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John P. Miller, Daniel Sedory and Ronald V. Croce

The purpose of this study was to examine the efficacy of closed kinetic chain exercises in preferentially recruiting the oblique fibers of the vastus medialis obliquus (VMO). Fifteen athletically active females, 6 with patellofemoral pain syndrome (PFPS) and 9 without PFPS, performed two isometric and two dynamic closed kinetic chain exercises. The isometric exercises were a static lunge with 30° of knee flexion (SL@30°) and with 70° of knee flexion (SL@70°). The dynamic exercises were a step-up/step-down exercise (SUSD) and a modified wall slide (MWS). Selective recruitment of the VMO occurred during the MWS (p < .05) and the SUSD in the subjects without PFPS (p < .05). For the SL@70° (p < .01), the MWS (p < .01), and the SUSD (p < .05), subjects with PFPS had greater activity of the vastus lateralis (VL), resulting in a lower VMO: VL ratio for those exercises (p < .05). It was concluded that the closed kinetic chain exercises examined in this study do not preferentially recruit the VMO in individuals with PFPS. In addition, individuals with PFPS have a lower VMO:VL ratio during these exercises compared to individuals without PFPS.

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Jeffrey J. Brault, Theodore F. Towse, Jill M. Slade and Ronald A. Meyer

Short-term creatine supplementation is reported to result in a decreased ratio of phosphocreatine (PCr) to total creatine (TCr) in human skeletal muscle at rest. Assuming equilibrium of the creatine kinase reaction, this decrease in PCr:TCr implies increased cytoplasmic ADP and decreased Gibbs free energy of ATP hydrolysis in muscle, which seems contrary to the reported ergogenic benefits of creatine supplementation. This study measured changes in PCr and TCr in vastus lateralis muscle of adult men (N = 6, 21–35 y old) during and 1 day after 5 d of creatine monohydrate supplementation (0.43 g·kg body weight−1·d−1) using noninvasive 31P and 1H magnetic-resonance spectroscopy (MRS). Plasma and red-blood-cell creatine increased by 10-fold and 2-fold, respectively, by the third day of supplementation. MRS-measured skeletal muscle PCr and TCr increased linearly and in parallel throughout the 5 d, and there was no significant difference in the percentage increase in muscle PCr (11.7% ± 2.3% after 5 d) vs. TCr (14.9% ± 4.1%) at any time point. The results indicate that creatine supplementation does not alter the PCr:TCr ratio, and hence the cytoplasmic Gibbs free energy of ATP hydrolysis, in human skeletal muscle at rest.

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Nicole M. Livecchi, Charles W. Armstrong, Mitchell L. Cordova, Mark A. Merrick and James M. Rankin

Objective:

To compare average electromyogram (EMG) activity of the vastus medialis obliquus (VMO) and vastus lateralis (VL) during straight-leg raise (SLR) and knee extension (KE) with the hip in neutral and lateral rotation.

Design:

1 × 4 factorial repeated-measures.

Setting:

Laboratory.

Participants:

13 male college students.

Intervention:

SLR with hip flexed at 40°, in neutral position, and maximally laterally rotated and KE with hip in neutral and maximally laterally rotated.

Main Outcome Measure:

Average EMG activity during each of the 4 conditions, normalized against peak muscle activity during that trial.

Results:

No differences were observed between exercises in VMO activity (F 3,36 = 0.646, P > .05), VL activity (F 3,36 = 1.08, P > .05), or VMO:VL ratio (F 3,36 = 0.598, P > .05).

Conclusions:

Electrical activity of the VMO or VL and VMO:VL ratio do not change with hip position or exercise.

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Ricky Anderson, Carol Courtney and Eli Carmeli

The purpose of this study was to see if vastus medialis oblique/vastus lateralis (VMO:VL) ratios could be increased by widening the squat stance and if the VMO activity increases with deeper ranges of knee flexion. Fifteen healthy subjects performed unloaded narrow and wide stance squats through three ranges of knee flexion: 30°, 60°, and 90°. The two squat stances were compared using a 2 × 3 ANOVA to see if the wide-stance squat had any significant difference in EMG activity for VMO: VL ratios compared to the narrow-stance squat. The difference in EMG activity of the VMO between the various angles for both squat stances was also compared. The ANOVA revealed no significant differences between the squat stances for VMO:VL ratios but did show the VMO:VL ratios to be significantly higher with increasing knee flexion angles. These findings suggest that the VMO is active throughout the 90° range and that increasing knee flexion angles can elicit greater activity of the VMO relative to the VL.

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Bret Contreras, Andrew D. Vigotsky, Brad J. Schoenfeld, Chris Beardsley and John Cronin

The back squat and barbell hip thrust are both popular exercises used to target the lower body musculature; however, these exercises have yet to be compared. Therefore, the purpose of this study was to compare the surface electromyographic (EMG) activity of the upper and lower gluteus maximus, biceps femoris, and vastus lateralis between the back squat and barbell hip thrust. Thirteen trained women (n = 13; age = 28.9 years; height = 164 cm; mass = 58.2 kg) performed estimated 10-repetition maximums (RM) in the back squat and barbell hip thrust. The barbell hip thrust elicited significantly greater mean (69.5% vs 29.4%) and peak (172% vs 84.9%) upper gluteus maximus, mean (86.8% vs 45.4%) and peak (216% vs 130%) lower gluteus maximus, and mean (40.8% vs 14.9%) and peak (86.9% vs 37.5%) biceps femoris EMG activity than the back squat. There were no significant differences in mean (99.5% vs 110%) or peak (216% vs 244%) vastus lateralis EMG activity. The barbell hip thrust activates the gluteus maximus and biceps femoris to a greater degree than the back squat when using estimated 10RM loads. Longitudinal training studies are needed to determine if this enhanced activation correlates with increased strength, hypertrophy, and performance.

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Bret Contreras, Andrew D. Vigotsky, Brad J. Schoenfeld, Chris Beardsley and John Cronin

Bridging exercise variations are well researched and commonly employed for both rehabilitation and sport performance. However, resisted bridge exercise variations have not yet been compared in a controlled experimental study. Therefore, the purpose of this study was to compare the differences in upper and lower gluteus maximus, biceps femoris, and vastus lateralis electromyography (EMG) amplitude for the barbell, band, and American hip thrust variations. Thirteen healthy female subjects (age = 28.9 y; height = 164.3 cm; body mass = 58.2 kg) familiar with the hip thrust performed 10 repetitions of their 10-repetition maximum of each variation in a counterbalanced and randomized order. The barbell hip thrust variation elicited statistically greater mean gluteus maximus EMG amplitude than the American and band hip thrusts, and statistically greater peak gluteus maximus EMG amplitude than the band hip thrust (P ≤ .05), but no other statistical differences were observed. It is recommended that resisted bridging exercise be prescribed according to the individual’s preferences and desired outcomes.

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Bret Contreras, Andrew D. Vigotsky, Brad J. Schoenfeld, Chris Beardsley and John Cronin

Front, full, and parallel squats are some of the most popular squat variations. The purpose of this investigation was to compare mean and peak electromyography (EMG) amplitude of the upper gluteus maximus, lower gluteus maximus, biceps femoris, and vastus lateralis of front, full, and parallel squats. Thirteen healthy women (age = 28.9 ± 5.1 y; height = 164 ± 6.3 cm; body mass = 58.2 ± 6.4 kg) performed 10 repetitions of their estimated 10-repetition maximum of each respective variation. There were no statistical (P = .05) differences between full, front, and parallel squats in any of the tested muscles. Given these findings, it can be concluded that the front, full, or parallel squat can be performed for similar EMG amplitudes. However, given the results of previous research, it is recommended that individuals use a full range of motion when squatting, assuming full range can be safely achieved, to promote more favorable training adaptations. Furthermore, despite requiring lighter loads, the front squat may provide a similar training stimulus to the back squat.

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Harry E. Routledge, Jill J. Leckey, Matt J. Lee, Andrew Garnham, Stuart Graham, Darren Burgess, Louise M. Burke, Robert M. Erskine, Graeme L. Close and James P. Morton

significantly greater in AF (1322 m) versus rugby league (327 m) and soccer (517 m). 2 To the authors’ knowledge, however, no researchers have yet quantified the muscle glycogen cost of AF match play in elite players. The aim of this case study was to quantify glycogen use in m. vastus lateralis from 2 elite

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Dustin J. Oranchuk, André R. Nelson, Adam G. Storey and John B. Cronin

, quadriceps muscle architecture at proximal, middle, and distal regions of the vastus lateralis, rectus femoris, and anterior and lateral vastus intermedius was examined using B-mode and EFOV ultrasonography. Each participant was tested on 3 separate occasions, separated by 5 to 8 days, and the ICC, TEM, and

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Kevin Yoh and Benjamin W. Infantolino