Machines vs. free weights? Short answer: free weights. It doesn’t matter if you’re an athlete trying to improve sport performance, or a bodybuilder trying to add another inch to your biceps – free weights are superior. With that uncertainty put to rest, let’s look at why it has been so difficult in the past to answer this question.
The first issue is with the objectivity of any particular study on this subject. Let’s say you want to determine which is better for building leg strength; squats or leg exercises with machines. In 1985 there was a study (published in Research Quarterly) on this exact question. The free weight group did squats and no leg extensions, whereas the group using machines was assigned the leg extension as one of the training exercises. The test to determine which training method was superior was the leg extension, and naturally the machine group had the advantage.
The next issue is that many of those who promote machines use different protocols. Unquestionably, one of the most influential individuals in the iron game, particularly in regard to promoting machine training, was the late Arthur Jones. Because Jones believed that the resistance curves of his machines more closely matched an individual’s strength curve, he incorrectly judged that fewer sets would achieve equal or superior results. As such, when assessing the results claimed by those who promote the use of machines, you need to consider that inferior training protocols were used.
Another issue is that studies may be of insufficient duration (typically, a study may only be conducted for one college semester, as that is often the time subjects would be available), and may use beginners. However, because beginners can make excellent progress over a minimal time span, it would be more useful to have longer studies to better indicate the effectiveness of a specific training protocol.
Fortunately, considerably more research has been conducted since Arthur Jones introduced his Nautilus “time machines” (so-called for their supposed superior efficiency) to the fields of bodybuilding, strength training and athletic fitness conditioning. One of the most significant outcomes of this new research is the answer to this question: Does the increased stability necessary to perform free weight exercises reduce their effectiveness in building strength and therefore muscle mass?
In a study published in the September 2009 issue of the Journal of Strength and Conditioning Research, it was found that performing free weight back squats – compared to performing Smith machine squats – more strongly activated the biceps femoris and gastrocnemius due to their role in stabilizing the ankle, knee and hip joints. Likewise, the free weight squat more strongly activated the vastus medialis and vastus lateralis. This is an especially important finding, because many bodybuilders mistakenly believe that the increased technical demands of the free weight squat decreases muscle fiber recruitment.
This study also supports the work of Dietmar Schmidtbleicher, who classified resistance training exercises according to their effect on neuromuscular activity. Schmidtbleicher ranked the exercises according to six levels of activation, and my Swedish colleague Rickard Nilsson and I added a seventh level. Here is how the exercises ranked:
Compound vs. Isolation Exercises: Neuromuscular Activity (NMA)
Level 1: Isolation exercise on variable resistance machine (e.g., leg extension on cam-type machine, Cybex Leg Extension, DAVID Leg Curl)
Level 2: Complex exercise on variable resistance machine (e.g., leg press on Nautilus machine, Life Fitness Incline Press machine)
Level 3: Isolation exercise with constant resistance machine (e.g., Scott pulley curls, triceps pressdown on pulley machine)
Level 4: Complex exercise with constant resistance machine (e.g., leg press on standard machine)
Level 5: Isolation exercise with free weights (e.g., Scott barbell curls, lying flyes)
Level 6: Complex exercise with free weights (snatch pulls, power cleans)
Level 7: Complex exercise with free weights (e.g., power snatch, dips on rings, rope climbing)
Although all these exercises can have a place in any athletic or physical fitness program, most training should be devoted to exercises that are level 5 and above.
As for the effectiveness of free weight exercises performed on rocker boards and other unstable devices, research by PICP Level 1 Coach Michael Wahl suggests that these variations are less effective than conventional exercises. In research for his master’s thesis, Wahl selected 16 competitive athletes who had played at college level or above. Using electromyogram (EMG) testing to measure the electrical activity in muscles, Wahl found that the brain motor patterns exhibited in performing exercises on unstable surfaces were exactly the same as those seen on stable surfaces. He concluded that because less resistance could be used due to the nature of these unstable exercises, they had to be considered inferior from a strength training perspective.
Certainly, machines have their advantages. In commercial gyms or school environments where there is minimal supervision and perhaps incompetent instruction, machines might be a better choice from a liability perspective. Many machines have selectorized weight stacks, and for those in a hurry (such as someone trying to get a workout in during a lunch hour) such convenience enables them to complete their workout faster. In addition, being able to isolate specific muscles has value, especially in the area of injury rehabilitation and structural balance training. Besides, some important exercises, such as leg curls, cannot effectively be performed with free weights.
Machines have their place, but the bottom line is that free weights are the superior method of achieving goals in body composition training, physical fitness and sports performance.