Effects of Eccentric Single-Leg Decline Squat Exercise on the Morphological and Structural Properties of the Vastus Lateralis and Patellar Tendon

Abstract

The purpose was to examine the effect of 6-week eccentric single-leg decline squat (SLDSe) training with two technical execution times (3 s or 6 s) on changes related to the structural properties of the vastus lateralis (VL) and patellar tendon (PT). Thirty-six physical active volunteers were randomly divided into three groups: control group (CG, n = 13, age = 20.8 ± 1.9 years, no intervention program), experimental group 1 (EG1, n = 11, age = 21.6 ± 2.5 years, execution time = 6 s) and experimental group 2 (EG2, n = 12, 21.1 ± 1.2 years, execution time = 3 s). Participants completed a 6-week SLDSe training program (80% of 1-RM) three days a week. The structural characteristics of the VL and the PT were measured with ultrasonography before and after 6-week SLDSe training and after 6 weeks of de-training. Our results indicate that EG1 increased ≈21.8% the thickness of the PT and EG2 increased ≈15.7% the thickness of the VL after the 6-week intervention program. EG1 and EG2 showed greater values (p < 0.05) of lean mass and lower values (p < 0.05) of fat percentage on the thigh after the intervention program. In conclusion, the SLDSe training carried out with the execution time of 6 s had greater effects on the structural and elastic properties of the PT, and the exercise with the execution time of 3 s caused greater structural adaptations in the VL musculature.

The Effects of Eccentric Contraction Execution Time on the Properties of the Patellar Tendon

“…The results obtained in tendon thickness agree with previous investigations that have analyzed the thicknesses of healthy and pathological tendons [ 16 , 40 ]. On the other hand, although most of the investigations that have achieved hypertrophic increases in the PT have used at least twelve weeks of intervention by means of eccentric exercise [ 10 , 11 , 33 , 35 ], the present study, according with Abian et al [ 16 ], shows that six weeks of intervention using the SLDSe exercise focused on its eccentric phase are sufficient to increase the thickness of the PT, independently of the execution time of the eccentric contraction performed. This may be due to the high load (80% of the eccentric 1 RM) and the type of exercise (SLDSe) used in our intervention program.…”

“…The thickness of the PT was measured by B-mode ultrasonography (LOGIQ E9, GE Healthcare, Milwaukee, WI, USA) with a 5.5 cm, high frequency 6–15 MHz linear probe. The participants lay supine on a stretcher, with the knee flexed to 15° [ 16 , 22 ]. The transducer was placed parallel to the direction of the PT fibers.…”

“…Movement speed during eccentric training alters important factors involved in muscular adaptations, such as time under tension and muscle activation [ 15 , 16 ]. Burd et al [ 17 ] found that greater muscle time under tension increased mitochondrial and sarcoplasmic protein synthesis.…”

“…Burd et al [ 17 ] found that greater muscle time under tension increased mitochondrial and sarcoplasmic protein synthesis. Fast eccentric movement during training has been found most effective for muscle hypertrophy and strength gain [ 16 , 18 ] and slow eccentric movement during training has had larger effects on the elastic and structural properties of the PT [ 16 ]. However, there is a need to investigate the different components of the eccentric exercise load on the morphological and mechanical properties of the muscle and tendon structures.…”

Morphology of the Patellar Tendon and the Contractility Response of the Quadriceps: Symmetry and Gender Analysis

“…The use of ultrasonography has become a standard method for measuring the mechanical properties of the tendon in vivo [ 8 ], like stiffness which can be assessed reliably and with validity using sonoelastography [ 9 , 10 ]. The majority of studies which use sonoelastography to evaluate tendon stiffness are focused on assessing the Achilles tendon [ 10 , 11 ], although some recent studies on the patellar tendon (PT) can also be found [ 12 , 13 , 14 , 15 ]. Porta et al [ 13 ] assessed the reliability and reproducibility of sonoelastography for describing the stiffness of the patellar tendon and found that a healthy patellar tendon presents high elasticity with excellent values of intra-examiner and inter-examiner reproducibility.…”