Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: Optical motion capture (Mocap) systems measure 3D human kinematics accurately and at high sample rates. One of the limitations of these systems is that they can only be used indoors. However, advances in inertial sensing have led to the development of inertial Mocap technology (IMCT). IMCT measures kinematics using inertial measurement units (IMUs) attached to a subject's body without the need for external sensors. It is thus completely portable which opens up new horizons for clinical Mocap. This study evaluates the use of IMCT for improving road cycling kinematics. Ten male sub-elite cyclists were recorded with an IMCT system for one minute while cycling at 2, 3.5 and 5.5 W.kg-1 on a stretch of road and on a stationary trainer. A benchmark test was also done where cycling kinematics was measured simultaneously with the IMCT and a gold-standard Vicon optical system. The first goal was to assess the feasibility of conducting field measurements of cycling kinematics. Magnetic analysis results showed that the IMUs near the pedals and handlebars experienced significant magnetic interference (up to 50% deviation in intensity) from ferrous materials in the road bicycles, causing significant errors in kinematic measurement. Therefore, it was found that the IMCT cannot measure accurate full-body kinematics with the subject on a road bicycle. However, the results of the benchmark test with the Vicon showed that the IMCT can still measure accurate hip (root mean square error (RMSE) < 1°), knee (RMSE < 3.5°) and ankle (RMSE < 3°) flexion using its Kinematic Coupling algorithm. The second goal was to determine whether there is a significant difference between road cycling kinematics captured on the road and in a laboratory. The outdoor flexion results were significantly different to the indoor results, especially for minimum flexion (P < 0.05 for all joints). Changes in rider kinematics between high and low power were also found to have significantly more variability on the road (R2 = 0.36, 0.61, 0.08) than on the trainer (R2 = 0.93, 0.89, 0.56) for the hip, knee and ankle joints respectively. These results bring into question the ecological validity of laboratory cycling. Lastly, applications of IMCT for optimizing cycling performance were to be identified. Several aspects of kinematic analysis and performance optimization using the IMCT were evaluated. It was determined that IMCT is most suited for use as a dynamic bicycle fitting tool for analysis of biomechanical efficiency, bilateral asymmetry and prevention of overuse injuries. Recommendations for future work include the elimination of the magnetic interference and integration of the IMCT data with kinetic measurements to develop an outdoor dynamic fitting protocol. / AFRIKAANSE OPSOMMING: Optiese bewegingswaarnemingstelsels (BWS) meet drie-dimensionele menslike kinematika met hoë akkuraatheid en teen hoë monstertempo's. Een van die nadele van BWS is dat hulle slegs binnenshuis gebruik kan word. Onlangse ontwikkelings in sensor tegnologie het egter gelei na die beskikbaarheid van traagheids-BWS-tegnologie (TBT). TBT gebruik traagheidsmetingseenhede (TMEs) wat aan 'n persoon se liggaam aangeheg kan word om die kinematika te verkry sonder enige eksterne sensore. TBT is dus volkome draagbaar, wat nuwe geleenthede skep vir kliniese bewingsanalises. Hierdie projek evalueer die gebruik van TBT vir die verbetering van fietsry kinematika. Tien kompeterende fietsryers (manlik) was getoets met 'n TBT terwyl hulle teen 2, 3.5 and 5.5 W.kg-1 gery het op 'n pad, en op 'n stilstaande oefenfietsraam. 'n Maatstaftoets was ook uitgevoer waar fietsry-kinematika gelyktydig met die TBT en die Vicon optiese BWS opgeneem was. Die eerste doel van die navorsing was om die moontlikheid te ondersoek of fietsryer kinematika op die pad gemeet kan word. Die resultate toon dat die ferro-magnetiese materiale wat in meeste padfietse voorkom, 'n beduidende magnetiese steuring (tot 50% afwyking in intensiteit) op die TMEs naby die pedale en handvatsels veroorsaak, wat lei tot aansienlike foute in die kinematiese metings. Gevolglik was dit gevind dat die TBT nie volle-liggaam kinematika op 'n fiets kan meet nie. Nogtans, het die resultate van die Vicon maatstaftoets bewys dat die TBT nog steeds akkurate heup (wortel van die gemiddelde kwadraad fout (WGKF) < 1°), knie (WGKF < 4°) en enkel (WGKF < 3°) fleksie kan meet met die “Kinematiese Koppeling” algoritme. Die tweede doel was om te bepaal of daar 'n beduidende verskil tussen die laboratorium en pad fietsry-kinematika is. Die buitelug fleksie data het beduidend verskil van die binnenshuise resultate, veral vir minimum fleksie (P < 0.05 vir alle gewrigte). Veranderinge in fietsryer kinematika tussen hoë en lae krag het ook beduidend meer variasie op die pad (R2 = 0.36, 0.61, 0.08) as op die oefenfietsraam (R2 = 0.93, 0.89, 0.56) vir die heup, knie en enkel gewrigte, onderskeidelik, gehad. Hierdie resultate bevraagteken die ekologiese geldigheid van kinematiese toetse op fietsryers in 'n laboratorium. 'n Laaste doel was om die toepassings van TBT vir die optimering van fietsry kinematika te ondersoek. 'n Verskeidenheid aspekte van die analise en verbetering van fietsry kinematika met die TBT word bespreek. Die gevolgtrekking is dat TBT geskik is vir gebruik as 'n dinamiese instrument vir die analise van biomeganiese doetreffendheid, bilaterale asimmetrie en die voorkoming van beserings. Aanbevelings vir toekomstige werk, sluit in die uitskakeling van die magnetiese inmenging, asook die integrasie van die TBT data met kinetiese metings.

O estudo investigou o efeito de diferentes competições de ciclismo de estrada e de um período de descanso na Creatina Kinase (CK), Lactato Desidrogenase (LDH), Interleucina-1 (IL-1), Interleucina-6 (IL-6), Fator de necrose tumoral (TNF-<font face=\"symbol\">a), prostaglandina E2 (PGE2) e na razão Glutamina/Glutamato (Gln/Glu). Para isso, 12 ciclistas profissionais que completaram 3 diferentes competições. A primeira e a terceira (C1 e C3) competições foram de uma 1 etapa e a segunda foi uma volta ciclística (C2) de 7 dias. A C3 foi realizada após um período de 20 dias de descanso. Foram coletadas amostras de sangue 24 horas antes do início e 24 horas após o término de cada competição. Não houve diferenças significativas para nenhum dos mediadores inflamatórios (p<0,05). Aumentos (p<0,05) foram encontrados após o término da C2 e da C3 para CK e LDH e diminuição (p<0,05) na razão Gln/Glu C3. A conclusão foi a de que lesões musculares são diagnosticadas em ciclistas profissionais de estrada após o término de uma volta ciclística e de uma competição precedida de um período de descanso. / The objective of this research was to observe the effect of different road cycling competitions and a 20 days break period in Creatine Kinase (CK), Lactate Dehydrogenase (LDH), Interleukin-1(IL-1), Interleukin-6 (IL-6), Factor necrosis tumoral-alpha (TNF-<font face=\"symbol\">a), prostaglandin E2 (PGE2) and in the ratio of Glutamine/Glutamate (Gln/Glu). The hypothesis tests were conducted with a sample of 12 professional cyclists which have completed 3 different road cycling races. The first and third ones (C1 and C3) were mass start races. The second one was a stage racing (C2). One analysis was made after a 20 days break period (C3). Blood samples were collected 24 hours before and 24 hours after each competition. There were no significant differences for none of the inflammatory mediators (p<0,05). Increases (p<0,05) were detected after the end of C2 and C3 for CK and LDH and low (p<0,05) in the ratio of Gln/Glu at C3. The conclusion of the research was that muscular damages are diagnostified in professional road cyclists 24 hours after the end of the stage racing and after mass start competition preceded by 20 days a break period.

O estudo investigou o efeito de diferentes competições de ciclismo de estrada e de um período de descanso na Creatina Kinase (CK), Lactato Desidrogenase (LDH), Interleucina-1 (IL-1), Interleucina-6 (IL-6), Fator de necrose tumoral (TNF-<font face=\"symbol\">a), prostaglandina E2 (PGE2) e na razão Glutamina/Glutamato (Gln/Glu). Para isso, 12 ciclistas profissionais que completaram 3 diferentes competições. A primeira e a terceira (C1 e C3) competições foram de uma 1 etapa e a segunda foi uma volta ciclística (C2) de 7 dias. A C3 foi realizada após um período de 20 dias de descanso. Foram coletadas amostras de sangue 24 horas antes do início e 24 horas após o término de cada competição. Não houve diferenças significativas para nenhum dos mediadores inflamatórios (p<0,05). Aumentos (p<0,05) foram encontrados após o término da C2 e da C3 para CK e LDH e diminuição (p<0,05) na razão Gln/Glu C3. A conclusão foi a de que lesões musculares são diagnosticadas em ciclistas profissionais de estrada após o término de uma volta ciclística e de uma competição precedida de um período de descanso. / The objective of this research was to observe the effect of different road cycling competitions and a 20 days break period in Creatine Kinase (CK), Lactate Dehydrogenase (LDH), Interleukin-1(IL-1), Interleukin-6 (IL-6), Factor necrosis tumoral-alpha (TNF-<font face=\"symbol\">a), prostaglandin E2 (PGE2) and in the ratio of Glutamine/Glutamate (Gln/Glu). The hypothesis tests were conducted with a sample of 12 professional cyclists which have completed 3 different road cycling races. The first and third ones (C1 and C3) were mass start races. The second one was a stage racing (C2). One analysis was made after a 20 days break period (C3). Blood samples were collected 24 hours before and 24 hours after each competition. There were no significant differences for none of the inflammatory mediators (p<0,05). Increases (p<0,05) were detected after the end of C2 and C3 for CK and LDH and low (p<0,05) in the ratio of Gln/Glu at C3. The conclusion of the research was that muscular damages are diagnostified in professional road cyclists 24 hours after the end of the stage racing and after mass start competition preceded by 20 days a break period.

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In an era that sees sports clubs facing a crisis, a few still grow and attract new members. They use technology for their benefit and provide a place where the members have fun, become aware of their competence, set goals for improvement and experience empowerment. The present qualitative study, conducted with a road cycling club in Germany, investigates how membership is negotiated and confirmed. By exploring the factors that influence the degree of belonging, this research aims to provide some answers on how active members of a cycling hobby club experience becoming part of such a community, what it takes to substantiate membership, and how individual and collective identities are formed and constantly negotiated. The situated learning perspective and Etienne Wenger's Communities of Practice concept have been adopted, and semi-structured interviews with ten participants were conducted. Moreover, observations and conclusions from a stimulated focus group discussion were used. The analysis shows that cycling in a group is a complex, multifaceted learning experience. Power, speed, or cycling skills do not suffice without the will and active efforts to harmonise with a group. Belonging grows parallel to competence, and the degree of competence gets constantly evaluated by the community in their practice, as a combination of contribution to the common goal and ability to be a trusted partner. Competence is thus a “becoming”, reflecting the members’ engagement with the sport and on an interpersonal level.