CN. Munger1, BC. Jones2, IJ. Halloran3, GG. Eggleston4, JM. Berning FACSM5

1The College of Idaho, Caldwell, ID; 2Texas Tech University, Lubbock, TX; 3Army-Baylor University, San Antonio, TX; 4University of Nebraska, Omaha, NB; 5New Mexico State University, Las Cruces, NM

Eccentric overload (EO) has shown to increased strength, explosiveness, and early skeletal muscle adaptation. Popularity of EO is increasing, however there is an inherent risk associated with using supramaximal loads. Obtaining a prediction equation for maximal eccentric strength will allow safer prescription of eccentric work while reducing risk. PURPOSE: The purpose of this study was to predict 3-second eccentric 1-repetition maximums (Ecc1RM) from 1RMs in the back squat. METHODS: For this study, 33 resistance-trained males were recruited (Age: 23.4 ± 2.7 years, Height: 174.9 ± 10.6 cm, Mass: 78.3 ± 10.6 kg). Testing consisted of back squat 1RM and Ecc1RM. For 1RM testing, subjects started by doing a 10-repetition warm-up set with a standard 20kg barbell. Then they did 7 back squats at 60%, 4 at 70%, 2 at 80%, and 1 at 90% of their predicted 1RM. Then they had 4 attempts to achieve a 1RM. Load was increased until an attempt resulted in failure to lift the weight. After 1RM, Ecc1RM testing began. Safety bars within the squat rack were adjusted so that the barbell rested on them when the subject reached a squat depth of thigh parallel to the ground. Subjects performed a warm-up of 4 eccentric-only back squats at 60%, 3 at 80%, 2 at 90%, and 1 at 100% of 1RM by lowering the bar to the safeties. A spotter assisted the lifter during the concentric phase of these reps. The squatting commands were said in cadence with a metronome at 60 beeps per minute. Then subjects had 4 attempts to attain their Ecc1RM. A spotter was not used during these repetitions. Lowering the bar to the safeties prior to the lapsing of 3 seconds resulted in a failed lift. Three minutes of rest was given between squat sets, 1RM attempts, and Ecc1RM attempts. RESULTS: Mean ± SD of post-test 1RMs and Ecc1RMs were 129.3 ± 31.3 kg and 154.6 ± 35.7 kg, respectively. A simple linear regression was calculated to predict eccentric 1RMs from concentric 1RMs. A significant regression equation was found [F(1, 31) = 458.81, p < .002] with an R2 of .937. Subjects’ eccentric back squat 1RM is equal to 12.22 + 1.10(1RM) when measured in kg and 1RM is between 79.4 kg and 190.5 kg. CONCLUSIONS: Ecc1RMS were successfully predicted from 1RMs with sufficient accuracy. The derived regression equation can now aid in the prescription of EO in the back squat and allow for training benefits with less risk.

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