Abstract
Background: In clinical practice, resistance training, which includes concentric and eccentric dynamic muscle movements, is widely used by physiotherapists to strengthen the quadriceps muscle. However, although eccentric training is assumed to induce greater hypertrophy compared to concentric contractions, there are also studies reporting that similar increases in muscle thickness can be seen in both eccentric and concentric training.Objective: This study aims to assess the effect of the eccentric and concentric squat exercise on quadriceps thickness, and lower extremity performance during jumping and walking in healthy young sedentary males. Methods: Participants were randomly divided into three groups: concentric exercise group (CE; n = 19), eccentric exercise group (EE; n = 13) and control group (CG; n = 16). Both exercises were performed seven days a week, for eight weeks with a gradual strength increase. The CG was not given any exercise. Ultrasound assessment of quadriceps muscle thickness, performance in Six-Minute Walk Test and vertical jump was measured. Results: Thickness of dominant side of rectus femoris (p = .008) and vastus lateralis (p = .021) differed significantly among the three groups; post hoc analysis revealed the thickness of rectus femoris in CG was significantly lower than in the CE (p = .046) and EE (p = .006) and the thickness of vastus lateralis in the EE was significantly higher than in the CG (p = .018). Six-Minute Walk Test score in the EE was significantly higher than in the CG (p = .025) and the vertical jump score in the CG significantly lower than in the EE (p = .002) and CE (p < .001). Conclusions: Eccentric and concentric training both benefits muscle hypertrophy and lower extremity functional performance. However, eccentric training also appears to offer a small advantage over concentric training.
Highlights
The quadriceps femoris is the most voluminous muscle group of the human body (Bordoni & Varacallo, 2021)
Forty-eight males with age 23.11 ± 0.87 years in concentric exercise group (CE) and 23.23 ± 1.16 years in exercise group (EE) and 22.81 ± 0.65 years in control group (CG) group participated in the study
Dominant side rectus femoris (p = .008, η2 = .191) and vastus lateralis (p = .021, r = .157) differed significantly among the three groups; post hoc analysis revealed the rectus femoris in CG significantly lower than in the CE (p = .046, d = .649) and EE (p = .006, d = .539) and the vastus lateralis in the EE was significantly higher than in the CG (p = .018, r = .710)
Summary
The quadriceps femoris is the most voluminous muscle group of the human body (Bordoni & Varacallo, 2021). Conventional multi-joint, closed kinetic chain exercises have several advantages because both proximal and distal body segments receive resistance training at the same time, allowing weight-bearing for the lower extremity, and produce superior eccentric contraction and co-contraction of the muscles, reduce shear forces while adding compressive forces to the joints. In this context, squat exercise, which is frequently used in the clinical setting, simulate functional activities, create minimal stress on the patellofemoral joint in the functional range of motion, and allow the use of muscles that contribute to joint stability (Dionisio et al, 2013; Escamilla, 2001). Eccentric training appears to offer a small advantage over concentric training
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