Introduction: Acute enhancements of muscle contractile properties and performance subsequent to a maximal or near maximal conditioning contraction are often termed post activation potentiation (PAP). Although still controversial, PAP is commonly linked to enhancements in the myosin regulatory light chain phosphorylation, leading to improvements in the excitation–contraction coupling. The PAP seen after a conditioning task often coexists with fatigue and is known to depend on strength level, muscle fiber type and age. Less is known about how factors such as static and dynamic changes in muscle length affect PAP, and on the relative contribution of contractile and tensile components to PAP. Aim: To enhance our understanding of how, and under what conditions, a single maximal isometric contraction affects plantar flexor muscle contractile performance, and other muscle tendon properties, in power athletes. Methods: Supramaximal twitches were evoked via electrical stimulation of the tibial nerve of athletes before and on several occasions after a 6-second maximal voluntary isometric contraction (6-s MVIC) in both static muscle, and during passive muscle lengthening and shorting at different angular velocities. Several contractile variables were measured from the twitches. The effects of a 6-s MVIC on Achilles tendon stiffness was calculated from torque and ultrasonography based measurements of tendon length at two submaximal contraction intensities. Overall stiffness index was calculated by analyzing the passive lengthening torque/angle curve.Results: A single MVIC enhanced muscle contractile properties and electromechanical delay for up to 5 minutes. Plantar flexor twitch variables such as peak twitch, rate of torque development and rate of torque relaxation were enhanced during shortening compared to lengthening muscle actions, and in an extended as compared to a flexed knee position. Achilles tendon stiffness and overall stiffness index were not significantly modulated by a single 6-s MVIC. Conclusion: The results of this thesis imply that functional enhancements from a 6-s conditioning MVIC would mainly come from improvements in contractile rather than tensile components. Stiffness changes should be monitored in future PAP-related studies since they may still occur after more extensive conditioning protocols than the current one. Improvements in contractile components subserving muscle strength after a conditioning MVIC suggests that enhancements in muscle power after a conditioning task should be greatest in fast concentric muscle actions, though still present in muscle lengthening. Conditioning should be performed in a position where full activation is easy to achieve and tailored to mach an athlete or group of athlete’s current status and characteristics, maximizing performance in a specific sport event. / <p>The project recived financial support from the Swedish National Centre for Research in Sports (CIF). Paulo Gago also wishes to thank the Fundação para a Ciência e Tecnologia (FCT), Portugal for the Ph.D. Grant (SFRH/BD/103572/2014).</p><p>New version 2015-01-25 updates the previous one by correcting the errors described in the correction list file (errata).</p> / Doctoral project: Post activation potentiation - Modulating factors and mechanisms for muscle performance.

Thesis (MScPhysio)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: This review aims to present the available evidence for the effect of McConnell taping on knee biomechanics in individuals with Anterior Knee Pain (AKP). Pubmed, Medline, Cinahl, Sportdiscus, Pedro and Science Direct electronic databases were searched from inception until September 2014. Experimental research into knee biomechanical or EMG outcomes of McConnell taping compared to no tape or placebo tape were included. Two reviewers completed the searches, selected the full text articles and assessed the risk of bias of eligible studies. Authors were contacted for missing data. Eight heterogeneous studies with a total sample of 220 were included in this review. All of the studies had a moderate to low risk of bias and compared taping to no tape and/ or placebo tape. Pooling of data was possible for three outcomes; average knee extensor moment, average VMO/VL ratio and average VMO-VL onset timing. None of these outcomes revealed significant differences. The evidence is currently insufficient to justify the routine use of the McConnell Taping technique in the treatment of Anterior Knee Pain. There is a need for more evidence on the aetiological pathways of Anterior knee Pain; level one evidence and studies investigating other potential mechanisms of McConnell taping. / AFRIKAANSE OPSOMMING: Die objektief van hierdie resensie was om te bepaal wat die effekte van McConnell Patellar Vasbinding is op knie kinematika, kinetiek en spier aktivering in diegene met Voorafgaande Knie Pyn (VKP). Die navorsers het elektroniese databases soos Pubmed, Medline, Cinahl, Sportdiscus, Pedro en Science Direct, van aanvang tot September 2014, ondersoek. Eksperimenteel studie ontwerpe wat biomeganiese of EMG gevolge van McConnell Vasbinding vergelyk met geen vasbinding of placebo vasbinding, is ingesluit. Twee resente het die ondersoek voltooi, die volle tekse artikels gekies en die partydigheid risiko van die ingeslote studies, geskat. Skrywers is gekontak vir enige verlore data. Agt heterogeen studies uit ‘n totalle monster van 220 is in hierdie resensie ingesluit. Al die studies het ‘n gematigde tot laag risiko vir eensydigheid en vergelyk vasbinding met geen of placebo vasbinding. Data saamvoeging was moontlik vir drie uitslae, naamlik: gemiddelde knie ekstensor moment; gemiddelde VMO/VL ratio en gemiddelde aanval tydmeting. Geen gevolge het veelseggende verskille of afwykings vertoon. Tans is die bewys nie genoegsaam om die routiene gebruik van McConnell Vasbinding tegniek te regverdig nie in die behandeling van VKP. Meer bewyslewering op die etiologiese paaie van VKP; Graad een bewys en studies wat ander moontlike meganisme van Mc Connell Vasbinding ondersoek, is noodsaaklik.

Thesis (M Sport Sc (Sport Science)--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: Knee injuries are common among the physically active population and are often severe enough that it requires surgery. Rehabilitation specialists are on the constant look-out for the most efficient and cost-effective treatment alternatives to provide athletes with an early return to sport. The inclusion of backward locomotion in knee rehabilitation programs has been proposed since it is considered a safe closed kinetic chain exercise which has been found to increase quadriceps strength and power as well as cardiorespiratory fitness. The primary aim of the study was to establish the efficacy of backward locomotion training during a knee rehabilitation program. Thirty nine men and women (aged 18 to 59 years) with knee pathologies volunteered for the study and were randomly assigned to the experimental group (EXP, n = 20) and control group (CON, n = 19). All participants underwent a 24 session knee rehabilitation program which included 20 – 30 minutes of cardiorespiratory training, either in backward mode (EXP), or forward mode (CON). Aerobic fitness, quadriceps and hamstrings strength and power, single leg balance, lower limb circumferences, and lower limb flexibility were measured before and after the rehabilitation program. Backward locomotion training resulted in a borderline statistical significant improvement in ventilatory threshold (VT) (p = 0.07) and a statistical significant improvement in peak power output (PPO) (p < 0.05). The VT and PPO of the backward locomotion group increased by 9 and 14%, respectively, compared to 0 and 4% in the forward locomotion group. Both groups showed statistically significant improvements in quadriceps and hamstrings strength, except the quadriceps of the uninvolved leg of the forward locomotion group. Similarly, both groups showed a statistically significant improvement in quadriceps and hamstrings average power, except the quadriceps of the uninvolved leg of the forward locomotion group. Single leg balance of the involved and uninvolved legs improved statistically significantly in both groups (p < 0.05). The differences in change between the two interventions were not statistically significantly different (p > 0.05) and the practical differences were small (ES ± 0.2). No statistically significant differences in the change in leg circumferences were observed between the two groups. Only the change in flexibility of the involved soleus was significantly different between the EXP and CON groups. The results show that backward locomotion training result in greater improvements in aerobic fitness and equal or greater improvements in quadriceps and hamstrings muscle strength and power, compared to forward locomotion training. Backward locomotion as well as forward locomotion contributes to the recovery of knee injuries, however, the practical significance of backward locomotion is greater than for forward locomotion. The conclusion of this is that backward locomotion is a better alternative rehabilitation program for athletes as this will affect a quicker return to their sport. / AFRIKAANSE OPSOMMING: Kniebeserings kom algemeen voor in die fisiek aktiewe bevolking en is dikwels so ernstig dat dit chirurgie vereis. Rehabilitasie-spesialiste is voortdurend op soek na die mees doeltreffende en koste-effektiewe alternatief vir behandeling om die atlete vinnig te laat terugkeer na hul sport. Die insluiting van agteruitbeweging in knie-rehabilitasieprogramme is al in die verlede voorgestel, aangesien dit beskou word as 'n veilige geslote-kinetieseketting oefening wat al geskik bevind is om quadriceps sterkte en krag, asook kardiorespiratoriese fiksheid te verbeter. Die hoofdoel van die studie was om die effektiwiteit van agteruitbewegingoefening in 'n knierehabilitasieprogram te bepaal. Nege-en-dertig mans en vroue (tussen die ouderdom van 18 en 59 jaar) met kniepatologieë het vrywillig ingestem om aan die studie deel te neem en is lukraak verdeel in die eksperimentele groep (EXP, n = 20) en kontrole groep (CON, n = 19). Alle deelnemers het 24 sessies voltooi waarvan 20 – 30 minute kardiorespiratoriese oefeninge was. Dit het óf in die agteruitrigting (EXP), óf vorentoe-rigting (CON) plaasgevind. Aërobiese fiksheid, quadriceps en hamstrings sterkte en krag, eenbeenbalans, omtrekke van die onderste ledemaat, en soepelheid van die onderste ledemaat is gemeet, voor en na die rehabilitasieprogram. Agteruitbeweging-oefening het 'n geringe verbetering in ventilatoriese draaipunt (VT) (p = 0.07) opgelewer wat grens aan 'n statisties betekenisvolle verbetering, asook 'n statisties betekenisvolle verbetering in piek kraguitset (PPO) (p <0.05). Die VT en PPO van die agteruitbeweging groep het onderskeidelik verbeter met 9 en 14%, in vergelyking met 0 en 4% in die vorentoe-beweging groep. Beide groepe het statisties betekenisvolle verbeteringe in quadriceps en hamstrings sterkte getoon, behalwe die quadriceps van die onbeseerde been van die vorentoe-beweging groep. Soortgelyk daaraan het beide groepe statisties betekenisvolle verbeteringe in quadriceps en hamstrings gemiddelde krag getoon, behalwe die quadriceps van die onbeseerde been van die vorentoe-beweging groep. Eenbeenbalans van die beseerde en onbeseerde bene het statisties betekenisvol verbeter in beide groepe (p < 0.05). Die verskil in verandering tussen die twee intervensies was nie statisties betekenisvol verskillend nie en die praktiese verskil was klein (ES ± 0.2). Geen statisties betekenisvolle verskille is waargeneem tussen die twee groepe in die verandering in beenomtrekke nie. Slegs die soepelheid van die beseerde soleus van die EXP groep het statisties betekenisvol verbeter tussen die twee groepe. Die resultate toon dat agteruitbeweging-oefening tot groter verbetering gelei het in aërobiese fiksheid en gelyke of groter verbetering in quadriceps en hamstrings sterkte en krag, in vergelyking met vorentoe-beweging oefening. Agteruitbeweging-oefening sowel as vorentoe-beweging oefening dra by tot die herstel van kniebeserings, maar die praktiese beduidendheid van agteruitbeweging-oefening is groter as vorentoe-beweging oefening. Die gevolgtrekking van die studie is dat agteruitbeweging 'n beter alternatiewe rehabilitasieprogram vir atlete is, met 'n gevolglike vinniger terugkeer na hul sport.

Anterior cruciate ligament injury leads to increased sagittal tibial translation, and perceptions of instability and low confidence in the knee joint are common. Many patients have remaining problems despite treatment and are forced to lower their activity level and prematurely end their career in sports. The effect of ACL reconstruction and/or rehabilitation on dynamic knee stability is not completely understood. The overall aim of this thesis was to study the dynamic knee stability during and after rehabilitation in individuals with ACL injury. More specific aims were 1) to elaborate an evaluation method for muscle strength, 2) to evaluate the effect of exercises in closed and open kinetic chain, and 3) to evaluate dynamic knee stability in patients with ACL deficiency or ACL reconstruction. Sagittal tibial translation and knee flexion angle were measured using the CA‐4000 computerised goniometer linkage. Muscle activation was registered with electromyography. The intra‐ and inter‐rater reliability of 1 repetition maximum (RM) of seated knee extension was clinically acceptable. The inter‐rater reliability of 1RM of squat was also acceptable, but the intra‐rater reliability was lower. The systematic procedure for the establishment of 1RM that was developed can be recommended for use in the clinic. One specific exercise session including cycling and a maximum number of knee extensions and heel raises did not influence static or dynamic sagittal tibial translation in uninjured individuals. A comprehensive rehabilitation program with isolated quadriceps training in OKC led to significantly greater isokinetic quadriceps strength compared to CKC rehabilitation in patients with ACL deficiency. Hamstring strength, static and dynamic translation, and functional outcome were similar between groups. Five weeks after ACL reconstruction, seated knee extension produced more anterior tibial translation compared to the straight leg raise and standing on one leg. All exercises produced less or equal amount of anterior tibial translation as the 90N Lachman test. Five weeks after the ACL reconstruction the static and dynamic tibial translation in the ACL reconstructed knee did not differ from the tibial translation on the uninjured leg. Patients in the early phase after ACL injury or ACL reconstruction used a joint stiffening strategy including a reduced peak knee extension angle during gait and increased hamstring activation during activity, which reduces the dynamic tibial translation. Patients with ACL deficiency that completed a four months rehabilitation program used a movement pattern that was more close to normal.

Bone bruise lesions (BBL) are documented on MRIs diagnosing acute knee ligament injury (AKLI). Recent evidence has indicated that a majority of patients that sustain an AKLI, especially anterior cruciate ligament (ACL) knee injury, will develop post-traumatic osteoarthritis (PTOA) 10-20 years following injury. It has been proposed that the initial damage sustained to the articular cartilage overlying BBL causes a cascade of events that may result in PTOA. Researchers have proposed a modification to treatment protocols for more severe BBL, or have stressed the need for the development of protective therapies to protect the articular cartilage. However, there are limited tools available to evaluate the clinical outcome of articular cartilage overlying BBL. Furthermore, damage to the cartilage overlying BBL may be different according to differing BBL severities. Therefore, the use of a cartilage degradation biomarker, serum cartilage oligomeric matrix protein (sCOMP) and the use of a BBL severity classification system may be useful to determine if differences exist between patients with and without BBL, and with differing BBL severities. The purpose of this dissertation was to investigate the utility of sCOMP as a biomarker for acute articular cartilage damage. The purposes of these studies were to determine the inter and intraday reliability of this marker, to document sCOMP longitudinally in collegiate athletes and following AKLI, and to determine if differences in sCOMP and self-reported pain and function exist for patients with and without BBL, and differing BBL following AKLI. The results of these studies indicated sCOMP measures had strong inter and intraday reliability. Additionally, exercise does seem to influence sCOMP levels; however, these elevations may not be clinically meaningful. Furthermore, sCOMP levels were not different between patients with BBL and without, and between differing BBL severities. The results of these studies support the use of a BBL severity classification for future research studies in order to further elucidate the outcomes of these lesions.

No description available.

Muscle strength capabilities are a determinant in the ability to successfully accomplish everyday tasks. As such, the quantification of this aspect of human performance is of interest in many settings. Currently, the validity of muscle strength test results is reliant on the notion that during testing, the participant exerted an effort that is sincere, and that consisted of maximal voluntary contractions. Therefore, the ability to differentiate between maximal and non maximal muscular exertions is of importance. The purpose of this dissertation was to develop and validate probability-based decision rules for differentiating between maximal and non-maximal voluntary exertions of the knee and shoulder joint musculature during isokinetic dynamometry-based testing. For development of the decision rules, healthy participants performed a series of maximal and non-maximal exertions at different testing velocities through a prescribed range of motion. Two different theory-based approaches were subsequently used for decision rule development: the first approach was based on expected better consistency in strength waveform shapes and relative magnitudes during performance of maximal efforts in comparison to non-maximal efforts. The second approach was based on the known force-velocity dependency in skeletal muscles. In terms of discriminatory performance, several of the decision rules pertaining to the knee joint markedly improve upon those previously reported. In addition, a separate investigation demonstrated that the decision rules offer excellent discriminatory performance when applied to test results of participants that have undergone surgical reconstruction of their anterior cruciate ligament. As such, clinicians and researchers may be able to ascertain voluntary maximal effort production during isokinetic testing of the knee joint musculature with a high degree of confidence, and thus be able to rely on such scores for decision-making purposes With regards to the shoulder musculature decision rules, several methodological issues related to test positioning and signal processing need to be addressed prior to consideration of their use in the clinical domain. / Thesis (Ph.D, Kinesiology & Health Studies) -- Queen's University, 2013-06-19 01:12:53.454

The purpose of this study was to examine the relationship between leg dominance and knee mechanics to provide further information about the etiology of ACL injury. Sixteen healthy females between the ages of 18 and 22 who were NCAA Division I varsity soccer players participated in this study. Subjects were instructed to perform a cutting maneuver; where they sprinted full speed and then performed an evasive maneuver (planting on one leg and pushing off to the other leg in a new direction) at a 45° angle with their dominate leg (DL) and non-dominate leg (NDL). Subjects were required to perform five successful cuts on each side given in a random order. Bilateral kinematic and kinetic data were collected during the cutting trials. After the cutting trials, subjects performed bilateral isometric and isokinetic testing using a Cybex Norm dynamometer at a speed of 60°/sec to evaluate knee muscle strength. During the braking phase the NDL showed greater (P=0.003) power absorption, greater (P=0.01) peak internal rotation angle and greater (P=0.005) peak flexion velocity. During the propulsive phase the DL showed greater (P=0.01) power production, greater (P=0.038) peak internal adductor moment and greater (P=0.02) peak extension velocity. In addition, no differences (P>0.05) in knee extensor and flexor isometric and isokinetic torques between the two limbs were shown. The results of this study show that a difference in knee mechanics during cutting does exist between the DL and NDL. The findings of this study will increase the knowledge base of ACL injury in females and aid in the design of more appropriate neuromuscular, plyometric and strength training protocols for injury prevention. / School of Physical Education, Sport, and Exercise Science

Bakgrund/problemformulering Knäskador inom handbollen är utbredda och allmänt kända. Kvinnliga handbollsspelare har visat sig ha en högre risk för långvariga knäskadeproblem. Knäskador inom handboll är beforskat utifrån incidens och även vilken typ av träning som är fördelaktig för att förebygga skador. Däremot har inga studier kring vad handbollstränare har för upplevelser och erfarenheter kring knäskadeförebyggande träning gjorts. Syfte Syftet med studien är att undersöka och kartlägga upplevelser och erfarenheter hos handbollstränare för flickor i 10–19 år angående knäskadeförebyggande träning. Design och metod Kvalitativ explorativ design. Fem semistrukturerade intervjuer med intervjuguide. Till databearbetning användes kvalitativ innehållsanalys Resultat Tränarna såg knäskadeförebyggande träning som en viktig del i träningen. Det förekom variationer i upplägg och innehåll. Flertalet faktorer kring skadeprevention belystes som exempelvis resurser, kompetens och motivation hos spelarna att delta i knäskadeförebyggande träning. Slutsats Bland de faktorer som påverkar möjligheten till optimal skadeförebyggande träning är motivation hos unga spelare en av de större. Det kan tänkas att om tränarna utbildas inom områdena beteende och motivation och hur dessa påverkar varandra, att den skadeförebyggande träningen får än större effekt. / Background Knee injury within handball are well heard of. Female handball players have shown a greater risk developing long term knee injury. Injury to the knee is well investigated from incidence and also what kind of training is beneficial for preventing knee injury. However no studies have yet enlightened what experiences handball coaches possess in the area. Purpose The purpose of the study was to investigate and to survey what experiences regarding knee injury prevention training handball coaches’, coaching girls between the ages of 10- 19 years old possessed. Design and method A qualitative explorative design was used. Five semi-structured interviews based on a interview guide fort. A qualitative content analysis was used for data processing. Result The handball coaches looked at knee injury prevention as an important part of the overall training though there were variations in set up and content. A great deal of factors about injury prevention where mentioned, for example, resources, knowledge and motivation to participate in knee injury preventive exercises among the players. Conclusion Amongst the factors affecting the possibility for effective knee injury prevention training, motivation of young players was one of the most important ones. If coaches acquire education within the area`s behavior and motivation and how they affect each other it might lead to knee injury prevention being more effective.

Class of 2017 Abstract / Objectives: The first aim is to assess efficacy of aspirin versus enoxaparin in preventing a venous thromboembolism (VTE) after a total knee arthroplasty (TKA) or total hip arthroplasty (THA) within 30 days after discharge. The second aim is to assess the safety of aspirin versus enoxaparin in preventing major bleeding events after a TKA or THA within 30 days after discharge. Methods: This study was a retrospective cohort study with data obtained from an online Veterans Affairs (VA) hospital database. For analysis, the primary outcome was assessed with a Chi-Square test, and the secondary outcome was reported with descriptive statistics.Results: Results: Demographics for 374 patients (TKA, n = 275; THA, n = 99): 90% male, average age of 65, average body mass index (BMI) of 32, 26% smokers, 72% had a history of hypertension, and 60% had a history of dyslipidemia. VTE events 30 days post-operatively: enoxaparin (n = 2), enoxaparin/aspirin (n = 1), and aspirin (n = 2) (P-value = 0.78). Safety events (major bleeding events): enoxaparin (n = 42), enoxaparin/aspirin (n = 7), and aspirin (n = 4). Conclusions: There was no significant difference between the treatment groups for VTE rate 30 days post- operation. The enoxaparin treatment group had the greatest number of safety events compared to the other groups.