The role of the gluteus maximus during prone hip extension

Rainsford, Ian George (2015-12)

Thesis (MSc)--Stellenbosch University, 2015.

Thesis

ENGLISH ABSTRACT: Background: The clinical prone hip extension (PHE) test is used to assess lumbo-pelvic function with a large focus placed on the activation of the gluteus maximus (Gmax), and is also used as a prescribed exercise in the treatment of Gmax recruitment deficits. The activation sequences (AS) are compared to those of the ‘golden standard’ as set out by Janda (1991). Gmax activation becomes important due to its role in injury prevention as well as maintenance of lower limb alignment. Previous research into the AS reveals no consistent order, questioning the functionality of the PHE. Objective: The current study set out to determine whether a consistent AS exists during the PHE and, in the presence of an erroneous AS, whether one can achieve the proposed AS with concentrated gluteal training. The current study also looked into the AS of more functionally loaded movements. The study further looked at the influence of improved Gmax recruitment on lower limb alignment. Methods: Pre- (n=18) and post-testing (n=7) of the muscle AS (time-normalized onsets) (with electromyography) were assessed in healthy young club-level netball players during the PHE, quadruped opposite arm/leg extension (QALE), and the single limb squat (SQT) along with lower limb alignment (valgus and knee-over-toe angles). The following muscles were included in the assessment: Gluteus maximus, bicep femoris, and lumbar erector spinae. Onsets were reported relative to gluteus maximus. Following pre-testing the players then entered a nine-week gluteal training intervention. Results: No consistent AS was noted at pre-testing (n=18) with the Gmax onset occurring after that of the lumbar erector spinae in both non-dominant and dominant PHE. At post-testing (n=7) the Gmax onset occurred earlier (non-dominant first and dominant second) with the lumbar erector spinae shifting later (dominant significantly, p<0.05). During the QALE and SQT movements, Gmax onset was consistently not the first muscle to become active at pre- and post-testing. No change in lower limb alignment was observed with no change in gluteal muscle onset or amplitude (p>0.05) during the SQT. Conclusion: The gluteal training intervention seems to have improved gluteal recruitment during the PHE but this did not have an influence on lower limb alignment during the SQT bringing to question the usage of the PHE in the assessment of Gmax function. The AS (both non-dominant and dominant PHE) agree more closely with the suggested norm and hence lends weight that it can be used as a reference. The QALE and SQT don’t appear to be suitable replacements for the PHE.

AFRIKAANSE OPSOMMING: “Prone hip extension (PHE)” is ‘n kliniese toets en word gebruik om die funksionering van die lumbo-pelviese kompleks te evalueer, met die hooffokus die aktivering van die gluteus maksimusspier (Gmax). Die toets word ook as oefening gebruik om wanbalanse in die aktivering van die Gmax aan te spreek. Die ‘goue standaard’ waaraan die aktiveringsvolgorde (AS) gemeet word, is deur Janda (1991) bepaal. Die Gmaks speel ‘n belangrike rol in die voorkoming van beserings en in die belyning van die onderbeen, daarom word die aktivering daarvan as baie belangrik beskou. Geen vorige navorsing kon ‘n konstante AS identifiseer nie en dus word die funksionaliteit van die “PHE” bevraagteken. Doelwitte: Die hoofdoel van hierdie studie was om te bepaal of daar ‘n konstante AS tydens die “PHE” is, en indien daar ‘n ‘foutiewe’ AS geïdentifiseer is, of dit reggestel kon word deur spesifieke gluteale oefeninge te doen. Daar is ook gekyk na die AS wat voorkom tydens meer funksionele bewegings. Laastens het die studie ten doel gehad om vas te stel wat die invloed van ‘n verbeterde Gmaks aktivering op die belyning van die onderbeen sal wees. Metodes: Die spieraktiveringspatrone (tyd-genormaliseerde aanvang) van jong, gesonde klub netbalspelers is tydens die uitvoering van ‘n PHE, “quadruped opposite arm/leg extension” (QALE) en enkelbeen squatbeweging (SQT) gemeet. Die belyning van die onderbeen (valgus- en knie oor die tone hoek) is ook gemeet. Pre- (n=18) en post-toetsing (n=7) is deur middel van elektromiografie gedoen. Die volgende spiergroepe is ingesluit: Gmax, bisep femoris en die lumbale erector spinae. Die aanvang van aktivering word relatief tot die aanvang van die Gmax weergegee. Na afloop van die pre-toetsings, het die netbalspelers ‘n nege weke gluteale intervensieperiode ondergaan. Resultate: Daar is geen konstante AS opgemerk tydens die pre-toetsings (n=18) nie, maar die aanvang van Gmax-aktivering het eers na die lumbale erector spinae in beide linker en regter PHE plaasgevind. Tydens die post-toetsing (n=7) was die aktivering van die Gmax vroeër (links eerste en regs tweede) met die aktivering van die lumbale erector spinae wat later plaasgevind het (regs was betekenisvol, p<0.05). Die Gmax was konstant nie die eerste spier wat geaktiveer word tydens die uitvoering van die QALE en die SQT in die pre- en post-toetsings nie. Geen verandering in die belyning van die onderbeen is opgemerk met die aanvang van aktivering van die gluteale spier of die maksimale aktivering (p>0.05) tydens die SQT nie. Samevatting: Dit blyk dat die intervensie van gluteale oefeninge wel ‘n verbetering in gluteale aktivering teweeg gebring het tydens die PHE, maar dit het geen effek op die belyning van die onderbeen gehad nie tydens die SQT nie. Die bewinding bevraagteken die gebruik van die PHE as ‘n toets vir Gmax funksie. Die AS tydens die linker en egter PHE is baie na aan die voorgestelde norme en dus kan dit as verwysing gebruik word. Die QALE en SQT blyk nie ‘n goeie plaasvervanger te wees vir die PHE nie.

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