Thesis (M.Tech.: Chiropractic)-Dept. of Chiropractic, Durban Institute of Technology, 2006 xiv, 61 leaves, Annexures 1-12, 20 leaves / It is well known that the lifetime incidence of lower back pain (LBP) is particularly high (Richardson et al., 1999). Most cases of LBP are self-limiting, however certain regional biomechanical deficits may be overlooked, such as core stability. As a result of this, LBP may become a chronic condition in the athletic and general population. This principle can be applied to road running, as the forces that pass through the muscles of the lower limbs and trunk cannot be properly absorbed if the trunk musculature is not properly trained. This may lead to lower back pain as a result of inadequate functioning and strength of stabilizing structures (Hedrick, 2000). The purpose of this exploratory cross-sectional study was to determine the relationship between core muscle strength and chronic lower back pain in amateur female road runners and non-runners. The focus was to determine the core stability values in mmHg between amateur female runners with and without chronic LBP, and female non-runners with and without chronic LBP; as well as to compare female runners and non-runners with regard to core muscle strength.

Thesis (M.Tech,: Chiropractic)- Dept. of Chiropractic, Durban Institute of Technology, 2005 xiii, 62, 19 leaves :|bill. ;|c30 cm / To document the relationship between total work and myofascial trigger points in the vastus lateralis and vastus medialis portion of the quadriceps femoris muscle, whilst providing baseline graphs of these muscles with the use of a Cybex 700 Isokinetic Dynanometer in long distance runners both with and without patellofemoral pain syndrome. Methods: A quantitative, non-intervention clinical exploratory study. Fifty participants were divided into two groups, Group A (40 symptomatics) and Group B (10 asymptomatics). Both groups were screened for vastus lateralis and vastus medialis trigger points. Subjective data was obtained from Group A only, using the Numerical Pain Rating Scale and the Patient Specific Functional Scale. Objective data was obtained from both groups using the algometer, Myofascial Diagnostic Scale, and the Cybex 700 Isokinetic Dynanometer. For descriptive analysis frequency tabulations, box and whisker plots were used to display distributions graphically. Comparisons of categorical and quantitative variables between independent groups were run using chi square and Mann-Whitney testing consecutively. Finally Spearman’s correlation, multivariate generalized linear modelling and repeated measures ANOVA were also used. All statistical analysis was completed at the 95% (p<0.05) level of confidence.

Bidrog långdistanslöpning till att sätta fart på människans evolution? Flertalet forskare argumenterar för att långdistanslöpning var en viktig drivkraft i människans evolution. Men har den här teorin ben att stå på? Arkeologiska fynd visar att släktena Homo och Pan skiljdes åt för 4,6 till 6,2 miljoner år sedan. Det är vid den här tiden människans förfader gick sin egen väg med andra ord och blev bipedala. Trots att bipedala gångarter inkluderar gång och löpning, anses löpning inte generellt ha spelat en stor roll i människans evolution eftersom människan är, likt andra hominider, underlägsna sprinters jämfört med de flesta fyrfotade däggdjur. Den här uppsatsen, baserad på en kvalitativ metod med en abduktiv ansats, kommer att bedöma hur bra människan är på fortlöpande långdistanslöpning och narrativt granska den fysiologiska kapaciteten att springa långa distanser hos människor och andra däggdjur. Långdistanslöpning och löpning i allmänhet ställer dock en del fysiska krav på kroppens rörelse- och stödjeapparat. Tack vare en mångfald av fysiologiska egenskaper som möter dessa krav presterar människan anmärkningsvärt bra på att springa långa distanser. Dessa fysiologiska egenskaper kan delas in i fyra krav löpning utsätter kroppen för; energetik, muskuloskeletal styrka, stabilitet och temperaturreglering, varav många lämnar spår i skelettet. De fossila spåren av dessa egenskaper tyder på att förmågan att springa uppkom inom det mänskliga släktet och att löpning kan ha varit en bidragande faktor till utvecklandet av den mänskliga kroppsformen. / Did endurance running drive human evolution? Some researchers argue that endurance running was a key driving factor of human evolution. But does this theory have legs? Archaeological finds show that bipedalism is a key derived behaviour of hominins that originated after the divergence of the human and chimpanzee lineages. Although bipedal gaits include walking and running, running is generally considered to have played no major role in human evolution because humans, like other hominids, are poor sprinters compared to most quadrupedal terrestrial mammals. In this paper, based on a qualitative method with an abductive reasoning, I assess how well humans perform at sustained long-distance running and narratively review the physiological bases for endurance running capabilities in humans and other mammals. Endurance running and running in general expose the locomotor system for several physiological demands. Thanks to a diverse array of features that meet these demands, humans perform remarkably well at endurance running. These features can be divided into four types of demands posed by endurance running; energetics, musculoskeletal strength, stabilization and thermoregulation. Many of these features have left traces in the fossilized skeleton of early hominins for paleoanthropologist and other researchers to examine. The fossil evidence of these features suggests that endurance running originated in the genus Homo and may have been a contributing factor in the evolution of the human body form.

Thesis (MScPhysio)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Introduction: Iliotibial band syndrome (ITBS), an overuse injury, is the second most common running injury and the main cause of lateral knee pain in runners. Due to the increasing number of runners worldwide there has been an increase in its occurrence. Runners with ITBS typically experience symptoms just after heel strike at approximately 20°-30° of knee flexion (impingement zone) during the stance phase of running. A variety of intrinsic and extrinsic risk factors may be responsible for why some runners are more prone to developing symptoms during the impingement zone as opposed to others. Abnormalities in running biomechanics is an intrinsic risk factor which has been most extensively described in literature but little is known about its exact relationship to ITBS. Objectives: The purpose of this systematic review was to provide an up to date evidence synthesis of the biomechanical risk factors associated with ITBS. These risk factors may need to be considered in the prevention or management of ITBS in runners. A clinical algorithm is also presented. Methods: A systematic review with meta-analysis was conducted. An electronic search was performed in PubMed, PEDro, SPORTSDisc and Scopus of literature published up-until May 2014. Cross-sectional and cohort studies were eligible for inclusion if they evaluated the lower limb biomechanics of runners with ITBS or those who went onto developing it. All studies included in the review were methodologically appraised. Evidence was graded according to the level of evidence, consistency of evidence and the clinical impact. Data was described narratively using tables or narrative summaries where appropriate. A meta-analysis was conducted for biomechanical risk factors which were reported in at least two studies, provided that homogeneity in the outcomes and samples were present. Results: A total of 11 studies were included (1 prospective and 10 cross-sectional). Overall the methodological score of the studies was moderate. Increased peak hip adduction and knee internal rotation during the stance phase may predict the development of ITBS in female runners. These biomechanical risk factors may need to be screened for ITBS prevention, despite the evidence base being limited to a single study. Currently there is no conclusive evidence that any of the biomechanical parameters need to be considered when managing runners with ITBS. Stellenbosch University https://scholar.sun.ac.za iii Conclusion: Biomechanical differences may exist between runners with ITBS and those who may develop ITBS compared to healthy runners. Although a large variety of biomechanical risk factors were evaluated, the evidence base for screening or managing these risk factors for runners with ITBS is limited. This is due to a small evidence base, small clinical effect and heterogeneity between study outcomes and findings. Further prospective and cross-sectional research is required to ascertain if abnormalities in running biomechanics may be related to why runners develop ITBS or to ascertain which risk factors may be involved when managing these runners. / AFRIKAANSE OPSOMMING: Inleiding: Iliotibiale-band-sindroom (ITBS), ’n besering vanweë oormatige gebruik, is die tweede algemeenste hardloopbesering en die hoofoorsaak van laterale kniepyn by hardlopers. Namate die getal hardlopers wêreldwyd toeneem, neem die voorkoms van hierdie toestand ook toe. Hardlopers met ITBS ervaar tipies simptome ná die hakslag met die knie ongeveer 20-30° gebuig (die wrywingsone of “impingement zone”) gedurende die staanfase van hardloop. Verskeie intrinsieke en ekstrinsieke risikofaktore kan ’n rol speel in waarom sommige hardlopers meer geneig is as ander om gedurende die wrywingsone simptome te ervaar. Abnormaliteite in hardloopbiomeganika is ’n intrinsieke risikofaktor wat reeds omvattend in die literatuur beskryf is. Tog is weinig bekend oor presies hoe dit met ITBS verband hou. Oogmerke: Die doel van hierdie stelselmatige ondersoek was om ’n sintese te bied van die jongste bewyse van die biomeganiese risikofaktore van ITBS. Hierdie risikofaktore kan dalk oorweeg word om ITBS by hardlopers te voorkom of te bestuur. ’n Kliniese algoritme word ook aangebied. Metodes: ’n Stelselmatige ondersoek is met behulp van meta-ontleding onderneem. PubMed, PEDro, SPORTSDisc en Scopus is elektronies deurgesoek vir literatuur wat tot en met Mei 2014 verskyn het. Deursnee en kohortstudies is ingesluit indien dit gehandel het oor die biomeganika in die onderste ledemate van hardlopers wat ITBS het of later ontwikkel het. Alle studies wat deel was van die ondersoek is metodologies geëvalueer. Bewyse is aan die hand van bewysvlak, bewyskonsekwentheid en kliniese impak beoordeel. Data is narratief beskryf met behulp van tabelle of narratiewe opsommings waar dit toepaslik was. ’n Meta-ontleding is onderneem waar biomeganiese risikofaktore in minstens twee studies aangemeld is, mits daar homogeniteit in die uitkomste sowel as die steekproewe was. Resultate: Altesaam 11 studies is ingesluit (een prospektief en tien deursnee). Die metodologiese telling van die studies was oorwegend gemiddeld. Verhoogde spitsheupadduksie en interne knierotasie gedurende die staanfase kan op die ontwikkeling van ITBS by vrouehardlopers dui. Hierdie biomeganiese risikofaktore kan dalk nagegaan word vir ITBS-voorkoming, al was die bewysbasis beperk tot ’n enkele studie. Daar is tans geen afdoende bewys dat enige van die biomeganiese parameters oorweeg behoort te word in die bestuur van langafstandatlete met ITBS nie. Gevolgtrekking: Daar bestaan dalk biomeganiese verskille tussen hardlopers wat ITBS het of kan ontwikkel en gesonde hardlopers. Hoewel ’n groot verskeidenheid biomeganiese risikofaktore beoordeel is, is die bewysbasis vir die toets of bestuur daarvan by atlete met ITBS beperk. Dít is vanweë die klein hoeveelheid bewyse, die klein kliniese impak, en heterogeniteit tussen studie-uitkomste en bevindinge. Verdere prospektiewe en deursneenavorsing word vereis om te bepaal of abnormaliteite in hardloopbiomeganika ’n rol kan speel in waarom langafstandhardlopers ITBS ontwikkel, of om vas te stel watter risikofaktore ter sprake kan wees in die bestuur van hierdie hardlopers.

Thesis (MScSportSc)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Neuromuscular control (NMC) plays a critical role in dynamic movement regulation such as running (Nyland et al., 2011) and injury prevention (Hübcher et al., 2010). This experimental study set out to determine whether an eight-week minimalist shoe training program influences NMC in recreational distance runners. Eleven experimental (EXP) (5 women; 6 men) (age 23.4 ± 2.98 yrs; VO2max 43.55 ± 5.04 ml.min-1.kg-1; BMI 22.61 ± 3.08 kg.m2; Training 17 ± 5km.w-1) and 12 control (CON) runners (7 women; 5 men) (age 25.42 ± 5.57 yrs; VO2max 43.67 ± 4.38 ml.min-1.kg-1; BMI 22.38 ± 3.12 kg.m2; Training 18 ± 6km.w-1) randomly completed an eight-week training program in either minimalist shoe (EXP) or their usual trainers (CON). Neuromuscular control components were measured before and after the intervention i.e. postural sway (Balance Biodex®), using the Athletic Single Leg (ASL) and modified Clinical Test of Sensory Integration and Balance (mCTSIB) tests, joint position sense (JPS) using joint angle reproduction tests (Biodex® Isokinetic Dynamometer), frontal and sagittal planes isokinetic strength testing, lower body electromyography (EMG) and kinematic measurements while participants ran on a treadmill. Plantar-dorsiflexion (PF/DF) or inversion eversion (IN/EV) proprioception did not differ between groups (p > 0.05). In selected trials EXP showed less deterioration in IN/ EV foot position error, when compared to CON, with medium to large practical significance. Athletic Single Leg scores for non-dominant (p < 0.01) and dominant M/L (p = 0.05) sway, and dominant overall sway (p = 0.04) improved in CON, with marked differences between genders. Dorsiflexor strength improved for 30∘.sec-1 and 60∘.sec-1speeds in CON (p < 0.01 & p = 0.04, respectively) and in the slower speed for EXP (p = 0.04). Plantar-flexion (PF) strength improved in EXP men (30∘.sec-1 p = 0.02; 60∘.sec-1 p = 0.02), while EXP women demonstrated a 7% deficit. At initial contact PF increased in EXP (8km.h-1 p = 0.01; 10km.h-1 p = 0.01; 12km.h-1 p = 0.01), with women showing a greater change in ankle angle (8km.h-1 p = 0.03; 10km.h-1 p = 0.02; 12km.h-1 p = 0.01) compared to men (8km.h-1 p = 0.05; 10km.h-1 p = 0.06; 12km.h-1 p = 0.05). Greater knee flexion (8km.h-1 ES = 0.64; 10km.h-1 ES = 0.49; 12 km.h-1 ES = 0.51) in EXP. Plantar-flexor pre-activation improved in EXP women, while co-activation improved in EXP men and total activation improved in both genders.Results suggest that women may require more time to transition into minimalist shoes. While minimalist shoes may moderately reduce foot position error, improve strength and muscle activation patterns, excessive plantar flexor muscle damage may reduce strength and muscle spindle proprioceptive feedback. / AFRIKAANSE OPSOMMING: Neuromuskulêre beheer (NMC) speel ‘n kritieke rol in dinamiese beweginsregulasie, soos met hardloop (Nyland et al., 2011) en beseringsvoorkoming (Hübscher et al., 2010). Hierdie eksperimentele studie het uit gesit om te bepaal of ‘n agt-week minimalistiese skoen oefenprogram NMB kan beïnvloed in rekreasie langafstand atlete. Elf eksperimentele (EXP) (5 vrouens, 6 mans) (ouderdom 23.4 ± 2.98 jr; VO2maks 43.55 ± 5.04 ml.min-1.kg-1; BMI 22.61 ± 3.08 kg.m2; Oefening 17 ± 5km.w-1) en twaalf kontrole (CON) hardlopers (7 vrouens, 5 mans) (ouderdom 25.42 ± 5.57; VO2maks 43.67 ± 4.38 ml.min-1.kg-1; BMI 22.38 ± 3.12 kg.m2; Oefening 18 ± 6 km.w-1) het lukraak ‘n agt-week oefenprogram voltooi, óf in minimalistiese skoene (EXP) of in hul gewone hardlooptekkies (CON). Neuromuskulêre beheer komponente was gemeet voor en na die intervensie i. e. posturale wieg (Balans Biodex®), met gebruik van Atletiese Enkelbeentoets (ASL) en die gemodifiseerde Kliniese Toets van Sensoriese Integrasie en Balans (mCTSIB), gewrigs posisie bewustheid (Biodex® Isokinetiese Dinamometer), frontale en sagitalle vlak isokinetiese kragtoetsing, onderlyf elektromiografie (EMG) en biomeganiese metings terwyl deelnemers op ‘n trapmeul gehardloop het. Plantaar dorsifleksie (PF/DF) of inversie eversie (IN/EV) propriosepsie het nie verskil tussen groepe nie (p > 0.05). In selektiewe proewe het EXP IN/ EV ‘n verminderde afname gehad in foutiewe voet posisieplasings, in vergelyking met CON, terwyl medium na groot praktiese betekenisvolle verskille. . Atleet enkel been toets tellings vir nie-dominant (p=0.001) en dominante M/L (p = 0.05) wieg, en dominant algehele wieg (p = 0.04) het verbeter in CON, met gemerkte verskille tussen geslagte. Dorsifleksor krag het verbeter vir 30∘.sec-1 en 60∘.sec-1spoed in CON (p = 0.01 en p = 0.04, onderskeidelik) en in die stadiger spoed vir EXP (p = 0.04). Plantaarfleksie (PF) krag het verbeter in EXP mans (30∘.sek-1 p = 0.02; 60∘.sek-1 p = 0.02), terwyl EXP vrouens ‘n 7% tekort gedemonstreer het. By initïele kontak het PF toegeneem in EXP (8km.h-1 p = 0.01; 10km.h-1 p = 0.01; 12km.h-1 p = 0.01), met vrouens wat ‘n groter verandering getoon het (8km.h-1 p = 0.03; 10km.h-1 p = 0.02; 12km.h-1 p = 0.01), in vergelyking met mans (8km.h-1 p = 0.05; 10km.h-1 p = 0.06; 12km.h-1 p = 0.05). Groter kniefleksie (8km.h-1 ES = 0.64; 10km.h-1 ES = 0.49; 12 km.h-1 ES = 0.51) in EXP. Plantaarfleksie pre-aktivering het verbeter in EXP vrouens, terwyl ko-aktivering verbeter het in EXP mans, en totale aktivering verbeter het in beide geslagte.Hierdie resultate stel voor dat vrouens moontlik meer tyd sal vereis om na minimalistiese skoene oor te skakel. Terwyl minimalistiese skoene matige verbetering in foutiewe voetposisieplasing, verbeterde krag en spieraktiveringspatrone kan veroorsaak, kan oormatige plantaarfleksie spierskade krag en spierspoel proprioseptiewe terugvoer ook verminder.

Exercise or activity in high ambient temperatures offers a particular challenge to the thermoregulatory system. It is likely that mechanisms such as sweat evaporation alone are not sufficient for maintaining body temperature within a safe limit (~36.5-38.5˚C) and below 40˚C, which may result in impaired physiological function and performance. Exogenous cooling may be of benefit prior to, during and after events that place increased thermal strain due to increased metabolic heat production and elevated environmental temperatures upon the thermoregulatory system. Conversely, in situations where it is not possible to maintain body temperature via either continued physical activity or elevated ambient temperatures, exogenous heating may be required in order to allow optimal physiological performance. Few studies have directly aligned cooling devices with data detailing effective target regions for cooling to allow a pre-cooling garment to be of minimal weight but maximal cooling efficiency. Conversely, no study has considered the effect of muscle temperature maintenance during rest periods on subsequent power-based activities. The aim of this thesis was to determine ways in which body temperature manipulation is capable of improving exercise performance in both power and endurance-based events. It was hypothesised that the manipulation of body temperature will result in subsequent changes in body temperature that would improve performance. Specifically, the use of pre-cooling would result in a reduction of body temperature and improve endurance exercise performance. Conversely, maintaining Tm following warm up completion would have a beneficial effect on sprint and power related performance. Study one set out to determine differences in regional body heat loss in 12 individual anatomical zones using a water perfused suit. Data obtained from this initial study allowed for the specific targeting of regions that were identified as having high rates of heat loss in subsequent studies that focused on pre-cooling and performance. The anatomical regions identified as having high potential affinity for heat exchange with the surrounding environment and cooling devices were the hands, forearms, upper and lower back and torso. Subsequent studies demonstrated that cooling of these areas was capable of lowering thermal sensation and improving thermal comfort prior to and during exercise in moderate environmental conditions (24˚C, 50% RH). In these moderate conditions, there was no statistically significant improvement in treadmill based self-paced 5000m running performance. However, in hot conditions (35˚C 50% RH), the use of a cooling vest and sleeves did yield a significant improvement in cycling time trial performance, which equated to 4.8%. This leads to the suggestion that there may be a threshold ambient temperature, above which pre-cooling becomes an important tool in maximizing performance potential. A parallel area of investigation, on the other side of the temperature spectrum, was the effect of muscle temperature manipulation on power-based exercise performance. The relationship between increased muscle temperature and power output is well established, however little is known about the effect of enforced rest or recovery between two bouts of exercise. Therefore, two studies were conducted to establish what affect a delay between warm up completion and exercise has on muscle temperature and subsequent sprint cycling performance. It was shown that with 30-minutes of rest between exercise bouts wearing tracksuit trousers, muscle temperature declined significantly (~1-1.5˚C). This decline was attenuated with the use of external passive electrical heating during the recovery compared to recovery completed in tracksuit trousers alone. The attenuated decline in muscle temperature following the use of the heated trousers resulted in an improvement in sprint cycling performance (~9%), with the use of insulated trousers having no effect on any variables measured, all relative to wearing tracksuit trousers in the rest period. In a follow-up study, the effect of implementing the heated trousers during the warm up and in addition to the rest period had on muscle temperature increase and sprint performance. A secondary area of investigation in this study was to determine the linearity of muscle temperature decline following warm up cessation. This study demonstrated that there was no additional benefit of combining passive heating with an active warm up on either muscle temperature elevations or subsequent sprint performance compared to the active warm up alone. It was shown that when the no heating was used at any stage, muscle temperature declined exponentially. However, when the heated trousers were used during recovery and/or during warm up, muscle temperature levelled off at a higher value towards the end of the recovery period. This study was also able to show significant improvements in absolute, relative and mean power output following the use of the heated trousers in the warm up and recovery, or the recovery alone. This thesis has identified ways in which body temperature may be manipulated in order to benefit both sprint and endurance exercise performance, using both pre-cooling and active heating. A novel concept for minimizing muscle temperature decline during periods of inactivity between different rounds of competition was shown to maximize sprint performance yielding significant improvements in peak and mean power outputs.

The aim of this research was to specify and develop a service that is capable of delivering personalisable running shoes with mass appeal. Current sports footwear personalisation services focus primarily on aesthetic design via the internet. Aesthetics do not appear to be the consumers primary interest when purchasing running shoes and a large number are also reluctant to purchase online; preferring to purchase from specialist running stores where they receive the advice needed and can directly interact with the product. After reviewing the literature, it was hypothesised that the implementation of a primarily comfort and performance running shoe personalisation service with an in store fitting element, utilising additive manufacturing as an enabling technology, would give the greatest opportunity for success. Survey methods and store visits were employed that targeted both qualitative and quantitative data, exploring consumer running shoe purchase preferences, running shoe use and opinions of current personalisation services. The findings from these studies supported the previously stated hypothesis and enabled the specification of a suitable service. Subsequently, the focus of this research was the development of a toolkit, a computer-based system that enables the consumer to make their selections, the core of most of the current services. Experts in biomechanics and additive manufacturing were consulted to ensure that a feasible yet innovative solution was delivered. The resultant toolkit prototype (www.yourstep.co.uk) was tested formatively, using multiple methods and summatively with a large sample. Using the toolkit was considered an enjoyable, intuitive experience; a large percentage (69%) of summative testing participants would consider purchasing personalised running shoes using this method. The approach adopted to specify and develop this service provides a framework, based upon empirical research, for those looking to implement a practical running shoe personalisation service that meets their consumers requirements.

published_or_final_version / Sports Science / Master / Master of Science in Sports Science

<p>The general trend in gear industry, today, is an increased focus on gear transmission efficiency. Gear transmission efficiency losses arise from loaded and unloaded gear contacts, seals, lubricant and bearings. One way of minimising the losses is to lower the lubricant viscosity. This will reduce the speed dependent losses. However, the load dependent losses might increase. To avoid this, the ratio between lubricant film thickness and surface roughness must be maintained, which can be fulfilled by producing smoother gear surfaces. As a starting point for this realisation process, the present manufacturing processes, the design tools and the characteristics of the gear flank interface must be further investigated and developed. This must be achieved with an emphasis on economic production.</p><p>This thesis focuses on our understanding of how different gear manufacturing methods —particularly the contribution of the running-in process—affect the surface characteristics, with the view of increasing gearbox efficiency. The thesis consists of a summary and three appended papers.</p><p>Paper A and paper B discuss the relationship between design parameters and real gear wheel surfaces manufactured with different manufacturing methods. The research hypothesis was that the contact area ratio is a descriptive parameter for the contact condition. Paper A deals with the influence of manufacturing method on the initial contact conditions and also serves as a validation of the simulation program used. The emphasis in Paper B is the changes that occur during running-in, and to correlate these changes to design requirements. Paper C approaches the influences of manganese phosphate-coating and lubricants with respect to friction and the risk of scuffing at the initial contact.</p><p>The main conclusions of this thesis are that the contact area ratio presents a descriptive measure of how surface topography influences the contact, seen at both a global (form deviation) and local (roughness) level. The surface topography caused by the manufacturing method has a significant influence on the contact area ratio. This is an important result, since neither national standards nor commercially available gear evaluation programs handle surface topography on the local scale. Shaving was found to have the highest contact area ratio, and should therefore be the best choice if deviations from case hardening could be minimised. It is also confirmed that gear-like surfaces coated with manganese phosphate have a low coefficient of friction, and raise the limiting load for scuffing failure enormously compared to the ground equivalent.</p> / QC 20100518 / KUGG / Sustainable gear transmission realization

This study examined the effects of two distinct phases of endurance training (summer and in-season training) in previously well-trained male and female high school cross-country runners. Eleven males and 11 females from the same high school training program were recruited for the three testing sessions: post-track season (June), postsummer training (mid-August), and post-cross-country season (early-November). However, due to injury and other circumstances, only 10 males and 4 females completed all testing sessions. Thus, baseline characteristics were analyzed for both genders; however, longitudinal analysis was only conducted using the males. Submaximal measurements included running economy (RE), blood lactate concentration ([BLa]), and heart rate (HR) at three running speeds in females (6, 7, and 8 mph), and males (7, 8, and 9 mph). Maximal measurements of oxygen uptake (VO2max) and HR, neuromuscular characteristics of isokinetic knee extension strength and vertical jump height, and body composition were also measured. Baseline results showed that the males possessed a higher VO2max, greater neuromuscular characteristics, and lower submaximal [BLa] and HR values than the females. Longitudinal analysis of the males showed that there was an increased VO2max, decreased maximal HR, and decreased neuromuscular strength following summer training. In-season training precipitated further increases in VO2max, an increase in maximal and submaximal HR, and increased neuromuscular characteristics. RE and [BLa] did not significantly change (p<_ 0.05) throughout the course of the study. Likely, it is the subtle changes in these variables in previously welltrained runners which account for the slower performance times at the beginning of the cross-country season and the improvements thereafter. / School of Physical Education