BACKGROUND: It has recently been reported that unilateral fatiguing exercise affects not only the motor area innervating the exercising muscle but also the ipsilateral motor area innervating homologous nonexercised muscle. OBJECTIVE: This study was designed to clarify the effects of fatiguing intermittent lower limb exercise on the excitability of the motor cortex representation of nonexercised muscles in the arm. METHODS: Eight subjects performed an intermittent leg press exercise composed of three bouts of 5-minute leg press (T1, T2, and T3) at 50% of maximal voluntary contraction separated by a 2-minute rest. Motor-evoked potentials (MEP), short interval intracortical inhibition (SICI), and intracortical facilitation (ICF), using paired-pulse transcranial magnetic stimulation, were assessed in two nonexercised arm muscles (first dorsal interosseous muscle: FDI, n = 8; biceps brachii muscle: BB, n = 6) and one exercised leg muscle (quadriceps femoris muscle: QF, n = 6) before and immediately after each bout of exercise and for 30 minutes during recovery after the end of the third exercise bout (Experiment 1). Experiment 2 was the same as Experiment 1, except that the test pulse intensity was adjusted to produce a given amplitude of MEP(TEST) at each time point. RESULTS: MEPs and SICI in the exercised QF muscle were depressed at all time points during and after fatigue. In contrast, MEPs in nonexercised arm muscles were facilitated from T1-T3 (T3, only FDI), but were then depressed for up to 20 minutes in the recovery period. SICI was reduced in both muscles during T1-T3 and remained depressed until 20 minutes into recovery. ICF was unchanged in arm muscles but depressed in QF over T1-T3. CONCLUSIONS: The current study indicates that muscle fatigue induced by exercise of a large lower limb muscle group has powerful effects on the excitability of both SICI and the corticospinal projection to muscles of the nonexercised upper limb.
BACKGROUND: It has recently been reported that unilateral fatiguing exercise affects not only the motor area innervating the exercising muscle but also the ipsilateral motor area innervating homologous nonexercised muscle. OBJECTIVE: This study was designed to clarify the effects of fatiguing intermittent lower limb exercise on the excitability of the motor cortex representation of nonexercised muscles in the arm. METHODS: Eight subjects performed an intermittent leg press exercise composed of three bouts of 5-minute leg press (T1, T2, and T3) at 50% of maximal voluntary contraction separated by a 2-minute rest. Motor-evoked potentials (MEP), short interval intracortical inhibition (SICI), and intracortical facilitation (ICF), using paired-pulse transcranial magnetic stimulation, were assessed in two nonexercised arm muscles (first dorsal interosseous muscle: FDI, n = 8; biceps brachii muscle: BB, n = 6) and one exercised leg muscle (quadriceps femoris muscle: QF, n = 6) before and immediately after each bout of exercise and for 30 minutes during recovery after the end of the third exercise bout (Experiment 1). Experiment 2 was the same as Experiment 1, except that the test pulse intensity was adjusted to produce a given amplitude of MEP(TEST) at each time point. RESULTS: MEPs and SICI in the exercised QF muscle were depressed at all time points during and after fatigue. In contrast, MEPs in nonexercised arm muscles were facilitated from T1-T3 (T3, only FDI), but were then depressed for up to 20 minutes in the recovery period. SICI was reduced in both muscles during T1-T3 and remained depressed until 20 minutes into recovery. ICF was unchanged in arm muscles but depressed in QF over T1-T3. CONCLUSIONS: The current study indicates that muscle fatigue induced by exercise of a large lower limb muscle group has powerful effects on the excitability of both SICI and the corticospinal projection to muscles of the nonexercised upper limb.
Authors: David George Behm; Tyler Cavanaugh; Patrick Quigley; Jonathan Christopher Reid; Priscyla Silva Monteiro Nardi; Paulo Henrique Marchetti Journal: Eur J Appl Physiol Date: 2015-09-26 Impact factor: 3.078
Authors: Paulo H Marchetti; Fernando H D de Oliveira Silva; Enrico G Soares; Erica P Serpa; Priscyla S M Nardi; Guanis de B Vilela; David G Behm Journal: J Sports Sci Med Date: 2014-12-01 Impact factor: 2.988
Authors: Olaf Prieske; Saied J Aboodarda; José A Benitez Sierra; David G Behm; Urs Granacher Journal: Eur J Appl Physiol Date: 2017-01-11 Impact factor: 3.078
Authors: Ashleigh E Smith; Mitchell R Goldsworthy; Tessa Garside; Fiona M Wood; Michael C Ridding Journal: Exp Brain Res Date: 2014-02-26 Impact factor: 1.972
Authors: D G Behm; E M Colwell; G M J Power; H Ahmadi; A S M Behm; A Bishop; C Murph; J Pike; B McAssey; K Fraser; S Kearley; M Ryan Journal: Eur J Appl Physiol Date: 2019-11-06 Impact factor: 3.078