Myoeletric Activity of the Quadriceps During Leg Press Exercise Performed With Differing Techniques

Abstract

Machado, W, Paz, G, Mendes, L, Maia, M, Winchester, JB, Lima, V, Willardson, JM, and Miranda, H. Myoeletric activity of the quadriceps during leg press exercise performed with differing techniques. J Strength Cond Res 31(2): 422-429, 2017-The quadriceps muscle supplies the motive force for dynamic knee extension. During this action, the vastus medialis oblique (VMO) and vastus lateralis (VL) co-contract to stabilize the patella as it tracks within the patellofemoral groove. The purpose of this study was to analyze surface electromyographic (SEMG) responses for the VL, VMO, rectus femoris (RF), and biceps femoris (BF), as well as the VMO:VL ratio during an open-kinetic chain 45° angled leg press (LP45). The traditional LP45 technique was compared with 2 alternative LP45 exercise techniques that used a physioball and elastic band, respectively. Thirteen female college students performed 3 protocols in random order: TRAD-1 LP45 set performed using the traditional exercise technique, PBALL-1 LP45 set performed with a physioball held between the knee joints, and PEB-1 LP45 set performed with an elastic band proximal to the knee joints. Ten repetitions at 70% of a 10 repetition maximum load were performed in each protocol, and the SEMG data were recorded for the VMO, VL, RF, and BF muscles. Significant increases in VMO activity were noted during PBALL vs. PEB (p = 0.001) and TRAD (p = 0.002). Higher VMO activity was noted during TRAD vs. PEB (p = 0.001). Greater VL activity was noted during PBALL vs. TRAD (p = 0.0001) and PEB (p = 0.0001). The PBALL condition elicited a greater VMO:VL ratio during the concentric phase vs. the PEB (p = 0.001) and TRAD (p = 0.001) protocols. Greater RF activity was observed during PEB vs. TRAD (p = 0.001) and PBALL (p = 0.001). Therefore, practitioners should consider placing a physioball between the knees during the LP45 exercise as an alternative technique when greater overall quadriceps activity is desired for clinical rehabilitation or a muscle strengthening program.

Evaluate the Medial Muscle Strength by Kick Training between the Standing and Sitting Postures

“…Assuming that a set of stationary horizontal signals was 10 and the standard deviation was 2, the range within 3 times of the standard deviation was equal to 10 ± 6 or 4-16, and the value of +16 was set to CT, as shown in Equation (6).…”

“…CT = Q + 3σ (6) This study used CT to capture the start and end positions of the threshold beyond and expressed it as a segment from a point to b point. The starting position higher than the threshold value was set to point a, and the ending position lower than the threshold value was set to point b.…”

“…In [6], the aim was to analyze surface electromyographic (SEMG) responses for biceps femoris (BF), rectus femoris (RF), VMO, and VL, as well as the VMO:VL ratio during an open-kinetic chain 45 • angled leg press (LP45). The traditional LP45 technique was compared with 2 alternative LP45 exercise techniques that used a physioball and elastic band, respectively.…”

“…The corresponding rehabilitation and conditioning programs are often applied. As same as [6], it also investigated LP45 by physioball and elastic band with submaximal loads on EMG amplitude and fatigue indices. Higher levels of CRMS (Coefficient of Root Mean Square) and Cf5 were noted for RF muscles, VL, and VM, respectively.…”

“…In [6,7], it sought to investigate the effect of performing leg press (LP) 45 degrees using a physioball and elastic band to reduce excessive varus and valgus forces, to increase quadriceps activation and improve knee joint stabilization. The use of surface electromyography is a widely accepted technique for measuring the electrical signals produced by muscle contractions and estimating the strength of muscle.…”