Your heart rate supplies essential information of effort and energy expenditure. Improvement in physical performance is associated with an enhancement of what has been labelled by physiologists as VO2 max. This is the standard measure of what is called aerobic fitness and indicates the maximum amount of oxygen that can be taken from circulating blood and used by active tissues for a specific period. It is measured in millilitres of oxygen consumed per minute adjusted for body size. A sedentary male would show a reading of 35 to 50 ml/kg/min. An elite runner would be something in excess of 70ml/kg/min.
Physiologists estimate that the greatest fitness gains come from work at between 80/100% of VO2 max. To calculate VO2 max it is necessary to know your maximum possible heart rate. Laboratory testing uses a treadmill for this assessment. A formula can be used which it is claimed has a 0.8 correlation with a laboratory test.
For a 25yr old female, assume a maximum heart rate of 209 beats per minute (bpm) minus 0.7 for each year of age, e.g. 209 minus 25 x 0.7 = (17.5), therefore, 209 minus 17.5 = 191.5 bpm. Assuming 80% of heart rate for what is called the lactate threshold run, would require a consistent effort of 153 bpm. It is claimed that this would be the minimum for a modest increase in VO2 max
For a 25yr old male athlete, take a maximum heart rate of 214 bpm and a minus of 0.8 for each year of age and the example would be 214 minus 25 x 0.8 = (20) therefore 214-20 = 194bpm. 80% of this would require a consistent effort of 155bpm. There is some controversy on maximum heart rate with some physiologists claiming that using this formula, a maximum heart rate of 200bpm is more realistic.
To calculate your maximum heart rate while actually running, check out a session in this article here.
The number and duration of lactate threshold runs undertaken should be a subject of discussion between the athlete and the coach and would obviously relate to an athletes level of fitness and experience, but 2 sessions would be the norm and 3 for well trained athletes.
The use of a heart rate monitor during the week will help you determine what pace to run at in each intensity zone. It is important to run at the right rate for the right zone to gain the maximum benifit from your training. This includes easy recovery runs. See our article regarding these zone rates here.
Also have a look at our guide to maximising your heart rate monitor. It's all very well buying one, but using it properly takes a time of time and know-how.