How training can spur greater improvement.

How to read this graph:   The four rectangular shapes represent the four types of training / fitness combinations directly related to forearm fitness described by the Anderson brothers in RCTM.

ARC/MSS (moves: 60 to 700; intensity: 10% to 40%) this training involves large numbers of consecutive moves at low to moderate effort levels, and requires climbers to manage their level of pump by controlling their activity and resting behaviors.  Seldom will performance oriented climbing days include these combinations of moderate intensity with extremely long duration, which defines the activity and spurs maximum endurance fitness growth.

Power endurance (moves: 12 to 30; intensity 60% to 90%, duty cycle 1 min effort to 2 min rest) workouts are can include 6 sets of 20-26 hand moves, at intensity high enough to prevent resting, organized in rapid 1 min on / 2 min off duty cycles.  While power endurance challenges are encountered in the context of climbing, they are not repeated sufficiently, nor are they organized into a series of duty cycles with only two min of rest between each 1 min of activity.  Thus the adaptive response is limited as climbers instead seek to maximize their chances of success on a particular route.

Finger strength (moves: 3 to 7, intensity 55% to 80%)  is best cultivated through hangboard workouts, organized around grip type, and with multiple sets of brief repetitions (7 seconds) separated by briefer (3 second) rests.   These workouts allow climbers to reach muscular fatigue for particular grip types in 5-7 reps, which maximizes adaptive response while minimizing risk of injury, unlike in route situations in which randomly encountering a grip type may be in a single repetition and near the climbers limit.

Limit bouldering and campusing (moves 1 to 5; intensity 80% to 100%) are the best ways to cultivate power, which is instantaneous application of finger strength.  This is best trained on comfortable consistent grip types over a short range of 1 to 5 moves.

There are at least three reasons that systematic training can spur greater amounts of adaptive fitness response than simply bouldering and climbing for fun.

1. Routes are too arbitrary. Arbitrary selections of holds, intensities, moves, and durations do not inspire as strong of an adaptive response from the forearm muscles.  
1. Most routes include a wide range of hold types, intensities, and durations.  This reduces the chance for systematic fatigue in any one set of forearm muscles.  
2. Route challenges will seldom match climbers specific training level needs.   The four different dimensions of forearm fitness are responses to different types of climbing challenges, and for any climber, these will require particular combinations of hold intensity, duration, and variety.  Most outdoor routes and problems are just too idiosyncratic to be effective training vehicles for general fitness goals (though parts of routes can be selected for fitness training).
1. It is possible to use outdoor routes as training resources, but most climbers tend to treat all outdoor routes as performance tests, rather than as a means to cultivating particular types of fitness (see 3 below). 
2. Routes are too limited in any one dimension.  Systematic training includes combinations of durations, intensities and hold types that are more extreme and are intentionally specific to types of climbing fitnesses. 
1. Hangboard workouts focus effort on repeated, controlled loadings of the exact same muscles until those muscles fatigue to failure.  Routes will seldom have repeated grip types to specifically fatigue forearm muscles to failure in a systematic, progressive way.   
2. Power-endurance workouts are tailored to generate and sustain intense forearm pump thought a series of numbered moves, and are repeated before full recovery is made.  Bouldering for fun would remain more performance than training oriented.  
3. ARC sessions are much longer duration than most climbers encounter in ordinary route and problem completing situations.
3. Climbing for fun is too focused on performance over process.  Climbers who only climb for fun tend to focus on their strengths and leave gaps in their training procedures, such that certain types of fitness are insufficiently cultivated.   
1. Fear of failure or pressure to complete routes can inspire climbers to risk injury or keep them from attempting routes that may actually provide the best workout.   Others may continually get on routes that are too difficult, only to spend most of their climbing time hanging at the next quick draw.
2. Everyday climbing can encourage climbers to stay in the comfortable middle ground of challenge.  For instance, it is easy to meet climbers who have been climbing for fun, but have never put in a session of ARC climbing with more than 100 moves in a row.  Correspondingly, these climbers are unable to rest and recover effectively on routes.   
3. Other climbers might climb in extremely static styles, and will have insufficient power and lack the neuromuscular habits of efficient deadpointing, and "go-for-it-ness" that they use in campusing or limit bouldering.