Probably the most commonly used term in cycling training. Threshold refers to the line that distinguishes between medium and hard training intensities. Threshold is commonly known by a number of names including “Functional Threshold Power (FTP)”, “Lactate Threshold” and “Anaerobic Threshold”. The variety of terms refer to the differing methods for determining a cyclist’s individual threshold.
Functional Threshold Power: is measured on the road or on a trainer. Usually regarded as a cyclists peak 60 min power output. Most commonly measured through taking 95% of a cyclists 20 min power output.
Lactate Threshold: Determined through the measurement of blood lactate, usually during cycling via a long graded exercise test in a lab. For more detailed see here
The maximum amount of oxygen that your body can consume during exercise. It is expressed in 2 ways as either and absolute value L/min or a as a relative value ml/kg/min. VO2 max is often viewed as the gold standard for measuring endurance athletes potential due to its correlation to performance.
VO2 max values in sub elite athletic population vary widely, with recreational athletes in the window of 35-65 ml/kg/min, sub elite 60-70 ml/kg/min and elite athletes usually greater than 70 ml/kg/min. elite athletes can be staggeringly high.
Reported values for Cadel Evans from testing at the AIS were 87 ml/kg/min.
Normalised Power (NP)
Power output during most cycling races and training sessions is not a consistent effort. This inconsistency comes at an increased metabolic cost. The calculation of normalised power attempts to predict the power that could have been maintained for the same metabolic cost had this effort been perfectly constant.
Training Stress Score (TSS)
Multiple attempts have been made over the years to objectively quantify rate and compare the cost of training sessions, including Dr Bannister’s TRIMPS and Skiba’s Govss algorithm. TSS utilizes a cyclist’s power meter, FTP and NP to attribute a numerical value to each workout completed. At a 100% of FTP points are accumulated at 100 per hour. As intensity increases or decreases points are accumulated at the corresponding rate.
TSS is also used as part of the performance management chart to calculate both acute and chronic training loads.
Algorithm = IF2 * 100* ride duration in hours
Example: 0.872*100* 2.157 = 163.3
Intensity Factor (IF)
Intensity factor is simply the ratio between your normalised power and your FTP.
Example 1) a 60 minute time trial at 100% FTP would be regarded as an FTP of 1.0.
Example 2) A rider with an FTP of 300w currently riding at a normalised power of 150w would be riding at an intensity factor of 0.5.
Watts per Kilogram (W/kg)
An easy way of comparing wattage’s between riders of different weights. Watts per kilogram becomes especially important during climbing numbers vary depending on rider ability and length of effort. An FTP of > 6.0 w/kg is world class.
Variability Index (VI)
Variability index is simply calculated by dividing an athlete’s normalised power by average power (NP/AP). It is designed as a measurement of the consistency of an athlete’s effort. The closer that VI is to 1.0 the more consistent an athlete has been is producing power. Variability index varies considerably between efforts for example a criterium race will have a far large VI then a well pace iron man bike split.
written by: Hamish Gorman