The effect of minimalist shoe training on lower limb kinematics and kinetics in experienced shod runners

Schutte, Kurt Heinrich (2012-12)

Thesis (M Sport Sc)--Stellenbosch University, 2012.

Thesis

ENGLISH ABSTRACT: Limited data exists on a transition process of minimalist shoe running, warranting longitudinally designed studies. The primary aim of this study was thus to determine whether lower limb kinematics can be adapted, whether vertical average loading rate (VALR) can be attenuated, and whether lower limb joint moments can be altered by either novice or short-term (seven-week) minimalist shoe training. Ten experimental (EXP) habitually shod male endurance runners (age 24.10 ± 1.74; weekly training mileage 29.36 ± 8.51 km; BMI: 22.83 ± 8.55 kg/m2) volunteered to participate in a seven-week minimalist shoe transition programme. Eleven age and training matched control participants (CONT) (age 24.00 ± 2.18; weekly training mileage 24.90 ± 3.30 km; BMI: 23.78 ± 6.12) continued to run in their usual running shoes during the intervention period. All participants were provided with a pair of Vibram Fivefingers ® (VF). The VF intervention started at ~ 11% to 22% and ended at ~ 52% to 132% of the participants‘ usual shod training distance, determined by subjective lower limb comfort ratings. Lower limb biomechanics for barefoot: BF, minimalist: VF, and shod: SH were recorded with an eight-camera Vicon ® motion capture system, synchronized with a Bertec ® force plate, both prior to and after the transition programme. Twelve running trials at self-selected speeds were recorded bilaterally for each shoe condition. An inverse dynamic approach was used to calculate lower extremity joint moments. Primary parameters of interest were kinematic: step frequency (steps/min), step length (m), footstrike angles (FSA, degrees), strike index (SI,%); average vertical loading rate (VALR, BW/S) and sagittal and frontal plane peak joint moments (Nm/kg.m) of the ankle, knee and hip. At pre-testing, the results showed that for VALR, VF running was significantly higher than SH running but significantly lower than BF running (P < 0.05). Statistically significant shorter step lengths, higher step frequencies, greater plantar-flexion FSA, higher strike index, greater knee flexion FSA, and greater ankle inversion FSA were seen in BF and VF conditions compared to SH (P < 0.05). Statistically higher plantarflexion moment peak (PFM) while lower ankle dorsiflexion moment peak (DFM) and knee abduction moment peak (KAM) was found while BF and VF than SH running. The only statistically significant effect of the VF training intervention on kinematics was that of higher step frequency for the SH condition (P < 0.05), and greater inversion FSA in the BF condition. A trend was seen for the EXP group to increase VALR (P > 0.05). Ankle PFM peak significantly increased, while knee extensor moment peak (KEM) peak significantly decreased for the EXP group only (P < 0.05). Contrary to the initial hypothesis, novice or short-term VF training did not result in significantly attenuated VALR. However, alterations in joint moments suggest a shift in the distribution of external loads due to the VF training. Insufficient kinematic adaptation with VF training could be attributed to inability to sense higher VALR or due to greater perceived ratings of calf-Achilles discomfort, and may indicate that more than seven-weeks are required to transition and adapt to VF running.

AFRIKAANSE OPSOMMING: Beperkte data is beskikbaar oor die oorgangs fase van hardloop met minimalistiese skoene, langtermyn studies is dus nodig. Die primêre doel van die studie is om te bepaal of gemiddelde vertikale ladingstempo (VALR) verminder kan word en onderste-ledemaat gewrigsmomente aangepas kan word deur ‗n korttermyn oefenprogram in minimalistiese skoene. Tien experimentaal (EXP) manlike uithouvermoë hardlopers (ouderdom 24.10 ± 1.74; weeklikse oefen afstand 29.36 ± 8.51; BMI: 22.83 ± 8.55) wat gewoonlik in skoene hardloop het vrywillig ingestem om aan die sewe week minimalistiese-skoen oorgangsprogram deel te neem. Elf kontrole deelnemers wat gepas is volgens ouderdom en oefening, (ouderdom 24.00 ± 2.18; weeklikse oefening 24.90 ± 3.30 km; BMI: 23.78 ± 6.12 kg/m2) het in hulle gewone oefenskoene bly hardloop. Alle deelnemers het ‗n paar Vibram Fivefingers ®-skoene ontvang. Die VF intervensie het begin met ~ 11% tot 22% en geeinde met ~ 52% tot 132% van die deelnemers gewone afstande in SH. Biomeganiese aspekte van die onderste ledemate vir kaalvoet: BF, minimalisties: VF, en skoene: SH is deur middel van ‗n agt-kamera Vicon ® bewegingsisteem gesinkroniseer met ‗n Bertec ® kragplatform, voor en na die oorgangsprogram bepaal. Twaalf hardloop-pogings teen ‘n self-bepaalde spoed is bilateraal vir elke skoenkondisie gemeet. ‗n Omgekeerde dinamiese benadering is gebruik om die gewrigsmomente van die onderste ledemate te bepaal. Die primêre parameters van belang was kinematies: treefrekwensie, treelengte, voettrefhoeke (FSA), tree-indeks (SI); gemiddelde vertikale ladingstempo (VALR), en sagittale en frontale vlak piek gewrigsmomente van die enkel, knie en heup. By voor-toetsing, die resultate toon aan dat vir VALR, VF-hardloop betekenisvol hoër was in vergelyking met SH-hardloop, maar betekenisvol laer was in vergelyking met BF-hardloop (P < 0.05). Statisties beduidende korter tree, hoër treefrekwnesie, meer plantaarfleksie FSA, hoer ―strike index‖, meer kniefleksie FSA, en meer enkel inversie FSA is gevind in die BF en VF kondisie in vergelyking met SH (P < 0.05). Statistiese betekenisvol hoër plantaarfleksiemoment pieke (PFM), en minder enkel dorsiefleksiemoment pieke (DFM) en knie abduksiemoment pieke (KAD) was gevind by BF- en VF- hardloop in vergelyking met SH-hardloop (P < 0.05) Die enigste statistiese betekenisvolle verskil in die kinematika van die VF intervensie was ‗n hoër tree frekwensie vir die SH kondisie (P < 0.05), en groter enkel inversie FSA in die BF kondisie. Die EXP groep neig om ‗n verhoging in VALR te hê (P > 0.05). ‗n Aansienlike verhoging is gevind in piek enkel PFM, terwyl piek knie KEM statisties wesenlik verlaag het in die EXP groep (P < 0.05). In teenstelling met die oorspronklike hipotese het onmiddellike en 'n korttermyn VF oefenprogram nie 'n bekenisvolle effek op VALR vermindering nie. Sommige veranderings in gewrigsmomente suggereer dat 'n verplasing in die verspreiding van eksterne ladings plaasvind as gevolg van die VF oefening. Die onvoldoende kinematiese aanpassing kan moontlik toegeskryf word aan die onvermoë om hoër VALR waar te neem, of as gevolg van die hoër waargenome lesings in kuit-Achilles ongemak. Dit kan aandui da 'n VF oorgang proses van meer as sewe weke vereis word om aan te pas aan.

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