Contraction mode shift in quadriceps femoris muscle activation during dynamic knee extensor exercise with increasing loads

Pincivero, Danny M.; Coelho, Alan J.; Campy, Robert M.

doi:10.1016/j.jbiomech.2008.09.003

Cited by 17 publications

(11 citation statements)

References 30 publications

(76 reference statements)

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“…EMG was taken only as an indicator of muscle activity to provide input data in the first step dedicated to the estimation of muscle group moments (see Eqs. (1) the strength of min/max optimization in force-sharing (Rasmussen et al, 2001) and provides muscle forces compatible with VL muscle dominance (Pincivero et al, 2006;2008), our results do not definitively resolve the question of appropriateness of force distribution within muscles. In the first step, the proposed method may benefit from more precise modeling of the forcegenerating potential of muscles.…”

Section: Discussionmentioning

confidence: 57%

A two-step EMG-and-optimization process to estimate muscle force during dynamic movement

Amarantini¹,

Rao²,

Berton³

2010

Journal of Biomechanics

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The present study proposed a two-step EMG-and-optimization method for muscle force estimation in dynamic condition. Considering the strengths and the limitations of existing methods, the proposed approach exploited the advantages of min/max optimization with constraints on the contributions of the flexor and extensor muscle groups to the net joint moment estimated through an EMG-to-moment approach. Our methodology was tested at the knee joint during dynamic half squats, and was compared with traditional min/max optimization. In general, results showed significant differences in muscle force estimates from EMG-and-optimization method when compared with those from traditional min/max optimization. Muscle forces were higher - especially in the antagonist muscles - and more consistent with EMG patterns because of the ability of the proposed approach to properly account for agonist/antagonist cocontraction. In addition, muscle forces agree with mechanical constraints regarding the net, the agonist, and the antagonist moments, thus greatly improving the confidence in muscle force estimates. The proposed two-step EMG-and-optimization method for muscle force estimation is easy to implement with relatively low computational requirements and, thus, could offer interesting advantages for various applications in many fields, including rehabilitation, clinical, and sports biomechanics.

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Section: Discussionmentioning

confidence: 57%

A two-step EMG-and-optimization process to estimate muscle force during dynamic movement

Amarantini¹,

Rao²,

Berton³

2010

Journal of Biomechanics

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“…Thus, body positioning, range of motion and time under tension per repetition was, if not identical, very similar for the two loading paradigms. It can only be speculated that training, at a diVerent action speed (Matheson et al 2001;Pincivero et al 2008), requesting more repetitions per set (Pincivero et al 2006), using other exercise modes (Andersen et al 2006;Wilk et al 1996) or employing other strategies (Sahaly et al 2003), would have impacted the outcome of the current study.…”

Section: Discussionmentioning

confidence: 86%

Flywheel resistance training calls for greater eccentric muscle activation than weight training

2010

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Changes in muscle activation and performance were studied in healthy men in response to 5 weeks of resistance training with or without "eccentric overload". Subjects, assigned to either weight stack (grp WS; n = 8) or iso-inertial "eccentric overload" flywheel (grp FW; n = 9) knee extensor resistance training, completed 12 sessions of four sets of seven concentric-eccentric actions. Pre- and post-measurements comprised maximal voluntary contraction (MVC), rate of force development (RFD) and training mode-specific force. Root mean square electromyographic (EMG(RMS)) activity of mm. vastus lateralis and medialis was assessed during MVC and used to normalize EMG(RMS) for training mode-specific concentric (EMG(CON)) and eccentric (EMG(ECC)) actions at 90°, 120° and 150° knee joint angles. Grp FW showed greater (p < 0.05) overall normalized angle-specific EMG(ECC) of vastii muscles compared with grp WS. Grp FW showed near maximal normalized EMG(CON) both pre- and post-training. EMG(CON) for Grp WS was near maximal only post-training. While RFD was unchanged following training (p > 0.05), MVC and training-specific strength increased (p < 0.05) in both groups. We believe the higher EMG(ECC) activity noted with FW exercise compared to standard weight lifting could be attributed to its unique iso-inertial loading features. Hence, the resulting greater mechanical stress may explain the robust muscle hypertrophy reported earlier in response to flywheel resistance training.

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“…Fast Fourier Transform (FFT) is the most general frequency analysis method; however, it was designed on the assumption that the calculated data range from − infinity to + infinity. Before analysis, the data are usually modified using some window function to correct the gap between the imaginary infinite data and real finite data if the amount of data is not sufficiently large 9,10. In the case of electromyography, several thousand temporal and linear data points are used for the analysis; however, only tens of spatial but two-dimensional data points are used because the pixel data from the region of interest (ROI) in each muscle must be calculated.…”

Section: Introductionmentioning

confidence: 99%

Frequency analysis of ultrasonic echo intensities of the skeletal muscle in elderly and young individuals

Nishihara¹,

Kawai²,

Hayashi³

et al. 2014

CIA

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BackgroundThe skeletal muscle echo intensity (EI) during ultrasound imaging has been investigated to evaluate the muscle quality. However, EI fluctuates according to the scanning conditions.MethodsThe motor functions and ultrasound images of 19 elderly (73±3.2 years) and 19 young (22±1.5 years) individuals were investigated and an EI frequency component was assessed for more reliable evaluations. Healthy elderly and young subjects participated in this study. The motor functions were assessed during walking and according to the knee extension muscle strength. The muscle thicknesses of rectus femoris (RF), vastus intermedius (VI), and quadriceps femoris (QF) were investigated. EIs were calculated and the mean frequencies of the regions of interest (MFROIs) for RF and VI were analyzed.ResultsEIs and MFROIs were greater in elderly subjects than in young subjects (P<0.01 for RF, and P<0.001 for VI, in EIs; and P<0.01 for RF, and P<0.05 for VI, in MFROIs). In young subjects, EI of RF was greater than that of VI; however, there was no difference between the RF and VI MFROIs in both elderly and young subjects. EIs of VI exhibited a significantly negative correlation with the QF thickness in both elderly and young subjects. RF MFROIs negatively correlated with the QF thickness and positively correlated with EI of VI in elderly subjects alone.ConclusionThese findings suggest that MFROIs of elderly individuals would have a larger value than those of young individuals; moreover, MFROIs did not fluctuate greatly with the tissue depth and scanning conditions. MFROIs might be thus useful for further investigations of muscle quality and applications for the early prevention of age-related motor functional decline.

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Contraction mode shift in quadriceps femoris muscle activation during dynamic knee extensor exercise with increasing loads

Cited by 17 publications

References 30 publications

A two-step EMG-and-optimization process to estimate muscle force during dynamic movement

A two-step EMG-and-optimization process to estimate muscle force during dynamic movement

Flywheel resistance training calls for greater eccentric muscle activation than weight training

Frequency analysis of ultrasonic echo intensities of the skeletal muscle in elderly and young individuals

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