Força máxima (TF) e potência (TP) são métodos de treinamento considerados distintos, na prática profissional e em diversos designs experimentais. O presente estudo testou a capacidade destes métodos promoverem o aumento do desempenho, assim como a similaridade das adaptações entre os métodos. Trinta e sete sujeitos foram divididos nos grupos: força (TF), potência (TP) e controle (C), sendo submetidos a oito semanas de treinamento nas seguintes zonas: TF (4-10 RM) e TP (30-60% 1RM). Os resultados significantes foram: força dinâmica máxima TF de 145,3 (±17,1) para 178,5 (±18,8) kg, TP de 147,2 (±16,8) para 171,6 (±19,9) kg; pico de força na contração voluntária isométrica máxima (CVIM) TF de 2240,52 (±448,76) para 2651,82 (±700,22) N, TP de 2249,86 (±427,95) para 2674,80 (±507,68) N; salto vertical a partir da posição de semi-agachamento (SJ) TF de 31,35 (±4,63) para 37,18 (±4,74) cm, TP de 34,44 (±3,90) para 39,61 (±4,70) cm. Apenas o TP gerou aumento no salto com contra-movimento (CMJ) de 35,52 (±4,43) para 38,50 (±4,34) cm. Nenhum dos protocolos promoveu o aumento do sinal eletromiográfico, seja na CVIM ou nos saltos. Verificou-se efeito principal para deslocamento do centro de gravidade, torque de joelho e quadril no SJ, assim como para o deslocamento excêntrico no CMJ. Observou-se similaridade entre os grupos em diversas variáveis analisadas, assim como a possível transferência coordenativa do TP para o CMJ. Assim, força máxima e potência parecem constituir estímulos de treinamento equivalentes em muitos aspectos e por isso, os padrões de especificidade atribuídos a ambos devem ser reconsiderados / Strength and power are considered different training methods in promoting neuromuscular adaptations in practice and in several research designs as well. In the present research, the efficacy of these methods in improving performance and resultant neural adaptations in some motor tasks was investigated. Thirty sevens subjects were divided in groups: strength (TF), power (TP) and control (C) and submited to eight weeks of training in different zones: TF (4-10 RM) and TP (30%-60% 1RM). Results that reached significance were the following, pre and pos-test, respectively: Maximum dynamic strength TF:145,3 (±17,1) and 178,5(±18,8), TP:147,2 (±16,8) and 171,6 (±19,9). Peak force in maximum isometric voluntary contraction (MIVC) TF: 2240,52 (±448,76) and 2651,82 (±700,22), TP: 2249,86 (±427,95) and 2674,80 (±507,68). Squat jump (SJ) TF: 31,35 (±4,63) and 37,18 (±4,74), TP: 34,44 (±3,90) and 39,61 (±4,70). In countermovement jump (CMJ) only TP improved: 35,52 (±4,43) and 38,50 (±4,34). No method could improve electromiographical signal. A main effect was noticed for center of mass displacement, knee and hip moments in SJ and eccentric displacement in CMJ. Similar results for many parameters analysed could be observed. The results indicate a possible transference from TP to CMJ as well. This way, strength and power can be considered equivalent in promoting performance in many tasks. Therefore, specificity patterns between strength and power should be reconsidered

Força máxima (TF) e potência (TP) são métodos de treinamento considerados distintos, na prática profissional e em diversos designs experimentais. O presente estudo testou a capacidade destes métodos promoverem o aumento do desempenho, assim como a similaridade das adaptações entre os métodos. Trinta e sete sujeitos foram divididos nos grupos: força (TF), potência (TP) e controle (C), sendo submetidos a oito semanas de treinamento nas seguintes zonas: TF (4-10 RM) e TP (30-60% 1RM). Os resultados significantes foram: força dinâmica máxima TF de 145,3 (±17,1) para 178,5 (±18,8) kg, TP de 147,2 (±16,8) para 171,6 (±19,9) kg; pico de força na contração voluntária isométrica máxima (CVIM) TF de 2240,52 (±448,76) para 2651,82 (±700,22) N, TP de 2249,86 (±427,95) para 2674,80 (±507,68) N; salto vertical a partir da posição de semi-agachamento (SJ) TF de 31,35 (±4,63) para 37,18 (±4,74) cm, TP de 34,44 (±3,90) para 39,61 (±4,70) cm. Apenas o TP gerou aumento no salto com contra-movimento (CMJ) de 35,52 (±4,43) para 38,50 (±4,34) cm. Nenhum dos protocolos promoveu o aumento do sinal eletromiográfico, seja na CVIM ou nos saltos. Verificou-se efeito principal para deslocamento do centro de gravidade, torque de joelho e quadril no SJ, assim como para o deslocamento excêntrico no CMJ. Observou-se similaridade entre os grupos em diversas variáveis analisadas, assim como a possível transferência coordenativa do TP para o CMJ. Assim, força máxima e potência parecem constituir estímulos de treinamento equivalentes em muitos aspectos e por isso, os padrões de especificidade atribuídos a ambos devem ser reconsiderados / Strength and power are considered different training methods in promoting neuromuscular adaptations in practice and in several research designs as well. In the present research, the efficacy of these methods in improving performance and resultant neural adaptations in some motor tasks was investigated. Thirty sevens subjects were divided in groups: strength (TF), power (TP) and control (C) and submited to eight weeks of training in different zones: TF (4-10 RM) and TP (30%-60% 1RM). Results that reached significance were the following, pre and pos-test, respectively: Maximum dynamic strength TF:145,3 (±17,1) and 178,5(±18,8), TP:147,2 (±16,8) and 171,6 (±19,9). Peak force in maximum isometric voluntary contraction (MIVC) TF: 2240,52 (±448,76) and 2651,82 (±700,22), TP: 2249,86 (±427,95) and 2674,80 (±507,68). Squat jump (SJ) TF: 31,35 (±4,63) and 37,18 (±4,74), TP: 34,44 (±3,90) and 39,61 (±4,70). In countermovement jump (CMJ) only TP improved: 35,52 (±4,43) and 38,50 (±4,34). No method could improve electromiographical signal. A main effect was noticed for center of mass displacement, knee and hip moments in SJ and eccentric displacement in CMJ. Similar results for many parameters analysed could be observed. The results indicate a possible transference from TP to CMJ as well. This way, strength and power can be considered equivalent in promoting performance in many tasks. Therefore, specificity patterns between strength and power should be reconsidered

Electric muscle stimulation (EMS) has been widely used in the rehabilitation of musculoskeletal injuries. Patterned electrical neuromuscular stimulation (PENS), a specific form of EMS, has been developed to better educate muscles to contract properly. The physiological efficacy of PENS has not been quantifiably identified. OBJECTIVES: The aim of this study is to determine the acute effect of one PENS training session (3 sets of 10 1-sec repetitions) on maximal isometric knee extensor (MVIC) torque production and surface EMG (sEMG) in healthy nonathlete college students. DESIGN: A randomized repeated-measures design was used in this study. METHODS: Twenty-two male college students participated in the study. All participants completed two training sessions, one with PENS and one without, in a randomized crossover design. RESULTS: One bout of PENS training significantly increased MVIC (3.1% ± 1.7%, p = 0.03) which was greater than the change in MVIC of the control group (p = 0.03). Control training did not alter MVIC but resulted in significant decrease in average sEMG amplitude (-7.8% ± 1.6%, p ≤ 0.01) and peak sEMG amplitude (-10.4% ± 2.7%, p ≤ 0.01). These reductions in sEMG following control training were significantly different from the PENS group (p = 0.03 and p ≤ 0.01). CONCLUSIONS: The findings suggest that strength training in conjunction with PENS can enhance torque production after just one bout of training. The increase in torque with no change in sEMG amplitude can be explained by increased motor unit synchronization or decreased cocontraction of antagonist muscles.

Context: Knee pain is a common symptom in knee pathology and is associated with alterations in quadriceps activation and movement patterns. Reducing pain through intervention may help reestablish neuromuscular function. The independent effects of knee pain are difficult to examine and unclear. Objective: To investigate the effects of transcutaneous electrical nerve stimulation (TENS) on quadriceps activation and vertical ground reaction force (VGRF) during walking. Design: Crossover. Setting: Laboratory. Subjects: 15 in the TENS group (10M and 5F, 23.5 ± 2.8 yrs, 70.5 ± 12.5 kg, 178.1 ± 7.4 cm), and 15 in the sham group (10M and 5F, 22.5 ± 2.0 yrs, 72.1 ± 13.7 kg, 177.5 ± 9.3 cm). Interventions: Subjects underwent three experimental conditions (pain, sham, and control). Measurements were recorded across four time points (preinfusion, infusion, treatment, and posttreatment). Hypertonic or isotonic saline, respectively, was infused into the infrapatellar fat pad for 48 minutes (total 7.7 mL). The TENS group received a 20-minute treatment. A sham treatment was administered to the sham group. Main Outcome Measures: Perceived knee pain on a 10-cm visual analog scale, knee extension maximum voluntary isometric contraction (MVIC) normalized to body mass, knee extension central activation ratio (CAR), and VGRF. Results: Knee pain peaked at 4 cm during infusion and remained consistent across time in the sham group (F2,28 = 49.90, P < 0.0001), while knee pain gradually decreased to 1.5 cm following TENS treatment (F2,28 = 23.11, P < 0.0001). A group x condition x time interaction was detected for both the MVIC (F6,168 = 2.92, P < 0.01) and CAR (F6,168 = 3.03, P < 0.008) measurements. Post hoc analysis revealed that the infusion of hypertonic saline reduced knee extension MVIC by 29% in the TENS group, and by 26% in the sham group (P < 0.05). However, while the MVIC remained depressed by 26% following sham treatment, the MVIC was found to improve by 12% following TENS treatment (P < 0.05). Similarly, a 10% decrease in CAR was detected in both sham and TENS groups prior to treatment. This 10% deficit held, with a 9% deficit following sham treatment, while the deficit of CAR was improved by 4% following TENS treatment (P < 0.05). For the TENS group, infusion of hypertonic saline changed VGRF at initial loading, midstance, and push-off phase. VGRF was only different at initial loading and push-off phase following TENS treatment. For the sham group however, sham treatment did not restore VGRF, showing alterations in initial loading, midstance, and push-off phase (α = 0.05). Conclusions: Infusion of hypertonic saline increased perceived knee pain, reduced knee extension MVIC, reduced CAR, and altered VGRF over some of stance phase. TENS lessened the deficits in MVIC, CAR, and VGRF, suggesting decreased muscle inhibition and improved movement function.