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Resistance Training/Periodization

(10) MULTI SET STRENGTH COMPARISON IN BRAKING AND PROPULSIVE FORCE-TIME CHARACTERISTICS DURING ACCENTUATED ECCENTRIC LOADING BACK SQUATS

Thursday, July 11, 2024
2:00 PM – 3:30 PM East Coast USA Time
Location: Exhibit Hall
Abstract Details: PURPOSE To examine differences in braking and propulsive force-time characteristics across multiple sets of accentuated eccentric loaded (AEL) back squats (BS) between stronger and weaker men.

Methods: 15 resistance-trained men were separated into stronger (S) (n = 8, age = 25.1 ± 5.2 years, height = 172.8 ± 5.6 cm, body mass = 80.2 ± 11.0 kg, relative one repetition maximum [1RM] back squat = 2.24 ± 0.12 kg/kg) and weaker (W) (n = 7, age = 23.6 ± 1.7 years, height = 182.9 ± 6.2 cm, body mass = 91.4 ± 12.4 kg, relative 1RM back squat = 1.76 ± 0.13 kg/kg) groups based on if they were able or unable to BS twice their body mass. Each subject participated in three separate testing sessions over the course of one week. After obtaining the BS 1RM of the subjects in the first testing session, they were also familiarized with AEL squats using weight releasers. During sessions two and three, the subjects performed three sets of three BS repetitions using weight releasers on the first repetition of each set. The final two testing sessions had the subjects perform AEL BS with 100% 1RM eccentrically on the first repetition and either 60 (100-60) or 80% (100-80) 1RM concentrically for the first and remaining repetitions. Each BS repetition was performed on a force platform and the raw force-time data were used to calculate net braking mean force (BMF), braking duration (BD), net propulsive mean force (PMF) and propulsive duration (PD) during each repetition. The average across all repetitions of each set were used for statistical comparison. A series of 2 x 3 repeated measures ANOVA tests were used to assess differences in force-time characteristics between groups and sets. Hedge’s g effect sizes were calculated between groups to examine the magnitude of the differences.

Results:  The force-time characteristics produced during each set are shown in Table 1. In both the 100-60 and 100-80 conditions, there was a main effect for BMF (p=0.005, p=0.016). However, the condition main effect was not significant for BD (p=0.893, p=0.835). Significant main effects were observed in both conditions for PMF (p=0.015, p=0.012) and for PD across both conditions for the S group (p=0.049, p=0.036). Finally, there was no strength x set interaction effect for any variable (p >0.05).

Conclusion: The S group produced greater BMF and PMF across sets in both the 100-60 and 100-80 condition compared to the W group. There was no difference for BD across groups in both conditions. The S group also performed the propulsive phase over shorter durations in both conditions. PRACTICAL APPLICATIONS: S and W groups can complete multiple sets of AEL BS; however, the S group may respond to the stimulus better than their W counterparts. Because the S group appear to enhance concentric performance to a greater extent than the W group, relative strength may be a limiting factor for AEL prescription in the BS.

Acknowledgements: NONE