Acute Responses to Sprint Exercise

Question 1

What is the concentration of ATP in a single cell? (mmol/kg)

Answer 1

5 mmol/kg

Question 2

What is the rate of ATP breakdown during maximal intensity sprinting, in mmol/kg/s?

Answer 2

2.5 mmol/kg/s

Question 3

How long would maximal sprint be able to be maintained if we only had the ATP available in the muscles before the sprint?

Answer 3

2 seconds

Question 4

What are the three main energy systems for maintaining ATP levels?

Answer 4

• ATP/PCR
• Lactic/Glycolytic
• Aerobic

Question 5

What is the ‘fatigue index’ and how is it measured?

Answer 5

Anaerobic Capacity/Endurance, measured in a wingate test.

[(PPO-EPO)/PPO]*100

Question 6

What are the general features of a Type I muscle fibre?

Answer 6

• Many mitochondria
• High fatigue resistance
• High efficiency
• Fuelled mostly Aerobically
• Max velocity is very low

Question 7

What are the general features of a Type IIx muscle fibre?

Answer 7

• Few Mitochondria
• Low resistance to fatigue
• Poor efficiency
• Fuelled mostly anaerobically
• Max velocity is high

Question 8

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?

Answer 8

• PCR produces about half
• Glycolysis produces slightly less than half
• Oxidative Phosphorylation produces some but very little

Question 9

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?

Answer 9

• Glycolysis produces about half of the energy
• Oxidative system produces about a quarter of the energy
• PCR produces the rest (not much)

Question 10

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?

Answer 10

• Oxidative produces about half
• Glycolysis produces a little more than a quarter
• PCR produces the rest (not much)

Question 11

How does ATP turnover rate change over a single 30s sprint, according to Parolin et al 1999?

Answer 11

-Starts high and then decreases over time

Question 12

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

Answer 12

-Produces most of the energy in the first 6s then produces the least of the 3 for the rest of the period

Question 13

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

Answer 13

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

Question 14

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

Answer 14

Starts producing very little form 0-6s, produces more from 6-15s, then produces more than half from 15-30s

Question 15

What fuels glycolysis in a Wingate test?

Answer 15

Muscle Glycogen

Question 16

What explains the variation in contribution of glycolysis to ATP production in a single 30s sprint, according to Parolin et al 1999?

Answer 16

• 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

Question 17

Why does lactate continue to increase after cessation of a sprint?

Answer 17

Lactate is produced in the muscle and takes time to get to the blood.

Question 18

What is the general understanding of the negative implications of elevated lactate?

Answer 18

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

Question 19

What are the positive implications of lactate production?

Answer 19

NAD+ regeneration, allowing for continued glycolysis

Question 20

When NADH is high, what reaction in glycolysis will increase in rate?

Answer 20

Pyruvate to lactate

Question 21

When NAD+ is high, what reaction in glycolysis will increase in rate?

Answer 21

Pyruvate to Acetyl CoA

Question 22

When NAD+ and Lactate is high, what reaction in glycolysis will increase in rate?

Answer 22

Lactate to Pyruvate

Question 23

What critique does Robergs et al 2004 put forward about the validity of the theory of ‘Lactic Acidosis’?

Answer 23

Lactate production TAKES UP hydrogen ions so prevents acidosis

Question 24

Name a source on either side of the argument that metabolic acidosis does or does not cause muscle fatigue

Answer 24

Does: Fitts, 2016

Does not: Westerblad et al., 2002

Question 25

How long does it take to recover PCr fully after a sprint accoridng to Bogdanis et al 1995?

Answer 25

about 6 minutes

Question 26

What are the two potential limiting factors of power output in repeated sprints?

Answer 26

• pH

- PCr regeneration

Question 27

What support exists for PCr being the limiting factor for peak power in repeated sprints?

Answer 27

The Peak Power output against time after sprinting graph is the same shape as the PCr regeneration against time after sprinting graph

Question 28

How does the energy system contribution to repeated sprints in the first 6 seconds compare to single sprints?

Answer 28

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

Question 29

Explain the changes in energy system contribution to the first 6 seconds of a repeated sprint compared to a single sprint

Answer 29

• 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