When it comes to repetition ranges when weight training, it is predominantly believed that; When trying to gain muscle/ muscle size, low reps and heavy weight are needed, and when cutting, high reps low weight are needed. However, all rep ranges work the body differently due to their reactions with muscle fibers, and muscle gain can be caused, all of which can aid in muscle growth and development.
There are two main types of muscle fiber: the red, slow-oxidative type and the white, fast-oxidative type. These are more commonly known as slow and fast-twitch muscle fibers. They are recruited when called on by signals to motor neurons from the brain in different ways. Muscle fibers create motor units which are made up of hundreds of slow and fast-twitch muscle fibers. Both types of fiber are important when it comes to training and exercise. Fast twitch contract quickly for use in short, intense activities of brief duration, whereas, contract slowly and support smoother, lower intensity repetitive contractions, related to endurance-type activities.
Different rep ranges stimulate muscle fibers differently. Low rep ranges are categorized between 1- 5, these are usually performed with heavy weights to a 1 – 5 rep MAX.
It has been claimed that, that low reps will stimulate ALL muscle fibers from slow to intermediate to fast and everything in between. When a load is placed on a muscle, each type of fiber is recruited, firstly the slow twitch. If the slow twitch fibers cannot generate enough force to lift the weight, then the body will call the intermediate fibers into action. Finally, if both of these fibers cannot handle the weight or the intensity, fast twitch will be recruited (this is why fast twitch are usually used for High Intensity and slow twitch for lower, endurance). So this means when you lift a heavy load you will fully stimulate slow and intermediate muscle fibers (Saladin, 2007; Wilson, nd). This is why it can be so tiring on the body when training heavy, but only for 1-5 reps.
This type of rep range is vital for optimal growth as it allows for strength gains and development of progressive overload during a training program. Low repetition/ strength training stimulates Myofibrillar Hypertrophy is an increase of actin and myosin filaments within muscle tissue, which also involves an increase in the contractile tissue (Zatsiorsky, 2006).
Moderate rep ranges are categorized as around 6-12 with a moderate to heavy weight. The reason that this rep range is seen to be so effective for building muscle is that it does a little bit of everything. The heavy loads allow for myofibrillar protein synthesis to take place which, as discussed, will increase the size of the contractile proteins. The increased time under tension will stimulate sarcoplasmic hypertrophy. Sarcoplasmic hypertrophy is an increase of the sarcoplasm in muscle tissue which is caused by training lighter weights, volumised reps, which does not improve strength but can create a more muscular look.
This type of rep range is also vital in achieving a muscular ‘pump.’ Studies show that cellular swelling causes both an increase in protein synthesis and a decrease in protein breakdown (Grant et al., 2000; Stoll et al., 1992; Millar et al., 1997).
Low reps with heavy weight are best at stimulating myofibrillar hypertrophy, and high reps with light weight are best at stimulating sarcoplasmic hypertrophy. So, moderate reps seem to strike a balance between inducing significant amounts of both.
High reps are categorized as 15+ and are usually referred to as “volume training.” This rep range is critical for glycogen on protein synthesis. Glycogen is primarily stored carbohydrate within muscle tissue and is used for energy when training. Glycogen is also hydrophilic and causes muscles to swell because, with every gram of glycogen, 2.7 grams of water are also stored (Chan et al. 1982). This added water will increase the size of your muscles; it will also increase protein synthesis as cellular hydration is an extremely strong anabolic trigger. This is also a reason it is important to keep hydrated while training.
High rep training will drastically deplete glycogen stores, causing the body to react by increasing muscular glycogen stores. This will allow cells to stretch and lead to greater overall muscle growth and release of anabolic hormones. This also prevents blood from leaving the area being trained, which can induce growth through increases in growth factor production and also increases muscular “pump”(Vierck et al., 2000).
In conclusion, all rep ranges will increase muscle growth but through different pathways. Therefore all ranges should be utilized, no matter if you are gaining or cutting. High rep ranges should not be used as a form of fat loss. All weight training will stimulate the metabolism and cause calories to burn. No one rep range will cause significant fat loss over another. Diet and cardio should be the primary tools you use to shed fat and get lean. Let the weight build muscle, let your diet cut the fat.
Make sure that when you are training, you are fuelling your body correctly!
My recommendation would be :
BEST BCAA Intra Workout
BEST WHEY Post Workout!