These are the things I hold to be true after my many years in the S&C / fitness world. I'll post all of my personal thoughts below (summed up and brief)
I do not plan on debating any of this stuff...So argue amongst yourselves if you choose to do so.
1. For muscle to grow and become stronger, it must be exposed to an overload stress. INTENSITY of effort is the key.
2. Muscle will adapt to the stress if given enough time to recover. AdequateRECOVERY time between workouts is the key.
3. For further adaptation (improvement), greater overload stresses must be applied. PROGRESSION of overload is the key.
4. To improve further, or maintain current ability, the overload stress must occur regularly. CONSISTENCY in training is the key.
5. Creating high tension in the muscle fibers and working to momentary muscular failure involves the greatest amount of relative muscle tissue. Effort (working to fatigue) and using good form (controlled movement with no bouncing or jerking) are important here. If in doubt, slow it down and aim for maximum repetitions (safely).
6. Muscle overload can be applied with a variety of tools: barbells, dumbbells, machines, manually applied resistance, body weight, sand bags, etc. Anything that can create high tension in the muscles can be used.
7. A variety of exercise prescriptions can be used provided muscle overload occurs, such as heavy resistances / few repetitions, lighter resistances / more repetitions, minimal exercise bouts (i.e., 1 to 3 sets per muscle group) and / or varied rest time between sets and exercises (i.e., 30 seconds to 3:00+).
8. No matter the speed of movement used, muscle fibers are recruited in a fixed order: slow twitch / type 1 --> intermediate / type 2 --> fast twitch / type 2A --> fast twitch / type 2B & 2C. Generally speaking, if the demand is low, the slow/type 1 fibers are called upon. As the demand for EFFORT increases, the higher threshold, fast / type 2 fibers are called upon.
9. There is no skill transfer from a weight room exercise to a totally different athletic skill done in competition. The principle of specificity clearly states that for a positive transfer to occur, exactness in a number of factors must be present. The fact is, no weight room exercise exactly replicates any sport skill (other than the sports of weightlifting and power lifting). That is why one should practice his / her sport skills separately, then generally improve total-body weight room strength.
10. Although anyone can alter their strength, muscle size and body composition via strength training, their genetic endowment effects the magnitude of potential gains in the weight room. Those blessed with a high percentage of the slow / type 1 muscle fibers may not develop large muscles or great strength. Likewise, those who more easily get bigger and super-strong most likely possess a greater volume of the larger, more powerful type 2 fibers. Also, longer arms / legs and unfavorable muscle origins and insertions hinder great strength demonstration. Ultra-strong humans – male or female – usually have exceptional body leverages to allow for this.