The reasons that show why compound exercises work better than isolation overlap in some ways with why the free weights vs. machines debate favors free weights.
Free weights are objects free to move within all three planes unbound to any axis. This includes bodyweight exercises. Machines keep you bounded to at least one axis.
Free weights, in the long run, match the demands of our bodies. In the short-run, you need to learn good form and perhaps install safety features specific to the exercises you choose. This defends against the disadvantages. Consider these reasons.
Reasons
- They let you control the movement.
This allows a unique path through the range of motion that feels best for you. This, when taught good form, allows you to train safely. Machines constrict you and may harm the joints by forcing a different path than you would have chosen.
The carrying angle of the elbow creates a non-linear path when moving the joint. The forearm moves off to the side to avoid hitting the hip when you use an underhand grip. A biceps curl machine would fail to allow for this slight deviation.
A bench press machine may force you to flare or tuck your elbows when lifting, which harms the shoulders. A free weight bench press would allow you to strike a balance. The perfect grip or stance requires medium positions that feel difficult to obtain with a machine.
- They are more functional.
Free weights, done right, load basic movement patterns such as pushing, pulling, and squatting.
Controlling a free weight develops stability and balance. Stabilizers work harder since they need to prevent lateral movement. The correct free weights exercises strike the right balance of addressing the deep, smaller muscles without an excessive need for balance, so as to train the prime movers well.
Free weights reflect real demands versus the artificial environment created by a machine. Even cable pulleys, that seem to capture benefits of both free weights and machines, allow for unnatural exercises.
More muscle used due to the stability required gets your heart rate up further for cardio. Using lots of muscle achieves the best cardio. Riding a bike will have a lesser effect versus sprinting up a hill.
Though skills do not transfer, free weight can teach you to use good mechanics in everyday life such as when you squat to lift an object.
They stimulate hormones due to more total stress on the body that comes with more muscle worked. Steroids show the power of improving your hormone levels. This increases overall strength and size further.
Machines train your body as separate parts instead of as a unit.
- They match our strength curves.
The resistance should feel heaviest at a medium muscle length. You create the greatest tension, the main stimulus for size and strength, at the midpoint of any normal movement. Free weights emphasize this by their very nature.
When doing a bench press, your muscles function most strongly in the middle. It only feels easier at the top when your elbows near locking out because you have better leverage. The muscles actually begin to bunch up like a ball of yarn here and overlap too much to create much tension. This matters little though because leverage makes up for it.
Machines often alter the feel of the resistance by using a lever arm, cam, or pulley. This may instead make the weight feel heavier near the lockout of the bench press, whereas you feel strong only because of better leverage and not because your muscles work best at this portion of the range of motion. With a free weight bench press, the weight feels heaviest halfway down, precisely where all the muscles involved function best.
- They prevent accommodating resistance.
Accommodating resistance means changing how heavy the weight feels throughout the range of motion. A squat machine may make it feel harder right before your knees lock out. Many machines change these strength curves but the concept is misguided.
You may feel stronger right before your knees lock out on the squat but only because your leverage improves. Your muscles function strongest about halfway down, when the leverages are worst. Since free weights stay the same, they overload this spot the most.
Free weights therefore supposedly tax only the weakest joint angles. These so-called weak joint angles though are where your muscles work best to make up for the lack of leverage. Athletes have attempted to use accommodating resistance even with free weights via chains, bands, and other equipment because they fail to understand this concept.
This argument also assumes we should move through a full range of motion. This may place the joints in a vulnerable state since muscles work weakly that at endpoints. Making a bench press harder at the top places even more stress on the elbows.
Avoid accommodating resistance of all types.
- They allow brief respites.
Machines often load the motion relentlessly throughout the exercise duration. Some argue this makes exercise more efficient and effective. This concept is unproven though and different training styles with short pauses between reps have shown to have the same or even results for building size and strength.
When running, you get brief pauses between foot strikes that may allow lactic acid and other fatigue by-products to get removed. Lactic acid buildup can prevent enough tension from forming for muscle growth. At the lockout of a bench press, you get a small break for the next rep that could have a similar effect.
As long as not extended for too long, these pauses work well for strength training.
- They somewhat restrict bad exercises.
Machines allow you to perform non-functional isolation exercises. They overload functions meant for very little or no resistance, such as hip flexion or dorsiflexion at the ankle. Isolation exists for repositioning your limbs and doing them heavily can hurt you. Using a free weight, barring some extreme creativity, prevents you from overloading motions never adapted to handle heavy weights.
- They are versatile, portable, less costly, and universal.
A barbell, dumbbell, weight plates, flat bench, and power rack allow you to train every muscle in the body. Free weight exercise can take place in all sorts of places and you can often bring some tools with you or use your bodyweight. You can buy all you need and more for the price of one machine. You can also compare performances more easily on other settings.
Free Weights over Machines
Free weights still have some issues.
They may provide too much or too little weight for bodyweight choices. Use barbell or dumbbell exercises instead.
You will need equipment for safety. With choices such as a power rack for the squat and bench press, you get rid of the main risk of training to failure.
Machines reduce the need for instruction and seem safer at first. Everyday life and sports challenge us in free weight settings though and machines seem safer only with a narrow point of view. Machines vary in quality too. They contain more parts that may fail such as bolts, cables, chains, and so on. They need more maintenance and may develop friction.
Learn good form on free weights and abandon machines to benefit in the long-run.