(5) PHASE DURATION IN ACCENTUATED ECCENTRIC LOADED BACK SQUATS IN RESISTANCE TRAINED WOMEN

Purpose: The purpose of this study was to compare the downward phase duration of traditional back squats to maximal and supramaximal accentuated eccentric loaded (AEL) back squats in resistance-trained women.

Methods: 14 resistance-trained women (age = 23.6 ± 2.6 years, height = 166.5 ± 6.5 cm, body mass = 70.3 ± 8.4 kg, relative one repetition maximum back squat [1RM BS] strength = 1.50 ± 0.19 kg/kg) with previous BS experience participated in four testing sessions. During the first session, subjects performed 1RM BS testing and were familiarized with weight releasers. The following three testing sessions were performed in a randomized order with various squat conditions. The traditional loading scheme required subjects to perform sets of three BS repetitions each with 50, 60, 70, 80% of their 1RM (TRAD). During the AEL conditions, the same TRAD loads were loaded on the barbell; however, weight releasers were added on the first repetition of each set to equate either 100 (AEL 100) or 110% (AEL110) 1RM, respectively. Therefore, the subjects performed the eccentric phase of the first repetition with100 or 110% of their 1RM and then 50, 60, 70, or 80% of their 1RM concentrically for the concentric phase of the first repetition and then both eccentrically and concentrically for the remaining two repetitions. Each BS set was performed on a force platform and the force-time data were used to calculate the downward phase duration of the first repetition of each set, which combines the unweighting and braking phase durations. A 3 (condition) x 4 (load) repeated measures ANOVA test was used to compare downward durations between the TRAD, AEL100 and AEL110 conditions. In addition, Hedge’s g effect sizes were calculated to examine the magnitude of the differences between the conditions.

Results: There was a significant load main effect (p < 0.001); however, the main effect for condition (p= 0.129) and the condition x load interaction effect (p= 0.396) were not significant. The downward phase durations of each loading condition are displayed in Table 1.

Conclusion: The load added to the barbell had a significant effect on downward phase duration.  However, the downward phase durations were consistent between TRAD and AEL conditions in resistance-trained women. PRACTICAL APPLICATIONS: Because downward phase duration may not differ between TRAD and AEL back squats, strength and conditioning practitioners should consider implementing AEL using the natural movement tempo of individuals to provide the most effective training stimulus. However, it is important to consider the prescribed loads as the downward phase duration may change.  


Acknowledgements: None