Recently my friend John and I sat down to discuss the use of free weights versus machines for strength training and bodybuilding. We also went over the benefits of training unilateral over bilateral exercises. Here are some of the key points:
WEIGHTS vs. MACHINES
Movement Of The Extremity
Machines: typically involve you being locked in or fixed into a certain position causing your body to follow the path of the machines design. This can often lead to improper joint positioning and injury.
Free Weights: allow your body or limb to move in a natural plane that may be safer and easier on your joints.
Machines: often have you sitting or lying down which does not require any balance or core engagement during the movement. This is problematic because it teaches the body to not fully rely on deep stabilizers while the larger muscle groups are active.
Free Weights: require a higher amount of core engagement, balance and co-contraction of synergist muscles. Free weights also require the small, stabilizer muscles to activate in order to control the weight.
Carryover To Daily Activities
Machines: that use back rests, chest supports, etc will not accurately train the body as a three dimensional system. For example, when pushing an object forward the trunk, hips, feet all engage to create trunk stiffness and prevent your body from moving backwards. A chest press machine with a back rest would teach your body to generate force forward without the need to stiffen the trunk. It neglects to teach your body the ability to counter balance against resistance.
Free Weights: performing a pulling/rowing motion on a free weight or cable system while standing requires you to use that same stabilizer system to counter balance the resistance. While pulling weight toward you your body will naturally have to create co-contraction in order to prevent you from falling forward.
Both free weights and machines have their pros and cons.
I believe in using both forms for optimal strength and hypertrophy training
If you predominately use machines in your training you should add in more free weights
I believe majority of your training should come from free weights and cable systems rather than machines
BILATERAL vs. UNILATERAL EXERCISES
We All Have A Weaker Side
Training bilateral lifts all the time will continue to keep an existing imbalance in your body. If you have a weaker or less dominant hip then you will probably rely on the dominant/stronger side to get you up from a squat. In the same fashion you may be using your dominant/stronger side during heavy bench press or military press. This will increase the strength in your dominant side and neglect the weaker side, further increasing the imbalance.
By implementing a unilateral exercise you help decrease the imbalance by training each side independently. A one arm dumbbell or kettlebell press will force you to move the weight without the assistance of the opposite (dominant) side.
A unilateral exercise also produces more engagement of the deep stabilizers of the trunk and back. For example, while perfuming a one arm dumbbell press from a lying position, your body naturally wants to go into rotation due to the weight and gravity. When you stiffen the trunk and avoid that rotation you increase your activation of the core and stabilizer muscles. The same benefit occurs during a one arm overhead press or unilateral farmers walk.
Majority of the movements we perform during sport, activity, and even our day to day lives involve off center loading or imbalanced movements. Imagine lifting a suitcase or jug of water up off of the floor and placing it onto a counter top. This very basic task involves transferring weight from one foot to the other, bracing the abdomen, and loading up on one hip while engaging the contralateral core muscles to prevent the spine from buckling. These type of asymmetrical and unpredictable movements are exactly what unilateral exercises aim to simulate and prepare you for.
train unilateral exercises often
start with the weaker side and stop at technical failure for your rep range
perform the stronger side next but stick with the same rep number
the goal is to minimize your right to left or front to back asymmetries
1) One arm chest press in the half kneeling and tall kneeling position.
2) One arm row in split stance and half kneeling position.
3) One arm military press standing and half kneeling position.