The effects of an eight-week customised endurance-training programme on running kinematics and impact associated with fatigue in recreational runners

Sackey, Saint Andrews (2019-04)

Thesis (PhD)--Stellenbosch University, 2019.

Thesis

ENGLISH ABSTRACT: Background: The unrestrained and easily accessible nature of running has led to an exponential increase in participation in running. However, the incidence rate of injuries is a concern. Loading and fatigability have been linked as underlying injury risk factors. It has been proposed that runners would automatically fine-tune their kinematics after exposure to training to be more efficient for better performance and reduce the occurrence of injuries. However, there is no evidence to support this hypothesis under fatigued conditions. Aim: The current study investigated the “self-optimisation hypothesis” under fatigued conditions. I again determined the influence of fatigue on novel running parameters that have previously been associated with running injury to provide foundational information on interventions for injury prevention and better performance. Methods: A pre-post interventional approach was deployed for the current study. Recreational runners (n = 40) were recruited from the Stellenbosch Boland community for the study. The study was carried out in two phases. In the phase I, the participants were subjected to a running fatigue protocol which involved running at incremental speed to volitional exhaustion on a motorised treadmill. Running impact variables at the tibia, lower back and upper back were assessed using tri-axial accelerometers whereas spatio-temporal, and upper extremity kinematic parameters were collected with an Opto-Gait photoelectric system and 2D video analysis respectively before and after the run. In the phase II, the runners were randomly assigned to either an intervention group or a control group. The intervention group underwent eight-weeks of endurance training while the control group continued with their normal running routine. After the eight-weeks, all the participants were subjected to the same running fatigue protocol and measurements as in the phase I. Results: Running induced fatigue resulted in significant increases in contact times, forward trunk lean, and body load (p ˂ 0.05). Running impact magnitude at the tibia, external distribution of impact, stride angle, step length, flight times, and arm carriage remained unchanged after fatigue (p ˃ 0.05). The eight weeks of endurance training caused reductions in step length, forward trunk lean, and contact times. Step frequency on the other hand increased after the eight weeks of endurance training. There were no significant differences in body load, and running impact variables. The changes in the running kinematics under fatigued conditions after the intervention was accompanied with a significant reduction in the oxygen cost of transport. Conclusions: Running-induced fatigue resulted in changes in some running kinematic parameters. Such changes are accompanied with increases in the oxygen cost of transport. An exposure to eight weeks of endurance training resulted in significant alterations in the kinematic parameters for better efficiency under fatigued conditions with a corresponding decrease in the oxygen cost of transport.

AFRIKAANSE OPSOMMING: Agtergrond: Die onbeperkte en toeganklike aard van draf het aanleiding gegee tot n’ eksponensiële toename in deelname daaraan. Die voorkoms van beserings is egter steeds rede tot kommer. Lading en vermoeibaarheid is aangedui as onderliggende faktore vir die risiko van beserings. Daar is voorgestel dat drawwers outomaties hul kinematika fyn aanpas naá oefening om meer doeltreffend te wees vir beter prestasie en die vermindering van beserings. Daar is egter nie bewyse om hierdie hipotese in toestande van vermoeienis te ondersteun nie. Doel: Die huidige studie het die ‘“self-optimaliseringshipotese”’ onder vermoeide toestande ondersoek. Die invloed van vermoeienis op nuwe drafparameters, wat voorheen met drafbeserings geassosieer is, is ondersoek om inligting te verkry oor intervensies om beserings te verminder en prestasie te verbeter. Metodes: ‘n Voor-naá intervensie-benadering is in die studie toegepas. Ontspanningsdrawwers (n = 40) is uit die Stellenbosch Boland drafgemeenskap gewerf. Die studie is in twee fases uitgevoer. In fase 1 is die deelnemers onderwerp aan ‘n draf vermoeienis protokol waar deelnemers op ‘n trapmeul teen ‘n stapgewyse spoed tot vrywillige uitputting gedraf het. Draf-impakveranderlikes by die tibia, laerug en bo-rug is bepaal met die gebruik van drie-as versnellingsmeters. Data oor tyd-ruimtelike en boonste-ledemaat kinematiese veranderlikes is deur middel van die OptoGait foto-elektriese stelsel en 2D video- ontleding, voor en ná die drafloopsessie ingesamel. In fase 2 is drawwers lukraak in ‘n intervensie- of kontrolegroep. Die intervensiegroep het agt weke van uithourvermoë oefening ondergaan terwyl die kontrolegeroep met hul normale drafoefening aangehou het. Na die agt weke is al die deelnemers aan dieselfde draf vermoeienisprotokol as in fase 1 onderwerp. Resultate: Draf geïnduseerde vermoeienis het gelei tot beduidende toenames in kontaktyd, vorentoe rompleun, enaá liggaamslading (p < 0.05). Die impakgrootte by die tibia, eksterne verspreiding van impak, tree-hoek, treelengte, vlugtye, en armdra-posisie was onveranderd na vermoeienis (p > 0.05). Die agt-week uithouvermoë-oefening het belei tot verkorte treelengte, minder vorentoe rompleun en korter kontaktye. Treefrekwensie het toegeneem na die agt-weke uithouvermoë-oefening. Daar was geen beduidende verskille in liggaamslading en hardloop-impak veranderlikes nie. Die veranderinge in die hardloop-kinematika tydens vermoeienis na die intervensie het saamgeval met ‘n beduidende afname in die koste van suurstofvervoer. Gevolgtrekkings: Draf-geïnduseerde vermoeienis het gelei tot ‘n verandering in sommige kinematiese parameters. Hierdie veranderinge het gepaardgegaan met ‘n toename in die suurstofkoste van vervoer. Blootstelling aan agt weke se uithouvermoë-oefening het gelei tot beduidende veranderinge in kinematiese parameters met verbeterde doeltreffenheid onder vermoeide toestande, met ‘n gepaardgaande afname in koste van suurstofvervoer.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/105846
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