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1.1.What is power?What is power?


2.2.Why is power important?Why is power important?



3.3.Why train and Why train and racerace using a using a power meter?power meter?



3.3.Why train and Why train and racerace using a using a power meter?power meter?

4.4.What else can a power meter What else can a power meter be used for?be used for?

1. What is power?1. What is power?

Physical definition of power


• Work = force x distance• Power = work/time


• Work = force x distance• Power = work/time

• Work = torque x angular displacement• Power = torque x angular velocity

SI units

SI units

• meter (m) for distance• kilogram (kg) for mass• second (s) for time

SI units

• meter (m) for distance• kilogram (kg) for mass• second (s) for time• newton (N) for force (1 N = 1 kgm/s2)

SI units

• meter (m) for distance• kilogram (kg) for mass• second (s) for time• newton (N) for force (1 N = 1 kgm/s2)• joule (J) for work (1 J = 1 Nm = 1 kgm2/s2)

SI units

• meter (m) for distance• kilogram (kg) for mass• second (s) for time• newton (N) for force (1 N = 1 kgm/s2)• joule (J) for work (1 J = 1 Nm = 1 kgm2/s2)• newton-meter (Nm) for torque (1 Nm = 1 kgm2/s2)

SI units

• meter (m) for distance• kilogram (kg) for mass• second (s) for time• newton (N) for force (1 N = 1 kgm/s2)• joule (J) for work (1 J = 1 Nm = 1 kgm2/s2)• newton-meter (Nm) for torque (1 Nm = 1 kgm2/s2)• radian (rad) for angular displacement (m/m)

SI units

• meter (m) for distance• kilogram (kg) for mass• second (s) for time• newton (N) for force (1 N = 1 kgm/s2)• joule (J) for work (1 J = 1 Nm = 1 kgm2/s2)• newton-meter (Nm) for torque (1 Nm = 1 kgm2/s2)• radian (rad) for angular displacement (m/m)• watt (W) for power (1 W = 1 J/s = 1 Nm/s = 1 kgm2/s3)

2. Why is power important?2. Why is power important?

Importance of power

Importance of power

• Direct determinant of performance velocity

Importance of power

• Direct determinant of performance velocity

• Direct determinant of physiological and perceptual responses to exercise

VO2, heart rate, lactate, and RPE vs. power

0

1

2

3

4

5

6

7

8

9

0 50 100 150 200 250 300 350 400 450

Power (W)

VO

2 (L

/min

), la

cta

te (

mM

), o

r R

PE

(U

)

0

20

40

60

80

100

120

140

160

180

HR

(beats/m

in)

VO2 Blood lactate RPE Heart rate

VO2max

Lactate threshold

OBLA

3. Why train and race using3. Why train and race usinga power meter?a power meter?

Advantages of HR based training


• HR monitors cheap, reliable, easy to use


• HR monitors cheap, reliable, easy to use• Large empirical knowledge base


• HR monitors cheap, reliable, easy to use• Large empirical knowledge base• Automatically accounts for variability in

fitness/physiological function?


• HR monitors cheap, reliable, easy to use• Large empirical knowledge base• Automatically accounts for variability in

fitness/physiological function?• Less responsive than power?

Disadvantages of HR based training


• Not scientifically proven



• Temporal delay in HR (t0.5 = ~20 s)




• HR-exercise intensity (power) relationship is variable

Factors influencing HR-power relationship


• Hypohydration/dehydration


• Hypohydration/dehydration• Environmental conditions (heat & altitude)


• Hypohydration/dehydration• Environmental conditions (heat & altitude)• Cardiac drift

Example of “cardiac drift”

Power Heart rate


• Hypohydration/dehydration• Environmental conditions (heat & altitude)• Cardiac drift


• Hypohydration/dehydration• Environmental conditions (heat & altitude)• Cardiac drift• Recent illness


• Hypohydration/dehydration• Environmental conditions (heat & altitude)• Cardiac drift • Recent illness• Sleeplessness


• Hypohydration/dehydration• Environmental conditions (heat & altitude)• Cardiac drift • Recent illness• Sleeplessness• Distribution of power

Effect of power distribution on HR

Speed

(km/h)

Power

(W)

HR

(beat/min)

Power/HR

(W/beat/

min)

Solo

(n=11)

29.9

±1.1

170

±13

134

±9

1.26

±0.05

Group

(n=7)

30.7

±0.2

147

±6

140

±5

1.05

±0.02


• Hypohydration/dehydration• Environmental conditions (heat & altitude)• Cardiac drift • Recent illness• Sleeplessness• Distribution of power


• Hypohydration/dehydration• Environmental conditions (heat & altitude)• Cardiac drift • Recent illness• Sleeplessness• Distribution of power• “Overreaching”

Effect of “overreaching” on power,HR, and power/HR

Speed

(km/h)

Power

(W)

HR

(beat/min)

Power/HR

(W/beat/

min)

Rested

(n=7)

42.2

±2.6

289

±7

161

±2

1.78

±0.03

Fatigued

(n=5)

42.4

±0.7

279

±10

150

±7

1.87

±0.09

Heart rate vs. power

y = 0.3020x + 59.8

R2 = 0.9910

60

80

100

120

140

160

180

0 50 100 150 200 250 300 350

Power (W)

Hea

rt r

ate

(bea

ts/m

in)

Ergometer (indoors)


y = 0.4172x + 44.0

R2 = 0.8238

y = 0.3020x + 59.8

R2 = 0.9910

60

80

100

120

140

160

180

0 50 100 150 200 250 300 350

Power (W)

Hea

rt r

ate

(bea

ts/m

in)

Outdoors Ergometer (indoors)


• Hypohydration/dehydration• Environmental conditions (heat & altitude)• Cardiac drift • Recent illness• Sleeplessness• Distribution of power• “Overreaching”• Individual differences


y = 0.7556x + 26.831

R2 = 0.8238

y = 0.4721x + 48.762

R2 = 0.4209

0

20

40

60

80

100

120

0 20 40 60 80 100 120

Ave. power (% of 40k)

Av

e.

HR

(%

of

40

k)


• Hypohydration/dehydration• Environmental conditions (heat & altitude)• Cardiac drift • Recent illness• Sleeplessness• Distribution of power• “Overreaching”• Individual differences


• Hypohydration/dehydration• Environmental conditions (heat & altitude)• Cardiac drift • Recent illness• Sleeplessness• Distribution of power• “Overreaching”• Individual differences• Power itself

Power/heart rate vs. power

y = 0.0029x + 0.9802

R2 = 0.5697

y = 0.0035x + 0.6301

R2 = 0.4921

0.00

0.50

1.00

1.50

2.00

0 50 100 150 200 250 300 350

Power (W)

Po

we

r/h

ea

rt r

ate

(W

/be

at/

min

)





• HR-exercise intensity (power) relationship independent of “metabolic fitness” (LT)

Advantages of power based training


• Immediate, direct measurement of most important factor


• Immediate, direct measurement of most important factor

• Easy to evaluate training efficacy (training is testing, testing is training)

Disadvantages of power based training


• Cost/complexity/reliability of power meters


• Cost/complexity/reliability of power meters• “Stochastic” nature of power output

Stochastic nature of power output(tempo training session)

Power Speed (x10) Torque Heart Rate Cadence


Power


Power

Average = 237 W



– How to analyze data?




– What are the physiological implications?

Frequency distribution of power output(tempo training session)

2 h 0 min @ 237 W ave.

Frequency distribution of power output(hilly road race)

2 h 6 min @ 227 W ave.

Frequency distribution of power output(circuit race)

1 h 1 min @ 269 W ave.

Frequency distribution of power output(criterium)

1 h 7 min @ 263 W ave.

Frequency distribution of power output(“micro” intervals)

2 h 0 min @ 215 W ave.

3D frequency distribution of power output(“micro” intervals)

0

50

10

0

15

0

20

0

25

0

30

0

35

0

40

0

45

0

<15

15-60>600

2468

10121416182022

% o

f to

tal

tim

e

POWER (watts)

Time (s)

Studies using “stochastic” cycling

• Coggan AR, Coyle EF. Effect of carbohydrate feedings during high-intensity exercise. J Appl Physiol 65:1703-1709, 1988.

• Palmer GS, Dennis SC, Noakes TD, Hawley JA. Effects of steady-state and stochastic exercise on subsequent cycling performance. Med Sci Sports Exerc 29:684-687, 1997.

• Palmer GS, Borghouts, Noakes TD, Hawley JA. Metabolic and performance responses to constant-load vs. variable-intensity exercise in trained cyclists. J Appl Physiol 87:1186-1196, 1999.

Studies of “micro” intervals

• Essen B, Hagenfeldt L, Kaijser L. Utilization of blood-borne and intramuscular substrates during continuous and intermittent exercise in man. J Physiol 265:489-506, 1977.

• Essen B. Studies on the regulation of metabolism in human skeletal muscle using intermittent exercise as an experimental model. Acta Physiol Scand Suppl 454:1-32, 1978.

• Essen B. Glycogen depletion of different fibre types in human skeletal muscle during intermittent and continuous exercise. Acta Physiol Scand 103:446-455, 1978.

• Essen B, Kaisjer L. Regulation of glycolysis in intermittent exercise in man. J Physiol 281-499-511, 1978.

Metabolic response to “micro” intervals

Half-lives of physiological responses

Power (force and/or velocity) (0 s)

Heart rate/cardiac output: ~20 s

Sweating: ~25 s

VO2: ~30 s

VCO2: ~45 s

Ventilation: ~50 s

Temperature (core): ~70 s

3D force-velocity plot of tempo training session





• A cruel mistress indeed!

Power based training levels

Level Name/purpose % of 40k power % of 40k HR RPE

1

Active recovery

<55%

<68%

<2

2

Endurance

56-75%

69-83%

2-3

3

Tempo

76-90%

84-94%

3-4

4

Lactate threshold

91-105%

95-105%

4-5

5

VO2max

106-120%

>106%

6-7

6

Anaerobic capacity

>121%

N/a

>7

7

Anaerobic power

N/a

N/a

(maximal)

Racing with a power meter


• Pacing in TTs

Use of power meter for TT pacing

0

100

200

300

400

500

0 10 20 30 40 50 60

Time (min)

Po

wer

(W

)

Blinded Unblinded

CV=13.7%

CV=9.9%


• Pacing in TTs


• Pacing in TTs

• Performance evaluation

4. What else can a power meter4. What else can a power meterbe used for?be used for?

Other uses

Other uses

• Fitness testing

Other uses

• Fitness testing– Lab-type testing

Other uses


– Critical power determination (Monod method)

Determination of critical power

0

600

1200

1800

2400

3000

3600

0 50 100 150 200 250 300 350 400 450 500

Power (W)

Tim

e (

s)

y = 24757 / (262 - x)

R2 = 0.9979

Area = anaerobic capacity (in J)

Asymptote = critical power (in W)

Determination of critical power

y = 263x + 22951

R2 = 0.9999

0

250,000

500,000

750,000

0 600 1200 1800 2400 3000 3600

Time (s)

Wo

rk (

J)

Slope = critical power (in W)

Intercept = anaerobic capacity (in J)

Other uses



Other uses



• Estimation of CdA

Estimation of CdA

Bike

Power

(W)

Speed (km/h)

Air density

(kg/m3)

Est. CdA

(m2)

Road

(n=3)

290

±9

41.0

±0.9

1.178

±0.011

0.252

±0.010

TT

(n=3)

282

±8

41.8

±0.9

1.176

±0.009

0.230

±0.008

Estimation of CdA (con’t)

TT date Power

(W)

Speed (km/h)

Air density

(kg/m3)

Est. CdA

(m2)

9/6/97 280 45.0 1.157 0.211

6/20/99 290 45.3 1.217 0.206*

7/24/99 277 44.6 1.154 0.216

7/24/99 258 43.5 1.154 0.215

6/23/01 297 44.3 1.156 0.238

Top 10 things I’ve learned using a power meter


10) I shouldn’t lose weight



9) I need big gears



9) I need big gears

8) I need small gears



9) I need big gears


7) Strength is irrelevant



9) I need big gears



6) Don’t start too hard in TTs



9) I need big gears




5) Train less, rest more



9) I need big gears





4) Heat acclimatization is critical



9) I need big gears






3) Specificity



9) I need big gears






3) Specificity

2) SPECIFICITY



9) I need big gears






3) Specificity

2) SPECIFICITY

1) SPECIFICITY!

Download - Power training seminar

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