Biomechanical Parameters in Children with Unilateral and Bilateral Clubfoot during Vertical Jumps

Abstract Gait analysis may offer information to choose the best exercise-based clinical intervention for the children with clubfoot. However, other motor abilities are not commonly investigated. The aim of this research was to analyze the biomechanics of countermovement vertical jumping in clubfooted children who had undergone surgery. Fourteen children with idiopathic clubfoot were selected and the control group consisted of 11 children. Clubfooted children showed less dorsiflexion in the jump preparation phase. In the impulse phase, this group showed more knee flexion and less plantarflexion associated with less magnitude of vertical reaction force and less muscular activity in the gastrocnemius medialis. In the landing phase, for clubfoot group, we found high loading rate for the first peak of vertical force, less plantarflexion and more knee flexion. Understanding the biomechanical changes of vertical jump landing should assist in better targeting of physical and sporting activities of this population.(AU)

Effect of 3 Different Applications of Kinesio Taping Denko® on Electromyographic Activity: Inhibition or Facilitation of the Quadriceps of Males During Squat Exercise.

Kinesio taping consists of a technique which uses the application of an elastic adhesive tape. It has become a widely used rehabilitation modality for the prevention and treatment of musculoskeletal disorders. The objective of this study was to verify the effect of the application of Kinesio Taping Denko® in three conditions (facilitation, inhibition, and placebo) on the electromyographic activity of the quadriceps and hamstrings muscles on facilitating or inhibiting the muscle function and on the perceived exertion during the barbell back squat exercise in healthy male subjects. METHODS: It was a randomized, single-blinded and controlled study in which 18 males (28.0 ± 6.7 years old; 85.8 ± 8.2 kg mass; 1.80 ± 0.07 m tall; 0.97 ± 0.04 m lower limb length) performed barbell back squat exercise with different conditions of Kinesio Taping Denko® applications: Facilitation, inhibition and placebo. Previous to the mentioned conditions, all individuals were assessed without applying kinesio Taping Denko® during the exercise. OMNI scale was used after each set for perceived exertion evaluation. No differences (p < 0.05) in the electromyographic activity of the biceps femoris, vastus lateralis and vastus medialis or OMNI scale were recorded under any conditions. The results show that the kinesio taping denko® may not alter the magnitude of the electromyography activity of vastus lateralis, vastus medialis, and biceps femoris during the squat exercise. Furthermore, the perceived exertion was not affected by the kinesio taping denko® application.

Dynamic Parameters Variability: Time Interval Interference on Ground Reaction Force During Running.

The aim of this study was to determine the effect of the time between measures on ground reaction force running variability; 15 healthy men (age = 23.8 ± 3.7 years; weight = 72.8 ± 7.7 kg; height 174.3 ± 8.4 cm) performed two trials of running 45 minutes at 9 km/hr at intervals of seven days. The ground reaction forces were recorded every 5 minutes. The coefficients of variation of indicative parameters of the ground reaction forces for each condition were compared. The coefficients of variations of the ground reaction forces curve analyzed between intervals and sessions were 21.9% and 21.48%, respectively. There was no significant difference for the ground reaction forces parameters Fy1, tFy1, TC1, Imp50, Fy2, and tFy2 between intervals and sessions. Although the ground reaction forces variables present a natural variability, this variability in intervals and in sessions remained consistent, ensuring a high reliability in repeated measures designs.

Autoregulating Jump Performance to Induce Functional Overreaching.

Claudino, JG, Cronin, JB, Mezêncio, B, Pinho, JP, Pereira, C, Mochizuki, L, Amadio, AC, and Serrão, JC. Autoregulating jump performance to induce functional overreaching. J Strength Cond Res 30(8): 2242-2249, 2016-The purpose of this study was to determine whether autoregulating jump performance using the minimal individual difference (MID) associated with countermovement jump (CMJ) height could be used to regulate and monitor a training phase that elicited functional overreaching and tapering in team sport athletes. The participants were familiarized with the jump and then the CMJ height reliability was quantified to determine the MID. Countermovement jump height was assessed in the pretesting session (T0), at the end of 4 weeks of intensified training (T1), and after 2 weeks of tapering (T2). Eighteen national level U17 male futsal players were randomly allocated into the regulated group (RG; n = 9) and the control group (CG; n = 9). The RG performed 6 weeks of training with the training load regulated by mean height of CMJ with MID, whereas the CG performed the preplanned training. The differences between groups and across time points were compared by a 2-way analysis of variance. In the RG, the MID loading was increased in weeks 3 and 4 (8.2 and 14.5%, respectively; p < 0.001) compared with the preplanned loading of the CG during the overreaching phase. In the jump results, the RG significantly (p ≤ 0.05) reduced CMJ height during T1 (effect size [ES] = -0.31; 95% confidence interval [CI]: -0.58 to -0.02); however, there were no significant changes in the CG jump height at T1 and T2. At T2, the RG significantly increased CMJ height above baseline (ES = 0.30; 95% CI: 0.09 to 0.51). Researchers and practitioners could use this autoregulating method to regulate and monitor training load to achieve functional overreaching in youth futsal players.

Usage of Running Drills in an Interval Training Program: Implications Related to Biomechanical Parameters of Running.

The purpose of this study was to investigate the effects of running drills during an interval training program on biomechanical parameters of running. Thirty recreational runners, divided into 2 groups (control group and experimental group [EG]), were submitted to a 15-week interval training, but only EG performed running drills in the training. The test sessions were accomplished before and after intervention. Spatiotemporal and kinetic variables were analyzed at 2 speeds: maximum (Smax) and comfortable (Scomf). For moment effect, significant increases were observed for Scomf (8.9%) and Smax (10.7%) after training. Variables related to mechanical load were also higher after training for both speeds (LR1: 16.4% and Imp75: 7.8% at Scomf; LR1: 21.4% and Imp75: 8.1% at Smax). For training approach effect, higher value of Imp75 was observed in EG (10.1% at Scomf and 11.9% at Smax, without performance improvements). Also, EG presented higher values of Fy2 (6.7% at Scomf and 6.1% at Smax) and FT (13.3% at Scomf), variables related to the center of mass oscillation. As a conclusion, including running drills in a 15-week interval running training seems not to be an efficient procedure to improve parameters related to mechanical load and performance.

Creatine monohydrate supplementation on lower-limb muscle power in Brazilian elite soccer players.

BACKGROUND: Studies involving chronic creatine supplementation in elite soccer players are scarce. Therefore, the aim of this study was to examine the effects of creatine monohydrate supplementation on lower-limb muscle power in Brazilian elite soccer players (n = 14 males) during pre-season training. FINDINGS: This was a randomized, double-blind, placebo-controlled parallel-group study. Brazilian professional elite soccer players participated in this study. During the pre-season (7 weeks), all the subjects underwent a standardized physical and specific soccer training. Prior to and after either creatine monohydrate or placebo supplementation, the lower-limb muscle power was measured by countermovement jump performance. The Jumping performance was compared between groups at baseline (p = 0.99). After the intervention, jumping performance was lower in the placebo group (percent change = - 0.7%; ES = - 0.3) than in the creatine group (percent change = + 2.4%; ES = + 0.1), but it did not reach statistical significance (p = 0.23 for time x group interaction). Fisher's exact test revealed that the proportion of subjects that experienced a reduction in jumping performance was significantly greater in the placebo group than in the creatine group (5 and 1, respectively; p = 0.05) after the training. The magnitude-based inferences demonstrated that placebo resulted in a possible negative effect (50%) in jumping performance, whereas creatine supplementation led to a very likely trivial effect (96%) in jumping performance in the creatine group. CONCLUSIONS: Creatine monohydrate supplementation prevented the decrement in lower-limb muscle power in elite soccer players during a pre-season progressive training.

Influence of exercise order on electromyographic activity during upper body resistance training.

The purpose of this study was to investigate the effects of exercise order on electromyographic activity in different muscle groups among youth men with experience in strength training. Three sets of 8 RM were performed of each exercise in two sequences order: (a) sequence A: bench press, chest fly, shoulder press, shoulder abduction, close grip bench press and lying triceps extension; (b) sequence B: the opposite order. The electromyographic activity was analyzed in the sternocostal head of the pectoralis major, anterior deltoid, and long head triceps brachii, normalized for maximal voluntary isometric contraction. The muscles activity of the sternocostal head of the pectoralis major, anterior deltoid, and long head triceps brachii showed significant interaction between sequence and exercise. The sternocostal head of the pectoralis major showed considerably higher activity in sequence A (100.13 ± 13.56%) than sequence B (81.47 ± 13.09%) for the chest fly. The anterior deltoid showed significantly higher electromyographic activity in sequence B (86.81 ± 40.43%) than sequence A (66.15 ± 22.02%) for the chest fly, whereas for the lying triceps extension, the electromyographic activity was significantly higher in sequence A (53.89 ± 27.09%) than sequence B (34.32 ± 23.70%). For the long head triceps brachii, only the shoulder press showed differences between sequences (A = 52.43 ± 14.64 vs. B = 38.53 ± 16.26). The present study showed that the exercise order could modify the training results even though there was no alteration in volume and intensity of the exercise. These changes may result in different training adaptations.

Estudo das diferencas de energia mecanica entre o andar e o correr em diferentes velocidades na esteira rolante / Mechanical energy differences between walking and rinning at different velocities on tradmill

CAVANAH(1990) relatou uma variacao de 170 a 1700 w na potencia da corrida entre3,3 e 3,9m/s,isto calculado por seis diferentes autores.O objetivo deste trabalho foi analisar as curvas de energia mecanica de seis individuos para o andar e o correr.Os individuos foram filmados enquanto andavam a 1,5m/s e corriam a 3,0 e 4,0m/s na esteira rolante.As componentes de energia mecanica foram calculadas se utilizando as equacoes descritas por ZATSIORSKY et al.(1987(.Com relacao as diferencas entre o andar e o correr:a) no andar a maior contribuicao para a alteracao total advem da energia interna,enquanto para a corrida deriva da energia externa;b)a energia interna e externa estao em fase no andar e em oposicao no correr.Ao comparar as variacao e entre as duas velocidades de corrida:a)com o aumento da velocidade,o aumento medio da contribuicao da energia interna para a alteracao total foi de em torno de 72 e da energia externa de 36;b)nao houve alteracao na contribuicao da energia potencial para a energia externa;c)o aumento na energia interna era principalmente dependente do aumento na energia cinetica

Avaliaçäo de parâmetros biomecânicos relacionados a um modelo de equilíbrio na postura ereta humana / Evaluation of biomechanical parameters related the an model of equilibrium in human erect posture

Estudar o controle postural é uma forma de compreendermos a contribuição do sistema sensorial na ativação do sistema motor e investiga as adaptações do movimento em função de alterações ambientais ou tarefas. O modelo biomecânico desenvolvido permite mensurar a diferença da oscilação do centro de massa do sistema e op ponto de aplicação da força de reação do solo, permitindo uma análise mais criteriosa dos estabilogramas

Abstract - Research in postural control enhances the comprehension about sensorial system and motor system and to investigate the adaptations of body movement due to changes in environment or task. The biomechanical model permits to measure the difference between body center of mass and ground reaction force's center of application, allowing us to a better judgement of stabilograms.