Lecture 5 Flashcards
Development of the Anaerobic System (22 cards)
What is the anaerobic system?
Linked with high-intensity exercise
Supplies energy not covered by aerobic system
Produces fatigue-inducing by-products, mainly hydrogen ions
Why does anaerobic metabolism occur at exercise start?
Anaerobic metabolism happens at exercise start because oxygen delivery is slow, so it provides quick energy until the aerobic system catches up.
A better aerobic system reduces this delay.
Repeated-sprints – energy system contributions
High anaerobic contribution early
Recovery driven by aerobic system
ATP & glycolysis decline; PCr stays stable
PC system (phosphocreatine) – how it works
PC + ADP → ATP + C (via creatine kinase)
PC is 3x more abundant than ATP
Rapid ATP resynthesis; doesn’t require O₂
Energy for first ~5 sec of maximal effort
Limitations of PC system
Energy from phosphocreatine (PC) lasts about 2–5 seconds
Creatine kinase (CK) controls the speed of this process
High ATP levels slow down CK activity (inhibition)
Creatine supplements might increase PC stores, but results are mixed
Glycolysis (lactic acid system)
Glycogenolysis = glycogen → G1P
Glycolysis = G1P → pyruvate/lactate
Doesn’t require O₂
Produces lactate and H⁺ ions
ATP production from glycolysis
Peaks ~3 sec into exercise
Slower than PC, faster than aerobic
Rate-limiting enzyme: PFK
Activated by: AMP, ADP, Pi, NH₄⁺, ↑pH
Inhibited by: ATP, PC, citrate, ↓pH
Interaction of PC and glycolysis
PC declines within 2 sec
Glycolysis peaks 3–5 sec, declines after 20 sec
PC buffers ATP drop until glycolysis kicks in
Fuel use in anaerobic work
High intensity = more carbohydrates used
Short, hard efforts mainly use muscle glycogen
Mechanisms of fatigue in anaerobic work
Reduced substrate (mainly PC)
↑ metabolic by-products (H⁺, Pi, lactate)
Inhibition of glycolysis, cross-bridge cycling
CNS fatigue from H⁺ pain signals
What is anaerobic training?
Intense, short-duration exercise near/at/max intensity
↓ PC concentration, ↑ lactate, ↓ pH
Aims to increase power output and tolerance
Adaptations to anaerobic training
↑ anaerobic enzymes (CK, PFK)
↑ muscle buffer capacity
↑ pH regulation transporters (NHE1, MCT1/4)
↑ Na⁺/K⁺ pump expression = preserves excitability & force
Key to anaerobic training structure
Shorter duration, longer recovery
Must empty then refill anaerobic systems
Best done with interval training
Why HR is less useful in anaerobic training
Because heart rate doesn’t respond quickly enough to match short, intense efforts, and recovers slowly Lag in HR & recovery
Not sensitive enough to assess anaerobic interval load
Anaerobic training examples
15–20 s @ 105–115% VO₂max: 15–20 s rest
Sprint repeats: 4–6 x 30–80m sprints with 30–90 s rest
Results: improved sprint time, fatigue index, and VO₂max
Repeated Sprint Ability (RSA)
Depends on oxidative capacity, PC recovery, H⁺ buffering, muscle activation
Best trained with aerobic + anaerobic methods
Often trained indirectly through other drills
Work:Rest ratios – energy system targeted
- 1:3 = Lactic anaerobic system
- 1:1 or less = Aerobic
- 1:2 = Mixed (lactic + aerobic)
Work:Rest ratios in team sports
Irregular, not steady-state
E.g. football = ~1:3 to 1:4
Training should mimic irregularity (vary length, rest, effort)
ATP resynthesis via phosphocreatine (PC)
ADP + PC (CK)) ATP + C
What is Beta-oxidation?
How fats are broken down
What is fatigue?
Fatigue is the reduced ability to produce force or power during physical activity.
Key Considerations for Anaerobic Development
It is essential to develop trainings relevant to what the athletes will be doing during competition
o Intensity?
o Duration?
o Interval?
