Inertial measurement units (IMUs) and wearable sensors have enabled athlete monitoring and research to become more ecologically valid due to their small size and low cost. IMUs and accelerometers that are placed on the body close to the point of impact and that record at sufficiently high frequencies have demonstrated the highest validity when measuring temporal gait event moments such as ground contact time (GCT) and flight time (FT) as well as peak forces (PF) during upright running. While the use of IMUs has increased in the sport performance and athlete monitoring realm, the potential of the technology’s ability to estimate running force-time curves utilizing the two-mass model (TMM) remains unexplored. The purpose of this study was two-fold. First, was to determine the validity of measuring temporal gait events and peak forces utilizing a commercially available shank-mounted inertial measurement unit. Second, was to determine the validity of force-time curves generated from the TMM utilizing data from shank-mounted inertial measurement units. Ten subjects voluntarily completed submaximal treadmill tests equipped with a force plate while wearing shank-mounted IMUs on each leg. Using the raw data from the IMUs, GCT, FT, total step time (ST), PF, and two-mass model-based force-time (F-t) curves were generated for 25 steps at 8 different speeds. Paired sample T-tests were performed on the gait events and peak force between the IMU and treadmill with both individual step comparison and averages per each speed. 95% confidence intervals were calculated for each timepoint of the force time curves. No statistically significant differences (p > 0.05) and nearly perfect relationships were observed for the step averages for each speed with FT, ST, and PF. Confidence intervals of the corrected mean difference suggest that F-t curves calculated from the TMM may not be valid when assessing the running population as a whole. When performing a sub-group analysis of skilled runners and recreational runners, F-t curves derived from shank-mounted IMUs may be more valid in skilled runners than recreational runners. In skilled runners, the 95% CI for the mean difference contained zero within the first 60% of the GCT duration, whereas the 95% CI recreational runners contained a zero-value in a smaller percentage of the GCT located only in the middle of the GCT at the curve peak height. The results of this study suggest that interchangeability between shank-mounted IMUs and force plates may be very limited when estimating temporal gait events and kinetics. While agreement was low between F-t curves after the peak in skilled runners, use of shank-mounted IMUs to estimate F-t curves may have several benefits still in skilled runners when assessing peak forces and force development from initial contact until peak force.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-10-04T11:31:20Z No. of bitstreams: 1 guillibercarlosdafonseca.pdf: 2026851 bytes, checksum: 6ccb372126c69004827ea484ee727b78 (MD5) / Approved for entry into archive by Diamantino Mayra (mayra.diamantino@ufjf.edu.br) on 2016-10-04T12:39:27Z (GMT) No. of bitstreams: 1 guillibercarlosdafonseca.pdf: 2026851 bytes, checksum: 6ccb372126c69004827ea484ee727b78 (MD5) / Made available in DSpace on 2016-10-04T12:39:27Z (GMT). No. of bitstreams: 1 guillibercarlosdafonseca.pdf: 2026851 bytes, checksum: 6ccb372126c69004827ea484ee727b78 (MD5) Previous issue date: 2010-03-25 / A Doença Renal Crônica (DRC) é caracterizada pela perda da capacidade de filtragem dos rins. O paciente com DRC tem diminuição dos níveis de força muscular e de condicionamento físico, os quais estão diretamente ligados à qualidade de vida e à realização das atividades da vida diária. A atividade física, especificamente o treinamento de força, pode ser utilizada como uma intervenção não farmacológica para o tratamento da doença. Para a realização desse tipo de programa há a necessidade da identificação do volume e intensidade do treinamento neuromuscular, através de testes de carga. No entanto, a aplicação dos testes de carga dinâmica máxima (uma repetição máxima ou de peso por repetição) não é adequada para pacientes com DRC em razão do seu baixo nível de força muscular. Antes de se definir qual o melhor teste para avaliação da carga de treinamento, é necessário, primeiramente, identificar as características da produção da força muscular nesses pacientes. Para tanto, os testes de esforço muscular isométrico parecem ser ideais para isso, em específico o da dinamometria computadorizada de preensão da mão que, além de fácil aplicação, possibilita a avaliação do comportamento da contração muscular através da análise da curva força-tempo. Neste estudo propõe-se uma técnica para análise das curvas, em sua fase de produção de força (fase rápida) através do ajuste, por quadrados mínimos, de um modelo matemático com quatro parâmetros (a,b,c,d). A amostra foi composta de 31 pacientes com DRC (51±15 anos, 69,94±13,34 kg e 1,65±0,08 m) e 4 sujeitos hipertensos (37 ± 14 anos, 75,1 ± 16,5 kg e 1,72 ± 0,12 m), como controle. Foram utilizados os dinamômetros JAMAR (referência) e o transdutor de preensão manual computadorizado, com empunhadura modificada. Não foram observadas diferenças significativas entre os valores de força máxima dos membros dominante e não dominante, e dos parâmetros b (p = 0,18), c (p = 0,35) e d (p = 0,05). Somente os valores da pré-carga (p < 0,001) e do parâmetro a (p < 0,001) foram significativamente diferentes, o que significa dizer que o paciente com DRC inicia o teste com força inicial maior do que o grupo controle e atinge mais lentamente o valor máximo de força. Novas pesquisas baseadas em diferentes protocolos de 6 testes de esforço muscular isométrico poderão confirmar as ações específicas das unidades motoras de contração lenta e rápida em cada fase da curva força-tempo. / The chronic kidney disease (CKD) is characterized by lost in kidney filtration capacity. These patients with CKD have decreased levels of muscle strength, physical functioning, which is connected with daily activities and quality of life. The physical activity can be employed as a non pharmacologic procedure, but to programming a physical training is necessary evaluated the features to be work. The standard of evaluations must be observed to ensure pureness of datum collected. The evaluation of strength-time curve can be one methodology used to clarify the muscle contraction behavior. So, we proposed a methodology of curve analysis of patients with CKD, using non linear and linear mathematic parameter mode, which when evaluated allow us make correspondence with muscle contraction physiology. The sample was determined by 31 patients (51±15 years old, 69,94±13,34 kg e 1,65±0,08 meters) with CKD and 4 individuals with high blood pressure (37 ± 14 years old, 75,1 ± 16,5 kg e 1,72 ± 0,12 meters), they were evaluated by handgrip test in 2 moments with 2 different dynamometers. Significative differences were not observe between values of maximal strength, between members and parameters [b] (p=0,18), [c] (p=0,35) e [d] (p=0,05). Merely the values of preload (p = 0,00000014),, of [a] parameter (p=0,00078), and the values of patients strength between dynamometers were significant different: right (p = 0,00003) and left (p = 0,0001). Using the parameters of strength-time curve become a methodology with good price, non-invasive and could be applied easily in the evaluations. The necessity of new instigations employed the analysis methods is evident.