Observational study with the objective of determining possible correlations between GRF and muscle activation at reception after a jump in an ACL injury

INTRODUCTION: The ACL injury is considered one of the most serious injuries and usually occurs in actions that include movements with changes of direction, jump and landing. It is a common injury between the young active population and the risk in women of suffering from non-contact injury is superior to that of men. Athletes who suffer from non-contact injuries of the ACL usually have common biomechanical profiles, with landings with large values in ground reaction force (GRF) and therefore, low cushioning on landing. OBJECTIVE: To determine possible correlations between GRF and muscular activation at lading after a jump. MATERIAL AND METHODS: The type of study carried out is an observational study in which, using surface electromyography (EMG), a force platform and an electrogoniometer, the aim is to assess muscle activation and its relationship with GRF (specifically the vertical component Fz). RESULTS: Correlations have been observed between the reaction force of the soil (Fz) in the moments where the reaction force of the soil is greater and the instant where the knee reaches maximum flexion after landing, with the activation of certain muscle groups and differences depending on the gender of the subject. DISCUSSION: The neuromuscular recruitment strategies in the phases of maximum GRF load and knee flexion are different depending on the sex of the individual, so it should be considered when scheduling prevention and recovery work. CONCLUSION: The evaluation of GRF and muscle activation patterns, allows to assess the dynamics of landing after a jump and to be able to detect different patterns according to sex, with the consequent importance that it can have in the injury mechanism

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

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.