Work bout handling of a search dog reduces handgrip strength and increases firefighters' risk of falls.

OBJECTIVES: Firefighters work with dogs as support for their search activities for victims. Firefighters who handle dogs supposedly have higher acute muscle pain, more stumbling, and fatigue. This study aimed to verify the influence of a mantrailing dog on the firefighter's psychophysiological and muscular responses and the number of imbalances in a simulated activity of searching for people. METHODS: The sample consisted of 10 canine operators characterized by mass (92.57 ± 9.66 kg), height (1.78 ± 0.06 m), age (37.8 ± 2.1 yr), and length of service (9.5 ± 4.6 yr), who performed a search activity under 2 experimental conditions (dog condition and control condition). The simulated search activity consisted of a predefined hike of 2.5 km between the beginning of a search and the place where the sham victim was hidden. Cardiometabolic variables, pain level, and muscular performance were measured pre and postactivity (time factor). The number of imbalances suffered during hiking was also quantified. RESULTS: ANOVA data indicated interactions (condition × time) related to handgrip strength (P < 0.05). Handgrip strength was reduced in the postsearch activity with the dog, and it increased the control when compared to the preactivity (-12.3% versus +9.2%). Also, the level of pain and discomfort in the neck, trunk, and hip regions was higher with dogs (P < 0.05). Under the dog and control conditions, there were 25 and 05 imbalances, respectively, during the hike. There were no significant differences between the experimental conditions for vertical jump performance and cardiovascular responses either with dog or control. CONCLUSIONS: The findings of this study highlight that a mantrailing dog with the firefighter increased the number of slips, trips, sudden changes in direction, and loss of body balance, accompanied by a reduction in handgrip strength, and increased acute pain in the neck, trunk, and hip. These findings may contribute to support strategies for mitigating injuries and optimizing the performance of canine operators in the fire department and other units cinotechnic.

Impact of different personal protective clothing for firefighters in mountain areas.

BACKGROUND: Mountain hiking is an unpredictable activity for firefighters during the search, rescue, and firefighting. Could the quality of the uniform worn by firefighters affect psychophysiological variables? OBJECTIVE: The objective of this study was to monitor the responses of perceived exertion (RPE), musculoskeletal pain (MP), and heart rate variability (HRV) responses in firefighters using different uniforms on a 5 km mountain walking activity. The feeling of comfort, safety, and ergonomic adjustment of the two types of uniforms also was verified. METHODS: Sixteen firefighters were divided into two groups: 4thRUPM"B2" (33% polyester and 67% cotton) vs. GOLD (50% polyamide and 50% cotton). The GOLD group wore a prototype that had not yet been operationally tested. RESULTS: The independent t-test showed that the groups had similar results in RPE at post-march (Omni-Walk/Run = 3.5±0.9 vs. 2.9±0.6 AU). ANOVA Two-way (2x group and 2x time) was used to verify differences in body mass (BM), MP, and HRV. There was a main effect of time (pre- vs. post-march; p < 0.05) for BM, MP, heart rate (HR), mean RR, RMSSD, pNN50, and HF, regardless of group (4thRUPM"B2" vs. GOLD). Rainwater increased post-march BM (92.2±9.8 kg vs. 93.5±9.9 kg). MP (28.9±2.9 vs. 33.2±7.7 AU), HR (71.6±14.2 vs. 99.0±26.3 bpm), RMSSD (74.8±53.7 vs. 126.5±74.4 ms) and HF (48.5±20.2 vs. 60.0±16.7 nu) also increased post-march. The mean RR (875.2±153.3 vs. 673.9±155.3 ms) and pNN50 (33.1±18.6 vs. 46.3±23.9%) reduced post-march. There was a subjective preference for GOLD. CONCLUSION: Different uniforms do not compromise psychophysiological variables during the mountain hike but differentiate ergonomic subjectivity.

Stress level and heart rate variability in police post-occurrence of bank robbery: an experience report.

Introduction: The expectation of armed confrontation is among the most stressful elements in police work. Knowledge about perceived stress and cardiovascular markers in police officers comes from simulations. However, to date, information about psychophysiological responses during high-risk occurrences is scarce. Objectives: To assess stress levels and heart rate variability in policemen before and afer atending a bank robbery. Methods: Elite police officers (30.4 ± 3.7yrs) filled in a stress questionnaire and had their heart rate variability monitored at the beginning (7:00 am) and at the end (7:00 pm) of a work shif. At about 5:30 pm, these policemen were called to respond to a bank robbery in progress. Results: No significant changes in sources or symptoms of stress were found between before and afer the incident. However, statistical reductions were found in heart rate range interval (R-R interval [-13.6%]), pNN50 (-40.0%), and low frequency (-28%) and the low frequency/high frequency ratio increased (200%). These results suggest that although no change in the level of perceived stress was found, a significant reduction in heart rate variability may be atributed to a reduction in activation of the parasympathetic system. Conclusions: The expectation of armed confrontation is among the most stressful occurrences in police work. Research knowledge about perceived stress and cardiovascular markers in police officers comes from simulations. Data on psychophysiological responses post-occurrence of high-risk scenarios are scarce. This research may help law enforcement organizations find means to monitor police officers' acute stress levels afer any high-risk occurrences.

Introdução: No trabalho policial, a expectativa do confronto armado está entre as ocorrências mais estressantes. O conhecimento sobre as alterações dos níveis de estresse e marcadores cardiovasculares são oriundas de condições simuladas. Até o momento, a descrição das reações psicofsiológicas após ocorrência de alto risco são escassas. Objetivos: Verificar o nível de estresse e a variabilidade da frequência cardíaca em policiais após uma ocorrência de roubo a banco. Métodos: Oito policiais de elite (30,4±3,7 anos) preencheram um questionário de estresse e tiveram sua variabilidade da frequência cardíaca monitoradas no início (7h) e no final (19h) do turno de trabalho. Entretanto, por volta das 17h30, esses policiais atenderam uma ocorrência de roubo a banco. Resultados: Não foram encontradas alterações significantes entre o início e o final do plantão para as fontes e sintomas de estresse. Entretanto, houve redução significante para o intervalo da variação de frequência cardíaca [intervalo R-R (-13.6%)], pNN50 (-40.0%), baixa frequência (-28%) e aumento para razão baixa frequência/alta frequência (+200%). Dessa forma, nossos resultados sugerem que embora nenhuma mudança no nível de estresse percebido tenha sido encontrada, uma redução importante na variabilidade da frequência cardíaca pode ser atribuída a uma redução na ativação do sistema parassimpático. Conclusões: A associação de indicadores qualitativos e quantitativos (questionário e variabilidade da frequência cardíaca) contribui para um melhor entendimento de como gerenciar e treinar as habilidades emocionais dos policiais. Esta pesquisa pode ajudar as organizações de aplicação da lei a encontrar propostas para monitorar os níveis de estresse agudo dos policiais após qualquer ocorrência de alto risco.

Can training trunk musculature influence musculoskeletal pain and physical performance in military police officers?

To investigate the effect of a Trunk Training (TT) program on the general musculoskeletal pain (GMP) and physical performance of Military Police Officers. Twenty officers were divided into either control group (CG) or TT group (TTG). Both groups performed nine weeks of traditional physical training. However, the TTG had 25-minutes allocated to TT during each scheduled physical training period. Anthropometric, trunk endurance, and physical fitness tests were completed pre- and post-training for both groups. Both groups also answered a weekly questionnaire about their GMP. Post-training, trunk endurance performance was significantly higher (p < 0.05) and the GMP significantly lower (p < 0.05) in the TTG when compared to the CG. Improvement in side plank test scores was associated with a decreased in GMP (r = -0.495, p < 0.05). TT can reduce the perception of GMP in addition to increasing the endurance of the trunk muscles. The side plank was the only physical test associated with GMP. Practitioner summary: Trunk Training can reduce general musculoskeletal pain and increase the endurance of the trunk muscles without a concomitant loss in general fitness in elite Military Police Officers. This research lasted 11 weeks and presents real-world and pragmatic findings.

A densidade como uma "não tão nova" métrica da quantificação de cargas no treinamento de força / Work to rest ratio as a "not so new"metric to quantify strength training loads

O objetivo dessa carta resposta foi tecer algumas considerações sobre o ponto de vista do manuscrito "A densidade como uma nova métrica da quantificação de cargas no treinamento de força", publicado nessa tradicional revista brasileira. Erroneamente, os autores apontaram que o termo work to rest ratio utilizado no estudo Blood Pressure Response During Resistance Training of Different Work-to-Rest Ratio e publicado no Journal of Strength Conditioning Research estaria equivocado. Os autores também sugerem que a densidade seja calculada apenas pela fórmula: total de peso levantado/total de pausa. Isso limitaria o cálculo da densidade em métodos isométricos de treinamento de força, que podem ter a densidade calculada pela fórmula: tempo de tensão muscular/total de pausa. Essa breve comunicação amplia o contexto conceitual e de aplicação prática dessa métrica que é pouco conhecida no treinamento de força. (AU)

The aim of this reply letter was to present some considerations about the point of view of the manuscript "Density as new metric to quantify strength training loads", published in this traditional Brazilian journal. The authors erroneously pointed out that term "work to rest ratio" used in the study "Blood Pressure Response During Resistance Training of Different Work-to-Rest Ratio" and published in Journal of Strength Conditioning Research, would be wrong. The authors also suggest that density must be calculated only by the formula: total weight lifted / total rest interval. This would limit density calculation in isometric strength training methods, which can have density calculated by the formula: muscle tension time / total rest interval. This brief communication broadens the conceptual context and practical application of this metric that is little known in strength training. (AU)

Physical fitness tests as a requirement for physical performance improvement in officers in the military police of the state of Paraná, Brazil.

INTRODUCTION: Physical fitness is crucial for the work of military police officers. Over time, officers show a substantial decrease in physical fitness. State military officers must undergo a physical fitness test every year, but prior to 2015, failure on this test had no impact on career advancement. State Law No. 18.659/2015 included passage of the physical fitness test as a requirement for promotion for officers in the Paraná military police (Polícia Militar do Paraná). OBJECTIVES: To verify whether the obligation to undergo the physical fitness test had any effects on the physical performance of military police officers. METHODS: The physical fitness tests results from 2016-2019 (n = 1705) were entered into an electronic spreadsheet and stratified by year. The spreadsheet included scores on individual tests (shuttle run, upper body and 12-minute run) as well as the sum total across all tests. Then, descriptive statistics, normality test, Kruskal-Wallis H test, and post-hoc comparisons were performed using the Mann-Whitney U test. with a significance level of p < 0.05. RESULTS: Significant differences (p < 0.05) were observed on all variables in the physical fitness test when compared between the years of 2016, 2017, 2018 and 2019. Mean scores on the shuttle run (96.91 ± 7.54) and upper body tests (82.60 ± 24.81) were highest in 2019, while the mean score on the 12-minute run test was highest in 2017 (60.33 ± 28.38). The effect size of these differences (r) was small. CONCLUSIONS: The evidence suggests that the inclusion of the physical fitness test as a requirement for promotion can contribute to the improvement of physical performance in military police officers.

Validação do questionário de saúde e performance para policiais e bombeiros militares (QSPM) / Validation of health and performance questionnaire for military police and firefighter (QSPM) / Validation of health and performance questionnaire for military police and firefighter (QSPM)

O objetivo deste estudo foi desenvolver e analisar a validade de conteúdo, constructo e a fidedigni-dade de um questionário para avaliar a demanda física e operacional, saúde e condições de trabalho em policiais e bombeiros militares. O Questionário de Saúde e Performance para Militares (QSPM) foi desenvolvido por pesquisadores militares e não militares, a validade foi analisada com o índice de validade de conteúdo (IVC), análise fatorial exploratória e a fidedignidade com o percentual de concordância (%C), coeficiente Kappa e alfa de Cronbach. Nove juízes participaram da validação de conteúdo, 732 militares (15% mulheres) participaram da etapa de validação de constructo e 262 militares (18% mulheres) responderam duas vezes ao QSPM para a verificação da fidedignidade. As análises foram realizadas no software SPSS 26 e o nível de significância mantido em 5%. O QSPM apresentou o IVC de 0,98 e variância total explicada em 54,7%. A reprodutibilidade apresentou valores de %C entre 97,2 - 100,0%, Kappa entre 0,94 - 1,00 (p < 0,05) e alpha de Cronbach entre 0,80 - 1,00 (p < 0,05). Conclui-se que o QSPM apresentou validade de conteúdo, constructo e fidedignidade para avaliar a frequência da demanda física e operacional, as condições de saúde e de trabalho de policiais e bombeiros militares

The aim of this study was to develop and analyze the content and construct validity and reliability of a questionnaire to assess the performance, health and working conditions of police officers and military fire-fighters (QSPM). Civilian and military personnel carried out the development of the QSPM. The validity was analyzed by the content validity index (CVI), factor analysis, and the reproducibility by the simple agreement (%SA), the Kappa coefficient, and Cronbach's alpha. Nine experts participated in the content validation, 732 military personnel (15 women) participated in the construct validation, and 262 military (18% women) answered the QSPM twice to measure reproducibility. The QSPM had a CVI of 0.98. In the exploratory factorial analysis, when considering four factors, and the total explained variance was 54.7%. The reproducibility showed %SA values varying between 97.2 to 100.0%, Kappa values varying between 0.94 to 1.00 (p < 0.05 for all questions) and, Cronbach's α values varying between 0.80 to 1.00 (p < 0.05 for all questions). In conclusion, the QSPM showed content validity, construct validity and reliability to measure the frequency of physical-operational demand, the presence of morbidities, and the working condi-tions of police officers and firefighters

Efeito da massagem e pseudomassagem no desempenho agudo e recuperação autopercebida: um estudo controlado por placebo / Effect of massage and pseudo massage on acute performance and self-perceived recovery: a study placebo-controlled

RESUMO O objetivo deste estudo foi verificar o efeito da massagem ou pseudomassagem no desempenho do salto vertical. Quinze participantes foram submetidos aleatoriamente a três condições experimentais: massagem, pseudomassagem e repouso. A condição de massagem exigiu três saltos verticais unipodais seguidos de dois minutos de massagem manual nos músculos flexores plantares e, antes de executar outros três saltos, foi aplicada a Escala de Recuperação de Qualidade Total (TQR). As duas condições a seguir foram estruturadas com os mesmos procedimentos, no entanto, os participantes foram submetidos à pseudomassagem (simples-cego) ou a dois minutos de descanso. Os resultados não mostraram diferenças estatísticas na altura do salto entre as análises pré e pós, nem entre as condições experimentais (massagem 18,7 ± 4,1 vs. 18,2 ± 4,1; pseudomassagem 19,1 ± 4,0 vs. 18,3 ± 3,8; descanso 19,0 ± 4,0 vs. 18,7 ± 3,9 cm). Também não houve diferenças estatísticas no TQR entre as condições experimentais (massagem 16,2 ± 4,3; pseudomassagem 16,4 ± 3,9; descanso 15,9 ± 2,6 ua). Tanto a massagem quanto a pseudomassagem não afetaram o desempenho no salto vertical e na TQR.

ABSTRACT The aim of this study was to verify the effect of massage or pseudo massage on vertical jump performance. Fifteen participants were randomly subjected to three experimental conditions: massage, pseudo massage and rest. The massage condition required three unipodal vertical jumps followed by two minutes of manual massage on plantar flexor muscles and, before performing another three jumps, the Total Quality Recover Scale (TQR) was applied. The two following conditions were structured with the same procedures, although participants were submitted either at pseudo massage (single-blinded) or two minutes of rest. Results showed no statistical differences on jump height between pre and post analysis nor between experimental conditions (massage 18.7 ± 4.1 vs 18.2 ± 4.1; pseudo massage 19.1 ± 4.0 vs 8.3 ± 3.8; rest 19.0 ± 4.0 vs 18.7 ± 3.9 cm). There were also no statistical differences in the TQR results between experimental conditions (massage 16.2 ± 4.3; pseudo massage 16.4 ± 3.9; rest 15.9 ± 2.6 ua). Both massage and pseudo massage did not affect performance on vertical jump and TQR.

Blood Pressure Increase in Hypertensive Individuals During Resistance Training Protocols With Equated Work to Rest Ratio.

Introduction: Despite growing evidence regarding the benefits of resistance training in hypertension, the large and abrupt rise of systolic blood pressure (SBP) observed during resistance exercise execution has resulted in concern about its safety. However, the manipulation of the resistance training protocol (RTP) organization, maintaining the work to rest ratio equated between protocols (W:R-equated), may reduce the SBP increase. Purpose: To compare cardiovascular responses during two W:R-equated RTPs (3 × 15:88 s vs. 9 × 5:22 s - sets × reps: rest between sets) performed in exercises for the lower and upper limbs. Methods: Twelve medicated hypertensives (48 ± 8 years) randomly performed two RTPs in the bilateral leg extension (BLE) and unilateral elbow flexion (UEF) exercises at 50% 1RM. Increases (Δ) of SBP, heart rate (HR) and rate pressure product (RPP) during the exercises were measured by photoplethysmography. Results: In both BLE and UEF exercises, Δ SBP was significantly greater during 3 × 15:88 s than 9 × 5:22 s (peak values: BLE = + 84 ± 39 vs. + 67 ± 20 mm Hg, and UEF = + 46 ± 25 vs. + 37 ± 18 mm Hg, respectively, both p < 0.05). ΔHR and ΔRPP were significantly higher in the 3 × 15:88 s than 9 × 5:22 s in BLE (peak values + 45 ± 17 vs. + 30 ± 8 bpm, and + 15,559 ± 5570 vs. + 10,483 ± 2614 mm Hg. bpm). Conclusion: In medicated hypertensives, a RTP combining more sets with less repetitions per set and shorter rest intervals between sets (i.e., 9 × 5:22 s) produced a smaller increase in cardiovascular load (ΔSBP, ΔHR and ΔRPP) during its execution than a protocol with fewer longer sets (i.e., 3 × 15:88 s).

Blood Pressure Response During Resistance Training of Different Work-to-Rest Ratio.

Paulo, AC, Tricoli, V, Queiroz, ACC, Laurentino, G, and Forjaz, CLM. Blood pressure response during resistance training of different work-to-rest ratio. J Strength Cond Res 33(2): 399-407, 2019-Changes in the work-to-rest ratio (W:R) of resistance training protocols (RTPs) (i.e., decreasing work or increasing rest) reduce the marked elevation in blood pressure (BP) that occurs during RTP execution. However, whether changes in RTP structure without changing W:R can change BP responses to RTP is unknown. To investigate the effect of different structures of rest intervals and number of repetitions per set on BP response among RTP equated and nonequated for W:R, 20 normotensive participants (25 ± 4 years) performed 4 different RTP of the leg extension exercise with the same work but different W:R structures. Two protocols followed the recommendations for cardiovascular disorders: (a) HIGHW:R-3×15:44s-3×15:44s (set×reps:rest between sets), which has high W:R (45reps:88s) and (b) LOWW:R-3×15:88s-3×15:88s, which has low W:R (45reps:176s). The other 2 protocols were W:R-equated to LOWW:R (45reps:176s): (c) LOWW:R-9×5:22s and (d) LOWW:R-45×1:4s. Systolic BP (ΔSBP) and diastolic BP (ΔDBP) were assessed by finger photoplethysmography. There were significant main effects for ΔSBP after RTP (p ≤ 0.05): HIGHW:R-3×15:44s = LOWW:R-3×15:88s > LOWW:R-45×1:4s > LOWW:R-9×5:22s (+87 ± 5 and +84 ± 5 vs. +61 ± 4 vs. 57 ± 4 mm Hg). For ΔDBP, there was a significant interaction between RTP and moment (p ≤ 0.05). Thus, HIGHW:R-3×15:44 > LOWW:R-3×15:88s > LOWW:R-45×1:4s > LOWW:R-9×5:22s (+53 ± 5 vs. +49 ± 5 vs. +44 ± 4 vs. +38 ± 3 mm Hg). HIGHW:R-3×15:44s produced the highest increase in ΔDBP, and LOWW:R-9×5:22s produced the lowest increase in ΔSBP and ΔDBP. Our findings may help the development of RTP protocols that may mitigate pressure peaks without changing important exercise variables (i.e., volume or duration).

Efeito agudo dos exercícios de flexibilidade no desempenho de força máxima e resistência de força de membros inferiores e superiores / Acute effect of stretching exercises on upper and lower limbs maximum strength and strength endurance performance

Este estudo verificou o efeito agudo dos exercícios de flexibilidade estática (EFlex) no desempenho de força máxima (FM) e de resistência de força (RF) em membros inferiores e superiores. Treze voluntários participaram do estudo e foram submetidos a testes de FM e RF (70% 1RM) nos exercícios supino e agachamento precedidos ou não de EFlex. O teste T pareado foi utilizado para comparação das médias nas duas condições. Os EFlex diminuíram a FM no agachamento (141,2±34,2 vs 132±34,9kg; p=0,007) e no supino (77,5±21,7 vs 71,7±17,7kg p=0,04). A RF no agachamento não sofreu efeito dos EFlex (16,2±5,7 vs 16,3±6,8 repetições p=0,48), porém, no supino a RF apresentou diminuição significante (11,7±4,8 vs 9,9±5,1 repetições; p=0,008). Portanto, os EFlex reduziram a FM nos membros inferiores e superiores e a RF somente nos membros superiores. Essa diferença na RF estaria relacionada ao volume de exercícios de flexibilidade pelo tamanho do grupo muscular.

This study investigated the acute effect of static stretching exercises (SSE) on maximum strength (MS) and strength endurance (SE) performance in lower and upper limbs. Thirteen volunteers participated in the study and were submitted to MS and SE (70% 1RM) tests in the bench press and squat exercises with or without SSE. The paired T test showed that the SSE decreased MS in the squat (141.2±34.2 vs 132±34.9kg, p=0.007) and in the BP (77.5±21.7 vs 71.7±17.7kg p=0.04). Squat SE was not affected by SSE (16.2±5.7 vs 16.3±6.8 repetitions p=0.48). On the other hand, bench press SE decreased significantly after SSE (11.7±4.8 vs 9.9±5.1 repetitions p=0.008). Therefore, SSE impaired MS performance on upper and lower limbs but SE was affected only on upper limbs. This difference in SE may be related to the stretching exercises volume applied to the size of each muscle group.

Influência do nível de força máxima na produção e manutenção da potência muscular / Influence of maximum strength on muscle power production and endurance

Indivíduos mais fortes (com nível mais elevado de força máxima, Fmax) demonstram menor resistência de força que indivíduos mais fracos (com nível mais baixo de Fmax) em uma mesma intensidade relativa. Como o nível de Fmax influencia a produção de potência, espera-se que sujeitos mais fortes também apresentem uma menor resistência de potência. O objetivo deste estudo foi avaliar a influência do nível de Fmax na produção e na resistência de potência durante repetições e séries múltiplas do exercício meio-agachamento. Quarenta e dois sujeitos foram classificados de acordo com o resultado no teste de força dinâmica máxima (1RM) e destes os 10 mais fortes e os 10 mais fracos foram selecionados para participar no estudo. Para avaliar a resistência de potência os dois grupos realizaram 10 séries de seis repetições a 40 por cento e a 60 por cento 1RM na maior velocidade possível. A potência absoluta (PA) e a potência relativa ao peso corporal (PR) desenvolvidas na fase concêntrica do exercício foram medidas. A análise de variância (ANOVA two-way) revelou que os sujeitos mais fortes diminuíram a PA a 60 por cento 1RM a partir da quarta repetição e a PR a partir da quinta repetição. Já os sujeitos mais fracos diminuíram a PA apenas na sexta repetição e mantiveram o rendimento na PR ao longo das 10 séries. Não houve efeito significante na intensidade de 40 por cento 1RM. Isso sugere que sujeitos mais fortes fadigam antes em maiores intensidades de carga. Essa fadiga precoce nos sujeitos mais fortes poderia estar ligada a diferentes fatores associados ao controle da homeostase orgânica como o comportamento da pressão arterial, da atividade eletromiográfica e a proporção de fibras musculares dos tipos I e II.

It seems that stronger subjects present less strength endurance compared to weaker subjects at the same relative intensity. Since the level of maximum strength affects power production, it is also expected that stronger subjects present lower power endurance. The aim of this study was to evaluate the effects of maximum strength on power production and endurance over multiple sets and repetitions of the half-squat exercise. Forty- two subjects were classified according to the result in the 1RM test and the 10 strongest and 10 weakest were selected to participate. In order to evaluate power endurance, both groups performed 10 sets of 6 repetitions at 40 percent and 60 percent 1RM as fast as possible. The absolute power (AP) and relative power (RP) (corrected by body weight) developed in half-squat concentric phase were measured. Analysis of variance for repeated measures (Two-Way ANOVA) revealed that the stronger subjects decreased AP from 4th repetition on and RP from 5th repetition on at 60 percent 1RM. The weakest subjects decreased AP from 6th repetition on and maintained RP production over the ten series. There was no significant effect on 40 percent 1RM. This result suggests that stronger subjects fatigue first at higher intensities. The early fatigue in stronger subjects could be associated with different factors related to body control of homeostasis such as blood pressure, motor units recruitment and proportion of types I and II muscle fibers.

Acute effect of two aerobic exercise modes on maximum strength and strength endurance.

The purpose of this study was to evaluate the effects of 2 modes of aerobic exercise (continuous or intermittent) on maximum strength (1 repetition maximum, 1RM) and strength endurance (maximum repetitions at 80% of 1RM) for lower- and upper-body exercises to test the acute hypothesis in concurrent training (CT) interference. Eight physically active men (age: 26.9 +/- 4.2 years; body mass: 82.1 +/- 7.5 kg; height: 178.9 +/- 6.0 cm) were submitted to: (a) a graded exercise test to determine V(.-)O2max (39.26 +/- 6.95 ml x kg(-1) x min(-1)) and anaerobic threshold velocity (3.5 mmol x L(-1)) (9.3 +/- 1.27 km x h(-1)); (b) strength tests in a rested state (control); and (c) 4 experimental sessions, at least 7 days apart. The experimental sessions consisted of a 5-kilometer run on a treadmill continuously (90% of the anaerobic threshold velocity) or intermittently (1:1 minute at V(.-)O2max). Ten minutes after the aerobic exercise, either a maximum strength or a strength endurance test was performed (leg press and bench press exercises). The order of aerobic and strength exercises followed a William's square distribution to avoid carryover effects. Results showed that only the intermittent aerobic exercise produced an acute interference effect on leg strength endurance, decreasing significantly (p < 0.05) the number of repetitions from 10.8 +/- 2.5 to 8.1 +/- 2.2. Maximum strength was not affected by the aerobic exercise mode. In conclusion, the acute interference hypothesis in concurrent training seems to occur when both aerobic and strength exercises produce significant peripheral fatigue in the same muscle group.

Efeito agudo dos exercícios de alongamento sobre o desempenho de força máxima / Acute effects of stretching exercises on maximal strength performance

O objetivo do estudo foi investigar o efeito agudo dos exercícios de alongamento estático no desempenho de força máxima.Onze sujeitos do sexo masculino foram submetidos a um teste de repetiçäo máxima (1RM) sob duas condiçöes experimentais: 1) precedido de exercícios de alongamento (CA) e 2) sem exercícios de alongamento (SA).Na condiçäo CA, Após a realizaçäo de aquecimento, os sujeitos executam uma sessäo de exercícios de alongamento estático para os membros inferiores com duraçäo aproximada de 20 minutos.Um total de seis exercícios foi executado com três repetiçöes de 30 segundos de duraçäo em cada exercício.Ao término da sessäo de alongamento os sujeitos foram testados.Na condiçäo SA os sujeitos foram testados logo após as sessöes de aquecimento.O teste consistiu na execuçäo completa do exercício de extensäo/flexäo de joelhos no aparelho leg-press.As cargas para os testes sofreram incrementos de 4 porcento, 3 porcento e 3 porcento da quantidade de peso levantada inicialmente a qual determinada durante uma sessäo de familiarizaçäo.Um intervalo de 3 minutos foi dado para cada novo esforço.Na condiçäo CA a média obtida no teste 1 RM foi significantemente menor que a média obtida na condiçäo SA.Conclui-se que, independente do mecanismo envolvido, uma sessäo de alongamento estático executada imediatamente antes da atividade física pode provocar uma queda no rendimento de força máxima.(au)