Does rest interval between unilateral exercise protocols influences on contralateral neuromuscular responses in untrained individuals?

INTRODUCTION

Effects on strength performance and muscle activation in the contralateral limb have been observed after training with the ipsilateral limb (IL). Cross fatigue effects in the contralateral limb (CL) can occur at intervals of up to 48 h after a training session performed with the ipsilateral limb. The objective of this study was to verify the effect of a training session in the ipsilateral limb, on the strength and activation of the muscles in the contralateral limb also submitted to the training protocol.

METHODS

10 untrained men (mean ± SD: age = 23.7 ± 4.9 years) performed unilateral knee extension with both limbs in equated protocols, in two conditions with different intervals between limbs - 20 min and 24 h.

RESULTS

There were no differences in the comparison of the force produced between the pre x post interventions with the CL limb, as well as in the activation of the quadriceps during its performance. These results were similar for the two different intervals between the protocols.

CONCLUSION

It was concluded that when the CL member performs the protocol after the IL, the responses in the CL depend mainly on the requirement imposed on the protocol performed by this member, without influence of the training protocol performed previously with the IL member.

Effect of Small-Sided Games with and without the Offside Rule on Young Soccer Players: Reliability of Physiological Demands

This study aimed to compare the physiological demand between three vs. three small-sided games (SSGs) with (3vs.3_WITH) and without (3vs.3_WITHOUT) the offside rule, as well as the within- and between-session reliability of this demand. Twenty-four U-17 soccer athletes performed various three vs. three (plus goalkeepers) SSGs with and without the offside rule. The data collection was performed within an eight-week period. Athletes' heart rate was monitored during the SSG. The variables analyzed were the percentage mean heart rate (HR_MEAN%) and the percentage peak heart rate (HR_PEAK%). For the analysis of within-session reliability, the mean value of the first two and last two SSG bouts performed within one day were used. The between-session reliability was calculated using the mean value of the four SSG bouts of each SSG type performed on two different days. In both SSGs, the values for reliability were significant and were classified as moderate to excellent. There were no significant differences in the physiological demand among SSG types. We concluded that the offside rule does not influence the physiological demand in a three vs. three SSG and the HR_MEAN% and HR_PEAK% present moderate to excellent reliability in a three vs. three SSG with and without the offside rule.

Resistance training intervention performed with different muscle action durations influences the maximal dynamic strength without promoting joint-angle specific strength gains

The present study investigated the effect of 10-week matched (range of motion, volume, intensity, rest, and repetition duration) training protocols with varying muscle action duration (MAD) on maximal voluntary isometric contraction (MVIC) test at eight different knee angles and one-repetition maximum (1RM) test after in seated knee extensor machine. Forty women were allocated into one control and three training groups with varying MAD: 5C1E (5s concentric action [CON] and 1s eccentric action [ECC]), 3C3E (3s CON and 3s ECC), and 1C5E (1s CON and 5s ECC). All training groups (5C1E, 3C3E, and 1C5E) showed a greater relative response in 1RM performance than the control group (0.1 ± 3.5%, p ≤ 0.05). The 1C5E group presented greater relative increases in the 1RM performance (22.1 ± 11.6%) compared to 5C1E (13.6 ± 9.2%; p ≤ 0.05) and 3C3E (14.1 ± 5.5%, p ≤ 0.05) groups. The training groups increased the MVIC performance more than the control group (p ≤ 0.05), although there were no significant differences between the training groups. This study demonstrated that isoinertial resistance training protocols with shorter CON MAD showed greater maximum dynamic strength performance response than matched training protocols with other MAD configurations. However, the configuration of MAD did not induce angle-specificity to increase the maximum isometric strength.

Resistance training with different repetition duration to failure: effect on hypertrophy, strength and muscle activation

Background

This study investigated the effects of two 14-week resistance training protocols with different repetition duration (RD) performed to muscle failure (MF) on gains in strength and muscle hypertrophy as well as on normalized electromyographic (EMG) amplitude and force-angle relationships.

Methods

The left and right legs of ten untrained males were assigned to either one of the two protocols (2-s or 6-s RD) incorporating unilateral knee extension exercise. Both protocols were performed with 3–4 sets, 50–60% of the one-repetition maximum (1RM), and 3 min rest. Rectus femoris and vastus lateralis cross-sectional areas (CSA), maximal voluntary isometric contraction (MVIC) at 30^o and 90^o of knee flexion and 1RM performance were assessed before and after the training period. In addition, normalized EMG amplitude-angle and force-angle relationships were assessed in the 6^th and 39^th experimental sessions.

Results

The 6-s RD protocol induced larger gains in MVIC at 30^o of knee angle measurement than the 2-s RD protocol. Increases in MVIC at 90^o of knee angle, 1RM, rectus femoris and vastus lateralis CSA were not significant between the 2-s and 6-s RD protocols. Moreover, different normalized EMG amplitude-angle and force-angle values were detected between protocols over most of the angles analyzed.

Conclusion

Performing longer RD could be a more appropriate strategy to provide greater gains in isometric maximal muscle strength at shortened knee positions. However, similar maximum dynamic strength and muscle hypertrophy gains would be provided by protocols with different RD.

Correlation between running asymmetry, mechanical efficiency, and performance during a 10 km run

Running asymmetry is considered a matter of concern for performance and injury, but the association between asymmetry and performance remain unclear. There are different strategies to address asymmetries and its relationship with performance. Here we investigated the correlation between global symmetry index and mechanical efficiency during 10 km running. Thirteen amateur trained athletes (8 men and 5 women) performed a 10 km running at a fixed pace while a 3D accelerometer attached to the pelvic region recorded position data throughout the course of the run and gas exchanges were monitored breath by breath. Global symmetry index was determined for 3 directions, and mechanical efficiency was calculated as the ratio of external work output to energy expenditure determined from gas analysis. Global Symmetry Index and mechanical efficiency decreased (-55.5% and -44.8%, respectively) during the course of the 10 km run (p < 0.01). A positive correlation was observed between global symmetry index and efficiency (r = 0.66, p = 0.01). Asymmetry in the vertical direction had a relatively higher impact on the global symmetry index. The global symmetry index accounted for 43.1% of the variance in mechanical efficiency (p = 0.015). Symmetry, evaluated by the global symmetry index, directly correlates with mechanical efficiency during a 10 km run.

Acute physiological responses with varying load or time under tension during a squat exercise: A randomized cross-over design

OBJECTIVES

Despite advancements in resistance training (RT) methods, the acute metabolic and neuromuscular responses to time under tension (TUT) and load remains poorly understood. The aim of the present study was to investigate how TUT or resistance load impact muscular activation and blood lactate during an RT session.

DESIGN

A randomized cross-over design.

METHODS

Participants performed a squat exercise in three different conditions: baseline protocol (B_PRO; three sets of eight repetitions with four second repetitions at 60% of 1RM) long duration protocol (LD_PRO: six second repetitions) and high load protocol (HL_PRO: 70% 1RM).

RESULTS

Muscular activation of the vastus lateralis and biceps femoris, and blood lactate were assessed. Blood lactate was ∼19% and ∼26% higher after set one and three in LD_PRO compared to B_PRO (P≤0.011) and ∼17% higher for LD_PRO compared to HL_PRO (P=0.002). Additionally, blood lactate was ∼17% higher for HL_PRO compared to B_PRO after the third set of exercise (P=0.003). Vastus lateralis activation was ∼10% higher for HL_PRO compared to B_PRO and LD_PRO for sets one and two. Biceps femoris activation was ∼17% higher for HL_PRO compared to B_PRO for set one (P= 0.023) while for set two HL_PRO was greater than B_PRO and LD_PRO (∼19% and ∼14%, respectively; P≤0.007).

CONCLUSIONS

Squatting with higher TUT caused a greater impact on the metabolic responses than lower TUT or higher loads, whereas an increase in training load resulted in greater muscle activation than higher TUT or lower training load.

The Effects of Altering the Concentric/Eccentric Phase Times on EMG Response, Lactate Accumulation and Work Completed When Training to Failure

This study compared the electromyographic response, the blood lactate concentration (BLC), and the maximum number of repetitions (MNR) between protocols of different concentric/eccentric duration taken to muscle failure. This comparison may help to understand how different concentric/eccentric duration may influence performance and the central and metabolic responses in trained men. Seventeen strength-trained men performed two protocols in a counterbalanced design. Three sets of the Smith bench press exercise were performed to failure at 60% of the one-repetition maximum (1RM) using each protocol (4-s concentric/2-s eccentric [4 s: 2 s]; and 2-s concentric/4-s eccentric [2 s: 4 s]). The normalized root mean square (EMGRMS) and the mean frequency (EMGMF) of the electromyographic signals for the pectoralis major and the triceps brachii were compared in the first, middle, and last repetitions. The BLC was assessed at rest, during and after the test sessions. To compare the EMG and BLC, a 3-way ANOVA with repeated measures with a post hoc Tukey's test was used. To compare the MNR performed across the sets, an ANOVA-type rank test with the Dunn's post hoc test was used. The ANOVA indicated a greater EMGRMS for Protocol 4 s: 2 s in the pectoralis major and a lower EMGMF for Protocol 4 s: 2 s in the triceps brachii at the middle and last repetitions. Both protocols increased the EMGRMS and decreased the EMGMF across repetitions. Despite the results show different levels of activation and neuromuscular fatigue between protocols, the BLC and the MNR were similar.

Effect of specific endurance on the physical responses of young athletes during soccer small-sided games

This study aimed to compare the physical responses of soccer players with different levels of specific endurance during SSG performed by teams balanced according to athletes’ specific endurance. Eighteen U-17 athletes from a team that participated in national competitions took part in this study. The Yo-Yo Intermittent Recovery Test Level 2 (YIRT2) was used to measure the athletes’ specific endurance. Then, athletes were allocated to two groups balanced according to their positional status and YIRT2 scores: in Group1 players with the highest results in the YIRT2 and in Group 2 with the lower YIRT2 scores. Athletes played two four-minute bouts of 3vs.3 small-sided games with goalkeepers with four minutes of passive rest. Total distance covered, average speed, and accelerations were obtained by GPS devices carried by each player. Group 1 presented higher total distance covered (large effect size), higher average speed (large effect size), and higher total distance covered in accelerations above 1 m·s-2 (moderate effect size), compared to Group 2. We concluded that specific endurance can partially influence physical responses of young soccer athletes during small-sided games. This information is important to appropriately prescribe small-sided games during the training process, possibly by grouping together athletes with similar specific endurance and, therefore, promoting an adequate stimulus to better-conditioned athletes.

The effect of 10 weeks of strength training on the electromyographic response of quadriceps portions

Abstract This study investigate the effect of 10-week strenght training on the amplitude of the electromyographic (EMG) signal of vastus medialis, vastus lateralis and rectus Femoris. Twenty three untrained volunteers performed 3-5 sets (3 sets - weeks 1 and 2; 4 series - weeks 3 and 4; 5 series weeks 5 to 10) with 6 repetitions, intensity of 50% of 1 repetition maximum (1RM), 3 min rest between sets and 6 s repetition duration at the knee extensor exercise. One group (5:1) performed concentric action of 5 s and eccentric of 1 s and the other (3:3) performed concentric of 3 s and eccentric of 3 s. The VM, VL and RF EMG (RMS) activities were recorded in each repetition of the three series at the first training session and the first three series at the last session. The protocol 5:1 led to EMG reduction in all portions, with a greater number of repetitions presenting differences at the VL and RF. VM and RF presented similar results at Group 3:3. It was verified that all the differences occurred in the second half of the series. It was also verified differences in EMG ratios just in group 3:3 and only in VM/VL and VM/RF. These results suggest that the coordination was not affected when equivalent repetitions of series were compared. It was also suggested that these results were influenced by the reduced degrees of freedom of the exercise and the training load progression adopted.

Changes in tactical behavior during small-sided and conditioned games performed within a training session

Abstract This study aimed to verify the acute effects of 3vs.3 soccer small-sided and conditioned games (SSCG) on the tactical behavior of youth soccer athletes within one training session. Twenty-four soccer athletes (U-13 and U-14 categories) from a professional club participated in the study. They played four 4-minute 3vs.3 SSCG with 4 minutes of passive recovery in-between. All SSCG were recorded and players’ tactical behavior was analyzed using the System of Tactical Assessment in Soccer. We compared the frequencies and percentages of successful tactical principles over the four 3vs.3 SSCG bouts performed within the training session. Results showed an increased number of defensive unity actions (p= 0.005; large effect size) and a higher percentage of successful defensive principles (p<0.001; moderate effect size) in the fourth bout. We can conclude that players’ tactical behaviors change over the SSCG bouts performed within one training session. This suggests that players adapt their tactical behavior according to the tactical problems presented in the SSCG performed within the training session. We can suggest that the long-term improvement in the tactical skills of soccer athletes may be based on these small acute changes in tactical behavior observed in each training session.

Influence of pitch size and age category on the physical and physiological responses of young football players during small-sided games using GPS devices

This study aimed to compare the physical and physiological responses of young football players of different categories during small-sided games (SSGs) played on different pitch sizes. Forty-eight (24 U-13 and 24 U-14) athletes played a 3 vs. 3 + 1 SSG in two experimental conditions: regular (36 × 27 m) and large pitch sizes (40 × 29 m). The total distance covered, the distances covered at different speed zones (0 to 6.9 km/h, 6.9 to 14.3, and 14.3 to 21.4), maximum heart rate, and mean heart rate were recorded. The results showed that older athletes covered larger distances during SSGs (p = 0.001; d = 0.937; large effect) and lower distances at the lowest (0-6.9 km/h) speed zone (p = 0.001; d = 0.657; moderate-to-large effect). Neither the physical nor physiological variables (except for distance covered between 14.3 and 21.4 km/h) differed between pitch sizes. This result indicates that pitch size may not impact the physical or physiological responses of U-13 and U-14 players during SSGs, but differences between categories were found. In conclusion, the development of tactical skills may be desirable to better explore the available space in the same age categories.

THE EFFECT OF BCAA ON ISOMETRIC FORCE FOLLOWING ENDURANCE EXERCISE IN A HOT ENVIRONMENT

ABSTRACT Introduction: Fatigue due to endurance exercise results from both peripheral and central changes, and may influence subsequent performance during a strength task. The increase in serotonin concentration is one of the central factors associated with endurance exercise-induced fatigue, particularly in hot environments. A nutritional strategy employed to reduce serotonergic activation is supplementation with branched-chain amino acids (BCAA). Objective: To investigate whether BCAA supplementation attenuates the reduction in isometric force caused by prior endurance exercise in a hot environment. Methods: Nine volunteers (aged 25.4 ± 1.2 years) performed a 2-min maximal voluntary isometric contraction (MVCISO) of upper limb muscles before and after an endurance exercise on a cycle ergometer at 40% of the maximal aerobic power. The volunteers underwent three experimental trials: 1) endurance exercise in a temperate environment (23°C and 60% RH); exercise in a hot environment (35°C and 60% RH) with the ingestion of: 2) a placebo solution or 3) a solution containing BCAA 30 mg.kg−1. During the MVCISO test, the isometric force of flexor muscles of the right elbow, core body temperature (TCORE) and heart rate (HR) were measured. Results: Isometric force decreased following endurance exercise in the hot environment, and BCAA administration did not attenuate this reduction. Greater TCORE and HR values were observed following endurance exercise in the heat, compared to pre-exercise values, and supplementation did not interfere with these physiological responses. Conclusion: The reduction in isometric force, caused by previous endurance exercise in a hot environment, was not diminished by supplementation with BCAA. Level of evidence I; Type of study: Therapeutic studies - Investigation of treatment outcomes.

IMPACT OF COMPETITIVE LEVEL AND AGE ON THE STRENGTH AND ASYMMETRY OF YOUNG SOCCER PLAYERS

ABSTRACT Introduction: Muscular strength is an essential capacity for soccer players; however, the profile of this capacity has not yet been clearly established in young players. Objective: To compare muscular strength performance in the countermovement jump (CMJ) task and the presence of lower limb asymmetry among soccer athletes of the under 15 (U15), under 17 (U17) and under 20 (U20) categories, and between two teams of different competitive levels. Methods: One hundred and fifty one young soccer players of three different categories (U15, U17 and U20) from two teams in the Brazilian first and second divisions performed six vertical jumps in a system of two force plates. Ground reaction force (GRF) was used to calculate jump height and to obtain the variables Peak force (FMAX), Impulse (I) and Peak power (PMAX) with regard to body mass and the respective asymmetry values. Results: No differences were found in the performance and asymmetry variable between the categories (Jump height: p=0.23; FMAX: p=0.15; I: p=0.11; PMAX: p=0.32; FMAX asymmetry: p=0.21; I asymmetry: p=0.58; PMAX asymmetry: p=0.58). The first division club had higher muscle strength and asymmetry values than the second division club (Jump height: p<0.01; I: p<0.01; PMAX: p<0.01; FMAX asymmetry: p<0.01; I asymmetry: p<0.01; PMAX asymmetry: p<0.01), except for FMAX (p=0.63). No variable had an interaction effect (club x category). Conclusion: As categories progress, jump height, relative I, PMAX and FMAX values and their respective asymmetries are stable. The asymmetry and strength performance of the first division club were higher than that of the second division club, except for FMAX, indicating that the competitive level may influence strength performance and the development of asymmetry. Level of Evidence II; Diagnostic study – Investigating a diagnostic test.

Comparação entre a altura do salto agachado e com contramovimento em idosas

O estudo teve como objetivo comparar a altura no salto agachado (SA) e no com contramovimento (SCM) de mulheres idosas. Vinte e oito mulheres idosas sedentárias voluntariaram-se para participar neste estudo (idade média de 68,7±5,9 anos). Cada sujeito foi instruído sobre como executar as técnicas de salto e descansaram 5 minutos entre a realização dos diferentes saltos. A média de 3 tentativas de cada salto foi utilizada para a análise estatística. A força de reação do solo (FRS) vertical durante o SA e o SCM foi mensurada por meio de uma plataforma de força. A integração numérica da FRS vertical no tempo foi utilizada para o cálculo do impulso e assim estimar a altura do salto. O teste T para amostras pareadas mostrou que a altura do salto no SCM foi significativamente maior do que no SA.

Existem diferenças nas ações técnicas realizadas por jogadores de diferentes posições durante os pequenos jogos?

This study aimed to compare technical actions of soccer players from different playing position during small-sided games in which teams were composed of players from the same position (e.g., three defenders). In total, 14 U-14 soccer players (14.43 ± 0.16 years), four defenders, four midfielders and four forwards, as well as 2 non-evaluated goalkeepers, participated in this study. The incidence of technical actions performed by players was analyzed through proportion chi-square test and omega effect sizes, and significance level was set at 5%. Results showed no differences in technical actions performed by players from different playing positions (p>0.05, small effect size). Thus, it is suggested that the 3v3 small-sided game, with teams composed of athletes with the same playing position, is characterized by a more general training stimulus, which can be particularly useful during the first years of deliberate practice.

TEST-retest reliability of kinetic variables measured on campus board in sport climbers

Sport climbers frequently use campus board (CB) to improve their upper limb strength under similar conditions of high-difficulty sport climbing routes. The objective of this study was to assess the test-retest reliability of peak force and impulse measured using a CB instrumented with two load cells on starting holds. The same evaluator examined 22 climbers on two days with 48 h between the assessments. The participants performed five concentric lunges (CL) and five lunges with stretch-shortening cycle with 1 min intervals between repetitions and 10 min between exercises. All variables were associated with significant intraclass correlation coefficient (ICC) values (p = 0.001), and none variable showed systematic errors (p > 0.05). Peak force ICC was higher than 0.88, and the standard error of measurement (SEM%) was less than 5%. Impulse ICC for the CL was greater than 0.90, and the SEM% was less than 14%. We conclude that the kinetic variables measured using the CB were reliable. The ability of the hands to maintain contact with the holds (peak force) and the abilities of the arms and shoulders vertically move the centre of mass (impulse) should be taken into account by coaches on CB training prescription as well for further research.

Tactical behavior in soccer small-sided games: inluence of team composition criteria

This study aimed to compare the tactical behavior of young soccer players during small-sided games played with team composition criteria based on procedural tactical knowledge, aerobic power and speed performance. Eighteen male soccer players played 3vs.3 small-sided games with teams balanced according to players’ performance on Sprint Test, Yo-Yo Intermittent Recovery Test and the ield test of the System of Tactical Assessment in Soccer. Data related to the incidence of tactical principles were analyzed through the proportions chi-square test with Bonferroni’s correction. One-way ANOVA was used to compare players’ ofensive and defensive tactical performance. Results showed diferent incidence of ofensive and defensive tactical principles in games with diferent teams’ composition criteria. It has also been shown a higher defensive performance when the teams’ composition criteria was based on players’ procedural tactical knowledge.

Confiabilidade das medidas de demanda física, fisiológica e tática em pequenos jogos com superioridade e igualdade numérica no futebol

DOI: http://dx.doi.org/10.5007/1980-0037.2016v18n5p602 The aim of this study was to investigate the physical, physiological (HR) and tactical demands of small-sided soccer games (SSG) with numerical equality (3x3) and numerical superiority (4x3). Eighteen male players of a soccer team played against each other both types of SSG, both played as two 4-minute bouts interspersed with 4-minute rest. Physical (distances, velocities and accelerations) and HR demands were recorded by a GPS system (15hz) and a heart rate monitor during SSG. The individual tactical behaviors proposed by the System of Tactical Assessment in Soccer were registered by an observer who analyzed the SSG videos. Reliability was verified calculating the intraclass correlation coefficient (ICC) and the absolute and percentage standard error of measurement (SEM and %SEM, respectively), both considering athletes’ individual scores in each SSG bout. As a result, higher number of variables related to physical and physiological demands presented significant ICC values, being classified as moderate to excellent in relation to variables related to tactical demands. Considering these variables that presented significant ICC values in both SSG, the SEM% values found for physical and physiological variables ranged from 3.0 to 42.0%, while those found for the tactical variables ranged from 31.6 to 75.0%. It could be concluded that several variables related to physical and physiological demands present moderate to excellent reliability. Differently, the majority of variables related to tactical demands were not reliable in both types of SSG. 

Analysis and comparison of intensity in specific soccer training sessions

This study compared the exercise intensity of four specific soccer training sessions (friendly and training match, tactical and technical workouts). Ten professional soccer players (24.2 ± 3.7 years, 177.9 ± 7.3 cm, 63.2 ± 4.6 mLO2•kg-1•min-l) were recruited. A treadmill progressive interval test was performed to determine the players' VO2max, maximal heart rate (HRmax), HR-VO2 curve, and the heart rate corresponding to blood lactate concentrations of 2 and 4 mmol/L. The heart rate during the training sessions was used to estimate the exercise intensity and to classify them into intensity zones (low-intensity: <2 mmol/L; moderate-intensity: between 2 and 4 mmol/L; high-intensity: >4 mmol/L). Exercise intensities were different among training sessions (friendly match: 86.0 ± 5.1% HRmax; training match: 81.2 ± 4.1% HRmax; tactical workout: 70.4 ± 5.3% HRmax; technical workout: 62.1 ± 3.6% HRmax). The friendly match presented the highest percentage of time performed in the high-intensity zone.

The effect of double--blind carbohydrate ingestion during 60 km of self-paced exercise in warm ambient conditions

This study evaluated double blind ingestions of placebo (PLA) versus 6% carbohydrate (CHO) either as capsules (c) or beverage (b) during 60 km self-paced cycling in the heat (32°C and 50% relative humidity). Ten well-trained males (mean ± SD: 26±3 years; 64.5±7.7 kg and 70.7±8.8 ml.kg⁻¹.min⁻¹ maximal oxygen consumption) completed four separate 60 km time trials (TT) punctuated by 1 km sprints (14, 29, 44, 59 km) whilst ingesting either PLA_b or PLA_c or CHO_b or CHO_c. The TT was not different among treatments (PLA_b 130.2±11.2 min, CHO_b 140.5±18.1 min, PLA_c 143.1±29.2 min, CHO_c 137.3±20.1 min; P>0.05). Effect size (Cohen’s d) for time was only moderate when comparing CHO_b – PLA_b (d = 0.68) and PLA_b – PLA_c (d = 0.57) whereas all other ES were ‘trivial’ to ‘small’. Mean speed throughout the trial was significantly higher for PLA_b only (P<0.05). Power output was only different (P<0.05) between the sprints and low intensity efforts within and across conditions. Core and mean skin temperatures were similar among trials. We conclude that CHO ingestion is of little or no benefit as a beverage compared with placebo during 60 km TT in the heat.

Efeito da aplicação de vibração mecânica sobre a impulsão vertical

Vários estudos apontam que o treinamento com vibrações pode contribuir no desenvolvimento da força muscular e do desempenho esportivo. O objetivo deste estudo foi verificar o efeito da vibração mecânica aplicada na direção da resultante das forças musculares sobre a impulsão vertical. A amostra foi composta por 18 voluntários que realizaram o teste de salto vertical antes e após 20 segundos de vibração mecânica, 20 Hz de frequência e 6 mm de amplitude, aplicada na direção da resultante das forças musculares. Os mesmos voluntários foram utilizados como controle e, para isto, realizaram pré e pós-teste sem treinamento com vibração. Houve um aumento significativo de 8,5% na altura de salto vertical após o treinamento com vibração. O procedimento controle não gerou alterações significativas. Estes resultados sugerem que a aplicação de vibração mecânica na direção da resultante das forças musculares de membros inferiores foi capaz de gerar aumentos agudos na impulsão vertical.

Comparação de duas diferentes intensidades de alongamento na amplitude de movimento

O alongamento é uma prática comum no treinamento da flexibilidade, porém existe uma deficiência de informações específicas sobre os componentes da carga utilizados, em especial, sobre a intensidade do alongamento. O presente estudo teve como objetivo investigar o efeito agudo de duas diferentes intensidades de alongamento na amplitude de movimento (ADM) de extensão do joelho. Participaram deste estudo 14 voluntários do sexo masculino. Os dois membros inferiores de cada participante foram avaliados, sendo que um membro executou o treinamento na intensidade submáxima de alongamento (TS, N=14) e o outro na intensidade máxima de alongamento (TM, N=14). O treinamento utilizou a técnica passiva-estática executando quatro repetições com duração de 15 segundos. Foi encontrada diferença estatisticamente significativa para os valores de ADM entre o pré-teste (68,0±10,5) e o pós-teste (74,0±10,0) no TM. Os valores de ADM para o pré-teste (68,9±14,0) e o pós-teste (71,0±14,4) no TS não apresentaram diferença significativa. Os resultados analisados através da ANOVA two-way apresentaram interação significativa entre o grupo e o teste (F=1.26; df=8,62; p=0,007). O estudo demonstrou que o treinamento na intensidade máxima de alongamento promove aumento agudo da ADM. Dessa forma, os estudos que avaliam os componentes ideais da carga de treinamento na melhora da flexibilidade não devem negligenciar o controle da intensidade do estímulo de alongamento.

Study of the force applied during anteroposterior articular mobilization of the talus and its effect on the dorsiflexion range of motion

OBJECTIVE

The aim of this study was to investigate the behavior of the force applied during the Maitland grade III anteroposterior joint mobilization of the talus and its effect on dorsiflexion range of motion (ROM).

METHODS

Two examiners performed measurements of dorsiflexion ROM on both ankles of healthy volunteers using a universal goniometer. The anteroposterior talus mobilization was first applied by examiner A for 30 seconds. Examiner B then repeated the same procedure. A platform was placed under the volunteer's leg to register the forces obtained during mobilization. After the procedure, examiner A assessed the ankle dorsiflexion.

RESULTS

The results showed consistency regarding maximal forces applied throughout the 30 seconds of mobilization as well as low consistency upon the minimal forces. A significant increase in dorsiflexion ROM of the ankle was found immediately after joint mobilization.

CONCLUSIONS

The results of the present study have shown consistent maximal forces applied by one examiner and inconsistent minimal forces during an ankle mobilization in healthy volunteers when the same examiner was compared. Moreover, the applied force was able to increase dorsiflexion ROM after the Maitland grade III anteroposterior mobilization of the talus.

Análise de dois treinamentos com diferentes durações de pausa entre séries baseadas em normativas previstas para a hipertrofia muscular em indivíduos treinados

Os programas de treinamento na musculação são comumente prescritos baseando-se em normativas de carga de treinamento sugeridas pela literatura. Dentre as normativas, a prescrição da duração da pausa tem variado normalmente de um a três minutos. Comparações entre intervalos de pausa de um e três minutos mostram diferenças significativas na resposta hormonal, metabólica e no desempenho. Existe carência de estudos que mostram se diferentes pausas são suficientes para a realização das outras normativas previstas para o treinamento da hipertrofia e se um acréscimo de 30 segundos possibilita melhor recuperação. O objetivo deste estudo foi analisar a realização de dois treinamentos baseados em normativas previstas para a hipertrofia muscular e diferenciadas pelas pausas de 90 e 120 segundos entre séries, no exercício supino executado na barra guiada. Participaram 26 voluntários do sexo masculino, treinados em musculação. Foram realizadas quatro sessões de testes em quatro dias. Após a realização dos procedimentos de familiarização e do teste de 1RM, o grupo realizou o exercício no supino guiado à intensidade de 70% de 1RM em quatro séries com o objetivo de alcançar 12 repetições por série, com pausas de 90 ou 120 segundos distribuídas aleatoriamente em diferentes dias. Não foi verificada diferença significativa no número de repetições nas séries quando comparado o desempenho obtido pelos sujeitos nas duas pausas. Independente da duração da pausa (90 ou 120 segundos) foi observada queda do rendimento no decorrer da realização das séries, caracterizada pela redução significativa no número de repetições realizado. Os resultados mostraram limitação da aplicação das normativas previstas para o treinamento da hipertrofia muscular em indivíduos treinados. Além disso, pode não haver diferenças no desempenho com a alteração da pausa entre séries de 90 para 120 segundos.