Is Adding Single Joint Movements on Top of Multi-Joint Exercises Necessary to Build Bigger & Stronger Arms?

If Arnold did them you should do them, too - right? Curls and triceps extensions for bigger arms.  A recent study in subjects with at least two years of resistance training experience negates that: Neither size nor strength of the arms will benefit from isolation exercises. At least in trained athletes on an ABAB regimen w/ 4 workouts per week that's the case.

Some people say: "Squats, deadlifts and the bench! That's all you need to do." Others compile a longer list, but still believe that there's no need or even no room for single joint exercises like biceps curls or triceps extensions. Are they right? I mean, there's no debating about the time-efficacy of multi-joint only workout routines, but what about the "gains"? Will you compromise your strength and size gains on the altar of time efficacy?

A recent study from the Santa Cecilia University and other universities in Brazil tried to answer this and related questions in a group of  trained subjects: Their study evaluated the differential effects on alterations in upper body muscle strength and size of resistance training protocols involving only multi-joint (MG) or both multi-joint (MJ) and single-joined (SJ) exercises in a single workout session in trained men (França. 2015).

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The participants were randomly assigned to one out of two groups: A combination group with both multi- and single joint exercise MJ+SJ (n = 10, 27.7 + 6.6 year) and a multi-joint only group MJ (n = 10, 29.4 + 4.6 years). To be included in the study, participants had to be currently practicing RT and have been continuously training for at least two years previous to the beginning of the study. Their programs had to involve both MJ and SJ exercises and had to be geared towards muscle hypertrophy. People with a history of anabolic steroid use were not accepted. Furthermore, all participants were instructed not change their nutritional habits or ingest ergogenic aids during the study. Minimum training attendance was set at 85% (all 20 volunteers complied).

"In order to increase ecological validity, RT [resistance training] program design and exercise choice were based on the common practices used in gyms and fitness centers by experienced trainees who desire to increase muscle strength and size. RT followed a linear periodization model with sequences of ordinary (two), shock (one) and restorative (one) microcyles as shown in Table 1" (de França. 2015).

During the ordinary microcycle, sets were performed to concentric failure - with one minute rest interval between sets. During the shock microcycle, each exercise was performed with the same load of the ordinary week, however, after failure, external assistance was given during the concentric phase to allow the performance of 2-5 additional repetitions, a method that's usually called forced repetitions (Ahtiainen. 2003).

Table 1: Periodization scheme used in the study (explanation follows | de França. 2015)

During the ordinary and shock microcycles,  the loads were reduced by ~10% from set to set to maintain the designated number of repetitions (Willardson. 2012). During the restorative microcycle, the loads were equivalent to 50% of the load used in the previous microcycle but the number of repetitions was kept at 10 and no load adjustment were necessary from set to set.

"Participants were instructed to take one second to perform the concentric and two seconds to perform the eccentric phase, whenever possible. Rest intervals were set at one minute between sets and two minutes between exercises" (de França. 2015).

Each session lasted approximately 35 and 50 minutes for MJ and MJ+SJ, respectively, and the subjects trained according to an A-B regimen that was performed twice a week for a total of four training days per week. In that, the lower limbs, low back and abdominal muscles were trained on Wednesdays and Saturdays through the same complementary training program for both groups.

Table 2: Overview of the RT programs | * denotes exercises done only in the MJ+SJ group (de França. 2015).

As show in Table 2, both groups performed the same MJ exercises, but the MJ+SJ groups also performed the exercises marked with asterisks. This means we are not comparing workouts with identical volume, but actually normal volume MJ only vs. high volume MJ + SJ workouts.

Why is it important that the scientists measured the size gains 5-7 days after the last workout? As a SuppVersity reader you should know that the exercise induced cell-swelling will mess with the results for at least 52h. If you don't remember that, read up on it in my previous article Cell Swelling Keeps Muscles "Pumped" For More Than 52h. Size Increases of Up to 16% After a Single Leg Workout!" (read it!)

To assess the results of the program, the researchers did 1-RM tests (for strength) and measured the flexed arm circumference (FAC) and arm muscle circumference (AMC) before the training program and 5-7 days after the last training session (see red box to learn why this is important).

Figure 1: Pre-/post-changes in arm circumference and biceps + triceps strength (de Franca. 2015).

The results of these measurements or, more specifically, the mean changes between pre- and post-test are shown in Figure 1. As the scientists highlight in their paper, significant differences between pre- and post-tests (p<0.05) were found for all variables analyzed. Comparison between groups, however, did not show significant differences for any variable (p>0.05).

SuppVersity Suggested: "Cut the Volume, Still Make Gains! Perfor-mance Gains in Sprinters Don't Suffer From Reduced Training Volume. Plus: Best Volume & Frequency for Size & Strength Gains?" | This study is also relevant because it confirms that volume reductions as it was the case for the MJ vs. MJ+SJ training in this study can often be positive | read it!

Yes, this does mean that within only 8 weeks the addition of single joint exercises on top of the "big moves" will not yield statistically significant increases in either strength or size gains in already trained individuals. 

Due to the design of the study we cannot exclude, though, that adding SJs would yield benefits in resistance training noobs, on a longer time-scale (unlikely, though, since there's rather a minor advantage for MJ only), or on a more complex split routine (e.g. arms on their own day), though. And still - in view of the fact that most trainees believe that they wouldn't gain an inch on their arms if they didn't train arms separately, thus wasting hours on doing all sorts of curls, the results of de França's study are unquestionably important. After all, they may sooth the minds of those who have long wanted to do a multi-joint only training, but have always been afraid that not doing all sorts of curls and triceps extensions may impair their "gains" | Comment!

References:

• Ahtiainen, Juha P., et al. "Acute hormonal and neuromuscular responses and recovery to forced vs maximum repetitions multiple resistance exercises." International journal of sports medicine 24.6 (2003): 410-418.
• de França, Henrique Silvestre, et al. "The Effects Of Adding Single-Joint Exercises To A Multi-Joint Exercise Resistance Training Program On Upper Body Muscle Strength And Size In Trained Men." Applied Physiology, Nutrition, and Metabolism (2015): Ahead of print.
• Willardson, Jeffrey M., Roberto Simão, and Fabio E. Fontana. "The effect of load reductions on repetition performance for commonly performed multijoint resistance exercises." The Journal of Strength & Conditioning Research 26.11 (2012): 2939-2945.