Tweet
Can We Really Prioritise Recruitment of the Vastus Medialis?
In gyms everywhere it is commonplace to hear of fitness professionals recommending specific exercises to their clients which attempt to preferentially increase recruitment of the vastus medialis over the other quadriceps femoris muscles. These exercises are often prescribed in response to their client's exhibition of knee valgus (collapsing knees) and much of the time consist of an alteration of squat stance width and foot placement angle.
Whether or not the vastus medialis even plays a significant role in knee valgus is a topic for another article and so this post will focus on whether or not it is actually possible to significantly recruit one quadriceps muscle over the other with respect to lower limb positioning. Let’s take a look at the research.
1. What does the various research say?
A study by Paoli A et al. (2009)[1] looked at the effect that stance width had on 8 superficial thigh muscles during the back squat.
This study - consisting of 6 men in their twenties with at least 3 years of lifting experience -tested EMG activity of the vastus medialis, vastus lateralis, rectus femoris, semitendinosus, biceps femoris, gluteus maximus, gluteus medius and adductor magnus muscles during different squatting stance widths and with various resistances.
The protocol was divided over two sessions. The first session the subjects familiarized themselves with the exercises before determining their individual 1RM for the back squat. During the second session surface electrodes were placed on the aforementioned muscles. Following this the subjects were required to perform 3 sets of squats (0% 1RM, 30% 1RM and 70% 1RM) for 10 repetitions at a stance width 100% of their greater trochanter distance (GTd – distance between tops of femurs), 3 sets of squats (0% 1RM, 30% 1RM and 70% 1RM) for 10 repetitions at a distance of 150% of GTd and finally 3 sets of squats (0% 1RM, 30% 1RM and 70% 1RM) for 10 repetitions at 200% of GTd. The subjects were given 3 minutes rest between sets and 6 minutes rest between trials. All trials were randomized for each subject and performed on the same day to avoid electrode placement inconsistency. Their results were as follows:
• Greater EMG activity was observed with increasing loads from 0% 1RM – 70% 1RM for each muscle.
• No significant differences were found in EMG activity between any of the quadriceps muscles with either of the three stance widths for 0, 30 and 70% 1RM.
• However gluteus maximus activity was significantly higher as stance width increased.
This is just one piece of research that suggests that altering squatting stance width has no significant impact on preferential activation of the vastus medialis. To get a more conclusive opinion on the subject it is worth looking at this systematic review carried out by Smith and colleagues back in 2009[2].
In their paper – “Can vastus medialis oblique be preferentially activated? A systematic review of electromyographic studies” – they collected all relevant EMG data surrounding the vastus medialis and vastus lateralis. Out of the 66 papers chosen for scrutiny following an electronic search of 8 medical databases, 20 papers met their criterion for inclusion. Listed below are some of their conclusions as it relates to targeting these quadriceps muscles:
• There is little evidence of preferential vastus medialis oblique activation through hip adduction or abduction. Out of 8 studies one did show that performing isometric hip adduction produced a significantly greater VMO:VL activation ratio compared to a control group. The remaining 7 showed no difference.
• Little evidence showing that hip internal and external rotation has any significant effect on VMO:VL ratio.
• When comparing tibial internal and external rotation there was no significant difference in activation levels between the VMO and VL compared to a neutral orientation.
• Both foot pronation/supination and ankle dorsi flexion and plantar flexion did not change VMO:VL activity during quadriceps exercises.
• Their findings show that there is insufficient evidence to suggest that the VMO can be preferentially activated and strengthed.
2. Take-home points.
It would appear that the evidence espousing the benefits of exercise alteration for the purposes of enhancing specific quadriceps muscle recruitment is lacking and therefore would suggest that attempting to do so, especially in a gym setting, is likely useless. Smith and colleagues also mention that “physiotherapists should not attempt to focus primarily on the VMO as traditionally recommended, because such exercises may be futile in enhancing VMO activity.” Rather than focusing on specifically trying to strengthen the vastus medialis muscle, it would make sense to spend time building up the quadriceps muscle as a whole.
Lastly, this doesn't include the rectus femoris which is a biarticular muscle and therefore undergoes different length-tension relationships depending on knee and hip angle.
1)The effect of stance width on the electr... [J Strength Cond Res. 2009] - PubMed - NCBI
2)http://www.bamt.be/nieuwsbrief/04-2013/art7.pdf
Bron: Shredded By Science
Denk dat de meesten dit wel wisten/verwachtten, maar desalniettemin een interessant artikel
In gyms everywhere it is commonplace to hear of fitness professionals recommending specific exercises to their clients which attempt to preferentially increase recruitment of the vastus medialis over the other quadriceps femoris muscles. These exercises are often prescribed in response to their client's exhibition of knee valgus (collapsing knees) and much of the time consist of an alteration of squat stance width and foot placement angle.
Whether or not the vastus medialis even plays a significant role in knee valgus is a topic for another article and so this post will focus on whether or not it is actually possible to significantly recruit one quadriceps muscle over the other with respect to lower limb positioning. Let’s take a look at the research.
1. What does the various research say?
A study by Paoli A et al. (2009)[1] looked at the effect that stance width had on 8 superficial thigh muscles during the back squat.
This study - consisting of 6 men in their twenties with at least 3 years of lifting experience -tested EMG activity of the vastus medialis, vastus lateralis, rectus femoris, semitendinosus, biceps femoris, gluteus maximus, gluteus medius and adductor magnus muscles during different squatting stance widths and with various resistances.
The protocol was divided over two sessions. The first session the subjects familiarized themselves with the exercises before determining their individual 1RM for the back squat. During the second session surface electrodes were placed on the aforementioned muscles. Following this the subjects were required to perform 3 sets of squats (0% 1RM, 30% 1RM and 70% 1RM) for 10 repetitions at a stance width 100% of their greater trochanter distance (GTd – distance between tops of femurs), 3 sets of squats (0% 1RM, 30% 1RM and 70% 1RM) for 10 repetitions at a distance of 150% of GTd and finally 3 sets of squats (0% 1RM, 30% 1RM and 70% 1RM) for 10 repetitions at 200% of GTd. The subjects were given 3 minutes rest between sets and 6 minutes rest between trials. All trials were randomized for each subject and performed on the same day to avoid electrode placement inconsistency. Their results were as follows:
• Greater EMG activity was observed with increasing loads from 0% 1RM – 70% 1RM for each muscle.
• No significant differences were found in EMG activity between any of the quadriceps muscles with either of the three stance widths for 0, 30 and 70% 1RM.
• However gluteus maximus activity was significantly higher as stance width increased.
This is just one piece of research that suggests that altering squatting stance width has no significant impact on preferential activation of the vastus medialis. To get a more conclusive opinion on the subject it is worth looking at this systematic review carried out by Smith and colleagues back in 2009[2].
In their paper – “Can vastus medialis oblique be preferentially activated? A systematic review of electromyographic studies” – they collected all relevant EMG data surrounding the vastus medialis and vastus lateralis. Out of the 66 papers chosen for scrutiny following an electronic search of 8 medical databases, 20 papers met their criterion for inclusion. Listed below are some of their conclusions as it relates to targeting these quadriceps muscles:
• There is little evidence of preferential vastus medialis oblique activation through hip adduction or abduction. Out of 8 studies one did show that performing isometric hip adduction produced a significantly greater VMO:VL activation ratio compared to a control group. The remaining 7 showed no difference.
• Little evidence showing that hip internal and external rotation has any significant effect on VMO:VL ratio.
• When comparing tibial internal and external rotation there was no significant difference in activation levels between the VMO and VL compared to a neutral orientation.
• Both foot pronation/supination and ankle dorsi flexion and plantar flexion did not change VMO:VL activity during quadriceps exercises.
• Their findings show that there is insufficient evidence to suggest that the VMO can be preferentially activated and strengthed.
2. Take-home points.
It would appear that the evidence espousing the benefits of exercise alteration for the purposes of enhancing specific quadriceps muscle recruitment is lacking and therefore would suggest that attempting to do so, especially in a gym setting, is likely useless. Smith and colleagues also mention that “physiotherapists should not attempt to focus primarily on the VMO as traditionally recommended, because such exercises may be futile in enhancing VMO activity.” Rather than focusing on specifically trying to strengthen the vastus medialis muscle, it would make sense to spend time building up the quadriceps muscle as a whole.
Lastly, this doesn't include the rectus femoris which is a biarticular muscle and therefore undergoes different length-tension relationships depending on knee and hip angle.
1)The effect of stance width on the electr... [J Strength Cond Res. 2009] - PubMed - NCBI
2)http://www.bamt.be/nieuwsbrief/04-2013/art7.pdf
Bron: Shredded By Science
Denk dat de meesten dit wel wisten/verwachtten, maar desalniettemin een interessant artikel
