Posted on August 06, 2014 by Jenny Cromack

The 8-12 rep range is also referred to as the moderate rep ranges with 1-7 reps being low and anything above 15 reps being high. Moderate rep ranges have consistently been proven in study after study to lead to the greatest amount of growth. The reason that this rep range is so effective for building muscle is because it does a little bit of everything.
This means that it provides many of the benefits of low rep training combined with the benefits high rep training by allowing for relatively heavy loads to be used while increasing time under tension. The heavy loads allow for myofibrillar protein synthesis to take place which will increase the size of the contractile proteins. The increased time under tension will stimulate sarcoplasmic hypertrophy.

Sarcoplasmic hypertrophy also known as “size” hypertrophy, leads to an increase in the amount of sarcoplasm in your muscle tissue. Sacroplasm is the fluid that surrounds the myofibrils in a muscle. The sarcoplasm contains things such as ATP, glycogen, creatine phosphate, and water. So when sarcoplasmic hypertrophy occurs, the amount of fluid (or cytoplasm) in the muscle increases developing a larger muscle. This type of hypertrophy is achieved by using slower, controlled movements to put the muscles under stress for longer and activate the slow and fast twitch muscle fibers and deplete the muscles of energy.
Although this rep range using lighter weights for more reps develops muscle growth it is not necessarily linked with strength gains. So to become muscular and strong  including strength based training in your training programme is key.

It is important to ensure that your rest time is sufficient to ensure you can recover and also that you stick to the correct tempo to maximise results

Here is a session plan for upper body working in the 8-12 rep range for hypertrophy

1A DB MIllitary Press (Seated) 8-12 reps / 4 sets 5010 60 sec
1b DB Bent Over Rows 8-12 reps / 4 sets 5010 60 sec
2A DB Bench Press (flat) 8-12 reps / 4 sets 5010 60 sec
2B Wide Grip Pull ups 8-12 reps / 4 sets 5010 60 sec
2C EZ Bar Curls 8-12 reps / 3sets 3010 60 sec

The weights should be increased by 2% every week if you are unable to maintain this weight increase then take a set off each exercise until you are able to complete the rep range and weight.