The below information should help provide you with guidelines for designing fitness and conditioning sessions with specific training objectives.  Due to the intermittent exercise profile of football, players require a strong aerobic base in addition to capabilities to perform maximal bouts (i.e. sprints) and must be exposed to various training zones. The energy systems of a player therefore have to be trained with this profile in mind.  An easy way to determine if the workrate matchs the desired training zone is to using Heart Rate (HR).  Calculate Training Zone Via Resting Heart Rate

Fig 1. 3 Basic Training Zones and for a Trained and Un-Trained Player

The diagram above (Fig 1.) displays the training zones for a trained and untrained player (20yrs).  The zones are indicated for the Trained Player only.  The Un-Trained Player would hit these zones earlier.   This chart above displays the three basics training zones.  We can however go into more detail (as described below and displayed in Fig 2.)  and sub-divide these zones.  The zones are set based on percentages of generally one of three values:

• Lactate Threshold
• VO2 Max
• Maximum Heart Rate

Fig2. Detailed Training Zones with Heart Rate for U-11 to U-21 ages.

Zone 1: Recovery

Also known as: Overdistance
Intensity: Very Low
% Lactate Threshold: 65%-84%
% VO2 Max: 55%-65%
% Max Heart Rate: 60%-70%
RPE Scale: 6-9

Used for: These are the easiest workouts, used to promote recovery after harder workouts. It is also generally the intensity level used during the recovery period of interval work and long slow distance (LSD) runs.

Zone 2: Endurance

Also known as: Extensive Endurance
Intensity: Moderate
% Lactate Threshold: 85%-91%
% VO2 Max: 66%-75%
% Max Heart Rate: 71%-75%
RPE Scale: 10-12

Used for: Used for long, endurance workouts and easy speed workout; builds and maintains aerobic endurance.

Zone 3: Lactate Threshold

Also known as: Intensive Endurance
Intensity: Moderate Plus
% Lactate Threshold: 92%-95%
% VO2 Max: 76%-80%
% Max Heart Rate: 76%-80%
RPE Scale: 13-14

Used for: Used for Tempo workouts, training in Zone 3 is usually done in the preparation and base phases. Generally, in the later phases you want to bump up to Zone 4.

Zone 4: VO2 Max Intervals

Also known as: Anaerobic Threshold, Race/Pace
Intensity: Race/Pace
% Lactate Threshold: 96%-100%
% VO2 Max: 81%-90%
% Max Heart Rate: 81%-90%
RPE Scale: 15-16

Used for: Intervals, hill work, and tempo work. Intervals in this zone generally have work-to-rest ratio of 3:1 or 4:1. Training at or slightly below your Lactate Threshold (a.k.a. Anaerobic Threshold) helps your body lean to "recycle" the lactic acid during high intensity work. This level is where you cross over from aerobic training to anaerobic training which is called the anaerobic threshold or AT. This is the point where the body cannot effectively remove lactic Acid from the working muscles quickly enough. Lactic Acid is a by product of glycogen consumption by the working muscles.

Zone 5a: Threshold Endurance

Also known as: Superthreshold
% Lactate Threshold: 100%-102%
% VO2 Max: 91%-93%
% Max Heart Rate: 91%-93%
RPE Scale: 17

Used for: Intervals, hill work, and tempo work; typically used after some Zone 4 time has already been done. Zone 5 workouts are very short because it is difficult to maintain this level for any length of time.

Zone 5b: Anaerobic Endurance

Also known as: Speed Endurance
% Lactate Threshold: 103%-105%
% VO2 Max: 94%-98%
% Max Heart Rate: 94%-98%
RPE Scale: 18-19

Used for: Intervals and hill work to improve anaerobic endurance. Intervals in this zone generally have work-to-rest ratio of 1:1, for example, a 20 second sprint followed by 20 seconds of easy recovery (Zone 1).

Zone 5c: Anaerobic Capacity

Also known as: Power
% Lactate Threshold: 106%+
% VO2 Max: 98%-100%
% Max Heart Rate: 98%-100%
RPE Scale: 20

Used for: Short-term Sprinting. Intervals in this zone have a work to rest ratio of 1:2 or more.