Alternate vs. Classic Resistance Training: Can You Bench in Between Your Squat Sets & Still Make Fabulous Gains?

What now? Wait 3 minutes or off to the bench for an alternate set of bench presses or pulls ?

Traditional strength training with 80% of one-repetition maximum (1RM) utilizes 2- to 5-minute rest periods between sets. These long rest periods minimize decreases in volume and intensity, but result in long workouts. Performing upper-body exercises during lower-body rest intervals may decrease workout duration, but may affect workout performance.

The above is how Anthony B. Ciccone, Lee E. Brown, Jared W. Coburn, Andrew J. Galpin kick off their latest paper in the venerable Journal of Strength and Conditioning Research (Publish Ahead of Print).
The purpose of the corresponding study was to compare the effects of traditional to those of alternating whole body strength training on squat performance. To this ends, Ciccone et al. recruites 20 youn men, who had to perform two workouts:

• The traditional set workout (TS) consisted of four sets of squats at 80% of 1RM on a force plate with 3-minutes rest between sets. 
• The alternating set workout (AS) also consisted of four sets of squats at 80% of 1RM but with bench press, and bench pull exercises performed between squat sets 1, 2 & 3 with between-exercise rest of 50 seconds, resulting in approximately 3-minutes rest between squat sets. 

For both workouts, sets 1-3 were performed for four repetitions, while set four was performed to concentric failure. The total number of completed repetitions, the peak ground reaction force (GRF), peak power, (PP), and average power (AP) of every squat repetition were recorded and averaged for each set.

Figure 1: Maximal # of reps on last set and average power in the classic vs. alternating condition (Ciccone. 2014)

Interestingly, there was no significant interaction for GRF, PP, or AP. Only, the volume-equated AP was ca. 5% greater during the TS condition (989 ± 183) than the AS condition (937 ± 176). A more pronounced difference which was yet still within the margin of one standard deviation (in this case 2.2. reps) was observed for the fourth squat set to failure, where the TS condition resulted in 15% more reps to failure (7.5 ± 2.2) than the AS condition (6.5 ± 2.2). Reason enough for Ciccone et al. to suggest that:

1. Individuals who aim to optimize squat AP should refrain from performing more than three AS sets per exercise.
2. Those who aim to maximize squat repetitions to failure should refrain from performing upper body multi-joint exercises during squat rest intervals.

Certainly a sound advice, but in the end, we all live in a world where time is a precious gem and some people give a fuck about average power and the number of reps until they fail.
References:

• Ahtianen, Juha P., et al. "Short vs. long rest period between the sets in hypertrophic resistance training: influence on muscle strength, size, and hormonal adaptations in trained men." The Journal of Strength & Conditioning Research 19.3 (2005): 572-582.
• Ciccone AB, et al. "Effects of Traditional Versus Alternating Whole-body Strength Training on Squat Performance." J Strength Cond Res. (2014) Jun 17. Ahead of print.
• de Salles, Belmiro Freitas, et al. "Rest interval between sets in strength training." Sports Medicine 39.9 (2009): 765-777.