces the rest (not much)
How does ATP turnover rate change over a single 30s sprint, according to Parolin et al 1999?
-Starts high and then decreases over time
Describe the general fluctuations of contribution of the PCR system to the ATP production of a single 30s sprint according to Parolin et al 1999
-Produces most of the energy in the first 6s then produces the least of the 3 for the rest of the period
Describe the general fluctuations of contribution of the glycolytic system to the ATP production in a single 30s sprint according to Parolin et al 1999
Produces slightly less than half in the first 6s, then produces most of the energy from 6-15s, then produces about a quarter from 15-30s
Describe the general fluctuations of contribution of the aerobic/oxidative system to the ATP production in a single 30s sprint according to Parolin et al 1999
Starts producing very little form 0-6s, produces more from 6-15s, then produces more than half from 15-30s
What fuels glycolysis in a Wingate test?
Muscle Glycogen
What explains the variation in contribution of glycolysis to ATP production in a single 30s sprint, according to Parolin et al 1999?
- Glycolysis is dependent on glycogenolysis for fuel.
- Maximal glycogenolysis is dependent on the activation of Glycogen Phosphorylase
- Glyc Phosphorylase rapidly increases in activation in the first 5 seconds, stays high until 15s then steadily decreases
Why does lactate continue to increase after cessation of a sprint?
Lactate is produced in the muscle and takes time to get to the blood.
What is the general understanding of the negative implications of elevated lactate?
Production of lactate from glycogen produces hydrogen ions, which drops muscle and blood pH, so:
- Inhibits phosphofructokinase, inhibiting glycolysis
- Interferes with muscle contraction as excessive hydrogen ions interfere with crossbridge formation
What are the positive implications of lactate production?
NAD+ regeneration, allowing for continued glycolysis
When NADH is high, what reaction in glycolysis will increase in rate?
Pyruvate to lactate
When NAD+ is high, what reaction in glycolysis will increase in rate?
Pyruvate to Acetyl CoA
When NAD+ and Lactate is high, what reaction in glycolysis will increase in rate?
Lactate to Pyruvate
What critique does Robergs et al 2004 put forward about the validity of the theory of ‘Lactic Acidosis’?
Lactate production TAKES UP hydrogen ions so prevents acidosis
Name a source on either side of the argument that metabolic acidosis does or does not cause muscle fatigue
Does: Fitts, 2016
Does not: Westerblad et al., 2002
How long does it take to recover PCr fully after a sprint accoridng to Bogdanis et al 1995?
about 6 minutes
What are the two potential limiting factors of power output in repeated sprints?
- pH
- PCr regeneration
What support exists for PCr being the limiting factor for peak power in repeated sprints?
The Peak Power output against time after sprinting graph is the same shape as the PCr regeneration against time after sprinting graph
How does the energy system contribution to repeated sprints in the first 6 seconds compare to single sprints?
in third sprint:
- Total energy is lower
- PCR is about the same absolute value but higher proportion of total energy
- Glycolysis is much smaller
- Oxidative phosphorylation is higher
Explain the changes in energy system contribution to the first 6 seconds of a repeated sprint compared to a single sprint
- Glycolysis decreased due to depleted glycogen and back-up of waste products
- Oxidative increased due to higher activation of ‘PDH’ enzyme due to total time of exercise
