A corrida de rua é uma das atividades que obteve maior número de adeptos entre a população idosa. É sabido que, durante a corrida, idosos apresentam padrões diferente de adultos jovens, como um maior ângulo de toe-out. No entanto, não é conhecida a relação com a carga mecânica nas articulações dos membros inferiores. Muitos estudos apontam para uma relação entre o momento adutor externo do joelho e o ângulo de toe-out, inclusive como mecanismo de proteção em indivíduos com osteoartrite do joelho, doença comum em pessoas acima dos 65 anos. Assim, pretendeu-se investigar uma possível relação do ângulo de toe-out aumentado nesses indivíduos e o momento do joelho no plano frontal. Vinte e dois adultos jovens corredores, 23 idosos corredores e 13 idosos sedentários andaram a 5 km/h e correram a 7, 10 km/h e na velocidade média da última prova de 10 km. Na velocidade de 5 km/h e 10 km/h os indivíduos corredores realizaram também uma condição com o toe-out aumentado além do natural. Os indivíduos executaram estas tarefas em uma esteira instrumentada com duas cintas independentes e com duas plataformas de força de seis componentes operando a 600 Hz (Bertec, USA) e tiveram os movimentos dos membros inferiores registrados por um sistema de análise tridimensional do movimento composto por oito câmeras de infravermelho operando a 150 Hz (Motion Analysis Corporation, USA). Uma completa análise cinemática e cinética das tarefas foi realizada por meio dos softwares Visual3D (CMotion. Inc., USA) e Matlab (Mathworks, USA). Em particular, o ângulo de toe-out e o momento adutor externo do joelho foram mensurados em todas as condições e comparados entre as condições com e sem o toe-out aumentado e entre os grupos a partir de análise de variâncias fatorial mistas e ANOVA, respectivamente. Os ângulos e momentos artivulares foram comparados entre os grupos com testes de Wicoxon Signed-rank com correção de Bonferroni. Em geral, os adultos corredores, idosos corredores e idosos sedentários apresentaram diferenças nos padrões cinemáticos e cinéticos do movimento dos membros inferiores durante o andar a 5 km/h e durante o correr a 7 km/h. Também foram observadas diferenças, porém em menor número, durante a corrida a 10 km/h e a corrida na velocidade média da última prova de 10 km para os adultos corredores e idosos corredores. Quanto à relação do ângulo de toe-out e o momento adutor externo do joelho, contrariamente à literatura, nós não observamos um aumento deste ângulo para os idosos durante o andar ou correr em relação aos adultos, assim como uma relação inversa entre o ângulo de toe-out e o momento adutor externo do joelho, talvez pelas coletas terem sido realizadas sobre uma esteira com cinta dupla, o que pode ter levado à alteração do posicionamento natural dos pés (toe-out) / Running is one of the activities that had the highest number of participants among elderly population. It is known that during running, elderly have different patterns of young adults, as a greater toe-out angle. However it is still unknown the relationship between the mechanical loads at the joints of the lower limbs. Several studies point to a correlation between the external knee adduction moment and the toe-out angle, including as a protective mechanism among people with knee osteoarthritis, a common disease in people over 65 years old. Thus, we sought to investigate a possible relationship between the toe-out angle increased in these individuals and the knee moment in the frontal plane. Twenty-two young adult runners, 23 elderly runners and 13 sedentary elderly walked at 5 km/h and ran at 7, 10 km/h and at the mean speed of the last 10 K race. At the speed of 5 km/h and 10 km/h the individuals who were runners also performed a condition with the toe-out angle increased beyond the natural. The subjects did all tasks in an instrumented treadmill with independent two belts and two force plates with six components operating at 600 Hz (Bertec, USA) and had the lower limb movements registered by a tridimentional motion analysis system with eight infrared cameras operating at 150Hz (Motion Analysis Corporation, USA). A complete kinematics and kinectics analysis were made using Visual3D (CMotion. Inc., USA) and Matlab (Mathworks, USA) softwares. The toe-out angle and the external knee adduction moment were measured during all conditions and compared between the condition with and without the toe-out angle increased, and between the groups with a mixed effects modeling and ANOVA respectivelly. The joint angles and joint moments were compared between groups with Wilcoxon Signed-rank tests with Bonferroni correction. In general, young adult runners, elderly runners and elderly sedentaries had differences in kinematic and kinetic pattern of movement of lower limbs during walk at 5 km/h and run at 7 km/h. There were also differences, though in smaller number, during run at 10 km/h and run at mean speed of the last 10 K race between young adult runners and elderly runners. Contrasting the literature there was no relation between toe-out angle and external knee adduction moment and we didnt observe a greater angle in elderly than young adults during walk or run, it maybe can be explained by the fact that the tasks were above a double belt treadmill, what can lead to a different feet position (toe-out)

There has been much debate on the benefits of a forefoot versus rearfoot strike pattern in distance running in terms of performance and injury prevalence. Shock attenuation occurs more prominently in soft tissues at impact in forefoot runners compared to the passive skeletal loading in rearfoot runners. Recent studies indicate that a forefoot strike pattern may not be maintainable over long distance efforts. Therefore, this study tested the hypothesis that habitual forefoot runners could not maintain their strike pattern throughout a prolonged, intensive run. Fourteen forefoot runners ran to voluntary exhaustion on an instrumented force treadmill (average run duration: 15.4±2.2 minutes). Kinematic and kinetic data were sampled each minute at 200Hz and 1000Hz, respectively. Ankle plantar-flexor torque was measured during pre- and post-run isometric contractions, during which electromyographic activity was measured in the soleus, lateral, and medial gastrocnemius. Loading rate (49.95±14.83 to 57.40±22.53 BW*s-1, p=0.0311) and impact peak (1.35±0.43 to 1.50±0.51, p=0.0207) increased significantly throughout the run. Both peak knee flexion (-33.93±3.67º to -36.21±3.48º, p=<0.0000) and sagittal ankle angle at touchdown (-11.83±5.33º to -9.33±6.29º, p =0.0202) increased significantly. Ankle torque decreased significantly from pre- to post-run (120.57±33.57 to 110.76±32.91 Nm, p = 0.0154). This was accompanied by a decrease in medial and lateral gastrocnemius integrated electromyographic activity (iEMG) (p=0.0387 and 0.0186, respectively). The results indicated that there were significant changes in landing mechanics in the habitual forefoot runners with increased levels of exertion, as they shifted towards strike patterns more similar to rearfoot runners throughout the run. These changes are in line with metabolic findings of other studies. There is increased eccentric loading of the ankle plantar-flexor muscles at touchdown in forefoot runners that may contribute to a decreased torque output by the end of the run. The decline in iEMG may indicate altered central drive of the system and a decline in the impact attenuation ability of the triceps surae, leading to the changes exhibited up the kinematic chain. These findings suggest that while forefoot strike patterns are good for speed, the onset of fatigue may affect the ability to maintain this pattern during a prolonged, intensive effort.

Runners adopt altered gait patterns as they fatigue which may increase energy expenditure and susceptibility to certain overuse injuries. Previous investigations have described changes in muscle performance and kinematic gait variables resulting from running fatigue. The purpose of this investigation was to characterize changes in joint moment patterns that develop as runners fatigue in order to better understand the kinetic bases for kinematic fatigue effects. It was hypothesized that when fatigued, runners would demonstrate increases in stance time, peak stance phase knee flexion angle, peak knee extension moment, peak swing phase hip flexion moment, and hip extension and plantarflexion angular impulse generated during stance. Eight recreational rearfoot-striking runners (height = 170.0 ± 9.8 cm; mass = 69.6 ± 15.1 kg) ran on a force-instrumented treadmill at a velocity 5% slower than that of lactate threshold until volitional exhaustion. Force and motion data were collected each minute and analyzed at six evenly-spaced time points over the run duration. Of the six hypotheses, only stance time changed significantly (p = 0.004), increasing in a linear manner over the course of the run (r2 = 0.946). Of the remaining hypotheses, peak knee flexion (r2 = 0.899) and hip extension angular impulse (r2 = 0.608) followed increasing trends over the course of the run. Individual participants often demonstrated joint moment trends consistent with fatigue effects reported in the literature, despite inconclusive group results. High variability in individual responses underscores the complexity of gait adaptations used by distance runners as they fatigue.

Biomechanical and physiological parameters related to running performance are usually studied separately. However, evaluating both aspects together could be beneficial in improving athletic performance. The purpose of this study was to observe the change in peak vGRF and asymmetry as speed increases, while observing physiological responses during a O2maxtest. Data from athlete monitoring of 12 cross-country and triathlon athletes were analyzed. The athlete monitoring protocol included three unweighted countermovement jumps and a O2maxtest performed by the athletes. The athletes had an average O2maxof 53.4 ± 7.7 mL/kg/min, while their average vGRF asymmetry throughout the O2maxtestwas 1.38 ± 0.68%. A strong, positive correlation was found between average vGRF and average blood lactate (r=0.93), indicating that as vGRF increased so did blood lactate. It was concluded that physiological and biomechanical parameters are related in athletic performance. Therefore, athlete monitoring should include analysis of both physiological and biomechanical parameters in order to form a more well-rounded analysis of athlete performance.

No description available.

Sarcopenia, loss of muscle mass and function, is a common feature of aging. Oxidative damage and apoptosis are likely underlying factors. Autophagy, a process for the degradation of cellular constituents, may be a mechanism to combat cell damage and death. We investigated the effect of age on autophagy and apoptosis in plantaris muscle of male Fischer 344 rats that were either fed ad libitum, or mild, life-long calorie restricted (CR) alone or combined with life-long voluntary exercise. Upstream autophagy-regulatory proteins were either upregulated with age (Beclin-1) or unchanged (Atg7 and 9). LC3 gene and protein expression pattern as well as LAMP-2 gene expression, both downstream regulators of autophagy, however, suggested an age-related decline in autophagic degradation. Atg protein expression and LC3 and LAMP-2 gene expression were improved in CR rats with or without exercise. The age-related increase in oxidative damage and apoptosis were attenuated by the treatments. Both, oxidative damage and apoptosis correlated negatively with autophagy. We conclude that mild CR attenuates the age-related impairment of autophagy in rodent skeletal muscle, which might be one of the mechanisms by which CR attenuates age-related cellular damage and cell death in skeletal muscle in vivo.

Running performance has increased immensely during the last few years, coinciding with multiple shattered world records in relatively short amount of time. Improvements in footwear material and design are likely reasons for this increase in running performance. Previous studies on the effect of footwear on running economy (RE), a determinant of running performance, have not included participant-blinding. Furthermore, they have yet to compare multiple carbon-fiber plated running shoes available for purchase, what differences there are across price ranges and shoe categories, and if there is such a thing as a placebo-effect. Aim: (1) Descriptively compare a set of heterogeneous running shoes, with regards to running economy, Foot Strike Type (FST), vertical oscillation, ground contact time, stride length and cadence; including (2) a ‘sham’ and ‘normal condition’ of the same running shoe model; and (3) explore the participant’s perception of the study-specific blinding protocol. Method: A Single Subject Experimental Study (N=1), comparing nine different shoe conditions using a crossover design. The assessment of RE was conducted using indirect calorimetry with mixing-chamber in a climate-controlled facility. Spatiotemporal parameters were assessed using a Garmin HRM-Run™, and foot strike type was visually assessed using a frame-by-frame approach based on 2D-video at 240 fps. Results: The average running economy across all shoe tests varied between 16.02 to 17.02 W/kg, with the ‘worst’ shoe costing 6.24% W/kg more than the ‘best’ shoe. The descriptive difference between the ‘sham’ and ‘normal condition’ were negligible and within the range of measurement error. Spatiotemporal parameters were overall descriptively similar between the shoes, with a few outliers who differed with regards to measure of central tendency or dispersion. FST differed between the shoes including the ‘sham’ and ‘normal condition’, but were overall consistent with the participant’s habitual FST. The study-specific blinding procedure was perceived to work well, but may also be improved in some remarks. Conclusion: Descriptive difference in some, but not all, physiological and biomechanical parameters were observed between the shoe conditions in this study, including the ‘sham’ and ‘normal condition’. Blinding procedures in experimental footwear research may be feasible and adopted with future studies.

There is epidemiological and experimental evidence suggesting that exercise training may reduce the mortality rate from coronary heart disease, in particular the sudden death rate, and that it may improve the peak functional capacity of the heart. This thesis includes experimental work that is relevant to both these questions.

On two occasions six competitive, male triathletes performed in random order, two experimental trials consisting of either a timed ride to exhaustion on a cycle-ergometer or a run to exhaustion on a motor-driven treadmill at 80% of their respective peak cycling and peak running oxygen uptakes (VO₂peak)- At the start of exercise, subjects drank 250 ml of a 15 g.100 ml⁻¹ w.v⁻¹ glucose solution with U-¹⁴C glucose added as tracer and, thereafter, 150 ml of the same solution every 15 min. Despite identical metabolic rates (VO₂ 3.51 ±0.06 vs. 3.51 ±0.10 l.min⁻¹; values are mean± SEM for the cycling and running trials, respectively), exercise times to exhaustion were significantly longer during cycling than running (96 ±14 vs. 63 ±11 min; P<0.05). The superior cycling than running endurance was not associated with any differences in either the rate of blood glucose oxidation (3.8 ±0.1 vs. 3.9 ±0.4 mmol.min⁻¹ ), nor the rate of ingested glucose oxidation (2.0 ± 0.1 vs. 1.7 ±0.2 mmol.min⁻¹) at the last common time point (40 min) before exhaustion, despite higher blood glucose concentrations at exhaustion during running than cycling (7.0 ±0.9 vs. 5.8 ±0.5 mmol.l⁻¹; P<0.05). However, the final rate of total CHO oxidation was significantly greater during cycling than running (24.0 ±0.8 vs. 21.7 ±1.4 mmol C6 .min⁻¹;P<0.01). At exhaustion, the estimated contribution to energy production from muscle glycogen had declined to similar extents in both cycling and running (68 ±3 vs. 65 ± 5%). These differences between the rates of total CHO oxidation and blood glucose oxidation suggested that the direct and/or indirect (via lactate) oxidation of muscle glycogen was greater in cycling than running.

Literature suggests that the original and "pure" elements of cross country course design have faded through time; in order to wholly enhance course design the original elements must be preserved and united with desired modern course elements. "Pure" sport is defined by an athlete's struggle and persistence that occur amidst tough competition, rugged course elements, and physical pain. In addition to identifying the desired elements through literature review, case studies, and self-experience of cross country course design, it was necessary to confirm the desired elements through interviewing eight key informants. The key informants were renowned and accomplished NCAA cross country coaches selected to represent a wide geographic. These eight informants were interviewed to unveil which elements of cross country courses were desired, important, essential, would advance design, and are underutilized and present in their favored courses. The results from the interviews confirmed a deep desire for enhanced course design by unionizing the elements present in the "pure" sport of cross country with contemporary desired elements. The new "pure" sport of cross country can be obtained through the utilization of the elements revealed within this thesis. Designing courses that will provide unchanged emotions from the "pure" sport of cross country, yet do not incorporate excessively rough course elements, will be the new "pure" sport of cross country. Overall, the results show designing for the athlete, which includes safety, well defined routing and proper carrying capacity, an accomplished sense of place, advanced technologies and facilities, sport appropriate and safe footing and reasonable terrain, and spectator engagement, would considerably improve design. In order to preserve the "pure" sport of cross country while also integrating modern desired and necessary elements, course designers must use pioneering design methods in order to incorporate all of the desired elements. The main objective of this research was accomplished and has established a foundation upon which subsequent research efforts may begin. This work serves as a catalyst to improving cross country course design by attaining the knowledge of proper, intensified, and innovative design.