Estimating bone mineral content based on different types of muscle strength tests.

The aims of this pilot study were to verify which muscle strength tests better explain bone mineral content (BMC) of the femoral neck and lumbar spine and to develop predictive equations to estimate femoral neck and lumbar spine BMC. Twenty-nine subjects aged 56-76 years old (12 women and 17 men) participated in the study. Femoral neck and lumbar spine BMC was evaluated by Dual X-ray absorptiometry (DXA). Muscle strength measurements included maximal isometric voluntary contractions of knee extensors and flexors, vertical jump, 5-repetition maximum of the leg press (5-RMLP) and seated leg curl (5-RMLC), and handgrip strength. Women presented a moderate to strong correlation between femoral neck BMC and 5-RMLP (r = 0.819), 5-RMLC (r = 0.879), knee extensors peak torque (r = 0.699), and handgrip strength (r = 0.663), as well as between lumbar spine BMC and the 5-RMLP test (r = 0.845) and manual grip strength (r = 0.699). For females, the 5-RMLP and 5-RMLC tests most fully explained femoral neck BMC (R2 = 0.859) and the 5-RMLP test and body mass explained lumbar spine density (R2 = 0.757) for females. Men did not present correlations between BMC and strength variables. For females, the 5-RMLP and 5-RMLC variables explained the variations of femoral neck BMC, while 5-RMLP and body mass explained lumbar spine BMC. Future studies should evaluate a larger sample size and prioritize the strength tests with a greater predictive capacity.

Leg press exercise can reduce functional hamstring:quadriceps ratio in the elderly.

The aim of this study was to investigate whether 12 weeks of leg press strength training exercise could affect the conventional and functional hamstring:quadriceps ratios in the elderly. Twelve elderly participants were submitted to a 12 week progressive training protocol (two sessions/week) using a 45° leg press exercise. A significant increase in the one repetition maximum was observed after 4, 8, and 12 weeks (p = 0.001, p < 0.001, and p < 0.001, respectively) compared to week 0 and after 8 (p = 0.011) and 12 weeks (p = 0.001) compared to week 4. The concentric knee extensor peak torque was significantly higher at weeks 8 (p = 0.001) and 12 (p = 0.024) compared to week 0. There was no change in the concentric and eccentric knee flexor peak torques (p = 0.629 and 0.274, respectively) and conventional ratio (p > 0.314) after 12 weeks of training. The functional ratio (eccentric knee flexor peak torque:concentric knee extensor peak torque) reduced significantly after 8 (p = 0.034) and 12 (p = 0.036) weeks of strength training. Although the 45° leg press exercise requires knee extensor and flexor, hip extensor, and plantar flexor muscle strength, our findings suggest that the isolated use of the 45° leg press exercise reduces the knee functional ratio after 8 weeks of training. Therefore, 45° leg press exercise alone, without a hamstring exercise, should not be recommended for elderly individuals.

Perfil antropométrico de bombeiros militares: comparação entre os grupos de trabalho operacional e administrativo / Anthropometric profile of military firefighters: comparison between operational and administrative work groups

Introdução: A composição corporal é importante para o bombeiro militar no que diz respeito a sua saúde e ao seu desempenho no trabalho. Porém, o comportamento desse parâmetro não é elucidado nos diferentes grupos de trabalho do bombeiro militar. Objetivo: Comparar o perfil antropométrico de bombeiros militares entre os grupos de trabalho administrativo (ADM) e operacional. Métodos: A amostra foi composta por 121 (ADM = 50 e operacional = 71) bombeiros militares do sexo masculino. Foram aferidas massa corporal (MC), percentual de gordura (%G), massa gorda, massa magra, índice de massa corporal (IMC), circunferência da cintura (CC) e somatotipia. Resultados: Houve diferenças entre os grupos para as variáveis massa corporal (ADM = 78,5kg ­ operacional = 84,6kg), IMC (ADM = 25,8 ­ operacional = 27,2) e massa magra (ADM = 61,9kg ­ operacional = 66,2kg). Conclusão: Conclui-se que os grupos apresentam diferenças entre os perfis antropométricos e apresentam %G e IMC acima do recomendável.

Background: Body composition is relevant for the health and work performance of firefighters. However, the behavior of these parameters has not been elucidated for groups of firefighters performing different tasks. Objectives: To compare the anthropometric profile of military firefighters who perform administrative (ADM) or operational work . Methods: The sample comprised 121 (ADM = 50 and operational = 71) male military firefighters. Body mass (BM), body fat percentage (BFP), fat body mass, lean body mass, body mass index (BMI), waist circumference and somatotype were analyzed. Results: Intergroup difference was found for body mass (ADM = 78.5 kg ­ operational = 84.6 kg), BMI (ADM = 25.8 ­ operational = 27.2) and lean body mass (ADM = 61.9 kg ­ operational = 66.2 kg). Conclusion: The groups exhibited differences in their anthropometric profile and BFP and BMI above the recommended range.

Reducing measurement errors during functional capacity tests in elders.

BACKGROUND: Accuracy is essential to the validity of functional capacity measurements. AIM: To evaluate the error of measurement of functional capacity tests for elders and suggest the use of the technical error of measurement and credibility coefficient. METHODS: Twenty elders (65.8 ± 4.5 years) completed six functional capacity tests that were simultaneously filmed and timed by four evaluators by means of a chronometer. A fifth evaluator timed the tests by analyzing the videos (reference data). RESULTS: The means of most evaluators for most tests were different from the reference (p < 0.05), except for two evaluators for two different tests. There were different technical error of measurement between tests and evaluators. The Bland-Altman test showed difference in the concordance of the results between methods. Short duration tests showed higher technical error of measurement than longer tests. In summary, tests timed by a chronometer underestimate the real results of the functional capacity. DISCUSSION: Difference between evaluators' reaction time and perception to determine the start and the end of the tests would justify the errors of measurement. CONCLUSION: Calculation of the technical error of measurement or the use of the camera can increase data validity.

Functional capacity improves in-line with neuromuscular performance after 12 weeks of non-linear periodization strength training in the elderly.

BACKGROUND: While it is accepted that resistance training can improve functional capacity in older individuals, the neuromuscular source of this improvement has yet to be identified. AIM: This study investigated the link between improved neuromuscular performance and functional capacity after a 12-week resistance training period in untrained healthy older individuals. METHODS: Fifteen older men and women (60-71 years) adhered to a 4-week control period, followed by 12 weeks of non-linear resistance training for the lower limbs. Maximum dynamic leg press strength (1-RM), maximum isometric knee extension torque and rate of torque development (RTD) were evaluated at - 4, 0, 4, 8, and 12 weeks, and muscle activity was assessed at 0, 4, 8, and 12 weeks. Functional capacity tests (chair rise, stair ascent and descent, and timed up and go) were performed at - 4, 0, and 12 weeks. RESULTS: No changes occurred during the control period, but the group increased their 1-RM strength (from 142 ± 53 to 198 ± 43 kg, p = 0.001), which was accompanied by an increase in vastus lateralis activation (p = 0.008) during the intervention. Increase was observed at all RTD time intervals at week 8 (p < 0.05). Significant improvements in all the functional capacity tests were observed at week 12 (p < 0.05). DISCUSSION: Despite the expected increase in strength, RTD, muscle activity, and functional capacity, there was no significant relationship between the changes in neuromuscular performance and functional capacity. While resistance training elicits various positive improvements in healthy older individuals, actual strength gain did not influence the gain in functional capacity. CONCLUSION: The present study highlights the exact cause that improved the functional capabilities during resistance training are currently unknown.

Efeitos do treinamento da força na capacidade funcional de idosos institucionalizados / Effects of strength training on the functional capacity of institutionalized elderly / Efectos del entrenamiento de la fuerza en la capacidad funcional de ancianos institucionalizados

Trata-se de um estudo quase experimental que verificou efeitos do treinamento da força na capacidade funcional de idosos institucionalizados. Os idosos foram avaliados pelos testes de capacidade funcional e submetidos a treinamento da força (nove exercícios; 3x12 repetições máximas; intervalo entre 60 a 90 segundos) por um período de 12 semanas (frequência 3x/semana). Observou-se que o programa de treinamento de força por um curto período melhora o desempenho das atividades da vida diárias dos idosos.

ABSTRACT: This is a quasi-experimental study that verified effects of strength training on the functional capacity of institutionalized elderly. The elderly were evaluated by capacity tests and submitted to strength training (nine exercises, 3x12 maximum repetitions, 60-90 seconds interval) for a period of 12 weeks (frequency 3x / week). It was observed that the short-term strength training program improves the performance of the daily life activities of the elderly.

Se trata de un estudio casi experimental que verificó efectos del entrenamiento de la fuerza en la capacidad funcional de ancianos institucionalizados. Los ancianos fueron evaluados por las pruebas de capacidad, funcionando y sometidos a entrenamiento de la fuerza (nueve ejercicios, 3x12 repeticiones máximas, intervalo entre 60 a 90 segundos) por un período de 12 semanas (frecuencia 3x / semana). Se observó que el programa de entrenamiento de fuerza por un corto período mejora el desempeño de las actividades de la vida diaria de los ancianos.

Birthplace and birthdate of Brazilian Olympic medalists / Local de nascimento e data de nascimento de medalhistas olímpicos brasileiros

Abstract The aim of the present study was to analyze the association between birthplace and relative age with winning Olympic medals in Brazilian athletes. he sample consisted of 186 Olympic medalist athletes born in Brazil. Data analysis was performed through descriptive (incidence and percentage) and inferential statistics (Chi-Square to binary logistic regression). The association between population contingents and Olympic champions presented a significant result (p <0.05); however, no significant associations were found with relative age. It was concluded that most Olympic medalists were born in places that present better living conditions, with intermediate MHDI, which appears only in cities with more than 100 thousand habitants, and relative age is not an important criterion in winning medals among athletes investigated.

Resumo O objetivo do presente estudo foi analisar a associação entre o local de nascimento e idade relativa com a obtenção de medalhas olímpicas em atletas brasileiros. A amostra foi constituída por 186 atletas medalhistas olímpicos nascidos em território brasileiro. A análise dos dados realizou-se por meio da estatística descritiva (incidência e percentual) e inferencial (Qui-Quadrado a regressão logística binária). A associação entre os contingentes populacionais e campeões olímpicos apresentou resultado significativo (p<0,05), porém, não foram encontradas associações significativas com a idade relativa. Concluiu-se que a maioria dos atletas medalhistas olímpicos nasceu em locais que apresentam melhores condições de vida, com o IDHM médio que aparece apenas nas cidades com mais de 100 mil habitantes, além de a idade relativa não ser um critério importante na obtenção de medalhas dos atletas investigados.

Effects of saddle height on performance and muscular activity during the wingate test / Efeitos da altura do selim no desempenho e na ativação muscular durante teste de wingate

ABSTRACT This study aimed to analyze the anaerobic performance and muscle activation during a supramaximal cycling test at three different saddle positions. Twelve competitive cyclists completed an incremental cycling test and three 30-s Wingate tests in three different saddle heights (reference, downward, and upward), in a random order, on different days. The saddle height was individually shifted downward and upward (seeing 2.5% of the distance from the pubic symphysis to ground) from the reference position. The electromyographic signal (EMG) data was obtained from the rectus femoris, vastus lateralis, biceps femoris (long head), and gastrocnemius lateralis in order to assess muscle activation during the entire test. The anaerobic variables and the EMG data were divided into six consecutive windows of 5-s. The EMG signals were normalized by the first 5-s window of the reference position to provide the percentage changes throughout the test. The results suggest that during a 30-s Wingate test small changes in saddle height result in greater peak power output (reference=1380±241 W; downward=1497±175 W, p=0.036; upward=1491±225 W, p=0.049) and greater activation period for vastus lateralis (reference=33.6%, downward=33.2%, upward=35.0%; p=0.001) in comparision to rectus femoris (reference=24.5%, downward=25.2%, upward=23.7%), biceps femoris (reference=20.7%, downward=20.8%, upward=19.9%), and gastrocnemius lateralis (reference=21.2%, downward=20.8%, upward=19.9%). The results suggest that small adjustments in saddle height may affect the force-length relationship of the muscles of the lower limb, and consequently their recruitment pattern and their ability to generate force.

RESUMO O presente estudo teve como objetivo analisar o desempenho anaeróbio e a ativação muscular durante um teste de ciclismo supramáximo em três diferentes alturas do selim. Doze ciclistas competitivos completaram um teste incremental em cicloergômetro e três testes de Wingate de 30 s em diferentes alturas do selim (referência, baixa e alta), de forma randomizada, em diferentes dias. A altura do selim foi alterada para baixo e para cima a partir da posição de referência usando como parâmetro o valor referente a (± 2,5%) da distância da sínfise púbica até o solo. O sinal eletromiográfico (EMG) foi obtido dos músculos reto femoral, vasto lateral, bíceps femoral (cabeça longa) e gastrocnêmio lateral. As variáveis anaeróbias e os dados de EMG foram divididos em seis janelas consecutivas de 5 s. Os sinals EMG foram normalizados pela primeira janela da posição de referência para estipular as mudanças percentuais ao longo do teste. Os resultados sugerem que durante o teste de Wingate de 30 s pequenas alterações na altura do selim resultam em aumento da potência pico (referência=1380±241 W; baixa=1497±175 W, p=0,036; alta=1491±225 W, p=0,049) e maior período de ativação percentual para o vasto lateral (referência=33,6%, baixa=33,2%, alta=35,0%; p=0,001) em relação ao reto femoral (referência=24,5%, baixa=25,2%, alta=23.7%), bíceps femoral (referência=20,7%, baixa=20,8%, alta=19,9%) e gastrocnêmio lateral (referência=21,2%, baixa=20,8%, alta=19,9%). Os resultados sugerem que pequenos ajustes na altura do selim podem afetar a relação força-comprimento e, consequentemente, a capacidade de gerar força e o padrão de recrutamento muscular dos membros inferiores.

Effect of squat depth on performance and biomechanical parameters of countermovement vertical jump / A influência da profundidade de agachamento no desempenho e em parâmetros biomecânicos do salto com contra movimento

The aim of this study was to analyze the effect of different squat depths in the performance and biomechanical parameters at counter movement jump (CMJ). Twenty-two male volleyball or basketball players volunteered to participate in this study and all were currently competing at the college level. The CMJ was performed in three different conditions: 1) with relative knee flexion at the end of counter movement phase smaller than 90° (<90°); 2) greater than 90° (>90°), and; 3) preferred position (PREF). During the CMJ, kinematic, kinetic, and electromyography parameters were assessed. ANOVA for repeated measures with post-hoc Bonferroni´s test was used for variables comparison, with a significance level set at p≤0.05. The higher performance was on PREF and <90° situations compared with CMJ>90°. Average and peak power, as well as absolute and normalized peak forces, were higher ​​in >90° CMJ. The peak velocity of CG and angular velocities of hip and knee were higher in the <90° condition. EMG activity of the vastus lateralis (VL) during the descending and ascending phases were higher in position >90°. Recuts femoris and biceps femoris did not show difference in any jump phases. In conclusion, the knee flexion interferes the performance and the biomechanical variables at the CMJ. The highest jumps were got at a deeper squat, so this technique could be used for athletes in order to optimize the vertical jump performance in the training and competitions.

O objetivo do presente estudo foi analisar a influência de diferentes profundidades de agachamento no desempenho e em parâmetros biomecânicos no salto com contra movimento (CMJ). Participaram do estudo 22 atletas de voleibol ou basquetebol do sexo masculino, participantes de competições em nível regional e universitário. Os CMJ foram realizados em três condições: 1) com flexão relativa do joelho ao final da fase de contra movimento menor que 90° (CMJ<90°); 2) maior que 90° (CMJ>90°) e; 3) posição preferida (CMJPREF). Durante os CMJ foram mensurados: altura do salto, variáveis cinemáticas, cinéticas e eletromiográficas. ANOVA para medidas repetidas com post-hoc de Bonferroni foi utilizado na comparação das variáveis, adotando-se nível de significância de p≤0,05. O desempenho foi maior na situação PREF e <90° comparado ao CMJ >90°. A potência média e pico, a força máxima normalizada e absoluta, apresentaram os maiores valores na posição >90°. O pico de velocidade e as velocidades angulares de quadril e joelho apresentaram os maiores valores na posição <90°. A EMG do vasto lateral, durante as fases descendente e ascendente, foi maior na posição >90°. Os músculos reto femoral e bíceps braquial não apresentaram diferença entre as condições. Conclui-se que o desempenho e as variáveis biomecânicas analisadas no CMJ são influenciados pelo nível de flexão do joelho. As maiores alturas foram obtidas nos saltos realizados a partir de uma maior profundidade de agachamento, assim, tal estratégia técnica poderia ser utilizada por atletas a fim de otimizar a altura do salto vertical nos treinamentos e competições.