Acute Effect of Cluster and Traditional Set Configurations on Myokines Associated with Hypertrophy

Abstract

This study compared the acute cytokine response, and kinetic and kinematic profile following back squat exercise in resistance-trained men. In a randomized, cross-over design, 10 resistance-trained men (27±4 y, 1.80±0.07 m, 82.8±6.7 kg, 16.3±3.5% fat) performed the back squat exercise using traditional and cluster set configurations. Kinetic and kinematic data were sampled throughout each condition. Venous blood was sampled prior, immediately post, 30 min, 60 min, 24 h, and 48 h post-exercise for plasma interleukin-6 (IL-6) and interleukin-15 (IL-15). Cluster sets allowed for greater mean power (mean difference, 110 W; 90% confidence interval, ±63 W; benefit odds, 41 447:1), driven by higher overall mean velocities (0.053 m∙s; 0.039 m∙s; 3 105:1) as evidenced by the lack of clear contrasts for mean force. IL-15 increased post-exercise in both conditions, but increased at 24 h (0.13 pg·mL; ±0.11 pg·mL; 486:1) and 48 h (0.12 pg·mL; ±0.10 pg·mL; 667:1) in traditional sets only. IL-6 increased similarly in both conditions, post-exercise through 60 min post. Cluster set configurations allow for greater mean power, attributed to higher velocities. Despite a similar response of IL-6, traditional set configuration may provide a greater stimulus for hypertrophy as evidenced by a secondary increase in IL-15.

Shorter but More Frequent Rest Periods: No Effect on Velocity and Power Compared to Traditional Sets not Performed to Failure

“…Hence, velocity and power output decreased in both protocols, but were not better maintained when more frequent inter-set rest periods were implemented with respect to the same load and total training volume while the perceptional fatigue was decreased. These results are in contrast with a large majority of studies in which higher frequency rest intervals allowed for greater maintenance of mean velocity and mean power output during RT (Joy et al, 2013; Oliver et al, 2016b, 2016a; Tufano et al, 2017c). There are a few potential explanations for our contradictory and novel findings.…”

“…Finally, based on the findings of the present study, it seems that rest redistribution protocols performed at 70% of 1RM are not very beneficial for maintaining movement velocity compared to traditional structures when traditional sets are not extremely fatiguing. In contrast, when traditional protocols are performed very close to mechanical failure, rest redistribution might be very beneficial, as previous studies have suggested (Joy et al, 2013; Oliver et al, 2016b, 2016a). Considering these points, cluster sets with extra intra-rest periods are still likely the best option when the aim is to maximize acute movement velocity and power output (Haff et al, 2003; Tufano et al, 2016, 2017b, 2017a), provided that time efficiency is not an issue.…”

“…Secondly, although one study (Mayo et al, 2016) showed that shorter but more frequent rest periods in the leg press exercise can positively impact MV when compared to traditional sets that do not lead to failure, many studies in free weight exercises that compared rest redistribution set structures to traditional sets had to either exclude some participants from the analysis (Joy et al, 2013) or decrease the load due to some subjects reaching momentary failure during traditional sets (Oliver et al, 2016a, 2016b). As participants in our study were able to complete all repetitions (3 sets of 10 repetitions with 70% 1RM) with RPE values averaging 7.5 out of 10 (versus an assumed 10 out of 10 during high-volume training to failure in other studies), it is possible that the effects of rest redistribution on performance maintenance are not as pronounced when sets are not performed to (or nearing) concentric muscular failure.…”

“…Regardless of how an RT protocol is designed, maintaining movement velocity seems to be the key for maintaining power output over the course of an acute RT session, especially when the force requirements remain relatively unchanged (Oliver et al, 2016a; Tufano et al, 2016). In addition, it has been shown that decreases in movement velocity during RT are a valid indicator of neuromuscular fatigue (Sánchez-Medina and González-Badillo, 2011), which can be detrimental to power development.…”

“…This strategy, known as rest redistribution, has been shown to be effective in numerous studies (Joy et al, 2013; Oliver et al, 2016b; Tufano et al, 2017c) that collectively show that when total rest time is the same, shorter but more frequent rest periods are most effective for maintaining acute RT performance. However, relatively few studies have examined such set structures in high-volume free weight RT (Joy et al, 2013; Oliver et al, 2016a, 2016b), many of which included traditional sets that were performed to failure (Iglesias-Soler et al, 2012; Joy et al, 2013; Oliver et al, 2016b). In doing so, these study designs resulted in fewer repetitions, a decrease in the external load, or both during traditional sets performed to failure.…”