Assessing Voluntary Muscle Activation with the Twitch Interpolation Technique

Shield, Anthony; Zhou, Shi

doi:10.2165/00007256-200434040-00005

Cited by 287 publications

(288 citation statements)

References 109 publications

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“…We can not address the impact of neural adaptations since no measurements of activation level were included in the present study. However, biceps curl is a coordinative easy exercise and by the twitch-interpolate technique it has been reported that untrained subjects have no or only minor activation deficits in simple movements (Shield and Zhou 2004). Thus, differences in neural adaptations should not explain the observed difference in 1RM biceps curl adaptations between L+A and A training.…”

Section: Discussionmentioning

confidence: 99%

Physiological elevation of endogenous hormones results in superior strength training adaptation

Rønnestad¹,

Nygaard²,

Raastad

2011

Eur J Appl Physiol

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This file was dowloaded from the institutional repository Brage NIH -brage.bibsys.no/nih Rønnestad, B. R., Nygaard, H., Raastad, T. (2011) ABSTRACTThe purpose of this study was to determine the influence of transiently elevated endogenous hormone concentrations during exercise on strength training adaptations. Nine subjects performed four unilateral strength training session per week on the elbow flexors for 11 weeks. During two of the weekly sessions, leg exercises were performed to acutely increase the systemic anabolic hormone concentration immediately before the exercises for one of the elbow flexors (L+A). On the two other weekly training sessions, the contralateral elbow flexors were trained without prior leg exercises (A). By randomizing one arm of the subjects to serve as a control and the other as experimental, both conditions have the same nutritional and genetic environment. Serum testosterone and growth hormone was significantly increased during the L+A training session, while no hormonal changes occurred in the A session. Both A and L+A increased 1RM in biceps curl, peak power in elbow flexors at 30% and 60% of 1RM, and muscle volume of the elbow flexors (p<0.05). However, only L+A achieved increase in CSA at the part of the arm flexors with largest cross sectional area (p<0.001), while no changes occurred in A. L+A had superior relative improvement in 1RM biceps curl and favorable muscle adaptations in elbow flexors compared to A (p<0.05). In conclusion, performing leg exercises prior to arm exercises, and thereby increasing the levels of serum testosterone and growth hormone, induced superior strength training adaptations compared to arm training without acute elevation of hormones.

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Section: Discussionmentioning

confidence: 99%

Physiological elevation of endogenous hormones results in superior strength training adaptation

Rønnestad¹,

Nygaard²,

Raastad

2011

Eur J Appl Physiol

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“…8 In patients, superimposed electrical stimulation is used to assess voluntary activation 9,10 or to assess changes in neural activation due to training or disuse. [11][12][13] With patients however, submaximal muscle stimulation is used frequently to calculate VA, 8,10,14,15 because submaximal currents are better tolerated. 10,16 Muscle stimulation is also easier to apply than nerve stimulation because of the location of the femoral nerve in the femoral triangle.…”

Section: Muscle Nerve 45: 841-848 2012mentioning

confidence: 99%

“…These experiments assess whether a practical modification of the interpolated twitch technique to make it less painful for subjects would result in similar levels of VA. A less stressful stimulation technique is important, because superimposed stimulation is the gold standard for measuring maximal voluntary activation in frail elderly subjects and subjects with musculoskeletal disorders. 8,10,14,15 MATERIALS AND METHODS Subjects. The participants were 13 healthy volunteers (9 male, 4 female) aged 26.0 6 3.6 years.…”

Section: Muscle Nerve 45: 841-848 2012mentioning

confidence: 99%

Effect of stimulation intensity on assessment of voluntary activation

2012

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Introduction: The interpolated twitch technique is often used to assess voluntary activation (VA) of skeletal muscles. We investigated VA and the voluntary torque-superimposed torque relationship using either supramaximal nerve stimulation or better tolerated submaximal muscle stimulation, which is often used with patients. Methods: Thirteen healthy subjects performed maximal and submaximal isometric knee extensions with superimposed maximal or submaximal doublets (100 Hz). Results: Superimposed torque relative to potentiated resting doublets was smaller with maximal nerve than with submaximal muscle stimulation. Maximal VA was 87 6 7% and 93 6 5% for submaximal muscle and maximal nerve stimulation, respectively. The individual voluntary torque-superimposed torque relationships were more linear for submaximal muscle stimulation, possibly leading to less overestimation of VA. Conclusions: Submaximal muscle stimulation can be used to estimate VA in the knee extensors. It is less painful, and overestimation of VA may be less compared with maximal nerve stimulation.

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“…15,16 Briefly, a single biphasic, supramaximal pulse (600 ms pulse duration) was delivered at rest and during maximal voluntary isometric contraction. Voluntary activation deficit was calculated using the ratio between the torques produced by the superimposition of a supra maximal twitch on a peak isometric contraction (a) and the torque produced by the same stimulus in the potentiated resting muscle (b).…”

Section: Voluntary Activation Deficitsmentioning

confidence: 99%

Resistance training and locomotor recovery after incomplete spinal cord injury: a case series

et al. 2007

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Study design: Longitudinal intervention case series. Objective: To determine if a 12-week resistance and plyometric training program results in improved muscle function and locomotor speed after incomplete spinal cord injury (SCI). Setting: University research setting. Methods: Three ambulatory individuals with chronic (18.772.2 months post injury) motor incomplete SCI completed 12 weeks of lower extremity resistance training combined with plyometric training (RPT). Muscle maximum cross-sectional area (max-CSA) of the knee extensor (KE) and plantar flexor (PF) muscle groups was determined using magnetic resonance imaging (MRI). In addition, peak isometric torque, time to peak torque (T 20-80 ), torque developed within the initial 220 ms of contraction (torque 220 ) and average rate of torque development (ARTD) were calculated as indices of muscle function. Maximal as well as selfselected gait speeds were determined pre-and post-RPT during which the spatio-temporal characteristics, kinematics and kinetics of gait were measured. Results: RPT resulted in improved peak torque production in the KE (28.974.4%) and PF (35.079.1%) muscle groups, as well as a decrease in T 20-80 , an increased torque 220 and an increase ARTD in both muscle groups. In addition, an increase in self-selected (pre-RPT ¼ 0.77 m/s; post-RPT ¼ 1.03 m/s) and maximum (pre-RPT ¼ 1.08 m/s; post-RPT ¼ 1.47 m/s) gait speed was realized. Increased gait speeds were accompanied by bilateral increases in propulsion and hip excursion as well as increased lower extremity joint powers. Conclusions: The combination of lower extremity RPT can attenuate existing neuromuscular impairments and improve gait speed in persons after incomplete SCI.

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Assessing Voluntary Muscle Activation with the Twitch Interpolation Technique

Cited by 287 publications

References 109 publications

Physiological elevation of endogenous hormones results in superior strength training adaptation

Physiological elevation of endogenous hormones results in superior strength training adaptation

Effect of stimulation intensity on assessment of voluntary activation

Resistance training and locomotor recovery after incomplete spinal cord injury: a case series

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