Quantifying training load

Andrew R. Coggan, Ph.D.

Cardiovascular Imaging Laboratory

Washington University School of Medicine

St. Louis, MO 63021

Questions to be addressed:

1) Why try to quantify the training load?

2) How can you quantify the training load?

3) Which method(s) is (are) best?

Why?

The relationship between trainingand performance

Training loadAthlete

Performance

(“dose”) (↑ or ↓)

StimulusSystem

Response

(stress) (strain)

Impulse-response model of training adaptation

Banister et al., Aust J Sports Med 7:57, 1975

Busso et al., J Appl Physiol 92:572, 2002

Prediction of training-induced changes in performance using impulse-response model

What?

Methods used to quantify training load

1) Session RPE

2) Training impulse (TRIMP)

3) EPOC

4) Training stress score (TSS)

Session RPE

• Proposed by Foster et al. in 1995

• Subjective, response (i.e., perceived effort) based method

• Calculated as:

Training load = duration (min) x RPE (10 pt Borg scale)

Mom asks, “Honey, how was your workout?”

0 = Rest 6 =

1 = Very, very easy 7 = Very hard

2 = Easy 8 =

3 = Moderate 9 =

4 = Somewhat hard 10 = Maximal

5 = Hard

Advantages of session RPE

1) Extremely simple to calculate

2) Can be used with practically any sport

3) “If it feels hard, it is hard”

Disadvantages of session RPE

1) Subjective nature of measurement

2) Inconsistency between athletes

3) Inconsistency within athletes (CV = 14%)

Training impulse (TRIMP)

• Proposed by Banister et al. in 1975

• Objective, response (i.e., heart rate) based method

• Calculated as:

TRIMP = duration (min) x fraction of heart rate reserve

x e(1.92 x fraction of heart rate reserve)

Advantages of TRIMP

1) Moderately easy to calculate

2) Requires only a heart rate monitor

3) Successfully used to model the relationship of training to performance in numerous scientific studies

Disadvantages of TRIMP

1) Heart rate may vary due to factors not directly related to training stress (e.g., lack of sleep)

2) Can only be used in (semi-) continuous sports

3) Provides no “credit” for supramaximal exercise, i.e., exercise at an intensity requiring >100% of HRmax/VO2max

EPOC

• Proposed by Rusko et al. in 2003

• Objective, response (i.e., heart rate) based method

• Calculated as:

EPOC(t) = f(EPOC(t-1), % of VO2max, ∆t)

Advantages of EPOC

1) Theory is based on using the body’s own integrated physiological response to exercise (i.e., EPOC) to quantify the stress of training

Disadvantages of EPOC

1) Calculation is complex (requires proprietary software/hardware)

2) Accuracy of prediction of true EPOC only moderate (i.e., R2 = 0.79) even with continuous exercise

3) Accuracy of prediction only tested at short durations

Disadvantages of EPOC (con’t)

4) Heart rate may vary due to factors not directly related to training stress (e.g., lack of sleep)

5) Can only be used in (semi-) continuous sports

6) Provides no “credit” for supramaximal exercise, i.e., exercise at an intensity requiring >100% of HRmax/VO2max

Training stress score (TSS)

• Proposed by Coggan in 2002

• Objective, stimulus (i.e., power) based method

• Calculated as:

TSS = duration (h) x IF2 x 100

where IF (intensity factor) = normalized power/functional threshold power

What is normalized power?

Normalized power is an estimate of the power that an athlete could have maintained for the same physiological “cost” if power had been perfectly constant (e.g., as on an ergometer) instead of highly variable.

Steps to calculate normalized power

1) Smooth the data using a 30 s rolling average to take into account the time course of physiological responses

2) Raise the data obtained in step 1 to the 4th power take into account the non-linear nature of physiological responses

3) Take the average of the values obtained in step 2

4) Reverse step 2 to obtain the normalized power

Normalized power = 301 W

Training stress score (TSS)

• Proposed by Coggan in 2002

• Objective, stimulus (i.e., power) based method

• Calculated as:

TSS = duration (h) x IF2 x 100

where IF (intensity factor) = normalized power/functional threshold power

Advantages of TSS

1) Relatively easy to calculate

2) Based on direct measurement of applied stimulus, not response to the stimulus

3) Provides “credit” for supramaximal exercise, i.e., exercise at an intensity requiring >100% of HRmax/VO2max

Disadvantages of TSS

1) Designed for use with sports for which external power is easily determined (i.e., cycling)

2) Validity has not been tested in any scientific studies

Which?

Just how long is “long”?

Time

Tra

inin

g lo

ad

session RPE TRIMP EPOC TSS

Just how hard is “hard”?

0.0

0.5

1.0

1.5

2.0

0 25 50 75 100 125 150

% of VO2max

Re

lati

ve

we

igh

tin

g

session RPE TRIMP EPOC TSS

The relationship between trainingand performance

Training loadAthlete

Performance

(“dose”) (↑ or ↓)

StimulusSystem

Response

(stress) (strain)