Muscular balance is much more than scoring well in front of the judges at a bodybuilding contest. If an imbalance exists between agonist-antagonist muscle groups, joint instability, muscular dysfunction, muscle weakness and increased risk of musculoskeletal pain and injury may result.
The goal of all professionally managed fitness programs is not only to balance the health and fitness needs of the client regarding all 10 Components of Fitness (strength, speed, power, anaerobic & aerobic endurance, agility, balance, coordination, flexibility and body composition), but to make sure the body is developed in complete balance. This will require more fitness assessments than their 1-RM Bench Press and more exercise prescription than 1 or 2 exercises per body part. Muscle balance ratios differ between muscle groups and are affected by the force-velocity of different muscle groups at specific joints. Ideally, you would use isokinetic dynamometers; however, in all practicality, most personal fitness trainers use 1-RM testing for each individual muscle group.
The current standard for muscle balance ratios recommended for the agonist-antagonist muscle groups are:
Muscle Groups Muscle Balance Ratio
1. Ankle Inverters & Everters 1:1
2. Ankle Plantar Flexors & Dorsiflexors 3:1
3. Elbow Flexors & Extensors 1:1
4. Hip Flexors & Extensors 1:1
5. Knee Flexors & Extensors* 2:3
6. Shoulder Internal & External Rotators 3:2
7. Shoulder Flexors & Extensors 2:3
8. Trunk Flexors & Extensors 1:1