Increased spinal reflex excitability is not associated with neural plasticity underlying the cross-education effect

2006 ◽  
Vol 100 (1) ◽  
pp. 83-90 ◽  
Author(s):  
Olle Lagerquist ◽  
E. Paul Zehr ◽  
David Docherty
Keyword(s):  
Strength Training ◽  
Plantar Flexion ◽  
Exercise Group ◽  
H Reflex ◽  
Spinal Reflex ◽  
Control Group ◽  
M Wave ◽  
Education Effect ◽  
Cross Education ◽  
The Cross

The purpose of this study was to examine the effects of a 5-wk unilateral, isometric strength-training program on plasticity in the spinal Hoffmann (H-) reflex in both the trained and untrained legs. Sixteen participants, 22–42 yr old, were assigned to either a control ( n = 6) or an exercise group ( n = 10). Both groups were tested for plantar flexion maximal voluntary isometric contractions (MVIC) and soleus H-reflex amplitude in both limbs, at the beginning and at the end of a 5-wk interval. Participants in the exercise group showed significantly increased MVIC in both legs after training ( P < 0.05), whereas strength was unchanged in the control group for either leg. Subjects in the exercise group displayed increased ( P < 0.05) H-reflex amplitudes on the ascending limb of the recruitment curve (at an equivalent M wave of 5% of the maximal M wave, HA) only in the trained leg. Maximal H-reflex and M-wave remained unchanged with training. Increased amplitude of HA in the trained limb concurrent with increased strength suggests that spinal mechanisms may underlie the changes in strength, possibly because of increased α-motoneuronal excitability or reduced presynaptic inhibition. Despite a similar increase in strength in the contralateral limb of the exercise group, HA amplitude was unchanged. We conclude that the cross-education effect of strength training may be due to supraspinal to a greater extent than spinal mechanisms.

scholarly journals Lifelong strength training mitigates the age-related decline in efferent drive

2016 ◽  
Vol 121 (2) ◽  
pp. 415-423 ◽  
Author(s):  
Runar Unhjem ◽  
Mona Nygård ◽  
Lene T. van den Hoven ◽  
Simranjit K. Sidhu ◽  
Jan Hoff ◽  
...  
Keyword(s):  
Strength Training ◽  
Plantar Flexion ◽  
H Reflex ◽  
Voluntary Activation ◽  
M Wave ◽  
Reflex Amplitude ◽  
Age Related ◽  
Musculus Soleus ◽  
V Wave ◽  
Voluntary Contractions

Recently, we documented age-related attenuation of efferent drive to contracting skeletal muscle. It remains elusive if this indication of reduced muscle strength is present with lifelong strength training. For this purpose, we examined evoked potentials in the calf muscles of 11 [71 ± 4 (SD) yr] strength-trained master athletes (MA) contrasted with 10 (71 ± 4 yr) sedentary (SO) and 11 (73 ± 6 yr) recreationally active (AO) old subjects, as well as 9 (22 ± 2 yr) young controls. As expected, MA had higher leg press maximal strength (MA, 185 ± 32 kg; AO, 128 ± 15 kg; SO, 106 ± 11 kg; young, 147 ± 22 kg, P < 0.01) and rate of force development (MA, 5,588 ± 2,488 N/s; AO, 2,156 ± 1,100 N/s; SO, 2,011 ± 825 N/s; young, 3,663 ± 1,140 N/s, P < 0.05) than the other groups. MA also exhibited higher musculus soleus normalized V waves during maximal voluntary contractions (MVC) [maximal V wave amplitude/maximal M wave during MVC (Vsup/Msup); 0.28 ± 0.15] than AO (0.13 ± 0.06, P < 0.01) and SO (0.11 ± 0.05, P < 0.01), yet lower than young (0.45 ± 0.12, P < 0.01). No differences were apparent between the old groups in H reflex recorded at rest or during MVC [maximal H reflex amplitude/maximal M wave during rest (Hmax/Mmax); maximal H reflex amplitude during MVC/maximal M wave during MVC (Hsup/Msup)], and all were lower ( P < 0.01) than young. MA (34.4 ± 2.1 ms) had shorter ( P < 0.05) H reflex latency compared with AO (36.4 ± 3.7 ms) and SO (37.3 ± 3.2 ms), but longer ( P < 0.01) than young (30.7 ± 2.0 ms). Using interpolated twitch analysis, MA (89 ± 7%) had plantar flexion voluntary activation similar to young (90 ± 6%), and this was higher ( P < 0.05), or tended to be higher ( P = 0.06–0.09), than SO (83 ± 10%) and AO (84 ± 5%). These observations suggest that lifelong strength training has a protective effect against age-related attenuation of efferent drive. In contrast, no beneficial effect seems to derive from habitual recreational activity, indicating that strength training may be particularly beneficial for counteracting age-related loss of neuromuscular function.

scholarly journals Cross-education and detraining effects of eccentric vs. concentric resistance training of the elbow flexors

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Shigeru Sato ◽  
Riku Yoshida ◽  
Ryosuke Kiyono ◽  
Kaoru Yahata ◽  
Koki Yasaka ◽  
...  
Keyword(s):  
Resistance Training ◽  
Training Session ◽  
Control Group ◽  
Elbow Flexors ◽  
Maximum Voluntary Isometric Contraction ◽  
Transfer Ratio ◽  
Education Effect ◽  
Significant Difference ◽  
Cross Education ◽  
The Cross

Abstract Background Unilateral resistance training increases the strength of the contralateral non-trained homologous muscles known as the cross-education effect. We tested the hypothesis that unilateral eccentric resistance training (ET) would induce greater and longer-lasting cross-education effect when compared with concentric resistance training (CT). Methods Young (20–23 y) participants were allocated to ET (5 males, 4 females) or CT (5 males, 4 females) group that performed unilateral progressive ET or CT of the elbow flexors, twice a week for 5 weeks (10 sessions) followed by a 5-week detraining, and control group (7 males, 6 females) that did not perform any training. Maximum voluntary isometric contraction torque of the elbow flexors (MVIC), one-repetition maximum of concentric dumbbell curl (1-RM), and biceps brachii and brachialis muscle thickness (MT) were measured from the trained and non-trained arms before, several days after the last training session, and 5 weeks later. A ratio between the trained and non-trained arms for the change in MVIC or 1-RM from pre- to post-training (cross-body transfer ratio) was compared between ET and CT groups. Results The control group did not show significant changes in any variables. Both ET and CT increased (P < 0.05) MVIC (22.5 ± 12.3 % vs. 26.0 ± 11.9 %) and 1-RM (28.8 ± 6.6 % vs. 35.4 ± 12.9 %) of the trained arm without a significant difference between groups. MVIC was maintained after detraining for ET but returned to the baseline for CT, and 1-RM was maintained after detraining for both ET and CT. For the non-trained arm, MVIC (22.7 ± 17.9 % vs. 12.2 ± 10.2 %) and 1-RM (19.9 ± 14.6 % vs. 24.0 ± 10.6 %) increased similarly (P > 0.05) after ET and CT, and MVIC returned to the baseline after detraining, but 1-RM was maintained for both groups. An increase (P < 0.05) in MT was found only after ET for the trained arm (7.1 ± 6.1 %). The cross-body transfer ratio for MVIC was greater (P < 0.05) for ET (90.9 ± 46.7 %) than CT (49.0 ± 30.0 %). Conclusions These results did not support the hypothesis and showed similar changes in the most of the variables between ET and CT for the trained and non-trained arms, and strong cross-education effects on MVIC and 1-RM, but less detraining effect after ET than CT on MVIC of the trained arm. Trial registration University Hospital Medical Information Network Clinical Trials Registry (UMIN000044477; Jun 09, 2021).

scholarly journals The Effects of Whole-Body Vibration on the Cross-Transfer of Strength

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
Alicia M. Goodwill ◽  
Dawson J. Kidgell
Keyword(s):  
Strength Training ◽  
Whole Body Vibration ◽  
Peak Height ◽  
Whole Body ◽  
Control Group ◽  
Body Vibration ◽  
Training Groups ◽  
Cross Education ◽  
The Cross ◽  
The Right

This study investigated whether the use of superimposed whole-body vibration (WBV) during cross-education strength training would optimise strength transfer compared to conventional cross-education strength training. Twenty-one healthy, dominant right leg volunteers (21±3years) were allocated to a strength training (ST,m=3,f=4), a strength training with WBV (ST + V,m=3,f=4), or a control group (no training,m=3,f=4). Training groups performed 9 sessions over 3 weeks, involving unilateral squats for the right leg, with or without WBV (35 Hz; 2.5 mm amplitude). All groups underwent dynamic single leg maximum strength testing (1RM) and single and paired pulse transcranial magnetic stimulation (TMS) prior to and following training. Strength increased in the trained limb for the ST (41%;ES=1.14) and ST + V (55%;ES=1.03) groups, which resulted in a 35% (ES=0.99) strength transfer to the untrained left leg for the ST group and a 52% (ES=0.97) strength transfer to the untrained leg for the ST + V group, when compared to the control group. No differences in strength transfer between training groups were observed(P=0.15). For the untrained leg, no differences in the peak height of recruitment curves or SICI were observed between ST and ST + V groups(P=1.00). Strength training with WBV does not appear to modulate the cross-transfer of strength to a greater magnitude when compared to conventional cross-education strength training.

scholarly journals Effect of Ankle Angles on the Soleus H-Reflex Excitability During Standing

Motor Control ◽  
2020 ◽  
Vol 24 (2) ◽  
pp. 189-203
Author(s):  
Aviroop Dutt-Mazumder ◽  
Richard L. Segal ◽  
Aiko K. Thompson
Keyword(s):  
Plantar Flexion ◽  
H Reflex ◽  
Spinal Reflex ◽  
System Control ◽  
M Wave ◽  
Reflex Excitability ◽  
Limb Loading ◽  
Upright Standing ◽  
Neurological Injuries ◽  
Full Body

This study investigated effects of ankle joint angle on the Hoffman’s reflex (H-reflex) excitability during loaded (weight borne with both legs) and unloaded (full body weight borne with the contralateral leg) standing in people without neurological injuries. Soleus H-reflex/M-wave recruitment curves were examined during upright standing on three different slopes that imposed plantar flexion (−15°), dorsiflexion (+15°), and neutral (0°) angles at the ankle, with the test leg loaded and unloaded. With the leg loaded and unloaded, maximum H-reflex/maximum M-wave ratio of −15° was significantly larger than those of 0° and +15° conditions. The maximum H-reflex/maximum M-wave ratios were 51%, 43%, and 41% with loaded and 56%, 46%, and 44% with unloaded for −15°, 0°, and +15° slope conditions, respectively. Thus, limb loading/unloading had limited impact on the extent of influence that ankle angles exert on the H-reflex excitability. This suggests that task-dependent central nervous system control of reflex excitability may regulate the influence of sensory input on the spinal reflex during standing.

scholarly journals Elbow Joint Angles in Elbow Flexor Unilateral Resistance Exercise Training Determine Its Effects on Muscle Strength and Thickness of Trained and Non-trained Arms

2021 ◽  
Vol 12 ◽  
Author(s):  
Shigeru Sato ◽  
Riku Yoshida ◽  
Ryosuke Kiyono ◽  
Kaoru Yahata ◽  
Koki Yasaka ◽  
...  
Keyword(s):  
Exercise Training ◽  
Resistance Exercise ◽  
Elbow Joint ◽  
Biceps Brachii ◽  
Training Session ◽  
Control Group ◽  
Education Effect ◽  
Joint Training ◽  
Cross Education ◽  
The Cross

The present study compared two unilateral arm curl resistance exercise protocols with a different starting and finishing elbow joint angle in the same ROM for changes in elbow flexors strength and muscle thickness of the trained and non-trained arms. Thirty-two non-resistance trained young adults were randomly assigned to one of the three groups: extended joint training (0°–50°; EXT, n = 12); flexed joint training (80°–130°; FLE, n = 12); and non-training control (n = 8). The exercise training was performed by the dominant arms twice a week for 5 weeks with gradual increases in the training volume over 10 training sessions, and the non-dominant (non-trained) arms were investigated for the cross-education effect. Maximal voluntary contraction torque of isometric (MVC-ISO), concentric (MVC-CON), and eccentric contractions (MVC-ECC), and thickness (MT) of biceps brachii and brachialis of the trained and non-trained arms were assessed at baseline and 4–8 days after the last training session. The control group did not show significant changes in any variables. Significant (P &lt; 0.05) increases in MVC-ISO torque (16.2 ± 12.6%), MVC-CON torque (21.1 ± 24.4%), and MVC-ECC torque (19.6 ± 17.5%) of the trained arm were observed for the EXT group only. The magnitude of the increase in MT of the trained arm was greater (P &lt; 0.05) for EXT (8.9 ± 3.9%) than FLE (3.4 ± 2.7%). The cross-education effect was evident for MVC-ISO (15.9 ± 14.8%) and MVC-CON (16.7 ± 20.0%) torque of the EXT group only. These results suggest that resistance training at the extended elbow joint induces greater muscle adaptations and cross-education effects than that at flexed elbow joint.

External Resistance Is Imperative for Training-Induced Efferent Neural Drive Enhancement in Older Adults

2020 ◽  
Author(s):  
Runar Unhjem ◽  
Tiril Tøien ◽  
Ann Charlotte Gjertsen Kvellestad ◽  
Thomas Storehaug Øren ◽  
Eivind Wang
Keyword(s):  
Older Adults ◽  
Strength Training ◽  
Plantar Flexion ◽  
Skill Learning ◽  
External Loading ◽  
Control Group ◽  
External Resistance ◽  
Neural Drive ◽  
Age Related ◽  
Heavy Loads

Abstract Strength training performed with heavy loads and maximal intended velocity is documented to enhance efferent neural drive to maximally contracting musculature in older adults. However, it remains unclear whether the neural plasticity following training result from motor skill learning or if external resistance is a prerequisite. To investigate this, we assessed electrically evoked potentials (H-reflex and V-waves normalized to maximal M-wave) and voluntary activation (VA) in 36 older adults (73 ± 4 years) randomized to 3 weeks of plantar flexion strength training, with (maximal strength training [MST]) or without (unloaded ballistic training [UBT]) heavy external loading (90% of one repetition maximum), or a control group. Both training groups aimed to execute the concentric phase of movement as fast and forcefully as possible. The MST group improved maximal voluntary contraction (MVC) and rate of force development (RFD) by 18% ± 13% (p = .001; Hedges g = 0.66) and 35% ± 17% (p &lt; .001; g = 0.94), respectively, and this was different (MVC: p = .013; RFD: p = .001) from the UBT group which exhibited a 7% ± 8% (p = .033; g = 0.32) increase in MVC and a tendency to increase RFD (p = .119; g = 0.22). Concomitant improvements in efferent neural drive (Vmax/Msup ratio: 0.14 ± 0.08 to 0.24 ± 0.20; p = .010) and a tendency towards increased VA (79% ± 9% to 84% ± 5%; p = .098), were only apparent after MST. No changes were observed in Hmax/Mmax ratio for the groups. In conclusion, external loading during exercise training appears to be a prerequisite for efferent neural drive enhancement in older adults. Thus, strength training with heavy loads should be recommended to counteract the typically observed age-related decline in motoneuron firing frequency and recruitment.

scholarly journals Intensity Sensitive Modulation Effect of Theta Burst Form of Median Nerve Stimulation on the Monosynaptic Spinal Reflex

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Kuei-Lin Yeh ◽  
Po-Yu Fong ◽  
Ying-Zu Huang
Keyword(s):  
Median Nerve ◽  
Amplitude Ratio ◽  
Motor Evoked Potentials ◽  
Short Interval ◽  
H Reflex ◽  
Spinal Reflex ◽  
M Wave ◽  
Therapeutic Benefits ◽  
Median Nerve Stimulation ◽  
Theta Burst

The effects of electrical stimulation of median nerve with a continuous theta burst pattern (EcTBS) on the spinal H-reflex were studied. Different intensities and durations of EcTBS were given to the median nerve to 11 healthy individuals. The amplitude ratio of the H-reflex to maximum M wave (H/M ratio), corticospinal excitability and inhibition measured using motor evoked potentials (MEPs), short-interval intracortical inhibition and facilitation (SICI/ICF), spinal reciprocal inhibition (RI), and postactivation depression (PAD) were measured before and after EcTBS. In result, the H/M ratio was reduced followed by EcTBS at 90% H-reflex threshold, and the effect lasted longer after 1200 pulses than after 600 pulses of EcTBS. In contrast, EcTBS at 110% threshold facilitated the H/M ratio, while at 80% threshold it had no effect. Maximum M wave, MEPs, SICI/ICF, RI, and PAD all remained unchanged after EcTBS. In conclusion, EcTBS produced lasting effects purely on the H-reflex, probably, through effects on postsynaptic plasticity. The effect of EcTBS depends on the intensity and duration of stimulation. EcTBS is beneficial to research on mechanisms of human plasticity. Moreover, its ability to modulate spinal excitability is expected to have therapeutic benefits on neurological disorders involving spinal cord dysfunction.

Set Configuration in Strength Training Programs Modulates the Cross Education Phenomenon

2019 ◽  
Vol Publish Ahead of Print ◽  
Author(s):  
Juan Fariñas ◽  
Xian Mayo ◽  
Manuel A. Giraldez-García ◽  
Eduardo Carballeira ◽  
Miguel Fernandez-Del-Olmo ◽  
...  
Keyword(s):  
Strength Training ◽  
Training Programs ◽  
Cross Education ◽  
The Cross

scholarly journals Ipsilateral corticomotor responses are confined to the homologous muscle following cross-education of muscular strength

2018 ◽  
Vol 43 (1) ◽  
pp. 11-22 ◽  
Author(s):  
Joel Mason ◽  
Ashlyn K. Frazer ◽  
Deanna M. Horvath ◽  
Alan J. Pearce ◽  
Janne Avela ◽  
...  
Keyword(s):  
Strength Training ◽  
Muscular Strength ◽  
Biceps Brachii ◽  
Control Group ◽  
Elbow Flexors ◽  
Corticomotor Excitability ◽  
Flexor Carpi Radialis ◽  
Cross Education ◽  
The Right ◽  
Wrist Flexors

Cross-education of strength occurs when strength-training 1 limb increases the strength of the untrained limb and is restricted to the untrained homologous muscle. Cortical circuits located ipsilateral to the trained limb might be involved. We used transcranial magnetic stimulation (TMS) to determine the corticomotor responses from the untrained homologous (biceps brachii) and nonhomologous (flexor carpi radialis) muscle following strength-training of the right elbow flexors. Motor evoked potentials were recorded from the untrained left biceps brachii and flexor carpi radialis during a submaximal contraction from 20 individuals (10 women, 10 men; aged 18–35 years; training group, n = 10; control group, n = 10) before and after 3 weeks of strength-training the right biceps brachii at 80% of 1-repetition maximum. Recruitment-curves for corticomotor excitability and inhibition of the untrained homologous and nonhomologous muscle were constructed and assessed by examining the area under the recruitment curve. Strength-training increased strength of the trained elbow flexors (29%), resulting in an 18% increase in contralateral strength of the untrained elbow flexors (P < 0.0001). The trained wrist flexors increased by 19%, resulting in a 12% increase in strength of the untrained wrist flexors (P = 0.005). TMS showed increased corticomotor excitability and decreased corticomotor inhibition for the untrained homologous muscle (P < 0.05); however, there were no changes in the untrained nonhomologous muscle (P > 0.05). These findings show that the cross-education of muscular strength is spatially distributed; however, the neural adaptations are confined to the motor pathway ipsilateral to the untrained homologous agonist.

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