The research presented in this thesis examined the issue of the compatibility of strength and endurance training within one training regime, termed concurrent training, in recreational cyclists. Various research designs used in the previous literature resulted in inconclusive findings. The overall aim of this thesis was therefore to examine, in three systematically designed studies, the effects of various components of concurrent training regimes on cycling efficiency and recovery, and to identify some of the mechanisms that may be responsible for the interference or impedance of strength and/or endurance adaptations.

The purpose of this study was to investigate the effects of Nordic hamstring strength training (NHST) program on (1) leg power, (2) vertical jump, (3) and knee proprioception measurements of 10-12 years old male basketball players. Nordic Hamstring Strength Training (NHST) group (N=16), participated in basketball training plus in Nordic hamstring strength training, while the control group (N=11) participated in basketball training only. Subjects were tested before and after 5-week training program for, vertical jump, isokinetic leg strength and knee proprioception. Each subject who agreed to participate in this investigation signed a consent form along their parent. Pre and post test differences between experimental and control group was investigated by MANOVA and paired sample t-test was used to evaluate the differences between pre and post tests of both groups. There was no significant difference in pre and post test results of NHST and control group. There were statistically significant increase in concentric quadriceps and hamstring strength, eccentric quadriceps strength, conventional H:Q strength ratio, and vertical jumping measurements in experimental group between the pre and post tests. It can be concluded that NHST program combine with basketball training has beneficial effects on the leg strength and H:Q strength ratio. These findings also suggest that hamstring exercise may be beneficial or helpful for preventing the hamstring injury occurrence and improving the physical performances such as jumping ability.

Neuromuscular explosive strength (defined as rate of force development; RFD) is considered important during explosive functional human movements; however this association has been poorly documented. It is also unclear how different variants of strength training may influence RFD and its neuromuscular determinants. Furthermore, RFD has typically been measured in isometric situations, but how it is influenced by the types of contraction (isometric, concentric, eccentric) is unknown. This thesis compared neuromuscular function in explosive power athletes (athletes) and untrained controls, and assessed the relationship between RFD in isometric squats with sprint and jump performance. The athletes achieved a greater RFD normalised to maximum strength (+74%) during the initial phase of explosive contractions, due to greater agonist activation (+71%) in this time. Furthermore, there were strong correlations (r2 = 0.39) between normalised RFD in the initial phase of explosive squats and sprint performance, and between later phase absolute explosive force and jump height (r2 = 0.37), confirming an association between explosive athletic performance and RFD. This thesis also assessed the differential effects of short-term (4 weeks) training for maximum vs. explosive strength, and whilst the former increased maximum strength (+20%) it had no effect on RFD. In contrast explosive strength training improved explosive force production over short (first 50 ms; +70%) and long (>50 ms; +15%) time periods, due to improved agonist activation (+65%) and maximum strength (+11%), respectively. Explosive strength training therefore appears to have greater functional benefits than maximum strength training. Finally, the influence of contraction type on RFD was assessed, and the results provided unique evidence that explosive concentric contractions are 60% more effective at utilising the available force capacity of the muscle, that was explained by superior agonist activation. This work provides a comprehensive analysis of the association between athletic performance and RFD, the differential effects of maximum vs. explosive strength training, and the influence of contraction type on the capacity for RFD.

Swallowing is a complex sensorimotor behaviour that includes precisely-timed bilateral activation and relaxation of muscles of the face, lips, tongue, cheeks, palate, larynx, pharynx and oesophagus. These events of activation and inhibition are controlled by many structures of the brain and are executed by cranial nerves that carry motor and sensory information to and from the swallowing muscles. Swallowing disorders are common sequelae of many neurological and structural disorders, including stroke, Parkinson’s disease, and head and neck cancer. Changes to swallowing physiology are also prevalent in older individuals, but these changes do not necessarily translate to dysphagia. Decreased muscle strength, changes to motor unit properties, and hypotrophic changes in skeletal muscles can result in age-related changes in swallowing physiology. In addition to muscular changes, neural changes might also change swallowing function in older subjects. The motor-learning literature presents a clear distinction between the differential applications and effects of skill- and strength-training approaches for rehabilitation of limb movement. In contrast to limb-movement rehabilitation, swallowing rehabilitation approaches consist mainly of strength training, although the pathophysiological basis for dysphagia is not always weakness. Therefore, this Phase I clinical-trial critically evaluated a unique swallowing skill training protocol in which the goal of intervention is to increase precision of motor control during swallowing. A Phase I clinical-trial was necessary to identify the appropriate protocol for inducing neurophysiological, biomechanical, and structural adaptations, to estimate effect sizes, and to identify adverse effects. The first and primary question addressed in this thesis was whether swallowing skill training would produce greater physiological effects in healthy subjects than a traditional swallowing strength training approach. In order to answer this question, three levels of assessment were included. Neurophysiological assessment consisted of delivering single-pulse transcranial magnetic stimulation (TMS) over the M1 area that sends efferent projections to the submental muscle group during a functional task of volitional saliva swallowing, and during a non-functional task of submental muscle group contraction. Biomechanical assessments consisted of pharyngeal and upper esophageal sphincter (UES) pressure measurements using pharyngeal manometry during effortful and non-effortful swallowing tasks, submental muscle activation measurements using surface electromyography (sEMG) during effortful and non-effortful swallowing tasks, and hyoid displacement using ultrasonography. Structural assessment consisted of measuring the cross sectional area of the submental muscle group. Finally, motor performance during training, and subjective ratings of the training protocols were assessed. Two skill training protocols were developed to assess the use of immediate versus delayed visual feedback in swallowing skill training. In addition, a pilot study aimed at examining the effects of increased dosage of training sessions was conducted. Forty healthy subjects (20 young, and 20 old; 20 females and 20 males) were allocated to skill and strength training groups in a counterbalanced manner. Strength training consisted of execution of the effortful swallowing technique targeting increased demand for strength. Skill training targeted precise timing and force execution during swallowing execution. Several motor-learning principles were considered in devising the training protocols, including the principles of task specificity and high intensity of training. Biofeedback was included to promote motor learning. Since the submental muscle group plays an important role in hyolaryngeal excursion, the current study utilized submental sEMG biofeedback using custom-made training software. The training protocols consisted of 1000 repetition of swallowing over a 2-week period. Subjects trained for an hour, five days a week, for 2 weeks (i.e., 10 training sessions). The extended dosage protocol included 10 subjects and comprised an additional eight sessions. The results indicated that there was a significant difference in submental activation following training, with strength training having an increase in sEMG peak amplitude in comparison to skill training. There were no other differences between groups at the 5% error level. Patterns of change were revealed when marginally significant results (0.05 < p ≤ 0.10) were investigated as well. Strength training resulted in a trend towards increased neural drive for volitional effortful-type tasks (i.e., effortful saliva swallowing, effortful water swallowing, and submental muscle contraction) as indicated by increased MEP magnitude (p = 0.07) which was consistent with significantly increased peak amplitude of submental activity measures (p < 0.001). This finding supports the task specificity principle of motor learning. Skill training resulted in no changes in MEP magnitude. There was a trend (p = 0.06) towards increased submental muscles activity during functional swallowing tasks (i.e., non-effortful swallowing) in young subjects,. Males in skill training had decreased duration of UES opening in 10 mL water effortful swallowing task (p = 0.02), a trend towards increased UES pressure in non-effortful saliva swallowing task (p = 0.07), and reduced hyoid displacement following training (p < 0.001). Changes in pharyngeal pressures were detected for skill training with delayed visual feedback that resulted in decreased pressure at mid-pharynx in effortful and non-effortful tasks (p < 0.05). No difference in submental CSA changes was detected in either training group. Both groups improved motor performance measured by data collected during the session (target hit-rate and muscle activity). The results of the pilot study that examined the effects of an extended dosage of training were difficult to interpret due to the small sample size. However, there were significant and marginally significant effects of skill training on mid-pharyngeal and UES pressure duration events. Dysphagia is common in patients with Parkinson’s disease, but no specific training programme exists for these patients, leading to the second question addressed through this research. Since movement planning is compromised due to dysfunction of the basal ganglia, providing external information for planning and executing swallowing was hypothesized to alleviate dysphagic symptoms. Ten subjects were recruited. Swallowing skill training with immediate feedback was administered for one hour every day, five days a week, for 2 weeks, similar to the training dosage and frequency in the healthy group. Biomechanical and structural changes were assessed. Swallowing skill training with immediate feedback led to an increase in submental activity in effortful swallowing tasks but not non-effortful tasks. In addition, it was found that individuals with dysphagia secondary to Parkinson’s disease have deceased submental muscle reserve relative to healthy subjects. Preliminary analysis of MEP data led to exploration of submental MEP measures between younger and older subjects. This ‘discovery’ research shed light on the third topic addressed in this thesis. There are contradicting results in the literature regarding age-related brain activity during swallowing. Since submental MEPs were included as an outcome measure in the main study, it was important to evaluate them at baseline in order to understand and interpret changes in this measure. Unlike other measures, such as pharyngeal pressure and hyoid displacement that have been documented in the literature to change with age, no similar study has been conducted to assess for differences in swallowing-related MEPs. Baseline data from the main study were analysed. Older subjects produced larger MEP magnitude in comparison to young in volitional saliva swallowing and volitional submental contraction. This finding raised some questions regarding the use of MEPs as an outcome measure, since it is not clear what constitutes a ‘positive’ change. This study documented, for the first time, the application of skill training in swallowing in a healthy and dysphagic population. Positive effects of treatment were found in the dysphagic group; an indication of negative effects was identified in the healthy group. In addition, this is the first study to compare skill to strength training in swallowing. The only significant difference between the two was significantly greater submental activation in effortful swallowing tasks following strength training in comparison to skill training; although there were some significant interactions between age and training type and gender and training type. This project represents the first Phase I clinical-trial of an innovative approach for addressing swallowing impairments. Achieving the ultimate aim of finding the most appropriate training protocol for treating individuals with a specific pathophysiological basis of dysphagia, requires the implementation of a long-term on-going research programme characterized by a staged process. This research programme sets an initial reference framework from which further projects can estimate the sample size required to answer specific questions, control for effects of age and gender and their interaction with training, increase precision in choosing assessment tools, and test new specific questions.

Rotator cuff pathologies involving supraspinatus are a common cause of musculoskeletal morbidity and can lead to significant disability affecting the overall quality of life. Architectural parameters of the muscle directly influence its functional properties. Therefore, understanding of fiber bundle changes with surgery and different exercises can assist clinicians in planning better surgical and shoulder rehabilitative protocols. The first objective of this thesis was to systematically review human cadaveric studies of the normal supraspinatus architecture and highlight the key aspects that should be considered while performing studies of skeletal muscle architecture. The second objective was to understand the impact of surgical repair on the structural and functional recovery of the supraspinatus. The final objective was to provide a scientific rationale behind choosing an exercise to strengthen supraspinatus by investigating its muscle architecture. Study 1 systematically reviewed human cadaveric studies of the normal supraspinatus architecture. Results showed that the overall quality of majority of included is poor and there was a large range in the reported architectural values of the entire muscle. In conclusion, there were only a few studies providing the level of detail and quality suitable for advancing our understanding of shoulder biomechanics. Study 2 quantified and compared the fiber bundle architecture of the pathologic supraspinatus pre- and post-operatively at multiple time points. Results showed significant lengthening of fiber bundles after one month of surgery which then decreased significantly by 6 months of surgery. In contrast, an initial decrease followed by an increase in pennation angle overtime was found. The results suggest that the stretching applied to the tendon and muscle during repair could affect the length-tension relationship of the muscle, which in turn can compromise its function and may lead to inferior surgical outcomes. Study 3 compared the efficacy of three commonly prescribed supraspinatus strengthening exercises in the rehabilitation setting based on the architectural changes following resistance training. Results showed there was no change in FBL and increased strength after resistance training with prone horizontal abduction exercise. Findings suggest that prone horizontal abduction may be a more suitable exercise to strengthen supraspinatus.

Bakgrund: Forskning som behandlar sarkopeni visar att muskelförtvining påverkar funktionsförmågan under åldrandets gång och går att förebygga med olika former av styrketräning. Forskningen kring muskelförtvining gjorde således att ett intresse av träning för äldre vuxna väcktes hos oss och därav också styrketräningens potentiella effekter på livskvaliteten. Syfte: Syftet med studien är att undersöka om en ökad fysisk styrka och explosivitet bidrar till en ökad livskvalitet hos personer mellan 55 och 65 år. Metod: Detta har undersökts i en grupp på femton deltagare med inspiration från aktionsforskning. Data har insamlats med hjälp av MuscleLab, SF-36v2 och memos. Resultat: Nio deltagare uppvisade en ökning av effektutvecklingen och sex deltagare en minskning. Livskvaliteten har ökat i samtliga åtta kategorier för gruppen som helhet, vilket innebär att både den fysiska och mentala hälsan har ökat i gruppen. Slutsats: En ökad styrka och explosivitet innebar inte nödvändigtvis en ökad livskvalitet, utan vi anser snarare att förändringen i livskvalitet är beroende av en högre aktivitetsnivå i sig. Detta för att styrkan för gruppen som helhet endast ökat marginellt, men att livskvaliteten har ökat desto mer. / Background: Research on Sarcopenia shows that muscle atrophy affects the physical functioning during aging and can be prevented by various forms of strength training. Research on muscle atrophy aroused our interest in strength training for older adults and also the strength training effects on quality of life. Aim: The aim of this study is to investigate whether an increase in physical strength and explosiveness contributes to a better quality of life in people aged between 55 and 65 years. Method: This has been explored with inspiration from action research in a group of fifteen participants. Data was collected with the instruments MuscleLab, SF-36v2 and memos. Results: Nine participants showed an increase in power development and six participants showed a decrease. Quality of life has increased in all eight categories for the group as a whole, meaning that both the physical and mental health has increased in the group. Conclusion: Increased strength and explosiveness does not, in our case, necessarily mean a better quality of life, but we consider that the change in quality of life rather depends on a higher level of activity in itself. This is because the strength of the group as a whole increased only marginally, but that quality of life has increased all the more.

The research presented in this thesis examined the issue of the compatibility of strength and endurance training within one training regime, termed concurrent training, in recreational cyclists. Various research designs used in the previous literature resulted in inconclusive findings. The overall aim of this thesis was therefore to examine, in three systematically designed studies, the effects of various components of concurrent training regimes on cycling efficiency and recovery, and to identify some of the mechanisms that may be responsible for the interference or impedance of strength and/or endurance adaptations.

Este trabalho apresenta como objetivo verificar os efeitos de um programa de 12 semanas de treinamento de força sobre variáveis neuromusculares e composição corporal de crianças e adolescentes. A amostra foi composta por alunos de ambos os sexos, entre 10 a 14 anos de idade, que foram divididos em grupo experimental (GE; n=14) e grupo controle (GC; n=11). Para a classificação maturacional, avaliou-se o pico de velocidade de crescimento e a Escala de Tanner. Foram realizadas as seguintes avaliações: ultrassonografia para analisar a espessura muscular e a eco intensidade; força máxima através do teste de uma repetição máxima (1-RM) de extensores de joelho; pico de torque (PT) isométrico e taxa de produção de torque (TPT), no dinamômetro isocinético; ativação muscular por meio do sinal eletromiográfico (EMG) do Vasto Lateral (VL) e Reto Femoral (RF); potência de membros inferiores, através de saltos com contramovimento (CMJ) em tapete de contato; composição corporal e densidade mineral óssea (DMO) por absorciometria de dupla energia de raios-x (DEXA). Para analisar a normalidade e a homogeneidade dos dados das variáveis dependentes, foram realizados o teste de Shapiro-Wilk e o Teste de Levene, respectivamente. Foi utilizado o teste T independente para comparar as variáveis dependentes no momento basal entre grupos Após, aplicou-se o teste de correlação de Pearson, seguido pelo teste de regressão linear com o método backward, entre as variáveis de caracterização da amostra e as variáveis dependentes, sendo que as variáveis significativas (p<0,05) foram utilizadas como covariantes. Para verificar o efeito do treinamento de força, foi aplicada a análise de variância (ANOVA) de duas vias entre os grupos. O índice de significância adotado foi de 0,05 em todas as comparações. Após 12 semanas de TF, o grupo experimental melhorou a qualidade muscular, espessura muscular do Reto Femoral, 1-RM e TPT 0-100 ms, quando comparado ao grupo controle (p<0,05). A partir disso, pode-se constatar que o treinamento de força induz melhorias no sistema neuromuscular de crianças e adolescentes, melhorando parâmetros de saúde física. / The gold from this study is to verify the effects of a twelve-week strength training program in neuromuscular variables, as well as the body composition from children and teenagers. The sample was comprised by the students of both sexes and divided into: experimental group (EG; n=14) and control group (CG; n=11). For the mature classification, it was evaluated the growth velocity peak (GVP) and the Tunner's stages. The following evaluations were done: ultrasonography to analyze the muscle thickness and echo intensity; maximum strength through the one repetition test (1RM) for the right knee extensors’; isometric peak torque (IPT) and rate of force development (RFD) at the isokinetic dynamometer; muscle activation by eletromiographic signal from the Vastus Laterallis (VL) and Recto Femoris (RF); lower limbs’ power through countermovement jumps (CMJ) at the contact rough; body composition and mineral bone density (MBD) by dual x-ray absormetry (DXA). The normality and homogeneity of the dependent variables were verified from the Shapiro-Wilk and Levene's tests, respectively It was made an independent t test in order to compare the differences between groups for the dependent variables at the basal moment. After, a Pearson correlation test was calculated, followed by a linear regression using the backward method, in order to compare the characterization variables from the sample and the dependent variables, using the ones with significance value (p<0,05) as a covariant. To verify the effect of the strength training, a two way analyzes of variance (ANOVA two way) was made between the groups. The 0,05 level of significance was adopted in all analyzes. After twelve weeks of strength training, the experimental group improved its’ muscle quality, Recto Femoris muscle thickness, 1-RM and RFD 0-100ms, when compared to the control group (p<0,05). From this, it could be stated that strength training induced improvements in the neuromuscular system of children and teenagers, improving physical health parameters.

A doença de Parkinson (DP) caracteriza-se por alterações deletérias no controle motor e, comumente, também produz prejuízos na regulação autonômica e função cardiovascular. O treinamento resistido traz benefícios motores para estes indivíduos, mas seus efeitos autonômicos e cardiovasculares ainda são desconhecidos. Assim, esta tese avaliou os efeitos do treinamento resistido sobre a regulação autonômica e a função cardiovascular de indivíduos com DP, comparando-os a indivíduos sem DP. Para tanto, 17 indivíduos sem DP (SDP, 67±10 anos) e 27 com DP (65±8 anos, estágios II-III da escala de Hoehn e Yahr modificado, estado \"on\" da medicação) foram estudados. Os indivíduos sem DP foram avaliados uma única vez e os com DP foram divididos aleatoriamente em dois grupos, grupo controle (DPCO: n=12) e treinamento resistido (DPTR: n=15 - 2 sessões/semana, 5 exercícios, 2-4 séries, 12-6 RM), e foram avaliados no início e no final das 12 semanas do estudo. No início do estudo, os indivíduos com DP apresentaram menor modulação parassimpática e maior modulação simpática e balanço simpatovagal cardíacos em repouso, além de pior resposta cardiovascular ao teste de se levantar e à manobra de Valsalva que os indivíduos sem DP. Ademais, apresentaram maior pressão arterial na posição deitada, maior débito cardíaco e menor resistência vascular periférica na posição sentada, menor descenso noturno da pressão arterial sistólica, maior frequência cardíaca de 24 horas e sono, e respostas cardiovasculares atenuadas ao exercício máximo. O treinamento resistido, no grupo DPTR, aumentou a força dinâmica máxima (88±23 vs. 108±27 kg, P &lt; 0,05) e diminuiu a modulação simpática cardíaca (banda de baixa frequência da variabilidade da frequência cardíaca - deitado: 61±17 vs. 47±20 un; sentado: 60±11 vs. 46±15 un, P &lt; 0,05) e a queda da pressão arterial sistólica ao teste de se levantar (-14±11 vs. -6±10 mmHg, P &lt; 0,05), enquanto que nenhuma alteração foi observada no grupo DPCO. Nos demais parâmetros avaliados, não houve nenhum efeito do treinamento nos indivíduos com DP. Após as 12 semanas de estudo, o grupo DPTR apresentou modulação simpática cardíaca de repouso e resposta da pressão arterial sistólica ao teste de se levantar semelhantes aos indivíduos SDP e menores que o grupo DPCO (banda de baixa frequência da variabilidade da frequência cardíaca - deitado: 47±20 e 45±9 vs. 63±10 un e sentado: 46±15 e 49±10 vs. 61±13 un; redução da pressão arterial sistólica - 6±10 e -1±10 vs. -11±9 mmHg, respectivamente, P &lt; 0,05). Em conclusão, em indivíduos com DP, o treinamento resistido diminuiu a modulação autonômica simpática cardíaca em repouso e a redução da pressão arterial sistólica ao teste de se levantar, igualando estas respostas às de indivíduos sem DP / Parkinson\'s disease (PD) is characterized by deleterious alterations in motor control, and it usually also presents with impairments on cardiovascular autonomic regulation and function. Resistance training promotes motor benefits in individuals with PD, but its autonomic and cardiovascular effects are still unknown. Thus, this thesis evaluated the effects of resistance training on cardiovascular autonomic regulation and function in subjects with PD, comparing them with subjects without PD. Seventeen subjects without PD (WPD, 67±10 years) and 27 with PD (65±8 years, stages II-III of modified Hoehn & Yahr scale, \"on\" state of medication) were studied. The subjects without PD were evaluated only once, while the subjects with PD were randomly divided into two groups, control (PDCO: n=12) and resistance training (PDRT: n=15 - 2 sessions/week, 5 exercises, 12-6 RM), and were evaluated at the beginning and after 12 weeks of study. At the beginning of the study, the subjects with PD presented, at rest, lower cardiac parasympathetic modulation and higher cardiac sympathetic modulation and sympathovagal balance as well as worse cardiovascular response to standing test and Valsalva Manoeuvre than individuals without PD. In addition, they had higher supine blood pressure, higher seated cardiac output, lower seated peripheral vascular resistance, lower nocturnal systolic blood pressure fall, higher 24 hours and nighttime heart rate and blunted cardiovascular responses to maximal exercise. Resistance training in the PDRT group increased maximal dynamic strength (88±23 vs. 108±27 kg, P &lt; 0.05), decreased cardiac sympathetic modulation (low component of heart rate variability - supine: 61 ± 17 vs. 47 ± 20 nu and seated: 60 ± 11 vs. 46 ± 15 nu, P &lt; 0.05) and systolic blood pressure decrease to standing test (-14±11 vs. -6±10 mmHg, P &lt; 0.05), while no changes were observed in PDCO group. In the other parameters, there was no effect of training in the subjects with PD. After 12 weeks of the study, the PDRT group presented rest cardiac sympathetic modulation and systolic blood pressure response to standing test similar to WPD and lower than PDCO (low component of heart rate variability - supine: 47±20 and 45±9 vs. 63±10 nu and seated: 46±15 and 49±10 vs. 61±13 nu; systolic blood pressure reduction - -6±10 and -1±10 vs. -11±9 mmHg, respectively, P &lt; 0.05). In conclusion, in individuals with PD, resistance training decreased rest cardiac sympathetic autonomic modulation and systolic blood pressure decrease to standing test, matching these responses to the ones observed in subjects without PD

This thesis examined the change in skeletal muscle architecture with contractile force production, the relationship of architecture with muscle strength parameters and if muscle tendinous tissue stiffness determines in vivo explosive strength (i.e. rate of torque development, RTD). Muscle and tendinous tissue adaptations to contrasting strength training regimes, and the potential capacity of these tissues to adapt following chronic strength training were also explored. Quadriceps femoris fascicle length (FL) decreased, while the pennation angle (PA) increased in a curvi-linearly manner from rest to maximal voluntary contraction (MVC) torque. Consequently, effective physiological cross-sectional area (effPCSA) during MVC was 27% greater than at rest, although effPCSA measured at rest and during MVC had similar correlations to maximal strength. In the earliest phase of contraction, FL, but not PA, was negatively related (R2=0.187) to voluntary RTD. Neither FL nor PA was related to maximal isometric or dynamic strength. Muscle-tendon unit (MTU) and patellar tendon (PT) stiffness were unrelated to voluntary and evoked RTD. Relative PT stiffness was also unrelated to relative RTD, although relative MTU stiffness was related to voluntary RTD (25-55%MVT, R2≤0.188) and evoked RTD (5-50%MVT, R2≤0.194). MTU stiffness increased after sustained-contraction (SCT, +21%), though not explosive-contraction strength training (ECT). PT stiffness increased similarly after ECT (+20%) and SCT (+16%), yet neither induced tendon hypertrophy. SCT produced modest muscle (+8%) and aponeurosis (+7%) hypertrophy. Chronic strength trained (CST: >3 years) males had substantially greater muscle and aponeurosis size, but similar tendon size as untrained controls (UNT) and short-term (12 weeks) strength trained (STT) individuals. Between these groups, at the highest common force, MTU stiffness was indifferent, while PT stiffness was similarly greater in STT and CST than UNT. These results suggest FL and PA have little influence on muscle strength and tendon stiffness has no influence on RTD. Maximum strength negated any qualitative influence of MTU stiffness on in vivo RTD. Component MTU tissues (muscle-aponeurosis vs. external tendon) adapt differentially depending on the strength training regime. Specifically, free tendon appeared to adapt to high magnitude loading, while loading duration is also an important stimulus for the muscle-aponeurosis. However, chronic strength training was not concordant with greater higher force MTU stiffness, and does not further increase higher force PT stiffness beyond the adaptations that occur after 12 weeks of strength training. Finally, no evidence was found for tendon hypertrophy in response to strength training.