Scale-ability

Monika doing some Overhead squats with a PVC pipe

The scalability of exercises is key when following a program not specifically tailored for one individual. It is exactly as it sounds - the scaling of an exercise to the abilities of that individual. It is a necessary part of any program involving complex movements over a full range of motion

"The question regularly arises as to the applicability of a regimen like CrossFit’s to older and deconditioned or detrained populations. The needs of an Olympic athlete and our grandparents differ by degree not kind. One is looking for functional dominance the other for functional competence. Competence and dominance manifest through identical physiological mechanisms. We’ve used our same routines for elderly individuals with heart disease and cage fighters one month out from televised bouts. We scale load and intensity; we don’t change programs. We get requests from athletes from every sport looking for a strength and conditioning program for their sport. Firemen, soccer players, triathletes, boxers, and surfers all want programs that conform to the specificity of their needs. While admitting that there are surely needs specific to any sport, the bulk of sport specific training has been ridiculously ineffective. The need for specificity is nearly completely met by regular practice and training within the sport not in the strength and conditioning environment. Our terrorist hunters, skiers, mountain bikers and housewives have found their best fitness from the same regimen."
Greg Glass - From the "What is Fitness" article, CFJ.

The general idea is to start with a light load and work on technique, once the technique is sound then and only then start increasing the (intensity) speed and load. Everyone has to master the basic movement patterns before they can increase the difficulty. We modify our workouts to fit the abilities of each individual trainee. Getting the most out of each client is the key to their success and by allowing them to achieve the highest output they are capable of by scaling the weights and exercises is only logical. Anyone can do "Crossfit" or any other strength and conditioning program provided you don't make them do more than they are capable of doing. If they can't run make them jog, if they can jog make them walk etc. If 200lbs is too much let them do 80#, if 80# is still to much scale them down to a PVC pipe or a weight they can handle. I put my mother through a workout with just a broom stick. Getting her to just practice doing deadlifts, press and overhead squats for 5-10 reps was a good start for someone who has not moved that way for years. It wasn't a huge task for her to complete but she felt it the next day and it was a great place to start. Now she has been doing it for a while and has better range of motion and flexibility throughout these movements, soon I will have her try it while holding soup cans. Once the basic movements are sound we can increase the load and eventually the intensity.

Below is a small list of subs. From hardest to easiest
Handstand Pushups - Handstand holds - declined pushups - pushups - inclined pushups - knee pushups.
Strict pullups - kipping pullups - jumping pullups - ring rows
GHD situps - V-ups - situps
Knees to elbows - knees to chest - knees to parallel

By decreasing the range of motion or by creating more favorable levers with our body we can simplify the exercise while still getting the desired muscular stimulus. Just start at a point where you are able to safely complete the movement and go up slowly from there. It's called scalability and it will eventually get you to where you want to be - the ability to do things unscaled.