Muscle activity of Bulgarian squat. Effects of additional vibration, suspension and unstable surface

Abstract

Practitioners of strength and conditioning are increasingly using vibration and unstable environments to enhance training effects. However, little evidence has been found comparing the use of suspension devices and vibratory platforms used in the Bulgarian squat. The purpose of this cross-sectional study was to examine the effect of suspension devices (TRX ® ), unstable surfaces (BOSU ® ), and vibration plates on muscle activity and force during the Bulgarian squat. Twenty physically active male students (age = 24.40 ± 3.63 years) performed a set of five repetitions of Bulgarian squats, suspended lunges, suspended lunges-BOSU, suspended lunges-Vibro30, and suspended lunges-Vibro40 (vibration 30 Hz or 40 Hz and 4 mm of amplitude). A randomized within-subject design was used to compare leg muscle activity, vertical ground reaction forces, and force exerted on the strap across the five exercises. Results showed no significant differences in muscle activity between the Bulgarian squat and suspended lunge ( p = 0.109, d = 2.84). However, the suspended lunge significantly decreased muscle activation compared to the suspended lunge-BOSU ( p = 0.012, d = 0.47), suspended lunge-Vibro30 ( p = 0.001, d = 1.26), and suspended lunge-Vibro40 ( p = 0.000, d = 1.51). Likewise, the Bulgarian squat achieved lower activity than the suspended lunge-Vibro40 ( p = 0.010, d = 0.96). The force on the strap significantly decreased in the suspended lunge-BOSU compared to the suspended lunge-Vibro30 ( p = 0.009, d = 0.56). The suspended lunge achieved higher front leg force production than the Bulgarian squat ( p = 0.006, d = 0.48). In conclusion, leaning the rear leg on a suspension device does not provoke an increase in the activation of the front leg during the Bulgarian squat but increases the vertical ground reaction forces. Thus, the use of unstable surfaces or vibration plates for the front leg increased muscular activity when performing a suspended lunge.

sEMG Activity in Superimposed Vibration on Suspended Supine Bridge and Hamstring Curl

“…The effect of additional vibration (30 Hz and 40 Hz with an amplitude of 4 mm) on unstable surfaces and suspension devices increased the demands of the exercise. Thus, eliciting a greater activation of the lower limb muscles (vastus medialis and lateralis, biceps femoris, and gluteus medius) during the suspended lunge combined with 40 Hz WBV than in unstable or suspended exercises without vibration ( Aguilera-Castells et al, 2019 ). Understanding what exercises generate more muscle activation and under what conditions they do so is essential for practitioners.…”

“…Considering acute effects, Bush et al (2015) reported a post-activation potentiation effect on knee extension torque after exposing healthy participants to a WBV dynamic squat with bodyweight resistance (30 Hz and 4 mm of amplitude). Additionally, Aguilera-Castells et al (2019) showed that combined WBV (40 Hz) with a suspended device elicited higher muscle activity than the suspended condition for hip and thigh muscles in the dynamic lunge bodyweight resistance.…”

Influence of the Amount of Instability on the Leg Muscle Activity During a Loaded Free Barbell Half-Squat

“…Indeed, although the BOSU-down condition created higher global instability, it offered a flat and rigid surface that compelled the participants to act differently in avoiding the knee valgus position. Although this study did not test this muscle, the role of the gluteus medius in stabilizing the posture can probably explain the lower activation of the vastus medialis in the BOSU-down [ 13 , 32 , 33 ] actions. Furthermore, the role of the biceps femoris co-contraction in the most unstable conditions seemed to be clear in a half-squat.…”

“…As mentioned earlier, several groups of researchers have studied the acute responses of different unstable environments on muscle activation and force/power production in the past [ 3 , 10 , 13 , 14 ], but to the best of our knowledge, none of them have quantified the amount of instability created. According to the studies’ designs, it can be inferred that some devices can create higher instability than others, but no data are available describing how unstable every condition is.…”

Variations in upper limb and trunk muscles activation during isometric exercises with or without exertion of control

“…The duration of the trials was determined based on the preliminary study and the participants' possible fatigue due to the maximum muscle exertion during the exercise task. The participants were given 90-s intervals between each performance for rest [14]. The participants were also instructed to perform the PBM and CIM under the same conditions.…”