Technological advances in physical activity measurement have increased the development and utilization of accelerometers and pedometers for assessing physical activity in controlled and free-living conditions. Individual differences in leg length, stride length and stride frequency may affect the reliability and validity of accelerometers in estimating energy expenditure. To address this theory, this thesis investigated the influence of leg length, stride length and stride frequency on accelerometer counts and energy expenditure using four accelerometers (AMP, Actical, MTI, and RT3) and one pedometer (Yamax). Eighty-six participants, age 8 to 40 (17.6 ± 8.0) years performed three ten-minute bouts of treadmill activity at self-selected speeds (4 to 12 km/h). Energy expenditure (kcal/min) was measured through expired gas analysis and used as the criterion standard to compare physical activity data from activity monitors. A 3 (models) x 2 (duplicates of each model) x 3 (speeds) x 7 (minutes) repeated measures ANOVA was used to assess intra-device, inter-device, and inter-model reliability. Coefficients of variation were calculated to compare within-device variation and between-device variation in accelerometer counts. Differences between measured and predicted energy expenditure were assessed across five height categories to determine the influence of leg length on the validity of accelerometer/pedometer data. Regression equations for each model were developed using mean activity counts/steps generated for each speed, adjusting for various predictor variables (i.e., age, weight, leg length). These were compared to model-specific equations to determine whether the addition of certain variables might explain more variance in energy expenditure. Leg length and stride frequency directly influenced variability in accelerometer data and thus predicted energy expenditure. At high speeds and stride frequencies counts began to level off in the Actical, however this did not occur in the other devices. Intra-device and inter-device variation in accelerometer counts was less than 10% and was lowest at very high speeds for the Actical, MTI, and RT3 (p<0.05). When compared to measured values, energy expenditure was consistently underestimated by the AMP, Actical, and Yamax models and consistently overestimated by the RT3 across speed. The MTI underestimated and overestimated energy expenditure depending on speed. Energy expenditure was both underestimated and overestimated to the greatest extent during the treadmill run for the tallest participants (p<0.05). Accelerometer counts or pedometer steps, when entered into regression equations with age, weight and leg length, explained from 85 to 94 % of the variance in measured energy expenditure, supporting the inclusion of these variables within manufacturer-based equations. These results suggest that individual differences in leg length and stride frequency affect the reliability and validity of accelerometer data and therefore must be controlled for when using accelerometry to predict energy expenditure.

Technological advances in physical activity measurement have increased the development and utilization of accelerometers and pedometers for assessing physical activity in controlled and free-living conditions. Individual differences in leg length, stride length and stride frequency may affect the reliability and validity of accelerometers in estimating energy expenditure. To address this theory, this thesis investigated the influence of leg length, stride length and stride frequency on accelerometer counts and energy expenditure using four accelerometers (AMP, Actical, MTI, and RT3) and one pedometer (Yamax). Eighty-six participants, age 8 to 40 (17.6 ± 8.0) years performed three ten-minute bouts of treadmill activity at self-selected speeds (4 to 12 km/h). Energy expenditure (kcal/min) was measured through expired gas analysis and used as the criterion standard to compare physical activity data from activity monitors. A 3 (models) x 2 (duplicates of each model) x 3 (speeds) x 7 (minutes) repeated measures ANOVA was used to assess intra-device, inter-device, and inter-model reliability. Coefficients of variation were calculated to compare within-device variation and between-device variation in accelerometer counts. Differences between measured and predicted energy expenditure were assessed across five height categories to determine the influence of leg length on the validity of accelerometer/pedometer data. Regression equations for each model were developed using mean activity counts/steps generated for each speed, adjusting for various predictor variables (i.e., age, weight, leg length). These were compared to model-specific equations to determine whether the addition of certain variables might explain more variance in energy expenditure. Leg length and stride frequency directly influenced variability in accelerometer data and thus predicted energy expenditure. At high speeds and stride frequencies counts began to level off in the Actical, however this did not occur in the other devices. Intra-device and inter-device variation in accelerometer counts was less than 10% and was lowest at very high speeds for the Actical, MTI, and RT3 (p<0.05). When compared to measured values, energy expenditure was consistently underestimated by the AMP, Actical, and Yamax models and consistently overestimated by the RT3 across speed. The MTI underestimated and overestimated energy expenditure depending on speed. Energy expenditure was both underestimated and overestimated to the greatest extent during the treadmill run for the tallest participants (p<0.05). Accelerometer counts or pedometer steps, when entered into regression equations with age, weight and leg length, explained from 85 to 94 % of the variance in measured energy expenditure, supporting the inclusion of these variables within manufacturer-based equations. These results suggest that individual differences in leg length and stride frequency affect the reliability and validity of accelerometer data and therefore must be controlled for when using accelerometry to predict energy expenditure.

The purpose of this study was to determine the acute effects of heavy resistance exercise on agility performance in court-sport athletes. Five men (age: 20.6 ± 1.9 years; body mass: 79.36 ± 11.74 kg; body height: 1.93 ± 0.09 m) and five women (age 21.2 ± 2.7 years; body mass: 65.8 ± 10.18 kg; body height 1.77 ± 0.08 m) volunteered to participate in the present study. All subjects were NCAA Division II athletes who currently participated in tennis or basketball and all had previous resistance training experience of at least one year. In a counterbalanced design, agility performance during a 10 m shuttle test was assessed following either a dynamic warm-up (DW) or heavy resistance warm-up (HRW) protocol. The HRW protocol consisted of three sets of squats at 50, 60, and 90% of 1-RM. Agility performance was captured using an eight camera motion analysis system and the mechanical variables of stride length, stride frequency, stance time, flight time, average ground reaction force, as well as agility time were recorded. No significant differences were reported for the HRW and DW protocols for any of the mechanical variables (p>0.05), although there was a trend towards the HRW protocol producing faster agility times compared to the control protocol (p = 0.074). Based on the trend towards a significant effect, as well as individual results it is possible that HRW protocols could be used as an acute method to improve agility performance in some court-sport athletes.

The purpose of this study was to determine the acute effects of heavy resistance exercise on agility performance in court-sport athletes. Five men (age: 20.6 ± 1.9 years; body mass: 79.36 ± 11.74 kg; body height: 1.93 ± 0.09 m) and five women (age 21.2 ± 2.7 years; body mass: 65.8 ± 10.18 kg; body height 1.77 ± 0.08 m) volunteered to participate in the present study. All subjects were NCAA Division II athletes who currently participated in tennis or basketball and all had previous resistance training experience of at least one year. In a counterbalanced design, agility performance during a 10 m shuttle test was assessed following either a dynamic warm-up (DW) or heavy resistance warm-up (HRW) protocol. The HRW protocol consisted of three sets of squats at 50, 60, and 90% of 1-RM. Agility performance was captured using an eight camera motion analysis system and the mechanical variables of stride length, stride frequency, stance time, flight time, average ground reaction force, as well as agility time were recorded. No significant differences were reported for the HRW and DW protocols for any of the mechanical variables (p>0.05), although there was a trend towards the HRW protocol producing faster agility times compared to the control protocol (p = 0.074). Based on the trend towards a significant effect, as well as individual results it is possible that HRW protocols could be used as an acute method to improve agility performance in some court-sport athletes.

No description available.

Submitted by Geandra Rodrigues (geandrar@gmail.com) on 2018-08-23T11:00:21Z No. of bitstreams: 1 giseleoliveirasantospires.pdf: 612429 bytes, checksum: 645905e744fd2a58ac4b8da2c3ffe2b2 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2018-08-28T12:36:45Z (GMT) No. of bitstreams: 1 giseleoliveirasantospires.pdf: 612429 bytes, checksum: 645905e744fd2a58ac4b8da2c3ffe2b2 (MD5) / Made available in DSpace on 2018-08-28T12:36:45Z (GMT). No. of bitstreams: 1 giseleoliveirasantospires.pdf: 612429 bytes, checksum: 645905e744fd2a58ac4b8da2c3ffe2b2 (MD5) Previous issue date: 2018-07-20 / Introdução - A esteira é um instrumento apropriado para fornecer uma tarefa de desempenho padronizado e confiável. Embora por tempos, as esteiras tenham sido usadas, principalmente, para pesquisas, atualmente são muito comuns em academias de ginástica e vêm, ao longo do tempo, ganhando popularidade no treinamento de resistência. A distância percorrida por cada passo durante a caminhada ou corrida é chamada amplitude de passos e o número de passos dados em um determinado período é a frequência. Desse modo, a velocidade é determinada pelo produto da frequência pela amplitude de passos. A cinemática é uma área da biomecânica que permite o cálculo da posição, do deslocamento, da velocidade e da aceleração do corpo ou de seus segmentos, tendo como principal foco a descrição de como um corpo se move. Os parâmetros cinemáticos para análise da velocidade da corrida incluem o comprimento e a frequência do passo e da passada, bem como todas as variáveis espaço-temporais derivadas dessas. Não são recentes as investigações que pretendem tecer um paralelo entre deslocamento em piso fixo e esteira, porém seus resultados são inconsistentes. Esta inconsistência parece estar relacionada com as diferenças metodológicas, na aptidão física dos voluntários, velocidades estabelecidas nos protocolos de teste e com os métodos para determinar essas velocidades de corrida em cada estudo. Objetivo – Analisar se as variáveis frequência e amplitude de passos comportam-se de maneira pariforme ao se comparar a corrida na pista com a corrida na esteira; havendo diferenças, verificar se essas seriam imutáveis ou se o indivíduo é capaz de escolher com que combinação de frequência e amplitude quer correr e, ainda, verificar se essas seriam aleatórias ou determinadas por alguma das variáveis que caracterizaram a amostra. Métodos - 22 corredores participaram do estudo, VO2max 59,8 ± 5,53; VMA 17,4 ± 1,59; idade 33,7 ± 10,84; estatura 1,76 ± 0,07; massa corporal 69,18 ± 9,31. Foram realizados 3 testes, teste máximo, na pista e na esteira, nessa ordem para todos os voluntários. Resultados - Para os percentuais 100 e 120 da VMA foram encontrados valores reduzidos de amplitude e aumentados de frequência na esteira em relação à pista. Ainda, podemos predizer que corredores bem treinados conseguem realizar corridas com menores diferenças entre esteira e pista, sobretudo a 120% da VMA. Conclusão - As variáveis frequência e amplitude de passos comportam-se de maneira pariforme ao se comparar a corrida na pista com a esteira nos percentuais 60 e 80 da VMA, para 100 e 120% a amplitude de passos é maior e a frequência menor na esteira em comparação ao solo para uma mesma velocidade. Essas diferenças não são imutáveis, os corredores são capazes de escolher com que combinação de amplitude e frequência de passos desejam correr. Ainda, as diferençaspodem ser determinadas, principalmente nos 120% da VMA, pelo nível de condicionamento dos corredores. / Introduction - A treadmill is an appropriate instrument to provide a standardized and reliable performance task. Although it had been used mostly for research, currently it has been widely used at gyms and has gained popularity at endurance training. The distance between strides during the walk or the run is called stride length, and the number of strides during a certain period of time is the frequency. This way, the speed is determined by stride length times stride frequency. The kinematics is a biomechanics subject that allows to measure the position, displacement, speed, and acceleration of the body or its segments. The kinematic major focus is to describe how the body moves. The kinematic parameters for speed analysis include stride and pace frequency and length as well as all space-time variables and all their variations. The researches which tried to draw a comparison between track and treadmill run are inconsistent nor even recent. This inconsistency seems to be related to the differences among methodology, endurance capacity of volunteers, speed at test protocols, and methods to estimate this speed in each study. Objective - To analyse if stride length and stride frequency behave similarly by comparing a track and a treadmill run. And if there are differences, the purpose is to check if they are unchangeable or if the subject is able to choose which frequency and amplitude they want to run and also to verify if they are randomized or pre-determinate by some peculiarity of the sample. Methods - 22 runners participated of this study with VO2max 59,8 ± 5,53, MAS 17,4 ± 1,59, age 33,7 ± 10,84, body mass 69,18 ± 9,31. Three tests were conducted in this order: maximal test, treadmill and track tests for all volunteers. Results - For a 100% and 120% MAS a decreased value of stride length and an increased value of stride frequency were found at treadmill compared to track. We believe runners prefer to run this way, because they run differently when they receive verbal stimulus to change the technique. We can also predict that well-trained runners manage to run at lower differences between treadmill and track, specially at 120 % of MAS. Conclusion - For stride length and stride frequency, no difference was found at 60% and 80% of MAS, but at 100% and 120%, stride length is higher and stride frequency lower at treadmill compared to track at same speed. These differences are not unchangeable; runners are capable of choosing which combination of stride length and stride frequency they prefer to run. Besides, the differences may be determined, mostly at 120% of MAS by the fitness level of the runners.

Orientador: Mauro Gonçalves / Banca: Júlio Cerca Serrão / Banca: Camila Coelho Greco / Resumo: O presente estudo teve como objetivo verificar se as intensidades do LFEMG e do ponto de quebra são semelhantes e se há diferença no valor do índice, calculando-se o RMS em intervalos referentes a cinco segundos ou ao ciclo de passada e estudar o comportamento da freqüência de passada (FP), amplitude (RMS) e freqüência da atividade eletromiográfica nos período pré (RMS-PRE, FM-PRE) e pós contato (RMS-PRE, FM-POS) dos músculos íleocostal (IC), reto femoral (RF), vasto lateral (VL), vasto medial (VM), bíceps femoral (BF), tibial anterior (TA) e gastrocnêmio lateral (GL), bem como da co-ativação dos músculos RF/BF, VL/BF, VM/BF e GL/TA nos períodos pré (PRE) e póscontato (POS) ao longo de um teste incremental, considerando as intensidades absolutas e quatro intensidades relativas: inicial (IIN), equivalente ao LFEMG (ILF), 15% abaixo (IAB) e 15% acima (IAC) do LFEMG. Onze voluntários foram submetidos a um teste incremental de corrida até exaustão voluntária. Os valores de RMS foram obtidos de duas formas, a cada cinco segundos do intervalo de corrida e a cada ciclo de passada. O LFEMG e o ponto de quebra foram determinados. Não houve diferenças significantes entre os valores dos índices obtidos pelas duas formas de análise nem entre os músculos. Entretanto, foi evidenciado que os valores de LFEMG foram maiores do que os do ponto de quebra apenas quando determinados pelos valores de RMS obtidos nos ciclos de passada. As velocidades relativas obtidas foram 9,2±0,4 km.h-1 na IAB, 10,6±0,7 km.h-1 na LFEMG e 12,3±0,5 km.h-1 na IAC. A partir dos 11 km.h-1 a FP, a RMS-PRE para o músculo IC e a RMS-POS para os músculos VL e VM apresentaram aumento. Nas intensidades relativas, houve aumento dos valores da FP, da RMS-PRE para os músculos BF, TA e GL, da RMS-POS e FM-POS para o músculo GL a partir da ILF. As correlações foram significantes para FP e FM-PRE do VL... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The aim of the present study was to verify whether eletromyographic fatigue threshold (EMGFT) and breakpoint intensities were similar and whether there is differences in the speed value between these indexes when calculated considering five seconds intervals or referent to stride cycle and study stride frequency (SF), amplitude and frequency of electromyographic activity behaviors on pre (PRE) and post (POS) contact periods for iliocostalis (IC), rectus femoris (RF), vastus lateralis (VL), vastus medialis (VM), biceps femoris (BF), tibialis anterior (TA) and gastrocnemius lateralis (GL), and co-activation ratio of RF/BF, VL/BF, VM/BF and GL/TA on PRE and POST periods during an incremental running protocol, considering absolute intensities and four relative intensities: initiail (IIN), equivalent to EMGFT (IFT), 15% below (IBE) and 15% above (IAB) EMGFT. Eleven males performed an incremental running test to exhaustion. RMS values were obtained every five seconds and during stride cycles of each running stage. EMGFT and breakpoint were determined for all muscles. There were no significant differences between two different indexes when calcula values obtained RMS calculation nor among different muscles. However, the EMGFT values were greater than breakpoint values when determined using RMS calculated for stride cycles, with no difference when obtained every five seconds. Relative intensities obtained were 9.2±0.4 km... (Complete abstract click electronic access below) / Mestre

Made available in DSpace on 2014-06-11T19:22:52Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-03-11Bitstream added on 2014-06-13T19:28:21Z : No. of bitstreams: 1 silva_pb_me_rcla.pdf: 790741 bytes, checksum: d5249659f04bcedba18543a60ee45546 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O presente estudo teve como objetivo verificar se as intensidades do LFEMG e do ponto de quebra são semelhantes e se há diferença no valor do índice, calculando-se o RMS em intervalos referentes a cinco segundos ou ao ciclo de passada e estudar o comportamento da freqüência de passada (FP), amplitude (RMS) e freqüência da atividade eletromiográfica nos período pré (RMS-PRE, FM-PRE) e pós contato (RMS-PRE, FM-POS) dos músculos íleocostal (IC), reto femoral (RF), vasto lateral (VL), vasto medial (VM), bíceps femoral (BF), tibial anterior (TA) e gastrocnêmio lateral (GL), bem como da co-ativação dos músculos RF/BF, VL/BF, VM/BF e GL/TA nos períodos pré (PRE) e póscontato (POS) ao longo de um teste incremental, considerando as intensidades absolutas e quatro intensidades relativas: inicial (IIN), equivalente ao LFEMG (ILF), 15% abaixo (IAB) e 15% acima (IAC) do LFEMG. Onze voluntários foram submetidos a um teste incremental de corrida até exaustão voluntária. Os valores de RMS foram obtidos de duas formas, a cada cinco segundos do intervalo de corrida e a cada ciclo de passada. O LFEMG e o ponto de quebra foram determinados. Não houve diferenças significantes entre os valores dos índices obtidos pelas duas formas de análise nem entre os músculos. Entretanto, foi evidenciado que os valores de LFEMG foram maiores do que os do ponto de quebra apenas quando determinados pelos valores de RMS obtidos nos ciclos de passada. As velocidades relativas obtidas foram 9,2±0,4 km.h-1 na IAB, 10,6±0,7 km.h-1 na LFEMG e 12,3±0,5 km.h-1 na IAC. A partir dos 11 km.h-1 a FP, a RMS-PRE para o músculo IC e a RMS-POS para os músculos VL e VM apresentaram aumento. Nas intensidades relativas, houve aumento dos valores da FP, da RMS-PRE para os músculos BF, TA e GL, da RMS-POS e FM-POS para o músculo GL a partir da ILF. As correlações foram significantes para FP e FM-PRE do VL... / The aim of the present study was to verify whether eletromyographic fatigue threshold (EMGFT) and breakpoint intensities were similar and whether there is differences in the speed value between these indexes when calculated considering five seconds intervals or referent to stride cycle and study stride frequency (SF), amplitude and frequency of electromyographic activity behaviors on pre (PRE) and post (POS) contact periods for iliocostalis (IC), rectus femoris (RF), vastus lateralis (VL), vastus medialis (VM), biceps femoris (BF), tibialis anterior (TA) and gastrocnemius lateralis (GL), and co-activation ratio of RF/BF, VL/BF, VM/BF and GL/TA on PRE and POST periods during an incremental running protocol, considering absolute intensities and four relative intensities: initiail (IIN), equivalent to EMGFT (IFT), 15% below (IBE) and 15% above (IAB) EMGFT. Eleven males performed an incremental running test to exhaustion. RMS values were obtained every five seconds and during stride cycles of each running stage. EMGFT and breakpoint were determined for all muscles. There were no significant differences between two different indexes when calcula values obtained RMS calculation nor among different muscles. However, the EMGFT values were greater than breakpoint values when determined using RMS calculated for stride cycles, with no difference when obtained every five seconds. Relative intensities obtained were 9.2±0.4 km... (Complete abstract click electronic access below)