The purpose of this study was to examine changes in muscle architecture and jumping performance in NCAA division I women's volleyball players throughout a competitive season and in preparation for conference championships. Ten women volleyball players were tested at preseason (T1), pretaper (T2), and post-taper (T3) on measures of vastus lateralis muscle thickness (MT), pennation angle (PA) and fascicle length (FL) using ultrasonography, and unloaded and loaded squat jump height (SJH) and peak power allometrically scaled to body mass (SJPPa) on a force platform. Rating of perceived exertion training load and strength training volume load were monitored weekly. Player's MT (p < 0.001, Glass's Δ = 2.8) and PA increased (p = 0.02, Δ = 3.9) after in-season training. However, MT decreased after the taper (p = 0.01, Δ = 0.6) but remained elevated above preseason values (p < 0.001, Δ = 1.7). There were no statistical changes in FL, SJH, or SJPPa. Large-to-very large negative relationships (r = −0.51 to −0.81) were observed between preseason relative maximal strength and changes in SJH and SJPPa with various loads over the season. These findings demonstrate that relatively low volumes of strength training and concurrent sport training during a tapering period are capable of preserving jumping performance, but not MT in women's volleyball players; however, jumping performance changes seem to be related to the player's strength level. Stronger players may benefit from an overreaching microcycle before the taper to preserve previously accrued muscular adaptations and jumping performance.

Background: Muscle thickness, pennation angle, and fascicle length describe the architecture of a muscle. These properties can be observed alongside subcutaneous fat thickness using ultrasonography; however, measurement is sensitive to the angle of the transducer against the skin. Typically, the transducer is held perpendicular to skin for imaging. Nonetheless, a convenient, reliable method to ensure transducer angle consistency has not been reported. Objectives: The purpose of this study was to determine the influence of transducer angle on muscle architecture and subcutaneous fat measurements of quadriceps muscles (vastus lateralis and rectus femoris) in healthy young adults. A secondary objective was to determine intra- and inter-rater reliability. Methods: Thirty men and women were recruited (25±2.5 years; BMI: 22.6±3.0 kg/m2). Ultrasound images were acquired from two muscles. An image was taken at an estimated perpendicular angle to the skin. Then, using a 3D-printed device with a protractor that attached to the ultrasound transducer, images were taken at measured angles 5-10˚ medial and lateral to perpendicular. Agreement and error were determined using intraclass correlation coefficients (ICCs) and standard error measurements (SEMs). Results: Good to excellent agreement was demonstrated for muscle and fat thicknesses regardless of transducer angle (ICC >0.66). Intra-rater reliability was excellent for all outcomes within both muscles (ICC >0.89). Inter-rater reliability for the rectus femoris was good to excellent for all transducer angles except for measurements of fascicle lengths at 85° (ICC: 0.33–0.99). Inter-rater reliability improved >20% for the vastus lateralis with the device. Conclusion: Measurements of muscle pennation angle and fascicle lengths, but not muscle or subcutaneous fat thicknesses, were sensitive to transducer angle. Reliability of pennation angle and fascicle lengths improved with the use of our device. Using our device, reliable muscle architecture measures can be made for the rectus femoris and the vastus lateralis in healthy young adults. / Thesis / Master of Science (MSc) / The arrangement of small muscle components, known as fascicles, can be observed in humans using ultrasound imaging. These fascicle arrangements can be measured to improve understanding of muscle function and disease processes. A potential problem of viewing muscle with ultrasound is that the angle of the probe head against the skin can alter the appearance of the muscle fascicles. The goal of this research was to improve current methods of ultrasound imaging of two thigh muscles. We have created a novel 3D-printed device to attach to the existing ultrasound probe. This 3D-printed device stabilizes the ultrasound probe head; and accurately determines the angles between the ultrasound probe head and the surface of the skin. In this study, the use of this device improved reliability of our ultrasound images by >20%. Future use of this device may improve measurements of muscle fascicles acquired with ultrasound imaging.

A estratégia de corrida utilizada durante uma prova de média e longa duração é dependente de fatores fisiológicos e psicológicos, sendo esses expressos de maneira integrada e consciente pela percepção subjetiva de esforço (PSE) e pelas sensações afetivas. A economia de corrida (EC) tem sido apontada por ter uma importante participação nos ajustes da estratégia de prova. Nesse sentido, a melhora na EC poderia alterar a PSE e o afeto durante a corrida e consequentemente a estratégia utilizada pelo atleta. Uma vez que o treinamento pliométrico tem sido demonstrado por melhorar a EC em corredores, o presente estudo teve como objetivo verificar se as mudanças na EC induzidas pelo treinamento pliométrico poderiam alterar a estratégia de prova em corrida de 10km contrarrelógio. Concluíram o estudo 28 corredores divididos em dois grupos, controle (C, n = 13) e treinamento pliométrico (TP, n=15). Ambos os grupos mantiveram suas rotinas de treinamento, porém o grupo TP realizou duas sessões semanais de treinamento pliométrico, durante oito semanas. Foram avaliados antes e após o tratamento experimental: o desempenho, a estratégia de prova, a PSE e o afeto durante uma corrida de 10km contrarrelógio; a altura, o tempo de contato com o solo e o índice de força reativa durante o salto em profundidade (SP) e a distância nos cinco saltos horizontais; a economia de corrida a 10km/h (EC10) e 12km/h (EC12) e o VO2 na velocidade média da prova (VM10); o VO2máx, o pico de velocidade na esteira (PV) e a velocidade do VO2max (vVO2máx) em um teste máximo; a força dinâmica máxima no teste de 1RM no leg-press 45º e a contração voluntária isométrica máxima no dinamômetro isocinético; o stiffness do tendão patelar, a espessura dos tendões patelar e calcâneo e a arquitetura muscular do vasto lateral e do gastrocnêmico. Os principais resultados mostram que o treinamento pliométrico melhorou a EC10 em 3,6% (p = 0,05) e a EC12 em 4,9% (p = 0,01). No entanto, não alterou a PSE, o afeto ou o padrão estratégia de prova utilizada durante a corrida. Entretanto, quando apenas os atletas responsivos ao TP (EC >3,5%, n = 11) foram avaliados, observamos maior velocidade média durante a segunda metade da corrida e melhor desempenho (1,6%, p = 0,01). O treinamento pliométrico melhorou a altura do SP (7,2%, p = 0,004), o VO2máx (3,4%, p = 0,03) e o PV (1,6%, p = 0,02). Foi observada maior espessura do tendão patelar na região distal (10,1%, p = 0,05) e menor ângulo de penação no músculo gastrocnêmio (-11,1%, p = 0,04). Em conclusão, a melhora na EC induzida pelo treinamento pliométrico não alterou o padrão de estratégia de prova utilizada durante uma corrida de 10km contrarrelógio. No entanto, permitiu que o atleta mantivesse maiores velocidades durante a segunda metade da prova. Os efeitos do treinamento pliométrico sobre a EC podem ter sido induzidos pela melhora na utilização do ciclo alongamento-encurtamento decorrente da redução no ângulo de penação dos fascículos no músculo gastrocnêmio / During middle and long distance races the pacing strategy is dependent on physiological and psychological factors which are expressed in a conscious way by the RPE and the affective feelings. The running economy (RE) has been suggested to be an important factor in the pacing strategy control. Improvements in RE may change the RPE and affective feeling during running which could change the pattern of the pacing strategy. Since the plyometric training has been shown to be an effective method to improve the RE, the aim of this study was to verify if the improvement of RE after a plyometric training program could change the pacing strategy during 10-km time-trial running. Twenty eight runners were divided into two groups, control (C, n=13) and plyometric training (TP, n=15). All of the athletes maintained their running training routines; however, the PT performed two sessions/week of plyometric training during eight weeks. Performance, pacing strategy, RPE and affective feelings during the 10-km time-trial running; the jump high, time of ground contact and reactive strength index in drop-jump and the distance of horizontal five bounds; RE to 10km/h (RE10) and 12km/h (RE12) and the VO2 to 10-km running average speed (VM10); VO2max, peak of velocity (PV) and velocity of VO2max (vVO2max) in a treadmill progressive maximal test; one repetition maximum strength in a 45º leg-press and the maximum voluntary isometric contraction (CVIM) in a isokinetic dynamometry; patellar tendon stiffness, patellar and calcaneus tendon thickness and muscle architecture of vastus lateralis and gastrocnemius muscles were analyzed pre and post experimental treatment. The main results showed that the plyometric training improved the RE10 (3.6%; p = 0.05) and RE12 (4.9%; p = 0.01). Nevertheless, it did not change the RPE, affective feelings or pacing strategy during the 10-km running. When just the responsive athletes (EC >3.5%, n = 11) were analyzed we observed higher average speed during the second part of the running and better performance (1.6%, p = 0.01). Drop-jump performance (7.2%, p = 0.004), VO2max (3.4%, p=0.03) and PV (1.6%, p=0.02) were also improved. It was observed increased of distal patellar tendon thickness (10.1%, p = 0.05) and a lower pennation angle in the gastrocnemius muscle (-11,1%, p = 0,04). In conclusion, the RE improvement did not change the pacing strategy during a 10-km time-trial running. However, the athletes were able to maintain higher speeds during the second part of the running and improve their performance. The effects of plyometric training on RE seems to be associated to stretch-shortening cycle improvement induced by changes in pennation angle of the gastrocnemius muscle

A estratégia de corrida utilizada durante uma prova de média e longa duração é dependente de fatores fisiológicos e psicológicos, sendo esses expressos de maneira integrada e consciente pela percepção subjetiva de esforço (PSE) e pelas sensações afetivas. A economia de corrida (EC) tem sido apontada por ter uma importante participação nos ajustes da estratégia de prova. Nesse sentido, a melhora na EC poderia alterar a PSE e o afeto durante a corrida e consequentemente a estratégia utilizada pelo atleta. Uma vez que o treinamento pliométrico tem sido demonstrado por melhorar a EC em corredores, o presente estudo teve como objetivo verificar se as mudanças na EC induzidas pelo treinamento pliométrico poderiam alterar a estratégia de prova em corrida de 10km contrarrelógio. Concluíram o estudo 28 corredores divididos em dois grupos, controle (C, n = 13) e treinamento pliométrico (TP, n=15). Ambos os grupos mantiveram suas rotinas de treinamento, porém o grupo TP realizou duas sessões semanais de treinamento pliométrico, durante oito semanas. Foram avaliados antes e após o tratamento experimental: o desempenho, a estratégia de prova, a PSE e o afeto durante uma corrida de 10km contrarrelógio; a altura, o tempo de contato com o solo e o índice de força reativa durante o salto em profundidade (SP) e a distância nos cinco saltos horizontais; a economia de corrida a 10km/h (EC10) e 12km/h (EC12) e o VO2 na velocidade média da prova (VM10); o VO2máx, o pico de velocidade na esteira (PV) e a velocidade do VO2max (vVO2máx) em um teste máximo; a força dinâmica máxima no teste de 1RM no leg-press 45º e a contração voluntária isométrica máxima no dinamômetro isocinético; o stiffness do tendão patelar, a espessura dos tendões patelar e calcâneo e a arquitetura muscular do vasto lateral e do gastrocnêmico. Os principais resultados mostram que o treinamento pliométrico melhorou a EC10 em 3,6% (p = 0,05) e a EC12 em 4,9% (p = 0,01). No entanto, não alterou a PSE, o afeto ou o padrão estratégia de prova utilizada durante a corrida. Entretanto, quando apenas os atletas responsivos ao TP (EC >3,5%, n = 11) foram avaliados, observamos maior velocidade média durante a segunda metade da corrida e melhor desempenho (1,6%, p = 0,01). O treinamento pliométrico melhorou a altura do SP (7,2%, p = 0,004), o VO2máx (3,4%, p = 0,03) e o PV (1,6%, p = 0,02). Foi observada maior espessura do tendão patelar na região distal (10,1%, p = 0,05) e menor ângulo de penação no músculo gastrocnêmio (-11,1%, p = 0,04). Em conclusão, a melhora na EC induzida pelo treinamento pliométrico não alterou o padrão de estratégia de prova utilizada durante uma corrida de 10km contrarrelógio. No entanto, permitiu que o atleta mantivesse maiores velocidades durante a segunda metade da prova. Os efeitos do treinamento pliométrico sobre a EC podem ter sido induzidos pela melhora na utilização do ciclo alongamento-encurtamento decorrente da redução no ângulo de penação dos fascículos no músculo gastrocnêmio / During middle and long distance races the pacing strategy is dependent on physiological and psychological factors which are expressed in a conscious way by the RPE and the affective feelings. The running economy (RE) has been suggested to be an important factor in the pacing strategy control. Improvements in RE may change the RPE and affective feeling during running which could change the pattern of the pacing strategy. Since the plyometric training has been shown to be an effective method to improve the RE, the aim of this study was to verify if the improvement of RE after a plyometric training program could change the pacing strategy during 10-km time-trial running. Twenty eight runners were divided into two groups, control (C, n=13) and plyometric training (TP, n=15). All of the athletes maintained their running training routines; however, the PT performed two sessions/week of plyometric training during eight weeks. Performance, pacing strategy, RPE and affective feelings during the 10-km time-trial running; the jump high, time of ground contact and reactive strength index in drop-jump and the distance of horizontal five bounds; RE to 10km/h (RE10) and 12km/h (RE12) and the VO2 to 10-km running average speed (VM10); VO2max, peak of velocity (PV) and velocity of VO2max (vVO2max) in a treadmill progressive maximal test; one repetition maximum strength in a 45º leg-press and the maximum voluntary isometric contraction (CVIM) in a isokinetic dynamometry; patellar tendon stiffness, patellar and calcaneus tendon thickness and muscle architecture of vastus lateralis and gastrocnemius muscles were analyzed pre and post experimental treatment. The main results showed that the plyometric training improved the RE10 (3.6%; p = 0.05) and RE12 (4.9%; p = 0.01). Nevertheless, it did not change the RPE, affective feelings or pacing strategy during the 10-km running. When just the responsive athletes (EC >3.5%, n = 11) were analyzed we observed higher average speed during the second part of the running and better performance (1.6%, p = 0.01). Drop-jump performance (7.2%, p = 0.004), VO2max (3.4%, p=0.03) and PV (1.6%, p=0.02) were also improved. It was observed increased of distal patellar tendon thickness (10.1%, p = 0.05) and a lower pennation angle in the gastrocnemius muscle (-11,1%, p = 0,04). In conclusion, the RE improvement did not change the pacing strategy during a 10-km time-trial running. However, the athletes were able to maintain higher speeds during the second part of the running and improve their performance. The effects of plyometric training on RE seems to be associated to stretch-shortening cycle improvement induced by changes in pennation angle of the gastrocnemius muscle

During muscle contraction, electrical signals are generated by the muscle cells. The analysis of those signals is called electromyography (EMG). The EMG signal is mainly determined by physiological factors including so called central factors (central nervous system origin) and peripheral factors (muscle tissue origin). In addition, during the acquisition of EMG signals, technical factors are introduced (measurement equipment origin). The aim of this dissertation was to develop and evaluate methods to estimate physiological properties of the muscles using multichannel surface EMG (MCsEMG) signals. In order to obtain accurate physiological estimates, a method for automatic signal quality estimation was developed. The method’s performance was evaluated using visually classified signals, and the results demonstrated high classification accuracy. A method for estimation of the muscle fibre conduction velocity (MFCV) and the muscle fibre orientation (MFO) was developed. The method was evaluated with synthetic signals and demonstrated high estimation precision at low contraction levels. In order to discriminate between the estimates of MFCV and MFO belonging to single or populations of motor units (MUs), density regions of so called spatial distributions were examined. This method was applied in a study of the trapezius muscle and demonstrated spatial separation of MFCV (as well as MFO) even at high contraction levels. In addition, a method for quantification of MU synchronisation was developed. The performance on synthetic sEMG signals showed high sensitivity on MU synchronisation and robustness to changes in MFCV. The method was applied in a study of the biceps brachii muscle and the relation to force tremor during fatigue. The results showed that MU synchronisation accounted for about 40 % of the force tremor. In conclusion, new sEMG methods were developed to study muscle function and motor control in terms of muscle architecture, muscle fibre characteristics, and processes within the central nervous system.

The purposes of the present study were to resolve a number of major inconsistencies found in the literature on the structure of the quadriceps femoris muscle and to extend knowledge of its structure using descriptive, qualitative methodology. The quadriceps femoris muscle was investigated in 41 cats, and the findings were confirmed in 6 human cadavers. Two aponeuroses with major biomechanical functions (rectus-vastus and vastus aponeurosis), neither of which had been previously described in the literature, were characterized in both species. The study also resolved many major inconsistencies in the literature: The muscle sometimes described as vastus intermedius (VI) was found to be the articularis genu, the muscle sometimes described as vastus medialis (VM) was found to be the VI, the rectus femoris head was found to have an additional proximal nerve branch not previously recognized, no anomalous 5th head was ever found, and the distal VM were not found to have 2 heads (in either cats or humans). The authors’ anatomical descriptions and bimechanical models of the muscles, tendons, and neurovascular should provide a helpful foundation for future studies on the quadriceps. Two general recommendations are made: 1) that the feline model be considered a viable model to elucidate human knee pathomechanics; and 2) that regardless of the anatomical structure of interest, orthopedic nurses, orthopedic surgeons, and research investigators should routinely use the research literature for anatomical guidance instead of standard anatomical textbooks. © 2002, Sage Publications. All rights reserved.

Physiological cross sectional area (PCSA) is used to compare force-producing capabilities of skeletal muscles. PCSA has been defined as the summation of the cross sectional area of the fiber bundles composing the muscle. As PCSA cannot be measured directly from a specimen, a formula requiring averaged muscle architectural parameters has traditionally been used. The purpose of this study was to develop a finite element method (FEM) to calculate PCSA of extensor carpi radialis longus (ECRL) and brevis (ECRB) directly from digitized fiber bundle data obtained throughout the volume of the muscle and to compare the PCSAs calculated using the FEM and formula methods. Differences were found between the FEM and formula method for both muscles. The FEM provides an approach that takes into account architectural variances while minimizing the need for averaged architectural parameters.

Physiological cross sectional area (PCSA) is used to compare force-producing capabilities of skeletal muscles. PCSA has been defined as the summation of the cross sectional area of the fiber bundles composing the muscle. As PCSA cannot be measured directly from a specimen, a formula requiring averaged muscle architectural parameters has traditionally been used. The purpose of this study was to develop a finite element method (FEM) to calculate PCSA of extensor carpi radialis longus (ECRL) and brevis (ECRB) directly from digitized fiber bundle data obtained throughout the volume of the muscle and to compare the PCSAs calculated using the FEM and formula methods. Differences were found between the FEM and formula method for both muscles. The FEM provides an approach that takes into account architectural variances while minimizing the need for averaged architectural parameters.

Körperliche Aktivität während der Schwangerschaft wirkt sich positiv auf die Gesundheit von Mutter und Kind aus. Trotzdem werden Schwangere häufig gewarnt, sich aufgrund der abnehmenden Muskelkraft, den nachgiebigeren Bändern und Sehnen sowie der verschlechterten Stabilität beim Sport verletzen zu können. Um Verletzungen während der Schwangerschaft vorbeugen zu können, wird in dieser Arbeit erstmalig der Einfluss von Schwangerschaft auf den Muskel-Sehnen-Komplex der unteren Extremitäten untersucht. Weiterhin werden der Effekt auf das statische Gleichgewicht und der Einsatz eines Schwangerschaftsgurtes als potentielle Präventionsmaßnahme gegen Sturzunfälle überprüft. Zur Untersuchung des Muskel-Sehnen-Komplexes wurde die Morphologie des m. vastus lateralis, die Muskelkraft der Knieextensoren und die Eigenschaften der Patellasehne am Anfang und am Ende der Schwangerschaft sowie ein halbes Jahr nach der Entbindung mittels Ultraschall und Dynamometrie analysiert. Das Gleichgewicht wurde anhand der Grenzen der Stabilität nach anterior und posterior und anhand des Körperschwankens im ruhigen Stand auf einer Kraftmessplatte bei Schwangeren in den unterschiedlichen Schwangerschaftstrimestern und bei Nicht-Schwangeren mit und ohne Schwangerschaftsgurt beurteilt. Diese Arbeit liefert relevante Erkenntnisse, die für die Beurteilung des Verletzungsrisikos von Schwangeren und für die Entwicklung geeigneter präventiver Maßnahmen nützlich sind. Es wurde zum wiederholten Male bestätigt, dass Schwangerschaft zu einer Verschlechterung der posturalen Stabilität führt. Ein Schwangerschaftsgurt stellt jedoch keine geeignete Methode zur Verbesserung der Stabilität dar. Während Muskelmorphologie und Sehnensteifigkeit keinen negativen Einfluss zeigen, könnte die zunehmende Sehnenruhelänge zu einer vergrößerten Gelenkbeweglichkeit beitragen und das Risiko für Verletzungen und Stürze erhöhen. / Physical activity during pregnancy has beneficial effects on maternal and fetal health. However, pregnant women are frequently cautioned when exercising since a loss in muscle strength, an increased compliance of ligaments and tendons as well as impairments in postural stability are assumed to lead to injuries in pregnant women. This thesis investigates for the first time the effect of pregnancy on the muscle-tendon unit of the lower extremities for the prevention of injuries during pregnancy. Furthermore, this thesis analyzes the effect of pregnancy on static postural stability and examines whether a maternity support belt is an appropriate method for fall prevention in pregnant women. To investigate the muscle-tendon unit, the morphology of the vastus lateralis muscle, muscle strength of the knee extensors and the properties of the patellar tendon were analyzed in the early and late stage of pregnancy as well as six months after delivery by means of ultrasound and dynamometry. Balance ability was assessed determining the limits of stability in the anterior and posterior directions and the postural sway during motionless upright standing on a force plate in pregnant women in different trimesters of pregnancy and in non-pregnant women with and without maternity support belt. This thesis provides relevant evidence for the assessment of the risk of injury in pregnant women and the development of appropriate prevention strategies. It confirmed that pregnancy is accompanied by impaired postural stability. However, a maternity support belt is not an appropriate method to improve stability. While muscle morphology and tendon stiffness were not negatively affected during pregnancy, the increase in tendon rest length might contribute to an increased joint mobility that may increase the fall and injury risk.