Changes in Functional Magnetic Resonance Imaging Cortical Activation with Cross Education to an Immobilized Limb

Farthing, Jonathan P.; Krentz, Joel R.; Magnus, Charlene R.A.; Barss, Trevor S.; Lanovaz, Joel L.; Cummine, Jacqueline; Esopenko, Carrie; Sarty, Gordon E.; Borowsky, Ron

doi:10.1249/mss.0b013e318210783c

Cited by 63 publications

(77 citation statements)

References 42 publications

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“…Recently, several trials have shown that the strength of an immobilized arm can be maintained when the contralateral limb undergoes resistance training during the immobilization period (Farthing et al. 2009, 2011; Magnus et al. 2010).…”

Section: Discussionmentioning

confidence: 99%

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Low-load resistance training during step-reduction attenuates declines in muscle mass and strength and enhances anabolic sensitivity in older men

et al. 2015

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Step-reduction (SR) in older adults results in muscle atrophy and an attenuated rise in postprandial muscle protein synthesis (MPS): anabolic resistance. Knowing that resistance exercise (RT) can enhance MPS, we examined whether RT could enhance MPS following 2 weeks of SR. In addition, as we postulated that SR may impair feeding-induced vasodilation limiting nutrient delivery to muscle, we also examined whether citrulline (CIT), as an arginine and nitric oxide precursor, could attenuate muscle anabolic resistance accompanying SR. We used a unilateral leg model to compare older subjects’ who had undergone SR to a loaded condition of SR plus RT (SR + RT). Thirty older men (70 ± 1 years) underwent 14 days of SR (<1500 steps/day) with supplementation of either 5 g/day CIT or glycine placebo. Throughout SR, subjects performed unilateral low-load RT thrice weekly. We assessed muscle protein synthesis in the postabsorptive and postprandial state (20 g whey isolate plus 15 g glycine or as micellar-whey with 5 g CIT or 15 g glycine, n = 10/group). As MPS was similar after ingestion of either whey isolate, micellar-whey, or micellar-whey + CIT data related to different dietary groups were collapsed to compare SR and SR + RT legs. Subjects’ daily steps were reduced by 80 ± 2% during SR (P < 0.001) compared with baseline. Leg fat-free mass decreased with SR (−124 ± 61 g) and increased in the SR + RT (+126 ± 68 g; P = 0.003). Myofibrillar FSR was lower (P < 0.0001) in the SR as compared with the SR + RT leg in the postabsorptive (0.026 ± 0.001%/h vs. 0.045 ± 0.001%/h) and postprandial states (0.055 ± 0.002%/h vs. 0.115 ± 0.003%/h). We conclude that low-load RT, but not supplementation with CIT, can attenuate the deleterious effects of SR in aging muscle.

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Section: Discussionmentioning

confidence: 99%

“…It is, however, equivocal as to whether cross education to an immobilized limb attenuates atrophy with studies showing no effect (Farthing et al. 2011) or a relative preservation of muscle thickness (Farthing et al. 2009; Magnus et al.…”

Section: Discussionmentioning

confidence: 99%

Low-load resistance training during step-reduction attenuates declines in muscle mass and strength and enhances anabolic sensitivity in older men

et al. 2015

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“…As the neurophysiological evidence for cross-education is demonstrating that the nervous system is responding to unilateral training, the logical step for further investigation is the clinical environment (such as immobilisation or un-weighting of a limb). Initial studies in upper limb have shown positive results (Farthing et al , 2011Magnus et al 2010) and it appears likely that the same protocol can be used to benefit people with lower limb injuries.…”

Section: Discussionmentioning

confidence: 99%

Reduction in corticospinal inhibition in the trained and untrained limb following unilateral leg strength training

2011

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This study used transcranial magnetic stimulation to measure the corticospinal responses following 8 weeks of unilateral leg strength training. Eighteen healthy, non-strength trained participants (14 male, 4 female; 18-35 years of age) were matched for age, gender, and pre-training strength; and assigned to a training or control group. The trained group participated in unilateral horizontal leg press strength training, progressively overloaded and wave periodised, thrice per week for 8 weeks. Testing occurred prior to the intervention, at the end of 4 weeks and at the completion of training at 8 weeks. Participants were tested in both legs for one repetition maximum strength, muscle thickness, maximal electromyography (EMG) activity, and corticospinal excitability and inhibition. No changes were observed in muscle thickness in either leg. The trained leg showed an increase in strength of 21.2% (P = 0.001) and 29.0% (P = 0.007, compared to pre-testing) whilst the untrained contralateral leg showed 17.4% (P = 0.01) and 20.4% (P = 0.004, compared to pre-testing) increases in strength at 4 and 8 weeks, respectively. EMG and corticospinal excitability did not change; however, corticospinal inhibition was significantly reduced by 17.7 ms (P = 0.003) and 17.3 ms (P = 0.001) at 4 and 8 weeks, respectively, in the trained leg, and 25.1 ms (P = 0.001) and 20.8 ms (P = 0.001) at 4 and 8 weeks, respectively, in the contralateral untrained leg. This data support the theory of corticospinal adaptations underpinning cross-education gains in the lower limbs following unilateral strength training.

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“…Recent physiological studies, with the quantification of some of the cardiorespiratory responses to predominantly static exercises using small and different muscle groups and with different percentages of maximal voluntary strength, have contributed to a better understanding of the mechanisms associated with IHT and similar exercises 14,15,[33][34][35][36][37] . Nevertheless, when these physiological data, respecting the methodological differences and small samples involved, are compared with our results, one can identify a 13 .…”

Section: Discussionmentioning

confidence: 99%

Respostas hemodinâmicas a um protocolo de treinamento isométrico de preensão manual

Araújo¹,

Duarte

Gonçalves

et al. 2011

Arq. Bras. Cardiol.

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Changes in Functional Magnetic Resonance Imaging Cortical Activation with Cross Education to an Immobilized Limb

Abstract: Handgrip strength training of the free limb attenuated strength loss during unilateral immobilization. The maintenance of strength in the immobilized limb via the cross-education effect may be associated with increased motor cortex activation.

Cited by 63 publications

References 42 publications

Low-load resistance training during step-reduction attenuates declines in muscle mass and strength and enhances anabolic sensitivity in older men

Low-load resistance training during step-reduction attenuates declines in muscle mass and strength and enhances anabolic sensitivity in older men

Reduction in corticospinal inhibition in the trained and untrained limb following unilateral leg strength training

Respostas hemodinâmicas a um protocolo de treinamento isométrico de preensão manual

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