Muscle Symmetry: Muscle Strength and Balance Checks
Muscle Symmetry is a critical component of Sports Conditioning. Without ideal symmetry in speed and strength between opposing (agonist/antagonist) muscle groups, an athlete cannot achieve their optimal performance. Coaches know how critical it is for an athlete to relax the antagonist muscles while the athlete is forcefully contracting the agonist muscle. However, it is physiological impossible to completely relax the antagonist.
The antagonist must maintain a low level of eccentric contraction to aid in stabilization of a joint/agonist contractions to maintain coordinated movement. If the agonist/antagonist muscle groups are not developed symmetrically, the agonist will be inhibited to contract with its’ greatest potential speed or strength. When the agonist is overly strong, or overly fast compared to its’ opposing antagonist, injuries can occur as the agonist overpowers its’ antagonist.
For example: Female athletes experience ten times the amount of hamstring tears as male athletes due to the fact that females hamstrings are far weaker when compared to their quadriceps. The following ratios are considered Sports Conditioning, Sports Performance and Fitness Industry acceptable guidelines for Muscle Ratios.
- Leg Press-Body Weight Ratio
This ratio is used to indicate how effectively you can accelerate to maintain high speeds. This is a critical ratio for speed improvements for short distance sprinting, baseball, basketball, football, track, etc. You should aim for a ratio of 2.5 times your body weight for these activities.
You should aim for 3 times your body weight if you plan on incorporating plyometric training into your program. Obviously, you need a serious strength training program to achieve and maintain these ratios.
- Leg Strength Test: Squat
The Squat is a highly functional exercise and considered by many to be the “King of all exercises!” The Squat is considered the most functional Leg Strength Test in predicting sprinting & jumping ability. The Squat has been highly effective at improving strength, speed and power especially when combined with plyometric training.
Good 1RM scores are 2 times your body weight. Though some coaches use 1.5 times a female body weight. However, women can easily achieve 2 times their body weight with proper training.
- Quadriceps: Hamstring Strength Ratio
Use the IFPA 1RM Testing Protocols to determine the 1RM Leg Extension for each leg and the 1RM Leg Curl for each leg. Divide your 1RM Leg Curl by the 1RM Leg Extension score for each leg.
Your goal is to achieve and maintain this score at 80% or better. Speed Performance drops and risk of injury increases if the Hamstrings do not have at least 80% of the strength of the Quadriceps.
- Upper Body Strength Test: Bench Press
The Bench Press is recognized as the “King of upper body exercises!” And since the chest is a far more “showy” muscle than the thigh, this is why Monday is the “Great International Bench Press Day!” The need for maximal upper body strength varies from sport to sport (and activity to activity).
Your client may not NEED maximal upper body strength, but if they do, a good 1RM score is 0.8 times body weight (females) and 1.25 times body weight (males).
Symmetry Tests: Left and Rights Sides
Most coaches prefer that the strength of the left and right sides not differ by more than 10%. To maintain long term health, safety and injury prevention, I recommend the strength of the left and right sides not differ by more than 5%. Typical Symmetry Checks can be performed with the following exercise:
- Single Arm Dumbbell Chest Press
- Single Arm Dumbbell Row
- Single Arm Dumbbell Bicep Curl
- Single Arm Dumbbell Shoulder Press
- Single Arm Dumbbell Shrug
- Single Leg-Leg Extension
- Single Leg-Leg Curl
- Single Leg Dumbbell Heel Raise
- Single Leg-Leg Press
Symmetry Check: Agonist/Antagonist Muscle Ratios:
|Ankle||Plantar Flexion/ Dorsi Flexion||3:1|
Exercise Prescriptions to correct Symmetrical Imbalances:
After the imbalance is detected, your exercise prescription to correct imbalances of strength are to perform 3 exercises on the weak side with the correct form, for every one exercise you perform on the strong side.
You must also be aware that the underlying cause of the imbalances may be Activities of Daily Living (ADLs). ADLs may cause the agonist to become hypertonic.
For example, sitting at a desk all day typing could result in your chest muscles becoming hypertonic, while your back muscles become stretched and weak. Hypertonic muscles will need a flexibility exercise Prescription.
The weak and stretched back muscles will need a strength training exercise prescription.
Poor lifestyle habits and exercise habits may also need correction.