Full Glossary2017-03-18T10:30:43+00:00

Xert Full Glossary with Description

  • Athlete Type

    These are categories that associate with a given Focus Duration point on the power-duration relationship and may or may not account for weight.  The categories for cyclists are defined as follows:


    • Power Sprinter : 20 second power
    • Road Sprinter : 2 minutes watts/kg


    • Pursuiter : 3 minute power
    • Puncheur : 4 minute watts/kg
    • Breakaway Specialist : 5 minute power


    • Rouleur : 6 minute power
    • GC Specialist : 8 minute watts/kg
    • Climber : 10 minute watts/kg


    • Sprint Time-Triallist : 20 minute power
    • Time-Triallist : 1 hour power
    • Century Rider : 2 hour power
    • Endurance/Triathlete : 3 hour power

  • Fatigue

    Fatigue represents a reduction in an athlete’s ability to produce power.  It either manifests as a reduction in Maximal Power Available (short-term fatigue) or a reduction in fitness signature values (long-term fatigue).  Short-term fatigue recovers during an activity whereas long-term fatigue does not, or does so very slowly.

    Two principles a fatigue are the foundation of Xert:

    1. Fatigue reduces power
      • MPA is a real phenomenon.  Although research has previously described the idea that power reduces with fatigue, Xert is the first model ever to quantify it during intermittent exercise and apply it for analysis and for training prescription.
    2. Fatigue increases strain
      • Fatigue makes things more difficult and the closer you work to MPA, the greater the strain.  Reaching your physical limits of power isn’t easy and the instances that these occur during exercise are infrequent and in many cases, avoided by athletes.
  • Fitness Breakthrough

    A fitness breakthrough is achieved when your power reaches or surpasses MPA for longer than 5 seconds during an activity. It typically represents a maximal effort. When a fitness breakthrough is seen in your data your fitness signature is extracted and updated. Most of the time, if your breakthrough included moments where your power exceeded MPA, you receive a medal and one or more of your Fitness Signature parameters increases. If you came very close but didn’t surpass your MPA, your Fitness Signature may decline. This is a near breakthrough, or colloquially a fakethrough.

  • Fitness Signature

    It is represented by three values: Threshold Power (TP),  High Intensity Energy (HIE) and Peak Power (PP). The three fitness values are used to calculate MPA interactively and can be depicted using a power-duration curve.  In principle, your Fitness Signature establishes your ability to perform during steady-state or variable intensity power.


  • Focus Duration

    This is a generalized concept that is quantified as duration value and categorized as an Athlete Type. The value is based on work allocation ratios determined by summing your low, high and peak work or strain values over the given period. This can be for an activity, workout or a period of activities. Focus is a duration (i.e. HH:MM:SS) on your Power Duration chart that has the equivalent ratio as the totals of your low, high and peak work or strain over the given period. For example, if your total low/high/peak strain values over a period are in the ratio of 70/26/4 and your power at 4:00 minutes on your Power Duration chart also has the ratio of 70/26/4, then the Focus Duration based on total strain for the period would be 4:00.

    Athlete Type simplifies the interpretation of the Focus Duration by providing a category for a range of durations. For example, a Focus Duration of 4:00 would be classified as a Puncheur (4 minute power) as the value 4:00 is closest to this Athlete Type.  A value of 8:43 would be classified as a GC Specialist and would have ratios 82/15/3.  Ratios and thus durations depend on the athlete’s Fitness Signature.

    The Strain Progression Chart uses exponentially weighted moving averages rather than using sum totals for low, high and peak strain values and uses these to establish Focus Duration and Athlete Type.

    For information on how to understand the Focus Target provided by the Adaptive Training Advisor, consult the FAQ on this topic.

  • Form

    This is determined by the formula Training LoadRecovery Load.  It is colour-coded on the XPMC chart according to the Fresh-Tired scale used on Training Status and Form.  It is analogous to Training Stress Balance or TSB used in the Banister Impulse Response Model.

  • FTP

    Also referred to as Functional Threshold Power, it is the exercise intensity at which lactate begins to accumulate beyond steady-state levels. It is often considered by athletes as the maximum power that can be sustained for an hour, however the duration at which an athlete can ride at FTP typically varies between 40 and 70 minutes. In Xert, Threshold Power closely matches that of FTP. In general, for most athletes, Threshold Power is slightly above FTP. Inspecting a power-duration curve using the Xert Fitness Signature calculator reveals the difference.  Here’s an example:

    Here we have FTP = 280.8 watts and Threshold Power = 282 watts.

  • Hardness

    This is a new performance metric introduced in Xert that provides a way to measure an athlete’s ability to endure discomfort.  It is determined via a Hardness Test.  There are 16 levels.  The basis for the tests is to use a similar workout pattern but increment total XSS for the workout, whereby Level 1 generates 50 XSS in one hour and Level 16 generates 200 XSS in one hour, with each level incrementing the total XSS by 10 XSS points.  Hardness tests are based entirely on XSSR intervals.

    Hardness Tests add more strain without bringing the athlete to a point-of-failure (i.e. without having power reaching MPA).  Each workout gets harder and harder, in effect, without forcing the athlete to have to stop.  Stopping is voluntary.

  • HIE

    See High Intensity Energy.

  • High Intensity Energy

    Also used as the acronym HIE, this is the amount of energy or work capacity an athlete has above Threshold Power (TP).  Analogous in many ways to the term W’ used in physiology research, which has also been referred to as Anaerobic Work Capacity (AWC) in the past, HIE is measured in kilojoules.  The most notable difference between HIE and W’ is that HIE can never be completely depleted.

    During exercise, HIE depletes when work is performed above TP and replenishes during rest or when work is performed below TP.   At TP, HIE remains unchanged.  For example, if your HIE is 20kJ, after performing 500 seconds at 10 watts above TP, your HIE would be reduced by 500*10 joules or 5kJ, i.e. 15kJ.

    HIE is used together with TP and Peak Power (which together form your Fitness Signature) in Xert to calculate MPA, second-by-second.   Note that mathematically-speaking, MPA limits how quickly HIE can be depleted.


  • Improvement Rate

    As a key part of Xert’s Adaptive Training Advisor engine, Improvement Rate describes the rate at which you would like your overall training to increase. The faster the rate, the more training you need to perform, both in intensity and in time. Ranging from Off-Season to Extreme-2, the values correspond to the following weekly XSS Ramp Rate:

    Improvement Rate Weekly XSS Ramp Rate Description
    Off-Season -2 The Off-Season Improvement Rate can be used during times when you are intentionally looking to decrease your Training Load in preparation for an increase in training in the future. Switching to Off-Season can help you recover from a long period of training and give your mind and body a rest before getting into a more intense training regimen.
    Taper -1 This is the rate to choose once you’ve reached your goal and would like to maintain your fitness a week before your event and ensure you are appropriately recovered.
    Maintenance 0 This is the rate to choose once you’ve reached your goal and would like to maintain that level of fitness and performance.
    Slow 1 Generally used for blocks where you’re wanting to ease into your training period without a large time investment.
    Moderate 2 / 3 This choice enables a balance of higher intensity and volume with consistent recovery, enabling this improvement rate to be sustainable over longer blocks of training.
    Aggressive 4 / 5 An aggressive improvement rate can offer an opportunity to generate a great increase in your training load and fitness levels for a 3-4 week block. When training is executed precisely, it should be followed by a rest week to regain sufficient freshness before starting the next block of hard training.
    Extreme 6 / 7 Extreme levels offer an opportunity for high overloading and are great as a short term boost before your taper. Requiring both an increase in time and intensity, use these sparingly throughout the training calendar as they quickly lead to fatigue, requiring additional recovery.


  • Lower Threshold Power

    Also referred to as LTP, this represents a modeling artifact associated with the depletion of Endurance Energy. As endurance energy declines over the course of a long activity, slow-recovery / long-term fatigue takes hold and Threshold Power, High Intensity Energy and Peak Power decline.  The affect of long-term fatigue manifests in reduced MPA and MPA that declines more rapidly.  LTP represents the lowest possible value for Threshold Power when all Endurance Energy reserves have been depleted:

  • LTP

    See Lower Threshold Power.

  • Maximal Effort

    Synonymous with point-of-failure, this refers to moments during an activity where an athlete attempts to produce as much power as he/she has available.   Maximal effort and point-of-failure are synonymous because both instances define the convergence of MPA and power.  A maximal effort has the athlete attempting to sprint and generate as much power to reach MPA whereas a point-of-failure has the athlete attempting to hold on to power has MPA declines and reaches the desired power.  In both cases, from the perspective of the data, MPA and power are equal.

  • Maximal Effort Time

    This is a duration, typically in seconds or sometimes minutes and seconds (mm:ss) that defines how much time during an activity, an athlete was close to MPA.  Because fatigue hurts, reaching and spending time at your absolute limit (a maximal effort or point-of-failure) doesn’t occur with great frequency in data.

    Maximal Effort Time uses an algorithm to determine how much time an athlete spent close to MPA.  It is assumed that if an athlete doesn’t spend much time near MPA, then the activity doesn’t express the athlete’s fitness signature.  That is, the activity is determined to be sub-maximal.  The signature extraction process is therefore skipped and it is assumed that the athlete’s signature remains relatively unchanged from the previous activity’s signature.

    However, when Maximal Effort Time is above a predefined level (current set at 5 seconds), it is presumed that those moments near MPA during the activity were expressive of the athlete’s fitness and a fitness signature is extracted from the activity and recorded.

    Maximal Effort Time is depicted in the size of the circles and medals shown on Progression Charts along the Threshold Power lines.  One may consider that the greater the Maximal Effort Time, the greater the expression of the athlete’s fitness occurred in the activity.

  • Maximal Power Available

    Also referred to as MPA™, Maximum Power Available or Max Power Available, it is a measure of the maximal power an athlete can generate at a given moment during exercise.  As an athlete fatigues, MPA declines.  As they recover, it increases. The point where the athlete’s power is equal to MPA is defined as a point-of-failure or maximal effort.  It is calculated by using power data together with an athlete’s Fitness Signature to calculate the athlete’s ability to generate power at any given point in time.

  • Mean Maximal Power

    Also referred to as the acronym MMP, this represents that highest average power for a given period.  It is used in Xert’s Workout Designer to represent the highest power that is sustainable for a given duration.  For example, 20 minutes MMP represents the highest power that can be sustained for 20 minutes.

    MMP is also used interactively in Xert Mobile to represent the highest power that could be sustained for a duration at a given moment.  For example, after 12 minutes at your 20 minute MMP which is, say, 250 watts, at that moment, your 8 minute MMP would be 250 watts.

    N.B. Although the term MMP is used in Xert, it would be more correctly described as maximal sustainable power, since Xert establishes your power duration relationship based on fresh-to-failure, steady-state efforts and not on average power.  Using MMP calculations from regular power data is more commonly used to establish the power-duration relationship, despite its limitations.  The term MMP has been chosen because the concept is more readily understandable.

  • MMP

    See Mean Maximal Power.

  • MPA

    MPA stands for Maximum Power Available. It is a measure of the maximum power an athlete can generate at a given moment during exercise. As an athlete fatigues, MPA declines. And as they recover, it increases. For more information, see Maximal Power Available.

  • Peak Power

    As one of the three parameters that define an athlete’s Fitness Signature, this is an athlete’s highest possible power.  Sometimes it is referred to as Pmax.  MPA is equal to Peak Power when an athlete is not fatigued.

    N.B. Mathematically, Xert’s calculation of the power-duration relationship is identical to P = CP + W’/t when Peak Power is infinite.

  • Polarity Ratio

    Polarity Ratio represents the total amount of strain above threshold power to the total amount strain below threshold power. It looks at your work/strain allocation ratios for the strain you accumulate during training to establish the follow ratio:   (peak strain + high strain) : low strain. For example, according to this chart, representing the work allocation for a 4 minute Puncheur Focus with Pure Specificity rating, the polarity ratio is 30:70.

  • Power Curve

    Synonymous with Power-Duration Chart and Power-Duration Curve, this describes the relationship between how long an athlete can sustain a given power, starting from fresh, at a steady-state, and ending with the inability to sustain the given power.  Inability to sustain the given power is also termed a point-of-failure.

    In Xert, your power-duration relationship is determined by applying a special use-case of MPA.  The duration that an athlete can sustain a given fixed work rate (i.e. state-state power) is determined by calculating how long will it take MPA to reduce from Peak Power until steady-state power equals MPA.  This calculation can be performed at any given intensity to determine duration or using a given duration to determine the steady-state power.  Note that since the athlete’s Fitness Signature is used to formulate MPA, your Fitness Signature can be depicted as a power-duration curve for visualization and to help interpret fitness.

    An alternative approach to defining the power curve is to use Mean Maximal Power (MMP) data.  Using MMP generally results in similar values to steady-state, fresh-to-failure efforts as described above but can have more variance.  A power curve defined using MMP data, obtains the highest average power over a given duration from an athlete’s power data.  There is a presumption that the efforts are started from fresh, didn’t have periods of rest or partial rest and ended with the athlete’s inability to sustain the average power over the period.  One must acknowledge that the occurrence of such data – where the athlete starts from fresh, doesn’t have any moments where power drops below Threshold Power and where the athlete’s inability to sustain the average power did not precede nor could have succeeded the end of the period – is rare in regular power data.

    Below are two power curves, the red curve is derived from MMP data whereas the purple curve is derived by determining the Fitness Signature that expressed the MPA for the activity.  Only when the red and purple coincide, was the corresponding MMP effort started from fresh, didn’t have moments below TP and ended in a point-of-failure.  In this sample activity, no MMP efforts exhibited this.

  • Program Phases

    Training Programs are currently set at 120 days and count backwards from your Target Event Date.  The first 45-days of your program is your Base Phase which incorporates mostly Endurance-focused training. The second 45-days is your Build Phase which starts to introduce greater intensity into your training. The final phase is your Peak Phase which lasts 30 days and targets your power for the Athlete Type you have selected.

    Here is an example training program for a Puncheur.  In the base phase, training is focused on Endurance. In the peak phase, it is focused on Puncheur. In between, the change is periodized.


    If your Training Program has not yet started, you are in the Pre Base phase of your program. If your Target Event Date is in the past, you’re in the Post Event phase of your program. In both cases, there is no specific guidance used for the Focus of your training; the advisor simply offers a wider variety of workouts that are near your Athlete Type.

  • Ramp Rate

    Ramp Rate is the numeric form of Improvement Rate. It is the rate at which your overall Training Load is increasing. It ranges from -2 (the “Off-Season” Improvement Rate) to +7 (“Extreme 2” Improvement Rate).

  • Rating

    Also referred to as Difficulty Rating, this is a calculation that uses the calculated Difficulty Scoring for a workout or activity and is determined as the highest difficulty score attained. As a general rule, those workouts/activities with greater difficulty require a higher training status to be successfully completed by the athlete, although there is variance amongst individuals. Races and/or intense groups rides often result in a higher Difficult Rating due to the added motivation on behalf of the athlete.

    The ratings are categorized as follows:

    Rating Recommended Minimum Training Status Level Difficulty Score
    1 Easy Less than 60
    1.5 Easy From 50 to 60
    2 Moderate From 60 to 75
    2.5 Moderate From 75 to 90
    3 Difficult From 90 to 110
    3.5 Difficult From 110 to 130
    4 Tough From 130 to 150
    4.5 Tough From 150 to 170
    5 Hard Greater than 170


  • Recovery Load

    Also referred to as RL, this is part of the XPMC and represents the exponentially-weighted moving average of activity XSS values based on the Recovery Load Time Constant.  It can be subdivided into Peak, High and Low Recovery Load.  It is analogous to Acute Training Load in Banister’s Impulse Response Model.

  • RL

    See Recovery Load.

  • Signature Decay Method

    The Signature Decay Method identifies the algorithm that will be used to model the detraining effects that occur between your activities. For example, if you go four weeks without training, the Fitness Signature you have now will not be the same as what it was four weeks ago.

    Xert will model this decline in fitness signature, i.e. a decay, after each activity. If you train on a regular basis, this decay will not be apparent. But if you stop or decrease down your training, there will be an affect on your fitness.

    There are 4 options when selecting a decay method:

    Decay Method Description
    No Decay – Training Load Matched The No Decay method can be used during periods where you are training but not performing any maximal efforts, AND you wish to have the system track your increases & decreases in fitness signature more precisely over this period. Using this method will tell the system to increase/decrease your signature parameters as your training load increases/decreases.

    WARNING: If you use this decay method over longer periods, particularly if anomalies exist in your data (even subtle ones), your fitness signature may end up being higher than what you can achieve and you will no longer be able to obtain a fitness breakthrough. If you are using this setting and haven’t seen a breakthrough in a while despite many efforts, you may want to choose another decay method.

    Small Decay This decay method falls in between Optimal and No Decay and can be used to fine tune your signature to reduce the impact of a decay, for training purposes.
    Optimal Decay – Default This is the default decay method used by the system. It will follow your breakthroughs and your training loads as they move up and down. It has an additional decay that will still express your fitness in cases where your signature numbers have inadvertently become too high. This ensures that your progression data stays accurate and provides opportunities for breakthroughs to validate your progress.

    Optimal Decay works well during all training phases, including during the base period, as it will generally maintain your fitness constant as your training loads increase, allowing you to maintain your training targets during the period.

    Aggressive Decay This decay method will trigger more breakthroughs and variation in your progression to help identify potential decreases or increases that may be missed when using the other methods.


  • Specificity Rating

    This is a percentage value that provides further detail on a Focus. With Focus Duration characterizing the duration along the Power Duration curve being focused on, Specificity Rating characterizes how specific the strain accumulated matches the precise work allocation ratios. 100% specificity rating is Pure and means that all the strain accumulated was at the power on the Power Duration chart associated with the Focus Duration. 0% specificity rating is Polar and all the strain accumulated was either at Peak Power or below Threshold Power. Generally speaking, cycling often has specificity ratings that are in-between pure and polar. These are classified as Mixed.

    • Pure = 100% – 67%
    • Mixed = 67% – 33%
    • Polar = 33% – 0%

    Ultra-Short Race Pace Training (USRPT), for instance, is an example of training at a pure specificity rating. Training is done at intensities that match a given intensity only.

    One way to conceptualize, Specificity Rating, especially if you plan on performing adhoc workouts:

    • Pure – You spent a majority of your time at or near the Focus intensity.
    • Polar – You spent a majority of your time at Endurance intensity with efforts above your Focus intensity.
    • Mixed – You had a mix of Endurance, Focus intensity and efforts above and below it.

    You can fine tune your riding/running on the fly in achieving the target Focus or choose your workout by using these concepts.

  • Strain

    Measured in joules, this quantifies how much work is performed close to MPA. As MPA drops with fatigue, strain increases at the same intensity. Each joule of strain can be divided into low, high and peak strain according work allocation ratios, based on per second work (equivalently each second’s power data value).

    When strain is normalized to equal 100 points for one-hour of unfatigued work at Threshold Power, it is referred as Xert Strain Score.

  • Stress

    Synonymous with work, this metric is measured in joules and is the total work performed over a given period or activity. Using work allocation ratios, stress can be divided into low, high and peak stress over any period.

  • Target MPA

    Also referred to as TMPA, this is used in the definition of intervals in the Xert Workout Designer and represents the end point for a given workout interval.  Rather than specifying a duration for an interval, a Target MPA based interval specifies an MPA value.  The Target MPA is determined either as an absolute value or as a percentage of PP, TP or Power Reserve.  Target MPA using percentage of Power Reserve is defined as TP + percentage * (PP-TP).

    Target MPA based intervals can be used for both high intensity efforts (where MPA declines) and recovery intervals (where MPA rises), where the target power is above and below TP, respectively.

    N.B. It is not possible to reach at Target MPA that is below the target power.  For example, if an interval’s target power is 500 watts, it is not possible to define a Target MPA of 400 watts since it would not be possible to reduce MPA below 500 watts at a target wattage of 500 watts.  Once MPA reaches 500 watts, the target power cannot be sustained and so the lowest Target MPA that can be assigned to a 500 watt interval is 500 watts.

    Xert Mobile’s Workout Player and Xert Player for Connect IQ support the ability to manage fatigue in order to ensure the Target MPA is reached during workouts.  Calculations are based upon whether the interval has a declining or rising MPA value.  For example, if an interval has a declining MPA to a given Target MPA level, the players will speed up interval time if the athlete maintains a power above the target power and will slow down interval time if the athlete maintains a power below the target power for the interval.  Conversely, during rising MPA intervals, interval time will speed up if that athlete maintains a power below the target power and will slow down the timer if the athlete maintains a power above the target power.  These dynamically managed fatigue intervals help ensure that the athlete achieves the goals as determined by the workout design.

  • Threshold Power

    Also used as an acronym TP in Xert and sometimes described using the more colloquial term FTP, Threshold Power is a Fitness Signature parameter that represents the highest power that can be sustained without accumulating short-term fatigue.  Threshold Power can generally be sustained for just under an hour by most athletes, assuming that the discomfort generated is tolerable by the athlete over the entire period.

    Worthy of note is that Threshold Power is affected by work performed, with work performed at higher intensities having greater affect.  This must be true otherwise it could be sustainable at any time, even after an hour of high intensity effort.

  • Time to Exhaustion

    Also referred to as TTE and time-to-failure, it is the time remaining, at a given work rate (power or intensity) before the given work rate cannot be maintained.  For example, TTE at 500W could be determined to be 60 seconds.  This means that if you were to start an effort at 500W, you could sustain it for 60 seconds before you wouldn’t be able to sustain 500W and reach a point-of-failure.  From an MPA perspective, after 60 seconds at 500W, MPA would be 500W.

    N.B. The term “exhaustion” is used but in many cases, particularly at very high intensities, failure is reached before the feeling of exhaustion.  Say for example, that your TTE at 1000 watts is 10 seconds.  After 10 seconds at 1000 watts, you would be unable to sustain 1000 watts.  However, you could still produce just under 1000 watts and would not yet *feel* exhausted, despite the inability to sustain the power.  TTE as used in this scenario but would more appropriately be termed time-to-failure and not TTE.  TTE has been selected as it is a more familiar term and concept.

  • Time to Recovery

    Also referred to by the acronym TTR, this represents the amount of time to recover from a high-intensity effort.  Time to recover can also be associated with a recovery intensity.  For example, TTR at rest (0 watts) is shorter than TTR at 150 watts, assuming Threshold Power is above 150 watts.  That is, you recover sooner at 0 watts than you do at 150 watts.  Using a recovery power other than 0 watts is useful to keep track of how long it will take to recover while still producing power, such as riding in a group behind the draft.  Recovery power cannot be greater than or equal to Threshold Power.

    TTR is a key feature in workout design using Target MPA.

  • TL

    See Training Load.

  • TP

    See Threshold Power.

  • Training Deficit

    See Training Deficit and Surplus

  • Training Deficit and Surplus

    The Xert Adaptive Training Advisor uses your chosen Improvement Rate to determine if you need to train or if you can afford to take time off in order to meet your Improvement Rate goals. By adding up the training you have done over the past week, the XATA calculates how much below (a deficit) or above (a surplus) you are at this moment compared to your weekly Improvement Rate goal. This provides feedback on the amount of training needed to deliver the improvement you’re looking for, and the progression in your fitness.

    The value is calculated based on your past week and doesn’t carry over, meaning that if you missed reaching your target the previous week, you don’t have to make up for it this week. Similarly, if you went over the previous week, it doesn’t mean you can stop training this week. The amount of training you need to perform is calculated on the current week (exactly 1 week ago to the minute).

    If you performed high XSS workouts a week ago you may find more variability of your deficit / surplus numbers than expected. This is normal as the XATA encourages you to keep progressing week-to-week based on the elevated levels your previous training achieved.

    If you start to fall behind with a large deficit, the XATA will boost your Workout Goal to encourage you to reduce the deficit. If you’re finding it too difficult to reduce your deficit your Improvement Rate may be set too high. If you’re finding you often have a large surplus and the XATA is giving you more time off than you’d like, your Improvement Rate may be set too low.

  • Training Load

    Also referred to as TL, and a component of the XPMC, this represents the exponentially-weighted moving average of activity XSS values based on the Training Load Time Constant.  It can be subdivided into Peak, High and Low Training Loads.  It is analogous to Chronic Training Load in the Banister Impulse Response Model.

  • Training Status and Form

    This provides a simpler way to view current Training Load and Recovery Load. The number of stars indicate the total amount of Training Load an athlete has accumulated. The colour indicates the total amount of Recovery Load an athlete as accumulated. Form (Training Load – Recovery Load) is calculated relative to Training Load to determine the colour:

    Status Description Training Advice Prescribed
    Freshness Blue – Fresh: 0 < Overall Form < 30% of Training Load

    Green – Very Fresh: Overall Form >= 30% of Training Load

    Brown – Detraining: Overall Form > 60% of Training Load

    Periodized based on Program Phase,
    increasingly towards your chosen Target Athlete Type
    Tiredness Yeslow – Tired: Low Form > -30% AND High + Peak Form > 0% of Training Load

    Red – Very Tired: Overall Form <= -30% of Training Load

    Yellow – Endurance Workouts
    Red – Recovery Workouts

    0 Stars – Untrained: Training Load < 25
    1 Star – Recreational: 50 > Training Load >= 25
    2 Stars – Trained: 75 > Training Load >= 50
    3 Stars – Competitive: 110 > Training Load > 75
    4 Stars – Elite: 150 > Training Load >= 110
    5 Stars – Pro Level: Training Load >= 150

  • TTE

    See Time to Exhaustion.

  • TTR

    See Time to Recovery.

  • Work Allocation Ratio

    Sometimes referred to as Work Contribution Ratios, these ratios divide work and strain into peak, high and low.  Since the three Fitness Signature parameters can be used to determine and predict your maximal power available, an athlete’s ability to perform must work integratively into each of these parameters.  That is, each parameter represents an integrated fitness measure and all three together can be used to effectively represent an athlete’s fitness.  This is true because MPA, which is derived from the Fitness Signature, is predictive of an athlete’s ability to perform.

    Therefore, we can assign for each joule of work performed, how much influence each fitness signature parameter had in the production of the work.  Similarly, we can assign for each joule of strain, how much influence each fitness signature parameter had in the generation of that strain.  When we do so, we allocate work or strain according to these ratios.

    • Low Work / Strain / Training Load / Recovery Load / XSS is determined by Threshold Power
    • High Work / Strain / Training Load / Recovery Load / XSS is determined by High Intensity Energy
    • Peak Work / Strain / Training Load / Recovery Load / XSS is determined by Peak Power

  • XATA

    The Xert Adaptive Training Advisor is a smart training recommendation engine that factors in many variables obtained from analysis of your data. See Xert Adaptive Training Advisor for more…

  • XEP

    See Xert Equivalent Power.

  • Xert Adaptive Training Advisor

    The Xert Adaptive Training Advisor is a smart training recommendation engine that factors in many variables obtained from analysis of your data. Here are some of the variables that are accounted for in the advice provided:

    • Current Training Loads by each system – Low, High, Peak
    • Current Recovery Loads by each system – Low, High, Peak
    • Current Form by each system – Low, High, Peak
    • Overall Training Status
    • Your current Fitness Signature, established via MPA Analysis and Fitness Signature extraction, including Threshold Power
    • Your freshness – Very Tired to Very Fresh
    • The rate at which each Training Load is increasing / decreasing
    • Your desired Improvement Rate
    • Your Target Event Date
    • The phase of your program
    • Your Target Athlete Type
    • The number of activities you performed recently
    • The average duration for your activities
    • The XSS you accumulated for each activity

    With this information, the training advisor then estimates:

    • The deficit / surplus of training you have at the moment
    • The amount of hours you will need to maintain to sustain the improvement rate you have selected
    • The target Focus you should have for your next workout, based on the phase  and target event date
    • The recommended Focus based on your target Focus and freshness
    • The workout XSS goal you should have for your workout
    • Whether you need a recovery week
    • The Difficulty you can handle in your training based on your current training loads and desired improvement rate

    With all this information, each workout is scored based on how they best match your current training needs.  From here, the best workouts are chosen and presented as recommended workouts.  When you load the workout onto one of the Xert Workout Players, they are tuned to your capabilities and training level automatically, adjusting target intensities on-the-fly, ensuring you reach the right targets as you execute the workout.

    When new activities are received, you update your Target Event Date,  update your Improvement Rate or just recover, the adaptive algorithm will readjust the recommendations, always ensuring you’re on the right track with your training.

  • Xert Difficulty Scoring

    Difficulty provides a measure of how much strain has accumulated over the course of an activity or workout.  Rather than using simple averages or normalized averages, Difficulty establishes the impact of repetition and constant, higher intensity efforts are to perform for the athlete based on their unique fitness signature.  It is determined as an exponentially weighted moving average of XSS Rate.  For example, single, exhaustive efforts are easier to perform then repeated, exhaustive efforts.  Difficulty captures and quantifies the effects of repeated and/or sustained hard efforts and is shown in activity charts and workouts. The highest value reached in an activity/workout determines the Difficulty Rating.  Reaching higher levels of difficulty corresponds with increasing athletic hardness and is a marker of elite athletic ability.

    Consider this metric to improve your pacing and strategy during group rides, races and time-trials by looking to prevent increasing the difficulty unnecessarily. One can compare the trade-offs in improved results with the challenge of meeting the higher levels of difficulty that will need to be endured.

  • Xert Equivalent Power

    Also called XEP, this represents the average power that more closely resembles what the athlete experienced during the activity. The more time the athlete spends working near MPA, the higher the XEP value will be relative to the average power.

  • Xert Progression Management Chart

    Also referred to as the XPMC, the chart plots your daily Training Load, Recovery Load (hidden by default), Form, daily XSS. For convenience, and Xert also plots Threshold Power / Best Activities line.

  • Xert Strain Score

    Also called XSS, this quantifies how much strain an athlete endures during an activity.  By taking strain, which is measured as the amount of work performed close to MPA, and normalizing it with the athlete’s Fitness Signature, one-hour at Threshold Power equates to 100 XSS.  Note that an athlete can experience greater than 100 XSS in an hour if the work is performed under short-term fatigue.  That is, 100 XSS is one hour at Threshold Power, unfatigued.  Under fatigue, one hour at Threshold Power can be much higher than 100 XSS.

    XSS can be subdivided into low (XLSS), high (XHSS) and peak (XPSS) according to work allocation ratios.  Xert Mobile, for example, will provide real-time XLSS, XHSS and XPSS totals during the recording of an activity.  Each of these strain scores can be used in separate Training Load and Recovery Load calculations which can then map to individual Impulse Response models for each Fitness Signature parameter.

  • Xert Training Pacer

    This gauge provides a visual representation of your Training Deficit and Surplus, determined by your relative change over the past week as compared to your chosen Improvement Rate.This gauge provides a simple visual cue as to whether your training is on-target (inner grey), is ahead of plan (inner blue) or if you are falling behind (inner red).  It also indicates if you need to train (outer grey) or if training is optional (outer blue).    The second arrow represents where you will be tomorrow (i.e. 24 hours from now) and is colour-coded using the same colours as your Training Status:

    • Brown: Detraining – No constraints
    • Green: Very fresh – No constraints
    • Blue: Fresh – No constraints
    • Yellow: Tired – Endurance only
    • Red: Very tired – Recovery only

    This second indicator can be interpreted as: “If I don’t train today, where will I be tomorrow?” with the colour indicating what type of training you will likely have recommended by the system.  No constraints means that the system won’t avoid recommending a high-intensity workout if your program suggests it. Endurance only means that the system will lean towards suggesting an Endurance workout and Recovery only means it will be a recovery day and only recovery workouts will be recommended.

    N.B. If you have a planned activity in the Fitness Planner within the next 24 hours, the triangle may point to the right of the main needle as it is accounted for in the calculation.

  • XHSS

    Xert High Strain Score.  See Xert Strain Score.

  • XLSS

    Xert Low Strain Score.  See Xert Strain Score.

  • XPMC

    See Xert Progression Management Chart.

  • XPSS

    Xert Peak Strain Score.  See Xert Strain Score.

  • XSS

    The Xert Strain Score quantifies how much Strain an athlete endures during an activity. By taking Strain, which is the amount of work performed close to MPA, and normalizing it with the athlete’s Fitness Signature, one-hour at Threshold Power equates to 100 XSS. Note that an athlete can experience more than 100 XSS in an hour if the work is performed under short-term fatigue. For more, see Xert Strain Score.

  • XSS Rate

    Also referred to as XSSR, it represents the work rate (power or intensity) that is equivalent to generating a given amount of XSS in one hour.  It is used in workout designs to provide a way to target an intensity that will produce a given amount of strain.  For example, maintaining an XSSR of 200 for 15 minutes will generate 50 XSS points (200 / ( 60 / 15)).

    XSSR based intervals can have variable power.  As MPA declines with fatigue, the work rate associated with a given XSSR also declines.  Similarly, during recovery, as MPA rises, XSSR based intervals also see a rising target power.  Xert Mobile and the Xert Workout Player for Connect IQ calculate power levels that are equivalent to XSSR values defined in the workout interactively using a complex algorithm.  These intervals can also be used in combination with Target MPA intervals which make these dynamic in both intensity and duration.

  • XSSR

    See XSS Rate.