Cables or Machines: Muscle Activity, Angle & ROM of Arms, Abs, Chest & Shoulders on Chest & Overhead P. & Curls

This is the cable curl as it was performed in the study at hand (Signorile. 2016)

As Joseph F. Signorile et al. point out in their latest paper, "cable resistance training machines are showing resurgent popularity and allow greater number of degrees of freedom than typical selectorized equipment" (Signorile. 2016). Ok, the "freedom" maybe not as absolute as it is with our beloved free weights, but cables come sign. closer than the average rigid Cybex machine. It is thus only logical that the scientists assume that "given that specific kinetic chains are used during distinct activities of daily living (ADL), cable machines may provide more effective interventions for some ADL" and eventually certain athletic endeavors (Signorile. 2016).

To identify these activities and corresponding exercise equipment, the scientists from the University of Miami came up with a study that examined differences in activity levels (rmsEMG) of six major muscles (Pectoralis major, PM; Anterior deltoid, AD; Biceps brachii, BB; Rectus abdominis, RA; External obliques, EO; and Triceps brachii; TB) and kinematics of multiple joints between a cable and standard selectorized machines (sounds special, but means the average rigid, plate-loaded resistance training equipment you will find in every gym). The exercises that were performed were the biceps curl, the chest press and the overhead press, all performed at 1.5s per contractile stage.

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For their study, the scientists recruited healthy, but only recreationally active 15 participants (9 men, 6 women; mean age ±SD, 24.33 ± 4.88 y) on a voluntary basis through personal contacts from an opportunity sample students in a university research program. The 15 subjects were then randomly assigned to do 5 reps of the previously listed exercises at their pre-determined 8-RM (less reps than maxto maintain optimal form) on either ...

• cable-based towers (Cybex Bravo Pro, multi-functional tower) or 
• rigid, plate-loaded machines (selectorized) from Cybex International.

To ensure optimal comparability, subjects in both groups did the same exercises, i.e. the bicep curl, chest press, and overhead press ... albeit with different motion sequences due to the restraints of the machines. 

Figure 1: Relative EMG acitivity (expressed as increase / decrease with using plates vs. cable-loaded machines) for  pectoralis major (PM), the anterior deltoid (AD), the biceps brachii (BB), the rectus abdominis (RA), the external obliques (EO) and the triceps brachii (TB) during chest press, overhead press and biceps exercises (Signorile. 2016).

The EMG values the scientists measured with electrodes that were attached to the pectoralis major (PM), the anterior deltoid (AD), the biceps brachii (BB), the rectus abdominis (RA), the external obliques (EO) and the triceps brachii (TB) speak for themselves:

• significant benefits favoring cable training were seen for all values beneath the x-axes of Figure 1 that are marked with the p < 0.05 asterisk (*), namely the pecs and the anterior deltaoid (=front delts) for curl exercises, the biceps, rectus abdominis (abs) and the external obliques for the chest press exercises with cables and the external obliques for the overhead press with cables
• significant benefits favoring plate-loaded machines, on the other hand, were observed only for the biceps on the curl machine (vs. cable curls) and the triceps that did half of the job during the chest press on the corresponding machine machine 

If we go by the number of significant benefits, cables do thus appear to be the better choice in many, but not all cases.

SuppVersity Suggested Read for those of you who are interested in learning more: "Angle, Grip Width, Free Weight or Ma-chine, Failure & More - What Really Works for Building A Bigger Bench & Pecs" - Click here to read this article from Monday, February 9, 2015, now!

Wait!? Aren't free weights always better? The number of studies conducting respective comparisons is limited. A study by Silvester and Bryce, however, may be seen as exemplary of the existing evidence and it shows quite conclusively that "exercises performed with variable resis-tance machines and free-weights [are] equally effective at developing strength" (Silvester. 1981)". Eventually, I would yet suggest to follow an advise you can find in a 2002 paper by Stone et al. who say that "the majority of resistance exercises making up a training programme should include free weight exercises with emphasis on mechanical specificity (i.e. large muscle mass exercises, appropriate velocity, contraction type etc.)[, while] machines should be used as [a sports- and goal-specific] adjunct to free weight training" (Stone. 2002).

Based on the results of study at hand, this recommendation could be extended with another half-sentence that reads: '... in that, cable machines are the legitimate link between the totally free regular weights and the very guided movements on regular, plate-loaded machines which should both be part of your (generally free-weight based) training regimen.'

Not all cases? Yes, if we go by the ranges of motion the scientists measured for all of the exercises as well, the ...

• greater starting and ending angles were seen for the elbow and shoulder joints during selectorized biceps curl speak in favor enforcing a certain motion sequence and range of motion by the means of of the plate-loaded machines, while ...
• the higher hip and knee starting and ending angles for cable machines during chest and overhead presses (p<.0001), as well as the overall greater range of motion (ROM) the subjects covered with the cable machines (p<.0001), on the other hand would argue in favor of increasing the degrees of freedom with cable machines.

With the study at hand being an acute EMS study, the bad news, however, is the fact that the ultimate litmus test, i.e. the effect on lean mass and strength gains differences that occur with chronic cable vs. machine training (and additional free weights), will have to be determined in another study. Thus, the probably most significant and eventually only relevant conclusion of the study at hand reads: 

"The major finding of this study was that the activities of selected muscles during comparative exercises varied by machine use as did beginning and ending angles and ROM for specific joints. In examining muscle activity levels, it should be noted that the differences recorded between machines were seen primarily in accessory, rather than the muscles commonly targeted during each exercise" (Signorile. 2016).

On the other hand, it is questionable whether it even makes sense to ask a classic gym-question like 'what is better cables or plate-based machines' even makes sense without specifying the purpose. I believe the answer is 'no!' and thus follow-up studies with sports-specific outcomes will have to show which athletes benefit most from using cables instead of rigid machines and, eventually, how they compare to the good old free weights, we all love so much. 

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Bottom line: Unfortunately, the focus of the study at hand was not on 'gains'. Accordingly, the scientists own conclusion discusses the possible transfer of training into activities of daily living (ADL) and here, "the higher activation levels of the core muscles during the chest press and overhead press exercises during cable versus selectorized machine use indicate that cable machines may be more effective when targeting sport and ADL activities that depend heavily on serape-dominated movements (transitions employing rotational movements that transfer force from the lower to upper body through the core)" (Signorile. 2016). In other words: Cables may help you sweep or transfer an object from one counter to another, or with groundstrokes in tennis or driving a golf ball. In contrast, more linear movements like the biceps curl or training of the front delts appear to benefit from limiting the degree of freedom and thus isolating the body segments on plate-loaded machines | Comment on Facebook!

References:

• Signorile, Joseph F., et al. "Differences In Muscle Activation And Kinematics Between Cable-Based And Selectorized Weight Training." The Journal of Strength & Conditioning Research (2016).
• Silvester, L. Jay, and G. Rex Bryce. "The Effect of Variable Resistance and Free-Weight Training Programs on Strength and Vertical Jump." Strength & Conditioning Journal 3.6 (1981): 30-33.
• Stone, M., S. Plisk, and D. Collins. "Training principles: evaluation of modes and methods of resistance training--a coaching perspective." Sports biomechanics/International Society of Biomechanics in Sports 1.1 (2002): 79-103.