In discussing your fundamental goals in weight training, your motivation and drive may come from one of two factors - either you are training for an increase in muscle size, or you are training for an increase in strength numbers. There is no right or wrong in the question of factors - but it is worth exploring what the difference between the two of these are - and mentioning how the two actually play off one another to help you reach your fitness goals.
What is Your Primary Training Goal?
In general, your driving factor is going to be largely dependant upon your sport or activity of choice. If you are a bodybuilder, then your goal is to be as aesthetic, or in this case, as big as possible. Size and aesthetics rule your fitness world. Conversely, if you are a powerlifter, a wrestler, or involved in any sport where your weight MUST fall within a certain range - then training for strength is the most palatable: since you want to be as strong as physically possible without adding weight or size to your frame. In both schools of training, ego is involved - as you want to either get as big or as strong as physically possible.
Hypertrophy: Sarcoplasmic Versus Myofibrillar
Regardless of whether your goal is increased size or strength, you can’t discuss one or the other without first discussing the biomechanical components. Muscle Hypertrophy is an increase in muscle size via growth in size of its component cells. Muscular Hypertrophy is reliant upon a combination of both Sarcoplasmic Hypertrophy and Myofibrillar Hypertrophy.
Sarcoplasmic Hypertrophy is the growth of sarcoplasmic fluid in the cells, which leads to an increase in muscular size, without necessarily increasing muscular strength. Sarcoplasmic hypertrophy relies upon increased muscular glycogen storage.
Myofibrillar Hypertrophy is an increase in myosin and actin (muscular contractile proteins), which increases the strength of the muscle without adding size to the muscle.
In both forms of hypertrophy, putting the body through continuous stress - via training - directly translates to an adaptive response in the body, whereby muscles become more efficient at handling progressive stress and transmitting force.
Training for Size
When weight training exclusively for muscle growth, or sarcoplasmic hypertrophy, the volume is higher - 12-15 reps on average. The rest periods are significantly shorter, and the load of weight lifted is more moderate than with strength training. Training for size is anaerobic in nature and does not rely upon oxygen.
With volume training, blood flow to the muscles is significantly increased, and an increase in lactic acid results both in a phenomenon known as the “pump”, and in the muscles reaching failure. More than just an aesthetic phenomenon, the pump serves up great benefits in the arena of muscle-building. For more information on the pump and what it is, check out this other great article from the Blackstone Labs Blog.
When a muscle fails, cortisol increases- causing a breakdown of the muscle, which is then built back up to be larger than it was before. Higher volume leads to a greater lactic acid buildup, which leads to greater concentrations of cortisol. This then leads to a greater increase in muscle size. Going to failure with little rest means that you are both depleting your ATP and glycogen stores, not giving your body a chance to flush out the lactic acid buildup - hence, seeing a greater pump, and more growth.
One method for increasing muscle size is occlusion training, which involves utilizing a device to restrict blood flow to a muscle group being trained. In occlusion training, you wrap a device around the top of a limb with tension high enough to restrict blood flow to the veins, but not the arteries. Occlusion training increases size by bringing muscle cells to a point where they become so full of fluid that they are forced to grow, restricting oxygen levels to the point at which muscles recruit the use of larger fast-twitch fibers. This, in turn, causes an increase in lactic acid, leading to an increase in protein synthesis.
To engage in occlusion training for the legs, wrap your limbs to a degree of tension perceived as a 7 out of 10, and perform your typical exercises for the legs at a weight that is 20-40 percent of your 1RM (One Rep Max - which is literally the maximum amount of weight you can lift in one rep). For the arms, wrap your limb at a 5 or 6 on the self-perceived tension scale, and perform the same exercises you usually do, once again working with a weight that is approximately 20-40 percent of your 1RM. Occlusion training is high on volume (repetitions), and low on rest.
Training for Strength
With strength training, the key components to increasing myofibrillar hypertrophy with weight lifting are: low volume on repetitions, an increasing weight load - known as progressive overload, and long rest periods. When we say long rest periods, we are talking about a period of 3-5 minutes, which is a long enough timeframe for your body to recover from the exercise set you just completed. In essence, the muscle is damaged during the exercise set itself, and the extended rest periods in between sets allows for the muscle to overcompensate in its repair efforts, making fibers stronger, but not necessarily larger.
Where Size and Strength Overlap:
Regardless of your primary objective, there are numerous benefits to utilizing both size and strength training methods, in alternating patterns. Besides preventing boredom, the two interact in complementary ways. Your muscles do have to get somewhat bigger to get stronger, after all.
DOGGCRAPP (DC) Training:
Funny name aside, DOGGCRAPP-style training is the perfect example of strength and size training interacting, to create gains all around. Founded by Dante Trudel, DOGGCRAPP training is designed to increase both muscle size and strength via use of heavy progressive overload, low volume/high frequency training, rest-pause sets, extreme stretching, and periodization. DOGGCRAPP training is incredibly intense, regimented, and not for beginners, so proceed with caution to maximum gains.
Whether you are training for strength or for size, you have to learn through trial and error how YOUR body works, and what ultimately works for you. Whatever your goals may be, utilize all of the resources at your disposal to custom-tailor the best results. Advancement and improvement is first and foremost the end-result, regardless of how you get there.