A Comparison Of Five Mechanical Work Algorithms For Different Footstrike Patterns And Speeds During Distance Running

The mechanical work done by a runner during an average stride cyde has been calculated with a variety of algorithms that generate values that may vary by an order of magnitude. The application of different algorithms to the same data set is uncommon, and does not seem to have been used at all to compare different foot strike patterns (FSP) during distance running. Average stride cycle values from five work algorithms for forefoot strike (ffs) and heel strike (hs) running at three different running speeds are presented. In general order from most to least restrictive: Wn allows no transfer between segments; Ww, within-segment transfer only; WwbAS, transfer within and between adjacent segments only; WwbLT, within and between segments of the same limb and the trunk; and, Wwb, within- and between-segment transfer with no restrictions. The primary difference in these algorithms is the amount of energy transfer they permit between and among body segments. Twelve highly skilled, male distance runners each ran with both FSP at three speeds ranging from 3.58 to 4.58 m-s-l. High-speed video (200 Hz) was used to track eight segment endpoint markers in the left sagittal plane. An ll-segment model was used with symmetry assumed to generate right side values. Among the algorithms, the no-transfer method (Wn) produced the highest work estimates. An absolute difference of -300 joules-stride-1 (-15-20%) existed across speeds between the no-transfer and within-transfer algorithms. There was then a relatively large decrease to the span of values generated from the other three algorithms. WwbAS was slightly higher than the remaining two algorithms, moreso in relative terms as speed increased. WwbLT increased slightly over speed (-40% slow->fast), while Wwb, the least restrictive, demonstrated almost no change across speeds (-1 % slow->fast). On average, these differences converged absolutely (75->20 joules-stride-1) and relatively (9.8%->2.5%) with increased speed; i.e., differences between the two .FSP decreased as speed increased. At all speeds for each algorithm, hs was lower than ffs. Collapsed across speeds, hs as percentage of ffs was 96.7 (Wn), 96.5 (ww)- 96.7 (WwbAS), 95.8 (WwbLT) and 89.4% (Wwb). Wwb across speeds consistently showed the largest relative differences between FSP, due perhaps in part to low absolute values. However, FSP differences still decreased with increased speed. This algorithm, therefore, appears to preserve the ordinal relationship and the trend in relative change between FSP across speeds reflected in the other four algorithms. Overall, the consistency across all algorithms of absolute and relative decrease between FSP with increased speed suggests variations in actual kinematics, not algorithms, are responsible for observed differences

A Case Study Of Muscle Activity In Giant Slalom Skiing

Speed of movement respresents the ability essential for successful performance of a sportsman in many branches of sport. This is especially important in ski-jumping where the skier must develop optimum vertical velocity corresponding to the correct ski-jumping technique in extremely complex and demanding inertial environment. The objective of this investigation was to establish the size of the attained vertical velocity measured both in the field and laboratory conditions; its stability and relation to the jump length. The results of the investigation will be, above all, useful to experts in developing the take-off techniqueElectromyography (EMG) and video data from a single female US. Ski Team member were acquired during giant slalom (GS) skiing at Beaver Creek, Colorado. The purpose of the testing was to examine muscle activity relative to the skiing motion. Muscles on the right side of the body, consisting of the lower leg (anterior tibialis (AT) and lateral gastrocnemius (LG», thigh (vastus medialis (VM), vastus lateralis (VL), rectus femoris (RF), semitendinosus (ST), gracilis (Gr), and gluteus maximus (GM», and trunk (rectus abdominis . (RA), external oblique (EO), and erector spinae (ES» were monitored. Maximal voluntary contractions (MVC) were performed pre- and post-skiing to provide a relative reference for the amplitude of muscle activity (%MVC). EMG during skiing was monitored via a four channel telemetry unit. The eleven muscles were partitioned into three sets. Three skiing trials of a seven gate GS course were completed for each set. Peak amplitude (uv) and time measures (ms) were digitized and averaged across trials for each gate. In six of the eleven muscles, the peak activity occurred when the right leg was the outside leg in a turn (turns 1, 3, 5, 7). The exception to this pattern was for the ES muscles of the lower back. %MVC ranged from 27% (EO at gate 4) to 206% (Gr at gate 5). The coeffcients of variation (CV) ranged from 2.3 (VM at gate 4) to 130% (EO at gate 4), indicating a large amount of variation in arnplitude for several muscle groups. The mean duration of muscle activity across all three muscle sets was consistent, ranging from 1.08 to 1.56 s. Roughly two-thirds of the CV's were less than 14%, indicating that the timing was more consistent than the peak EMG. This case study of EMG activity in GS skiing revealed substantial muscle activity at large percentages of MVC with considerable variation. A large amount of cocontraction between opposing muscles and relatively long duration of muscle activity suggest a quasi static nature of muscle activity during a GS turn. These findings have implications for dryland training of GS skiers. of ski jumpers, and in building a model of performance in ski jumping

Bone turnover markers in sheep and goat: a review of the scientific literature

Bone turnover markers (BTMs) are product of bone cell activity and are generally divided in bone formation and bone resorption markers. The purpose of this review was to structure the available information on the use of BTMs in studies on small ruminants, especially for monitoring their variations related to diet, exercise, gestation and metabolic lactation state, circadian and seasonal variations, and also during skeletal growth. Pre-clinical and translational studies using BTMs with sheep and goats as animal models in orthopaedic research studies to help in the evaluation of the fracture healing process and osteoporosis research are also described in this review. The available information from the reviewed studies was systematically organized in order to highlight the most promising BTMs in small ruminant research, as well as provide a wide view of the use of sheep and goat as animal models in orthopaedic research, type of markers and commercial assay kits with cross-reactivity in sheep and goat, method of sample and storage of serum and urine for bone turnover markers determination and the usefulness and limitations of bone turnover markers in the different studies, therefore an effective tool for researchers that seek answers to different questions while using BTMs in small ruminants.José Arthur de A. Camassa acknowledges to the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Brazil, for his PhD scholarship 202248/2015-1.info:eu-repo/semantics/publishedVersio

Effectiveness of individualized physiotherapy on pain and functioning compared to a standard exercise protocol in patients presenting with clinical signs of subacromial impingement syndrome. A randomized controlled trial

<p>Abstract</p> <p>Background</p> <p>Shoulder impingement syndrome is a common musculoskeletal complaint leading to significant reduction of health and disability. Physiotherapy is often the first choice of treatment although its effectiveness is still under debate. Systematic reviews in this field highlight the need for more high quality trials to investigate the effectiveness of physiotherapy interventions in patients with subacromial impingement syndrome.</p> <p>Methods/Design</p> <p>This randomized controlled trial will investigate the effectiveness of individualized physiotherapy in patients presenting with clinical signs and symptoms of subacromial impingement, involving 90 participants aged 18-75. Participants are recruited from outpatient physiotherapy clinics, general practitioners, and orthopaedic surgeons in Germany. Eligible participants will be randomly allocated to either individualized physiotherapy or to a standard exercise protocol using central randomization.</p> <p>The control group will perform the standard exercise protocol aiming to restore muscular deficits in strength, mobility, and coordination of the rotator cuff and the shoulder girdle muscles to unload the subacromial space during active movements. Participants of the intervention group will perform the standard exercise protocol as a home program, and will additionally be treated with individualized physiotherapy based on clinical examination results, and guided by a decision tree. After the intervention phase both groups will continue their home program for another 7 weeks.</p> <p>Outcome will be measured at 5 weeks and at 3 and 12 months after inclusion using the shoulder pain and disability index and patients' global impression of change, the generic patient-specific scale, the average weekly pain score, and patient satisfaction with treatment. Additionally, the fear avoidance beliefs questionnaire, the pain catastrophizing scale, and patients' expectancies of treatment effect are assessed. Participants' adherence to the protocol, use of additional treatments for the shoulder, direct and indirect costs, and sick leave due to shoulder complaints will be recorded in a shoulder log-book.</p> <p>Discussion</p> <p>To our knowledge this is the first trial comparing individualized physiotherapy based on a defined decision making process to a standardized exercise protocol. Using high-quality methodologies, this trial will add evidence to the limited body of knowledge about the effect of physiotherapy in patients with SIS.</p> <p>Trial registration</p> <p>Current Controlled Trials ISRCTN86900354</p

ESTIMATION OF VO2MAX FROM A ONE-MILE TRACK WALK, GENDER, AGE, AND BODY-WEIGHT

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Reformas del sector Agrícola y el campesinado en Mexico. Estrategias para mitigar la pobreza en América Latina y el Caribe

454p. FIDA/ IICA 4.El análisis detalla un contexto del desarrollo rural, reformas macroeconómicas, sectoriales y comerciales, así como una caracterización de la heterogeneidad de los hogares y comunidades rurales, factores conexos a la pobreza de estas zonas