iBike Newton+ Operating Instructions Manual page 47

ride.
In events such as a time trial or climbing hills where the wattage holds very steady, NP and
average power will be very close to each other because you pedal almost all the time.
Using Intensity Factor (IF) to gauge the difficulty of your Workout
If you do cycling workouts regularly you know that some of your workouts are more
intense than others. Average power and NP alone won't quantify the intensity of
your workout, because the intensity of a workout is not based on power output
alone but also the time length of your workout and how hard you work during each
moment of your workout.
Normalized Power (NP) and Functional Threshold Power (FTP) can be used together
to quantify the overall intensity of each of your workouts. The Intensity Factor (IF)
is very simple to calculate: divide your NP by your FTP. The number IF represents
the intensity of your workout as compared to the effort you expend in a one hour
Time Trial. So, an IF of 1.0 represents a time trial effort and in theory can only be
maintained for an hour.
One of the great things about an IF measurement is that you can manage your
training schedule to make sure you're training hard, but not training too hard. Here
are some values for IF and the kind of rides they represent:
• Less than 0.75 - recovery rides
• 0.75-0.85 - endurance-paced training rides
• 0.85-0.95 - tempo rides, aerobic and anaerobic interval workouts (work and
rest periods combined), longer (>2.5 h) road races
• 0.95-1.05 - lactate threshold intervals (work period only), shorter (<2.5 h)
road races, criteriums, circuit races, longer (e.g., 40 km) TTs
• 1.05-1.15 - shorter (e.g., 15 km) TTs, 10 minute hill climb
• Greater than 1.15 - prologue TT, track pursuit, 5 minute hill climb
One more way to gauge your workouts: Training Stress Score
We now know the true tax on our body (NP), and how intense each workout is (IF)
compared to a reference one hour TT, but there is still one more thing to think
about. For example, what is the comparative stress on the body from riding at
50% of our FTP for two hours, compared to a 100% FTP effort for one hour? A
simple number called Training Stress Score (TSS) allows you to quantify and
compare your different workouts, even when they are considerably different in time
length and power intensity.
TSS is designed to give you a numeric value for each ride that tells you how much training
load was on your body for that day's ride. A TSS of 100 equals an hour at an IF of 1.0. So,
if you were out for a fairly easy four hour ride, and accumulated 200 TSS points, it's the
same training load as doing two hours at time trial pace.
Importantly, TSS also quantifies how tired you can expect to be after a workout and
how long the residual fatigue might last.
• Less than 150 - low (recovery generally complete by following day)
• 150-300 - medium (some residual fatigue may be present the next day, but
gone by 2nd day)
• 300-450 - high (some residual fatigue may be present even after 2 days)
• Greater than 450 - very high (residual fatigue lasting several days likely)
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