You're very welcome Jennie

Aerobics... aerobic zone... aerobic base... a lot of different words to mean the same thing, in as far as training aerobically is concerned; it means
"with air". Yes obviously one always trains with air, however the correct information is ; Aerobic, training aerobically, whatever you want to label it comes down to this, (from latin, well before a USAF chap) training within the physiological ability of each athlete, where there is no acidosis build up, hence, sufficent delivery of oxygen to the muscle cells to buffer the lactic/lactate acid buld up (called buffering) which avoids acidosis.
Past this point, you start going into different levels of "anaerobic" (without air). This means that there is not sufficient oxygen being delivered to the muscles cells, and not quick enough to avoid acidosis, which is a result of no , or a failure of buffering of the lactic/lactate acid build up.
One that starts training running (or cycling, swimming...) should ALWAYS build up a base of aerobic base training.
This is essential. It allows the build up of the mitochondria, cells essential for the transfer of oxygen to ATP (fuel). The more mitochondria you have (genetically determind, but can be improved with adequate aerobic base training), the better the oxygen transfer, and hence, improved ability of buffering lactic/lactate acid...
It is advisable for any athlete to start with a aerobic base training period of at least 2 months, whatever the distance training for. Yes, obviously, this aerobic base does not stop one from participating in races, as a tempo session, every now and then during the aerobic period, is a good change, and reminds the "fast twitch" fibers to prepare to work with the "slow twitch" fibers, called "sparing"
Obviously, each person has their own aerobic heart rate zone. Many formulas exist fo rthis which are all inaccurate... The only way to precisly find out ones (amongst the other heart rate zones ; Recovery, aerobic, Sub L.T (lactate threshold), L.T, Anaerobic, Power...is to effect a Vo2 max test)
The coopers test is a test in which you can "judge" your ability to exercise till exhaustion, or a certain point of performance within a defined time limit, and does not give any true indication of ones aerobic heart rate zone, as it is based on "charts", which are very generalized and do not "pertain" at all to any individual. Remember, each "individual" has their own physiological make up. This cannot be generalized.
Calculating H.R zones from a Vo2 max test are based on proven bases of percentages that stay the course in modern effective sports science from the past decade, and not "charts" based on outdated theories of the past. Look at all top athletes, amateur athletes and any athletes wanting to keep abreast of today's methods that bring proven results that train with these now (as well as other more even advanced tools; for example; power meters zones for cyclists.)
Training in the aerobic zone, (in ones correct aerobic H.R zone), will build a decent base for the athlete to go onto to more intense training in sub L.T and L.T zones. This is where the faster, harder, more intense efforts will be done, building strength, muscular endurance, (as well as anaerobic and power abilities (sprints...).
Any person that neglets the aerobic base, will not have a long lasting season, and will experience the well known "over trained or burnt out" phase, often resulting in big fatigue, listlessness, injury...
So thats what its all about folks, basic physiological science, used corectly can do wonders for your sporting abilities, performances and health...
Enjoy!