Webinar for USA Cycling Coaching Education program.

1. Laboratory-based testing
of competitive cyclists
Andrew R. Coggan, Ph.D.
Cardiovascular Imaging Laboratory
Washington University School of Medicine
St. Louis, MO 63021

2. Laboratory-based testing
• What is it?
– For purposes of this seminar, anything done indoors!
• Why should you do it (compared to using a field test)?
– Controlled environment
– Submaximal testing possible
– Can obtain greater insight into athlete’s strengths and weaknesses
and/or effectiveness of training program
– Not necessarily more accurate/precise
• Why should you not do it?
– Cost
– Convenience (may interfere with routine training)
– Psychological factors
• When should you do it?
– Depends on many factors, but frequent testing not necessarily better
• How do you do it?

3. Determinants of endurance performance

4. Maximal oxygen consumption (VO2max)
• What is it?
– The highest rate of oxygen uptake (VO2) achievable during exercise
that utilizes a large muscle mass (e.g., running).
• Why is it important?
– VO2max is the best overall measure of cardiovascular fitness and
sets the upper limit to the production of energy (ATP) via aerobic
metabolism (i.e., mitochondrial respiration). As such, having a high
VO2max is a necessary but not a sufficient condition to be an elite
endurance athlete.
• How do you measure it?
– By using a “metabolic cart” (gas analyzers, flow measuring device)
to quantify respiratory gas exchange (VO2, CO2 production (VCO2))
across the lungs/at the mouth during an incremental exercise test.
• Related concepts
– VO2peak, RER

5. Subject performing VO2max test

6. Calculation of VO2, VCO2, and RER
.
VO2 = rate of O2 uptake (L/min or mL/min/kg).
.
VCO2 = rate of CO2 release (L/min or mL/min/kg).
.
.
.
VO2 = (VI • FIO2) - (VE • FEO2)
.
.
.
VCO2 = (VE • FECO2) - (VI • FICO2)
.
.
RER = VCO2 / VO2
.
.
Where VE = expired ventilation; VI = inspired ventilation;
FIO2 = fraction of oxygen inspired; FICO2 = fraction of carbon
dioxide inspired; FEO2 = fraction of oxygen expired; and
FECO2 = fraction of carbon dioxide expired.

7. Characteristics of “ideal” VO2max test
• Total duration 8-12 min
• Stages typically 1-3 min in length
• Exercise intensity increased by <5-8% of VO2max per
stage, at least towards end of test
• For athletes, sports-specific mode of exercise:
∴ cyclists → cycling

8. Criteria for determination/definition of VO 2max
• Absolute or relative plateau in VO2 despite increase in O2
demand (e.g., <150 mL/min or <1.5 mL/min/kg increase
between stages)
• RER > 1.10
• Heart rate w/in 10 beats/min of age-predicted maximum
• Blood lactate concentration > 8 mmol/L
• Volitional fatigue is not evidence that VO2max has been
achieved!

9. VO2 and heart rate vs. power
VO2
Heart rate
180
6
160
140
120
4
100
3
80
60
2
40
1
20
0
0
0
50
100
150
200
250
Power (W)
300
350
400
450
HR (beats/min)
VO 2 (L/min))
5

10. Role of genetics in determining baseline VO2max

11. Role of genetics in determining change in
VO2max with training

12. Lactate threshold (LT)
• What is it?
– The exercise intensity at which lactate production exceeds lactate
utilization, such that lactate begins to accumulate in muscle and
hence blood.
• Why is it important?
– LT is the best measure of metabolic fitness and determines the
fraction of VO2max that may be sustained for any duration from a
few minutes to many hours. LT is therefore the most important
physiological factor determining endurance exercise performance.
• How do you measure it?
– By obtaining blood samples to quantify lactate concentrations
during an incremental exercise test.
• Related concepts
– Onset of blood lactate accumulation (OBLA), maximal lactate
steady state (MLSS), individual anaerobic threshold (IAT), lactate
minimum (lactate balance point), ventilatory (anaerobic) threshold
(VT/AT), critical power.

13. LT test results for a cyclist-turned-duathlete
OBLA
LT

14. Blood [lactate] as a function of time during
exercise at a constant power
Subject BL
6
Blood HLa (mmol/L)
5
4
245 W
275 W
310 W
325 W
Time to fatigue @ 310 W: 58 min
3
2
1
0
0
2
4
6
Time (min)
8
10

15. Blood [lactate] as a function of time during
exercise at a constant power
Subject AC
6
Blood HLa (mmol/L)
5
Time to fatigue @ 325 W: 75 min
4
260 W
295 W
310 W
345 W
3
2
1
0
0
2
4
6
Time (min)
8
10

16. Blood [lactate] as a function of time during
exercise at a constant power
Subject GC
6
Blood HLa (mmol/L)
5
4
210 W
245 W
275 W
310 W
Time to fatigue @ 310 W: 22 min
3
2
1
0
0
2
4
6
Time (min)
8
10

17. Determination of
ventilatory (“anaerobic”)
threshold (VT) based
on ventilation (Ve)

18. Determination of VT based on ventilatory
equivalents (Ve/VO2 and Ve/VCO2)

19. Determination of critical power
(hyperbolic model)
3600
3000
y = 24757 / (262 - x)
R2 = 0.998
Time (s)
2400
Critical power (in W)
1800
1200
Anaerobic work capacity (in J)
600
0
0
50
100 150 200 250 300 350 400 450 500 550 600
Power (W )

20. Determination of critical power
(linear model)
Work (J)
750,000
y = 263x + 22951
R2 = 0.99998
500,000
Slope = critical power (in W)
250,000
Intercept = anaerobic work capacity (in J)
0
0
600
1200
1800
Time (s)
2400
3000
3600

21. Gross efficiency (GE)
• What is it?
– The ratio of work out/energy in x 100%.
• Why is it important?
– Gross efficiency determines the power output corresponding to a
exercise at a given percentage of VO2max and/or LT.
• How do you measure it?
– By quantifying energy production via indirect calorimetry
(respiratory gas exchange) in relation to power output on a cycle
ergometer.
• Related concepts
– Net efficiency, delta efficiency, economy,

22. Power-VO2 relationship (economy/efficiency)
5
y = 0.0112x + 0.45
R2 = 0.997
VO2 (L/min)
4
y = 0.0106x + 0.45
R2 = 0.998
3
2
1
0
0
50
100
150
200
Power (W)
250
300
350
400

23. Energy yield and relative contribution of
carbohydrate and fat calculated from RER
Energy yield
% kcal from
RER
kcal/L O2
Carbohydrates
Fats
0.71
4.69
0.0
100.0
0.75
4.74
15.6
84.4
0.80
4.80
33.4
66.6
0.85
4.86
50.7
49.3
0.90
4.92
67.5
32.5
0.95
4.99
84.0
16.0
1.00
5.05
100.0
0.0

24. Effect of VO2 “drift” on power-VO2 relationship

25. Power-VO2 relationship (economy/efficiency)
5
y = 0.0112x + 0.45
R2 = 0.997
VO2 (L/min)
4
y = 0.0106x + 0.45
R2 = 0.998
3
2
1
0
0
50
100
150
200
Power (W)
250
300
350
400

26. Muscle fiber type, cycling economy,
and ‘hour power’
From: Horowitz JF, Sidossis LS, Coyle EF. High efficiency of type I fibers improves performance. Int. J. Sports Med. 15:152, 1994.

27. Determinants of “anaerobic” performance
Performance
velocity
Resistance to
movement
Performance
power
Performance abilities
Efficiency /
economy
Neuromuscular
power
Neural
control
Fiber type
(% type II)
Anaerobic
capacity
Muscle
mass
Functional
abilities
Muscle buffer
capacity
Physiological determinants

28. Neuromuscular power
• What is it?
– Maximum power developed by muscle in unfatigued state – limited
by rate of energy utilization (i.e., rate of ATP hydrolysis), not energy
production.
• Why is it important?
– High power obviously critical to achieve high speed/rapid
acceleration (e.g., sprinting, standing start).
• How do you measure it?
– No gold standard exists, but inertial load method is probably the
most convenient and accurate approach.
• Related concepts
– Wingate peak power

29. Anaerobic capacity
• What is it?
– The maximum amount of work (not the rate of doing such work, i.e,
power) that can be performed using ATP produced via anaerobic
metabolism.
• Why is it important?
– Sustained efforts at supramaximal (I.e., requiring >100% of
VO2max) intensities obviously critical in many races/race situations
(e.g., pursuit, bridging gaps, shorter hills).
• How do you measure it?
– Again, no true gold standard exists, but maximal accumulated O2
deficit (MAOD) probably comes closest. MAOD is determined by
measuring the difference between O2 demand and O2 uptake during
exercise to fatigue at 110% of VO2max.
• Related concepts
– Wingate average power, anaerobic work capacity (AWC)
determined using critical power approach.

30. The classic Wingate test
1. Warm-up at a moderate intensity
for 3-5 min.
2. Pedal Monark ergometer “all out”
against no resistance.
3. Within 3 s, apply braking force of
0.075 kg/kg body mass and start
timing.
4. Record number of pedal
revolutions completed every 5 s
for 30 s.
5. Warm down for at least 2 min.
6. Optional: go puke in wastebasket!

31. Data derived from Wingate test
1.
Peak power (first 5 s) in W =
braking force (kg) x 9.81 N/kg x 6 m/rev x
revolutions/5 s
2.
Mean power (30 s) in W =
braking force (kg) x 9.81 N/kg x 6 m/rev x
revolutions/30 s
3.
Fatigue index in % =
(peak power – power during last 5 s)/peak power
x 100%

32. Normal values and percentile rankings for mean
power during a Wingate test
Maud & Schultz, Research Quarterly. Vol 60 pp 144-149. 1989
Males (N=60) and Females (N=69)
Percentile Rank
95
90
85
80
75
70
65
60
55
50
45
40
35
30
25
20
15
10
5
Mean
Minmum
Maximum
SD
Watts
Male
676.6
661.8
630.5
617.9
604.3
600.0
591.7
576.8
574.5
564.6
552.8
547.6
534.6
529.7
520.6
496.1
484.6
470.9
453.2
562.7
441.3
711.0
66.5
Female
483.0
469.9
437.0
419.4
413.5
409.7
402.2
391.4
386.0
381.1
376.9
366.9
360.5
353.2
346.8
336.5
320.3
306.1
286.5
380.8
235.4
528.6
56.4
W•kgBW-1
Male
Female
8.63
7.52
8.24
7.31
8.09
7.08
8.01
6.95
7.96
6.93
7.91
6.77
7.70
6.65
7.59
6.59
7.46
6.51
7.44
6.39
7.26
6.20
7.14
6.15
7.08
6.13
7.00
6.03
6.79
5.94
6.59
5.71
6.39
5.56
5.98
5.25
5.56
5.07
7.28
6.35
4.63
4.53
9.07
8.11
.88
.73

33. Advantages and disadvantages of Wingate test
• Advantages
– Simple
– Common
– Relevant
• Disadvantages
– Strenuous
– Not a ‘pure’ test of anything:
• Typically underestimates
true neuromuscular power
• Does not really measure
anaerobic capacity
• Aerobic contribution
significant in endurance
trained cyclists

34. Maximal power as a function of cadence

35. Jim Martin’s inertial load ergometer

36. Example of data obtained from inertial load test

37. Difference between O2 deficit and O2 debt
(Excess Post-Exercise Oxygen Consumption)

38. Role of VO2max, gross efficiency, MAOD, and
aerodynamic drag characteristics (CdA) in
determining 3 km pursuit performance
Rider A
900
Total
VO2max = 4.45 L/min
800
G.E. = 23.9%
Est. MAOD = 5.11 L
Ave. power = 411 W
600
600
CdA = 0.236 m2
500
3 km time = 3:49.7
400
28%
300
200
G.E. = 24.1%
Total
700
Power (W)
700
Power (W)
900
VO2max = 4.20 L/min
800
Rider B
Ave. power = 390 W
CdA = 0.204 m2
500
3 km time = 3:47.3
400
18%
300
200
Maximal aerobic
72%
100
Est. MAOD = 3.09 L
Maximal aerobic
82%
100
0
0
0
30
60
90
120
150
Time (seconds)
180
210
240
0
30
60
90
120
150
Time (seconds)
180
210
240

39. Determination of critical power
(hyperbolic model)
3600
3000
y = 24757 / (262 - x)
R2 = 0.998
Time (s)
2400
Critical power (in W)
1800
1200
Anaerobic work capacity (in J)
600
0
0
50
100 150 200 250 300 350 400 450 500 550 600
Power (W )

40. Determination of critical power
(linear model)
Work (J)
750,000
y = 263x + 22951
R2 = 0.99998
500,000
Slope = critical power (in W)
250,000
Intercept = anaerobic work capacity (in J)
0
0
600
1200
1800
Time (s)
2400
3000
3600