I also agree with Malmo, but I think his idea of Specific is not as mine.
His example (which is the difference between 4x1600 or 6x1200 or 8x1000 or 20x400) is not something regarding "Specific", but regarding "Particulars inside the specific".
Specific means, for example, to have a session with the final goal to work for increasing the Aerobic Power.
We can reach this target using different "Particular workouts":
* short interval a little faster than the An Threshold, with high volume (for example, 20x400) and short recovery, and we can develop this system in different ways :
a) reducing, later on, the recovery time
b) moving, with the same total volume, to longer intervals, woth the same recovery time (instead 20x400, 16x500, for example)
* long intervals at the speed of AnT (for example, 5x1600 or 8x1000m), reducing recovery times or modulating them in order to move to longer distances (8x1000 with 2' rec. can become 4x2x1000 alternating 1'and 2' creating couples, after 1' becomes 30", and after the workouts becomes 4x2000 with 2' recovery at the same speed)
* long continuous run, at the speed around AnT.
On the opposite, SPECIFIC means that we can (in my opinion MUST) have different physiological goals during every period of preparation :
About biomechanics :
* To increase the muscle strength (using weights if you are in a Country with long winter, or hills, at max speed in order to recruit the most part of fibers, including the Fast fibres that we don't activate during long run)
* To increase the muscle elasticity (using plyometric exercises, or easy circuits with particular eye for the reactivity)
* To increase the technical efficiency, according to the individual characteristics (for example, if an athlete uses too long strides, to improve his frequency ; or, is a runner use too short strides, to improve the wideness of his strides)
About bioenergetics :
* To increase BASIC AEROBIC RESISTANCE (long run not too slow, depending on the distance)
My suggestion, for Fast and Resistant type of runners, about long run in the Fundamental period, is as follows :
800m : 8 - 12 km
1500m : 12 - 18 km
Steeple : 15 - 20 km
5000m : 20 - 25 km
10000m : 20 - 30 km
HM : 25 - 35 km
Marat. : 35 - 50 km
* To increase AEROBIC POWER (the system I showed before)
* To increase ANAEROBIC RESISTANCE (quality connected with the AnT, that directly influences the rasing of the Threshold itself)
About this, for example, we can use medium intervals (400/600m) with short recovery, at a speed connected with the speed of the race.
For example, for a runner of 800m able running in 1'48" (13"5 every 100m), we cannot develop the ANAEROBIC RESISTANCE using speed slower than 85% of his speed (15"5 per 100m), that means time of 62" / 1'17"5 / 1'33" for distance as 400 / 500 / 600, with a total volume of 7-8 times the distance of the race (in this case, 6/7 km).
Instead, for a runner of 5000m able running in 13'45", we can use speeds till 5% faster than the speed of the race (16"5 per 100m, so we must use speeds as 15"6, practically similar what we use for the 800m runner, with the difference that recovery times are between 1/3 and 1/2 of the 800m runner, and the volume must be between 8 and 12 km).
* To increase ANAEROBIC POWER (tests on distances between 600m and 3000m depending on the distance of the athlete). This is possible including, at the end of some long run of regeneration, one single test at max speed for the athlete.
Somebody can say that 3000m is the way for identifying the VO2 max. This is true, but for a specialist of long distance (HM / Marathon) the speed of VO2 max has also the function to adapt his metabolic system to produce lactate that he can later use as energy for his competition. This is because I speak about ANAEROBIC POWER.
At the end, what we DON'T do today during the preparation period is to assemble together the nost qualified elements, that can be synthesized with the introduction of workouts of ANAEROBIC CAPACITY (for example, 3x600 at 98% with recovery 8' for 800m runners, or 4x800 at 98% with recovery 6' for 1500m runners, or 4x2000 at race pace rec. 4' + 1000m at max speed for 10000m runners).
So, SPECIFIC is the physiological goal, and this is very important. PARTICULARS used for reaching a "specific" goal are not important.
Under this point of view, the ability of a coach to make EASY what in the mind of many athletes is DIFFICULT (when not IMPOSSIBLE) is not to give too much importance to PARTICULARS, giving great importance to SPECIFICITY.