There are 3 zones defined by the blood lactate level: green, yellow and red.
Blood lactate level is the physiological characteristic of the human body to perceive the physical activity.
Higher intensity workouts result in a higher blood lactate levels.
Low intensity 60min+ duration activities: walking, jogging, cycling, swimming etc.
Lactate blood concentration is low and ranges from 0 to 2 mmol/l.
Health benefits you get working out in the green zone:
The cardiovascular system stimulation / blood pressure normalization / blood work improvements
Increased body oxygen consumption / improved endurance
Fat burn for the energy production
Positive effect on the immune system / infections resilience
Stress relief and endorphins
It feels good
Intense 40min+ duration activities: running, skiing, cycling, swimming etc.
Interval training, cross fit, circuit training, step, aerobics, pilates, yoga etc.
Team sports: soccer, basketball, etc. Individual sports: alpine skiing, tennis, squash etc. Fight sports.
Lactate blood concentration is medium and ranges from 2 to 4 mmol/l.
By working out in the yellow zone you train:
Carbohydrates metabolism: increasing the body glycogen reserves
Ability to perform activities with a high blood lactate
Maximum oxygen consumption: increasing VO2max
Anaerobic threshold heart rate: shifting to a higher HR values
Finish spurts, climbs, accelerations etc
Speed endurance and repeated short sprint capacity
Strength
Safe yellow zone workouts requires a foundation of a large amount of the green zone completed work.
High intensity explosive workouts: sprints, jumps, short interval training, heavy lifting etc.
Lactate blood concentration is high and ranges from 4 mmol/l and above.
Red zone workouts allows you to:
Increase the body ATP and phosphocreatine reserves and its regeneration speed
Improve the starting speed and acceleration
Train and gain explosive power
Attention: Lactate accumulation above 6 mmol/l (acidosis) may cause muscle cells walls damage, aerobic endurance impairment, fat burn blockage, overload; it reduces coordination and increases the injury risks.
During a workout all three energy systems are ON supplying energy.
The contribution of each system depends on the activity type.
Green zone energy demand is covered mostly by the aerobic system.
Yellow zone energy demand is covered mostly by the anaerobic system.
Red zone energy demand is covered mostly by the phosphate system.
Learn more about the Body Energy Systems.
Peter Janssen. Training Lactate Pulse-Rate. Polar Electro (January 1, 1987). ISBN-13 : 978-9529006687
Martin Kusch etc. Training im Griff. EKF diagnostic Sales GmbH (Auflage 2006). ISBN-Nr. 3-935185-42-1
Raymond Verheijen. Conditioning for Soccer. Reedswain (August 1, 1998). ISBN-13 : 978-1890946050