Alactic -----> lactic powerlifting, strongman, and crossfit all have different energy system requirements.
'Conditioning' is the new 'Cahdio'. It is a term that gives people a general sense of meaning... something something capacity.... but is so broad in it's reach that it can be used as a vague filler word without being incorrect. Let's be clear on something: you can condition anything. I can condition you to be strong. Or fast. Or enduring. I can condition you to recite conversions from degrees to radians along a unit circle or to salivate when I ring a bell. What you are trying to condition and how you go about it are the important questions.
Keep in mind that this is 'Conditioning 101' 101. I'm just scratching the surface.... of an iceberg. Over time, hopefully this information will be a spring board to more advanced ways of thinking in your own programming and in others as well as a way for you to connect the dots of other things you see, hear, and experience yourself. To start, there are three main energy pathways that we concern ourselves with, and they are listed in order of duration:
An easy way to conceptualize this is as gears in a car. Low gear is great for building up speed and power but pretty terrible for cruising. Likewise, high gear is great for maintaining speeds for a long period of time, but useless for going 0-60. Now that you understand that analogy, forget it, because that's where the similarities end. Energy systems in your body, unlike gears of a car, are constantly on but in different proportions. Depending on duration and activity, one energy system will be the dominant contributor of an activity while another takes a backseat, but they are all constantly working.
Since these systems are dependant on duration and output drops the longer an activity is performed, it makes sense that they are linked to intensity. The ATP/CP(alactic) is the shortest, puttering out at around 12 seconds of activity. This is the system used for all explosive and maximal strength activities. Starting speed off of sprinting blocks, jumping as high as possible, quick changes of direction, thrusting into a max power clean, throwing a punch, pulling a deadlift, etc. etc. There is no waste product, as evident by the lack of 'pump' or fatigue from a heavy triple or max broad jump.
Once this energy system is used up, the body moves into lactic(glycolytic) pathways. This is mistakenly associated with 'lactic acid'; a compound that is credited with the deep burn of high repetition lifting but is really only found in milk products. The burn is the result of hydrogen ions released during the process, which makes the cellular environment more acidic. The acidic environment interferes with substrates used for muscular contraction, which is pretty evident to anyone who has done a concentration curl or stadium runs. This means that the limiting factor of performance at this threshold is your ability to buffer out these ions and maintain a less acidic environment. Anyone who has done a set of lunges past 20 seconds is familiar with this threshold. Without overwhelming you with flow charts from my old Ochem text books, just know that training in the glycolytic threshold is usually associated with reduced power output and force production.
Lastly, we have aerobic work, our 'high gear'. Aerobic is the long term energy pathway; slow and less powerful, but enduring. The primary role for aerobic pathways is to replenish ATP so that muscular contractions can continue. One of the problems with internet fitness culture over the last 10 years has been the rally against any sort of steady state training in favor of sprint intervals. The fact is, elevating aerobic capacity through specific aerobic work isn't just beneficial, but optimal for most athletes. Football, rugby, basketball, and soccer all involve short all out bursts in the context of more general fatigue and consistent movement. Anyone ignoring solid aerobic work(slow steady movement) for intense glycolytic conditioning (120 yard sprints, gassers, hill runs, etc.) is going to find that they have a harder time getting their resting heart rate down and are less explosive after each successive play.
The next installment on conditioning will cover which thresholds are important for which athletes (i.e. powerlifters vs. Crossfit athletes) along with examples of exercise selection and work/rest ratios.