Cross-education: effects of age on rapid and maximal voluntary contractile characteristics in males

Electromyography (EMG) is a research tool used in gait analysis, muscle coordination evaluation, clinical evaluation and sports techniques. Electromyography can provide an insight into neural adaptations, cross education effects, bilateral contraction deficiencies, and antagonist activity in exercise-related movements. While there are clear benefits to using EMG in exercise-related professions, accessibility, cost, and difficulty interpreting the data limit its use in strength and clinical settings. We propose a practical EMG assessment using the isometric squat to identify compensatory activation patterns and report early observations. Ten healthy participants were recruited. Participants performed a 2-min isometric handgrip protocol and an isometric squat protocol. The isometric handgrip was used to identify the expected EMG amplitude response solely due to fatigue. There was a significant increase in EMG amplitude after 2 min (p < 0.05), with the relative increase of 95% CI (1.4%; 27.4%). This indicates the relative increase in EMG amplitude expected if the only influence was fatigue in the 2-min protocol. In the isometric squat protocol, we identified a number of different muscle activation compensation strategies with relative EMG amplitude increases outside of this bandwidth. One subject demonstrated a quadricep compensation strategy with a 188% increase in activation, while reducing activation in both the hamstrings and lower back by 12%. Exercise professionals can use this information to design exercise programs specifically targeting the unloaded muscles during the isometric squat.

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Local and Contralateral Effects after the Application of Neuromuscular Electrostimulation in Lower Limbs

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph17239028 ◽

2020 ◽

Vol 17 (23) ◽

pp. 9028

Author(s):

Elisa Benito-Martínez ◽

Diego Senovilla-Herguedas ◽

Julio César de la Torre-Montero ◽

María Jesús Martínez-Beltrán ◽

María Mercedes Reguera-García ◽

...

Keyword(s):

Healthy Subjects ◽

Local Level ◽

Lower Limbs ◽

Anterior Region ◽

Measurement Tool ◽

Cross Education ◽

Education Effects ◽

Neuromuscular Electrostimulation ◽

Dominant Side ◽

Contralateral Effects

Neuromuscular electrostimulation (NMES) has been used mainly as a method to promote muscle strength, but its effects on improving blood flow are less well known. The aim of this study is to deepen the knowledge about the local and contralateral effects of the application of symmetric biphasic square currents on skin temperature (Tsk). An experimental pilot study was developed with a single study group consisting of 45 healthy subjects. Thermographic evaluations were recorded following the application of NMES to the anterior region of the thigh. The results showed an increase in the maximal Tsk of 0.67% in the anterior region of the thigh where the NMES was applied (p < 0.001) and an increase of 0.54% (p < 0.01) due to cross-education effects, which was higher when the NMES was applied on the dominant side (0.79%; p < 0.01). The duration of the effect was 20 min in the dominant leg and 10 min in the nondominant one. The application of a symmetrical biphasic current (8 Hz and 400 μs) creates an increase in the maximal Tsk at the local level. A temperature cross-education effect is produced, which is greater when the NMES is applied on the dominant side. This could be a useful noninvasive measurement tool in NMES treatments.

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Evidence of homologous and heterologous effects after unilateral leg training in youth

Applied Physiology Nutrition and Metabolism ◽

10.1139/apnm-2017-0338 ◽

2018 ◽

Vol 43 (3) ◽

pp. 282-291 ◽

Cited By ~ 4

Author(s):

Aymen Ben Othman ◽

David G. Behm ◽

Anis Chaouachi

Keyword(s):

Handgrip Strength ◽

High Load ◽

Upper Body ◽

Knee Extensors ◽

Leg Press ◽

Positive Effects ◽

Low Load ◽

Cross Education ◽

Education Effects ◽

Unilateral Training

The positive effects of unilateral training on contralateral muscles (cross education) has been demonstrated with adults for over a century. There is limited evidence for cross education of heterologous muscles. Cross education has not been demonstrated with children. It was the objective of this study to investigate cross-education training in children examining ipsilateral and contralateral homologous and heterologous muscles. Forty-eight male children (aged 10–13 years) were assessed for unilateral, ipsilateral and contralateral lower limb strength, power and endurance (1-repetition maximum (RM) leg press, knee extensors (KE) and flexors (KF) maximum voluntary isometric contractions (MVIC), countermovement jump, muscle endurance test (leg press repetitions with 60% 1RM)), and upper body unilateral MVIC elbow flexors (EF) and handgrip strength. An 8-week training program involved 2 unilateral leg press resistance-training groups (high load/low repetitions: 4–8 sets of 5RM, and low load/high repetitions: 1–2 sets of 20RM) and control (untrained) group. All muscles exhibited improvements of 6.1% to 89.1%. The trained limb exhibited greater adaptations than the untrained limb for leg press 1RM (40.3% vs. 25.2%; p = 0.005), and 60% 1RM leg press (104.1% vs. 73.4%; p = 0.0001). The high load/low repetition training induced (p < 0.0001) greater improvements than low load/high repetition with KE, KF, EF MVIC and leg press 1RM. This is the first study to demonstrate cross-education effects with children and that the effects of unilateral training involve both contralateral homologous and heterologous muscles with the greatest strength-training responses from high-load/low-repetition training.

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Contralateral effects of unilateral training: sparing of muscle strength and size after immobilization

Applied Physiology Nutrition and Metabolism ◽

10.1139/apnm-2018-0073 ◽

2018 ◽

Vol 43 (11) ◽

pp. 1131-1139 ◽

Cited By ~ 8

Author(s):

Justin W. Andrushko ◽

Layla A. Gould ◽

Jonathan P. Farthing

Keyword(s):

Strength Training ◽

Potential Interaction ◽

Muscle Size ◽

Clinical Settings ◽

Cross Sectional ◽

Published Evidence ◽

Cross Education ◽

New Research ◽

Education Effects ◽

Contralateral Effects

The contralateral effects of unilateral strength training, known as cross-education of strength, date back well over a century. In the last decade, a limited number of studies have emerged demonstrating the preservation or “sparing” effects of cross-education during immobilization. Recently published evidence reveals that the sparing effects of cross-education show muscle site specificity and involve preservation of muscle cross-sectional area. The new research also demonstrates utility of training with eccentric contractions as a potent stimulus to preserve immobilized limb strength across multiple modes of contraction. The cumulative data in nonclinical settings suggest that cross-education can completely abolish expected declines in strength and muscle size in the range of ∼13% and ∼4%, respectively, after 3–4 weeks of immobilization of a healthy arm. The evidence hints towards the possibility that unique mechanisms may be involved in preservation effects of cross-education, as compared with those that lead to functional improvements under normal conditions. Cross-education effects after strength training appear to be larger in clinical settings, but there is still only 1 randomized clinical trial demonstrating the potential utility of cross-education in addition to standard treatment. More work is necessary in both controlled and clinical settings to understand the potential interaction of neural and muscle adaptations involved in the observed sparing effects, but there is growing evidence to advocate for the clinical utility of cross-education.

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