•   I firstly think it is prudent to stress that neither type of exercise is “bad” or should be avoided in a program of exercise. I do think though that depending on an individual’s training goals or experience might influence when either is prescribed. I also think there are some misconceptions around the benefits and safety of fixed motion machine exercises that need to be addressed.

• So, if we consider what I think is the primary benefit to resistance machines being their ability to target specific muscle groups, this might influence when they would be best prescribed. For example, in an individual with an imbalance or weakness in a particular muscle group; machine exercises would be excellent to isolate and target these muscles to increase size, strength and possible subsequent performance.  

 I would also consider them easier to perform and might be prescribing to individuals with a low training age, or those that lack experience with more complex movements, helping to develop well-rounded strength across all muscle groups; whilst teaching them how to engage, or contract, or “feel” for engagement of particular muscle groups important for more “functional” exercises.

• I would argue that their biggest limitation is that during functional movements, muscles rarely function in an isolated fashion, such as the way they are engaged in fixed motion resistance machines. As a result, it is likely that the strength gains from fixed motion machine-based exercises have negligible impact on functional performance when compared to free-weight exercises.

• I also think there is a misconception that fixed motion machine-based exercises are safer. To be honest, there is no evidence to suggest this, and I think people often confuse easier to teach and perform (in the case of fixed motion machine exercises) for safer. Now whilst I do not think free-weight exercises are without risk (particularly if performed with incorrect technique or supervised poorly), there might be a case that they are in fact safer and offer more advantages. For example, stabiliser muscle activation is significantly reduced with machine-based training compared with free-weight training, potentially leading to a lack of development in these muscle groups, which could lead to muscle imbalances and an increased injury risk.

• I think a good example of this is provided in this 2005 paper from Anderson and Behm who investigated differences in muscular activity whilst participants performed squats on a Smith machine in comparison to a free-weight squat. The reason I find this study particularly interesting is that I often see people choosing to perform squats on a smith machine over a free-weight version of the exercise, often citing that they consider it to be safer. If we consider (and this was not investigated in this study) that the smith machine forces individuals to squat with their feet further out in front of them, thereby increasing shear forces on the knee, I do not think there is a case for this argument. Furthermore (and relating back to the finding from this study), the authors reported that the activation of the prime movers and stabilizers were reduced upto 30% during a smith machine squat in comparison to a free-weight squat. The increased muscular activity (during the free-weight squat) may be attributed to their postural and stabilization role and suggests a greater recruitment of these muscles during the free-weight version of the exercise. Again, I think increasing the recruitment of stabiliser and postural control muscle negates the safer argument and suggests these muscles might be under-developed if individuals restrict their training to fixed motion machines exercises only; thereby creating potential imbalances or weaknesses that might predispose individuals to increased risk of injury.

• I will also leave you with a quote from Mark Rippetoe from his book Starting Strength; “Squatting in a Smith machine is an oxymoron …. The job of keeping the bar vertical should be done by the muscles, nervous system and skeleton, not by grease fittings, rails, and floor bolts”.

• So, I think to summarise, both fixed motion machine-based exercises and free-weight training have their place in any exercise program. Now, at CVP we prescribe a variety of functional free-weight exercises as we believe they offer greater carry over to athletic/sports performance and common functional activities of daily living; thereby better preparing you for the everyday demands of life.