All else being equal between two athletes, the one who can express their strength faster will dominate in most sport settings. This is because there is a time component in nearly all situations where half a second too late can have serious consequences; an interception, a blocked pass, etc. Training should therefore be structured to develop and optimize speed and power, the foundation for which is of course, maximal strength. Traditional resistance training protocols that involve straight sets at a given intensity may not be optimal for the expression and maintenance of bar velocity during a given exercise (e.g., squats). Notice how the last few reps of a set of 5 start to look different than the first few reps? Bar speed tends to slow down and technical performance may even begin to deteriorate with heavier loads. Breaking away from traditional approaches with simple adjustments in set structure and rest periods may better promote increases in power.
Recent research out of Edith Cowan University in Australia by Tufano et al. (2014) compared the effects of straight set verses cluster set training in twelve resistance trained men. Each participant performed a control workout (straight sets) of 3 sets of 12 repetitions with 60% of their back squat 1RM and a cluster set workout which included 3 sets of 12 repetitions with 60% of their 1RM and 30 seconds of rest between the 2, 4, 6, 8, and 10th reps. Each workout was separated by at least 48 hours. Two minutes were provided for rest between sets. Total work, peak power and peak velocity were measured for all sets and reps and compared. The results showed that total work did not differ between the control and cluster set protocols. However, peak power and peak velocity were significantly higher in the cluster sets compared to control. Thus, given the same workload, the cluster set configuration enabled greater expression of power and bar speed among the current sample of resistance trained men.
One of the obvious draw backs of the cluster set configuration is the increase in time required to complete the same workload. This may be problematic in large group settings where dozens of athletes need to get their workouts in within a relatively short time period. However, if this issue does not apply to you, it may be worth programming some cluster sets within your training. The clusters enable a greater focus on repetition quality, both technically and relative to power and speed expression. Clusters will be most effective with main compound movements like squats, bench presses, Olympic lifts and so forth. Clusters are a simple modification to traditional approaches that can enhance speed and power without the need for additional equipment (i.e., bands and chains).
Tufano, JJ., et al. (2014) Acute effects of hypertrophy-oriented cluster sets on work, power and velocity. Eur J Sports Sci, (suppl to Vol. 2) Oral Presentation.