Critical Power Flashcards
1
Q
Monod and Scherrer (1965)
A
The asymptote of the hyperbolic relationship between power output and time to fatigue
*The maximum work rate which can be sustained for “a very long time without fatigue”
2
Q
Poole et al (1988)
A
- Early paper
- Participants on bike cycled at CP or CP+5% above CP (only 16Watts above CP)
- After 24 mins they just stopped experiment because bored
- CP kept going
- CP+5% exhausted at 20mins
CP = maximal work rate whereby a physiological steady state can be attained
3
Q
Jones et al (2008)
A
- MRI scanner data
- Knee extensor exercise
- Working either 10% above or 10% below CP (only 4 Watts difference)
- Terminated test for 10% below after 20 mins
- 10% above – muscle pH massively falls, inorganic phosphate rises = Fatigue
CP = A critical threshold for metabolic control
4
Q
Florence and Weir (1997)
A
- Amateur entrants to New York marathon
- Critical velocity and marathon time
- r2 = checking error around line (higher it is the tighter it is around the line)
- 76% of marathon time can be explained by variation in Critical Velocity
- 51% can be explained by VO2 max and 28% VT
- CP was the best predictor of marathon time!
- The predictability of CP concept can be improved
5
Q
Jones (2006)
A
Submaximal fitness
- Paula Radcliff’s marathon time hasn’t changed for like 11 years
- Measured ml of oxygen she used per kilo that she weighed per km she ran
- VO2 max didn’t change, but became more efficient over time
- LT = not producing any at 17km/h (CRAZY!)
- VO2 max didn’t change between 1992 and 2003
6
Q
Housh et al (1990)
A
- Bouts to exhaustion were between 1-10min
- 2 bouts per day on consecutive days (morning and afternoon today and morning and afternoon tomorrow)
- Day 1 = bouts 1 and 2
- Day 2 = bouts 3 and 4
- Compared the different ways of doing this to what we think the gold standard is
- Good agreement provided that one bout performed each day and that difference in length of trials is >5mins in length (one bout should be approx. 4 mins long and the other approx. 9 mins)
7
Q
Bishop and Jenkins (1995)
A
- Days 1-5 they did familiarisation tests
- Looked at importance of familiarisation trials and reproducibility of 3 bouts on 1 day vs 3 bouts on 3 days
- Trying to find out the best way of doing it
- No difference if do 3 trials in one day or 3 bouts on 3 days
- You can use a 1 day familiarisation trial
8
Q
Vanhatalo et al (2007)
A
How do you deplete the W’?
- 3 minute all out test
- When sprinting their dipping into their anaerobic work tank (W’)
- Once this has run out and he has nothing left, whatever he is still able to do, must be his critical power
- EP = end power = 330W
- At end of stage get a plateau but still sprinting maximally (WEIRD) (moving at about 1meter/ps – but still a sprint)
- Mathematically the end power is 330W
- Anaerobic work tank (W’ = area under the curve)
1 Watt = 1 joule per second
Work = power x time
(kJ) = Watts x Seconds / 1000 - W’ = measured in kJ
9
Q
Burnley et al (2007)
A
Is it reliable?
- Coefficient of variation for end power (i.e. CP) =3%
- Coefficient of variation for CP estimated from traditional repeated trials to exhaustion =6%
- So, this one test is actually better than traditional test only costs you one 3 min all out exercise
- The 3 min all out test provides a valid and reliable assessment of: CP, W’, VO2 max
10
Q
Poole et al (1992)
A
- 3 days a week for 8 weeks
- Each session: 30min at CP
35min in weeks 6+7
40min in week 8
power output allowed to increase during training - Experimental and control group
- Control: pre and post training no difference in VO2 max, CP, y intercept (anaerobic work capacity)
- Experimental: increase CP but not W’ (increase in CP wasn’t related to increase in VO2 max)
- Increase in CP can happen without changes in VO2 max
11
Q
Vanhatalo et al (2008)
A
• 3 days per week for 4 weeks
- 2 sessions per week: 6x5min at 105% CP
- 1 session per week: 10 x 2 min (designed to expend 50% of W’ with 2 mins recovery
- 3 min all out study
- Pre training vs post training
- 10% increase in CP
- Evidence that 3 min all out test is sensitive to training
12
Q
Jenkins and Quigley (1993)
A
Training the W’
- 3 days per week for 8 weeks
- Each session = 5 x1min all out with 5 min recovery
- Significant increase if 49% W’ but not CP
- Can have a massive shift in W’ without ever moving CP
13
Q
(Miura et al, 1999)
A
Training the W’
- Double-blind, randomised crossover trial
- 6 week wash out
- Pre and post Cr supplementation
- 20g/day for 5 days
- Significant increase in W’ (~25%) but not CP
- Makes sense – have more PCr = going to have a better anaerobic work tank
- A limitation that PCr not directly measured
