The aim of this study was to evaluate the acute effect of the use of stable and unstable surfaces on electromyography (EMG) activity and coactivation of the scapular and upper-limb muscles during the push-up plus (with full protraction of the scapula). Muscle activation of anterior deltoid (AD), posterior deltoid (PD), pectoralis major, biceps brachii (BB), triceps brachii (TB), upper trapezius (UT), middle trapezius (MT), lower trapezius (LT), and serratus anterior (SA) levels and coactivation index were determined by surface EMG in 20 young men during push-up plus performed on a stable and unstable condition (2 unstable devices applied to hands and feet). The paired t test and Cohen d were used for statistical analysis. The results showed that during the execution of the push-up plus on the unstable surface an increased EMG activity of the scapular stabilizing muscles (SA, MT, and LT) was observed, while AD and PD muscles showed a decrease. During exercise execution on the unstable surface there was a higher index of coactivation of the scapular muscles (SA-MT and UT-LT pairs). No significant differences were observed in TB-BB and AD-PD pairs. These results suggest that the push-up-plus exercise associated with unstable surfaces produced greater EMG activity levels and coactivation index of the scapular stabilizing muscle. On the other hand, the use of an unstable surface does not promote the same effect for the shoulder muscles.
Context: It is believed that conscious abdominal contraction (CAC) during exercise encourages greater periscapular activation through existing myofascial connections. On the other hand, it is postulated that the use of unstable surfaces would promote greater neuromuscular demand. Objective: To analyze the effect of CAC on periscapular muscle activity during push-up plus exercise on stable and unstable surfaces and to evaluate the correlation between electromyographic (EMG) activity of the serratus anterior (SA) and abdominal oblique muscles. Design: Repeated-measures design in a single group, pre–post CAC. Setting: Biomechanics laboratory. Participants: Twenty-three male volunteers without a history of lesions in the upper limbs participated in the study. Main Outcome Measures: Five repetitions of push-ups on stable and unstable surfaces were performed with and without instruction for CAC. The normalized amplitude of the EMG activity was obtained from the muscles of the upper, middle, and lower trapezius, SA upper (SA_5th) and lower (SA_7th) portions, external oblique (EO), and internal oblique. Results: CAC increased the activity of the EO, internal oblique, middle trapezius, and SA (P < .05) in both surfaces. The use of the unstable surface increased the EMG activity of the EO, SA_7th, and middle trapezius and decreased the EMG activity of the SA_5th. However, all changes observed in EMG signals were of low magnitude, with effect sizes lower than 0.45. There was a weak correlation between the EMG activity of the EO and SA_5th (r = .24) and a strong correlation between the EO and SA_7th (r = .70). Conclusion: The isolated use of CAC or unstable surface during push-up seems to present no practical relevance, but the combined use of these strategies may increase activation of the SA_7th and middle trapezius muscles.
Background/aims Core training has been recommended in shoulder rehabilitation programs. However, the evidence on this topic is still scarce. The aim of this study was to investigate the effect of conscious abdominal contraction combined with unstable surfaces on electromyographic activity of periscapular muscles during the plus phase of a push-up. Methods A total of 20 male participants (22.8 ± 2.5 years) were evaluated. Electromyographic signals were collected from the upper, middle and lower trapezius, serratus anterior, and external and internal oblique muscles during push-up exercises on a stable and unstable surface with and without the conscious abdominal contraction. Each participant performed four variations of the plus phase of a push-up. Results The results demonstrated that the conscious abdominal contraction caused an increase in the electromyographic activity of external oblique, internal oblique, serratus anterior and lower trapezius muscles (P≤0.008). The unstable surface caused only a relevant increase in electromyographic activity of the abdominal muscles (P≤0.025). Combining the two strategies did not increase the electromyographic activity of any muscles (P≥0.238). Conclusions The conscious abdominal contraction seems to be a viable strategy to increase the electromyographic activity of the periscapular muscles.
This study evaluated the effects of instability on the EMG activity of scapular stabilizing and upper limb muscles during exercises with axial and rotational load. Twenty male volunteers (20.9 ± 1.8 years, 174.1 ± 0.04 cm, 73.17 ± 8.77 kg) experienced in strength training participated in a crossover design. Muscle activation of anterior deltoid (AD), posterior deltoid (PD), pectoralis major (PM), biceps brachii (BB), triceps brachii (TB), upper trapezius (UT), middle trapezius (MT), lower trapezius (LT), and serratus anterior (SA) were determined on both conditions. Participants performed a single series of 10 repetitions of bench press and fly exercises on stable (bench) and unstable (proprioceptive disc) conditions at 60% of 1-RM. The Friedman test and post hoc Dunn's indicated that the unstable condition showed greater EMG activity for AD (P = .001) and BB (P = .002) on the fly exercise, SA (P = .001) and LT (P = .048) on the bench press, and PM (P ≤ .002) on both exercises. These results show that using an unstable surface in exercises with rotational load provides superior EMG activity of the agonist muscles, while in exercise with axial load, the instability favors EMG activity of the scapular stabilizing muscles.
INTRODUÇÃO: Capacidade intrínseca (CI) é um construto que engloba capacidades físicas e mentais para o autocuidado e envelhecimento saudável. A compreensão do papel potencial do treinamento resistido, com e sem instabilidade, para promover o CI precisa ser esclarecida. OBJETIVO: Avaliar o impacto do treinamento de força sobre os níveis de capacidade intrínseca em idosos com queixas cognitivas. MÉTODOS: Idosos com queixas cognitivas (n=67) foram aleatoriamente designados para 12 semanas de TF tradicional (n=23), TF com dispositivos de instabilidade (TFI) (n=22) ou controle (n=22). Ambos os grupos de treinamento realizaram três séries de 10-15 repetições. O grupo TFI realizou exercícios utilizando dispositivos de instabilidade. O grupo controle recebeu aulas semanais de educação em saúde. Os domínios da CI foram de mobilidade e velocidade da marcha (locomotora), função global e executiva (cognitivo), força de preensão e teste de caminhada de seis minutos (vitalidade), e sintomas depressivos e autoeficácia (psicológicos) por meio de escores-z compostos. Calculamos os níveis globais de CI pela soma de cada pontuação composta. RESULTADOS: Diferença significativa intragrupo nos níveis gerais de CI (∆TFI = +1.69, ∆TF = +1.30) e seus respectivos domínios (Locomoção: ∆TFI = +2.32, ∆TF = +3.21; Cognição: ∆TFI = +2.31; Vitalidade: ∆TFI = +1.23, ∆TF = +1.42; e Psicológico: ∆TFI = -0.65, ∆TF = -0.62). Contudo, não houve diferenças entre os grupos. Análise de sensibilidade mesclando os grupos de treinamento revelou diferença significativa para o domínio locomotor após 12 semanas (+1.97, p=0.045). CONCLUSÃO: Treinamento de força com e sem dispositivos de instabilidade não melhorou os níveis de CI em idosos com queixas cognitivas.
To verify the effects of flexibility training conducted at different intensities in young adults. Methods: young adults of both genders with no history of surgery, fracture, and/or rheumatic diseases in the lower limbs and hip, were randomly assigned to low intensity (LI) or high intensity (HI) stretching groups. Two researchers were assigned to evaluate the active knee extension range of motion (ROM) of the volunteers and two other researchers were responsible for the training program. The training consisted of a single exercise for the hamstring muscles (biceps femoris, semimembranosus, semitendinosus). Each session consisted of three repetitions of passive static stretching, maintained for the 60s each, with 30s interval between them, and performed three times a week for four weeks. The stretching intensity was based on the Numerical Verbal Scale, the LI group maintained the intensity between 1 and 2, while the HI group between 9 and 10. Three ROM evaluations were performed pre-intervention, after the 6th session and at the end of the 12th session. Results: No difference was observed between the groups that underwent either high-or low-intensity programs. Both groups achieved gains in flexibility after four weeks of training. Conclusions:The study demonstrated that both high-and low-intensity stretching exercises are effective for ROM and there were no differences between them. Therefore, the intensity can be defined by the preference of the therapist or patient.
BACKGROUND: Mounting evidence has demonstrated functional and cognitive-related benefits after Instability Resistance Training (IRT) in individuals, healthy as wellas patients presenting with neurological disorders. However, whether IRT may play a significant role in the postural control of older adults has not been established. OBJECTIVE: To evaluate the effects of 12- weeks of IRT on static postural control of older adults with subjective cognitive impairment. METHODS: In this randomized controlled trial, a total of 67 participants (aged 65 years and older) were randomly assigned to either 12 weeks of IRT (n= 22), traditional resistance training (RT) (n= 23), or a health education control group (CON) (n= 22). Static postural control was assessed using a force platform that recorded the displacement amplitude of the center of pressure (CoP) in the anteroposterior (AP) and mediolateral (ML) directions in bipedal support (30 seconds) with eyes open and closed. RESULTS: All groups increased AP displacement in the conditions of eyes open and closed. During the eyes-closed condition, only the IRT group increased the ML displacement. No between-group differences were detected in any postural control (p> 0.05). CONCLUSIONS: 12 weeks of IRT does not improve the static postural control in older adults with cognitive impairment.
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