Isolation vs. Compound Exercises

There are two different types of strength-based exercises: isolation exercises and compound movements. Isolation exercises focus on one specific muscle; this can be useful for a few different purposes.

• Rehabilitation of a muscle can be facilitated with isolation exercises. If you have muscular imbalances or under-active muscles, isolation exercises are perfect for strengthening those areas. For example, if you have pain in your hip flexors after squatting, you may have under-active glutes. Isolations like glute bridges or clams can help you reactivate your gluteal muscles and prevent further pain or injury down the road.
• Aesthetics athletes (e.g. bodybuilders or bikini competitors) may utilize isolation exercises to really hone in and focus on one specific area. A lot of these athletes include exercises like lateral shoulder raises and biceps curls in their routines to really define those areas most important to the judges.

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While there are certain advantages to using these exercises, isolation exercises place a lot of shear forces on your joints. Put simply, shear force occurs when a joint is being pulled or pushed in two different directions. To better understand this, imagine a leg extension machine: the seat is pushing your femur upwards, while the pad is pushing your tibia down. This shear force can cause ACL strains as you start to use a heavier weight and higher reps. If you have preexisting knee problems, exercises like leg extensions or leg presses may not be well suited for you.

Compound exercises utilize multiple different muscles. Because more muscles are recruited, compound movements are more efficient. Instead of spending hours in the gym doing multiple triceps and shoulder exercises separately, you can use exercises like dips, push-ups or bench presses to target all of these areas simultaneously. You only need a handful of exercises to adequately train every muscle in your body. Spending hours on isolations exercises is unnecessary when you can spend half of that time in the gym and get just as great of a workout. 

Similarly, compound exercises are more efficient from a metabolic standpoint. The metabolic cost of doing squats far surpasses that of doing leg curls and leg extensions. Not only do you recruit more muscle groups, but you are also stimulating more muscle fibers. The more muscle fibers stimulated, the more anaerobic hormones (i.e. testosterone, Human Growth Hormone, etc.) that are released. If you're looking to have a greater caloric expenditure, compound exercises are the way to go.

Finally, compound exercises train multiple different aspects of athleticism. While isolations only focus on muscular hypertrophy, compound exercises function as a great neuromuscular exercise as well: they teach proper bodily positioning, improve range of motion, enhance core stability and balance, in addition to strengthening the muscles.

Depending on your goals, you may find it necessary to incorporate both types of exercise into your fitness regimen. Find exercises that work best for you and stick with them! Ultimately, any type of exercise is great for your body, and as long as you're working hard, your body will thank you.


Sources:

1. Lutz, G. E., R. A. Palmitier, K. N. An, and E. Y. Chao. "Comparison of Tibiofemoral Joint Forces during Open-kinetic-chain and Closed-kinetic-chain Exercises." The Journal of Bone and Joint Surgery (1993): n. pag. Web. 02 Sept. 2013.
2. Mihalik, Jason, Jeremiah Libby, Claudio Battaglini, and Robert McMurray. "Comparing Short-Term Complex and Compound Training Programs on Vertical Jump Height and Power Output." Journal of Strength & Conditioning Research 22.1 (2008): 47-53. Print.
3. Wilk, Kevin E., Rafael F. Escamilla, Glenn S. Fleisig, Steve W. Barrentine, James R. Andrews, and Melissa L. Boyd. "A Comparison of Tibiofemoral Joint Forces and Electromyographic Activity during Open and Closed Kinetic Chain Exercises." The American Journal of Sports Medicine 24.4 (1996): n. pag. A Comparison of Tibiofemoral Join... Preview & Related Info. July 1996. Web. 03 Sept. 2013.