Effects of Eccentric Single-Leg Decline Squat Training Performed With Different Execution Times on Maximal Strength and Muscle Contraction Properties of the Knee Extensor Muscles.

ABSTRACT Abian-Vicen, J, Martinez, F, Jimenez, F, and Abian, P. Effects of eccentric single-leg decline squat training performed with different execution times on maximal strength and muscle contraction properties of the knee extensor muscles. J Strength Cond Res XX(X): 000-000, 2021-The eccentric phase of the single-leg decline squat (SLDSe) has been described as a method to maximally load the knee extensor and has been used as an easy and effective rehabilitation exercise for patellar tendinopathy. The purpose of this study was to examine the impact of 6-week SLDSe training with 2 technical execution times on changes related to strength and muscle contractile properties. Thirty-six healthy volunteers were randomly divided into 3 groups: a control group (CG, n = 13, no training), a slow training group (n = 11, SLDSe in 6 seconds), and a fast training group (n = 12, SLDSe in 3 seconds). Subjects completed a 6-week SLDSe training program (80% of eccentric one repetation maximum [1RM]) 3 days a week. Pre, post, and 6-week follow-up of maximal dynamic and isometric strength and muscle contractile properties were assessed. After 6 weeks, training maximal loads showed a significant increase (p < 0.05) in 1RM of the SLDSe (∼92-95%), the concentric peak torque at 180°·s-1 (∼38%) and 60°·s-1 (∼25%), and the extension isometric peak torque (∼12%), with no differences between both experimental groups. Moreover, a decrease (p < 0.05) was found in the contraction time of the vastus medialis (VM) and the response time of the 3 analyzed quadriceps muscles. After the 6-week detraining period, there was a decrease in strength in all tests and in both experimental groups (1RM = 28-37%, isometric and isokinetic tests = 7-17%) and all contractile properties returned to baseline, except for the response time of the vastus lateralis in the fast training group and the contraction time of the VM in the STG. In conclusion, the SLDSe training protocol produced significant increases in muscle strength, showing important neuromuscular changes regardless of the technical execution time. It was also found that the training reduced the response and contraction time of the knee extensor musculature.