Neural Plasticity with Age: Unilateral Maximal Strength Training Augments Efferent Neural Drive to the Contralateral Limb in Older Adults

Tøien, Tiril; Unhjem, Runar; Øren, Thomas Storehaug; Kvellestad, Ann Charlotte Gjertsen; Hoff, Jan; Wang, Eivind

doi:10.1093/gerona/glx218

Cited by 33 publications

(32 citation statements)

References 59 publications

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“…The results of the present study add to the growing body of evidence supporting the use of MST in healthy sedentary adults as an effective intervention to mitigate the loss of muscle function and mobility accompanying aging (Toien and others 2018; Wang and others 2017). Indeed, MST carries a lower risk of injury compared to endurance training in elderly (Pollock and others 1991), provides robust benefits in numerous key components of muscle function (rate of force development, strength, W’), and improves exercise efficiency (Heggelund and others 2013; Wang and others 2017).…”

Section: Discussionsupporting

confidence: 54%

Maximal strength training increases muscle force generating capacity and the anaerobic ATP synthesis flux without altering the cost of contraction in elderly

Berg

Kwon

Hureau

et al. 2018

Experimental Gerontology

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Aging is associated with a progressive decline in skeletal muscle function, then leading to impaired exercise tolerance. Maximal strength training (MST) appears to be a practical and effective intervention to increase both exercise capacity and efficiency. However, the underlying physiological mechanisms responsible for these functional improvements are still unclear. Accordingly, the purpose of this study was to examine the intramuscular and metabolic adaptations induced by 8 weeks of knee-extension MST in the quadriceps of 10 older individuals (75 ± 9 yrs) by employing a combination of molecular, magnetic resonance H-imaging andP-spectroscopy, muscle biopsies, motor nerve stimulation, and indirect calorimetry techniques. Dynamic and isometric muscle strength were both significantly increased by MST. The greater torque-time integral during sustained isometric maximal contraction post-MST (P = 0.002) was associated with increased rates of ATP synthesis from anaerobic glycolysis (PRE: 10 ± 7 mM·min; POST: 14 ± 7 mM·min, P = 0.02) and creatine kinase reaction (PRE: 31 ± 10 mM·min; POST: 41 ± 10 mM·min, P = 0.006) such that the ATP cost of contraction was not significantly altered. Expression of fast myosin heavy chain, quadriceps muscle volume, and submaximal cycling net efficiency were also increased with MST (P = 0.005; P = 0.03 and P = 0.03, respectively). Overall, MST induced a shift toward a more glycolytic muscle phenotype allowing for greater muscle force production during sustained maximal contraction. Consequently, some of the MST-induced improvements in exercise tolerance might stem from a greater anaerobic capacity to generate ATP, while the improvement in exercise efficiency appears to be independent from an alteration in the ATP cost of contraction.

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Section: Discussionsupporting

confidence: 54%

Maximal strength training increases muscle force generating capacity and the anaerobic ATP synthesis flux without altering the cost of contraction in elderly

Berg

Kwon

Hureau

et al. 2018

Experimental Gerontology

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“…MST performed with maximal intended velocity in the concentric phase of the movement stimulates neural firing frequency and motor unit recruitment (Toien et al 2018), and yields effective improvements in muscle FGC (Heggelund et al 2013). The present study aimed to investigate if applying an eccentric overload would enhance neural stimulation and, in turn, augment FGC adaptations.…”

Section: Discussionmentioning

confidence: 95%

“…Third, from a purely practical standpoint, MST is simpler to administer since no or extra personnel or special equipment is required to add and remove the excess weight in the eccentric phase. Finally, of clinical importance, MST has been documented to be feasible and safe to carry out in elderly and a wide range of frail patient populations (Hoff et al 2007;Toien et al 2018;Unhjem et al 2015Unhjem et al , 2016aWang et al 2017) and contribute to improved function and ability to maintain independence in daily activities (Unhjem et al 2017).…”

Section: Discussionmentioning

confidence: 99%

Maximal strength training: the impact of eccentric overload

Tøien

Haglo

Unhjem

et al. 2018

Journal of Neurophysiology

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The search for the most potent strength training intervention is continuous. Maximal strength training (MST) yields large improvements in force-generating capacity (FGC), largely attributed to efferent neural drive enhancement. However, it remains elusive whether eccentric overload, before the concentric phase, may augment training-induced neuromuscular adaptations. A total of 53 23 ± 3 (SD)-yr-old untrained males were randomized to either a nontraining control group (CG) or one of two training groups performing leg press strength training with linear progression, three times per week for 8 wk. The first training group carried out MST with four sets of four repetitions at ~90% one-repetition maximum (1RM) in both action phases. The second group performed MST with an augmented eccentric load of 150% 1RM (eMST). Measurements were taken of 1RM and rate of force development (RFD), countermovement jump (CMJ) performance, and evoked potentials recordings [V-wave (V) and H-reflex (H) normalized to M-wave (M) in musculus soleus]. 1RM increased from 133 ± 16 to 157 ± 23 kg and 123 ± 18 to 149 ± 22 kg and CMJ by 2.3 ± 3.6 and 2.2 ± 3.7cm for MST and eMST, respectively (all P < 0.05). Early, late, and maximal RFD increased in both groups [634–1,501 N/s (MST); 644–2,111 N/s (eMST); P < 0.05]. These functional improvements were accompanied by increased V/M-ratio (MST: 0.34 ± 0.11 to 0.42 ± 14; eMST: .36 ± 0.14 to 0.43 ± 13; P < 0.05). Resting H/M-ratio remained unchanged. Training-induced improvements did not differ. All increases, except for CMJ, were different from the CG. MST is an enterprise for large gains in FGC and functional performance. Eccentric overload did not induce additional improvements, suggesting firing frequency and motor unit recruitment during MST may be maximal. NEW & NOTEWORTHY This is the first study to apply evoked potential recordings to investigate effects on efferent neural drive following high-intensity strength training with and without eccentric overload in a functionally relevant lower extremity exercise. We document that eccentric overload does not augment improvements in efferent neural drive or muscle force-generating capacity, suggesting that high-intensity concentric loads may maximally tax firing frequency and motor unit recruitment.

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“…Of those, 126 units (from 87 studies) included young, able-bodied participants with a median age of 23 years and a median sample size of 11 (range 3-342) participants. Nine units (from 8 studies[13,27,72,92,93,[98][99][100]) included older, able-bodied participants with a median age of 69 years and a median sample size of 11 (range[6][7][8][9][10][11][12][13][14].The remaining 6 units (from 6 studies…”

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confidence: 99%

The effect of unilateral training on contralateral limb strength in young, older, and patient populations: a meta-analysis of cross education

Green

Gabriel

2018

Physical Therapy Reviews

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Background: Cross education is the contralateral strength gain following unilateral training of the ipsilateral limb. This phenomenon provides an ideal rehabilitation model for acute or chronic rehabilitation; however, previous cross education meta-analyses have been limited to a handful of studies. Objectives: The present meta-analysis aimed to (1) be as inclusive as possible, (2) compare cross education in young able-bodied, older able-bodied, and patient populations, (3) compare cross education between training modalities, and (4) detail the impact of methodological controls on the quantification of cross education. Methodology: A review of English literature identified studies that employed unilateral resistance training and reported contralateral strength results. Studies were separated to examine the effect of population, training modality, limb, sex, and familiarization on the magnitude of cross education. The percent strength gain and effect size were calculated for ipsilateral and contralateral limbs. Results: A total of 96 studies fit the predetermined inclusion criteria and were included in the analysis. The included studies were further divided into 141 units employing separate unilateral training paradigms. These were separated into young, able-bodied (n ¼ 126), older, able-bodied (n ¼ 9), and neuromuscular patients (n ¼ 6). Cross education was an average of 18% (standardized mean difference (SMD) ¼ 0.71) in young, able-bodied participants, 17% (SMD ¼ 0.58) in healthy able-bodied participants, and 29% (SMD ¼ 0.76) in neuromuscular patients. Conclusion: Cross education was present in young, older, and patient populations and similar between upper and lower limbs and between males and females. Electromyostimulation training was superior to voluntary training paradigms.

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Neural Plasticity with Age: Unilateral Maximal Strength Training Augments Efferent Neural Drive to the Contralateral Limb in Older Adults

Cited by 33 publications

References 59 publications

Maximal strength training increases muscle force generating capacity and the anaerobic ATP synthesis flux without altering the cost of contraction in elderly

Maximal strength training increases muscle force generating capacity and the anaerobic ATP synthesis flux without altering the cost of contraction in elderly

Maximal strength training: the impact of eccentric overload

The effect of unilateral training on contralateral limb strength in young, older, and patient populations: a meta-analysis of cross education

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