Increased rate of force development and neural drive of human skeletal muscle following resistance training

The maximal rate of rise in muscle force [rate of force development (RFD)] has important functional consequences as it determines the force that can be generated in the early phase of muscle contraction (0–200 ms). The present study examined the effect of resistance training on contractile RFD and efferent motor outflow (“neural drive”) during maximal muscle contraction. Contractile RFD (slope of force-time curve), impulse (time-integrated force), electromyography (EMG) signal amplitude (mean average voltage), and rate of EMG rise (slope of EMG-time curve) were determined (1-kHz sampling rate) during maximal isometric muscle contraction (quadriceps femoris) in 15 male subjects before and after 14 wk of heavy-resistance strength training (38 sessions). Maximal isometric muscle strength [maximal voluntary contraction (MVC)] increased from 291.1 ± 9.8 to 339.0 ± 10.2 N · m after training. Contractile RFD determined within time intervals of 30, 50, 100, and 200 ms relative to onset of contraction increased from 1,601 ± 117 to 2,020 ± 119 ( P < 0.05), 1,802 ± 121 to 2,201 ± 106 ( P < 0.01), 1,543 ± 83 to 1,806 ± 69 ( P < 0.01), and 1,141 ± 45 to 1,363 ± 44 N · m · s−1( P < 0.01), respectively. Corresponding increases were observed in contractile impulse ( P < 0.01–0.05). When normalized relative to MVC, contractile RFD increased 15% after training (at zero to one-sixth MVC; P < 0.05). Furthermore, muscle EMG increased ( P < 0.01–0.05) 22–143% (mean average voltage) and 41–106% (rate of EMG rise) in the early contraction phase (0–200 ms). In conclusion, increases in explosive muscle strength (contractile RFD and impulse) were observed after heavy-resistance strength training. These findings could be explained by an enhanced neural drive, as evidenced by marked increases in EMG signal amplitude and rate of EMG rise in the early phase of muscle contraction.

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Early phase adaptations in muscle strength and hypertrophy as a result of low-intensity blood flow restriction resistance training

European Journal of Applied Physiology ◽

10.1007/s00421-018-3918-8 ◽

2018 ◽

Vol 118 (9) ◽

pp. 1831-1843 ◽

Cited By ~ 10

Author(s):

Ethan C. Hill ◽

Terry J. Housh ◽

Joshua L. Keller ◽

Cory M. Smith ◽

Richard J. Schmidt ◽

...

Keyword(s):

Blood Flow ◽

Resistance Training ◽

Muscle Strength ◽

Early Phase ◽

Blood Flow Restriction ◽

Flow Restriction ◽

Low Intensity

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Early-phase Adaptations Of Three Resistance-training Protocols On Muscle Strength In Untrained Young Women

Medicine & Science in Sports & Exercise ◽

10.1249/01.mss.0000479272.43536.eb ◽

2015 ◽

Vol 47 ◽

pp. 935

Author(s):

Andre Martorelli ◽

Rodrigo Celes ◽

Saulo Martorelli ◽

Eduardo Cadore ◽

Pedro Henrique Lucas ◽

...

Keyword(s):

Resistance Training ◽

Muscle Strength ◽

Young Women ◽

Early Phase ◽

Training Protocols

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Neural adaptation to resistance training: changes in evoked V-wave and H-reflex responses

Journal of Applied Physiology ◽

10.1152/japplphysiol.01185.2001 ◽

2002 ◽

Vol 92 (6) ◽

pp. 2309-2318 ◽

Cited By ~ 341

Author(s):

Per Aagaard ◽

Erik B. Simonsen ◽

Jesper L. Andersen ◽

Peter Magnusson ◽

Poul Dyhre-Poulsen

Keyword(s):

Resistance Training ◽

Muscle Strength ◽

Muscle Contraction ◽

Presynaptic Inhibition ◽

H Reflex ◽

Neural Adaptation ◽

Reflex Amplitude ◽

Reflex Responses ◽

Adaptation Mechanisms ◽

V Wave

Combined V-wave and Hoffmann (H) reflex measurements were performed during maximal muscle contraction to examine the neural adaptation mechanisms induced by resistance training. The H-reflex can be used to assess the excitability of spinal α-motoneurons, while also reflecting transmission efficiency (i.e., presynaptic inhibition) in Ia afferent synapses. Furthermore, the V-wave reflects the overall magnitude of efferent motor output from the α-motoneuron pool because of activation from descending central pathways. Fourteen male subjects participated in 14 wk of resistance training that involved heavy weight-lifting exercises for the muscles of the leg. Evoked V-wave, H-reflex, and maximal M-wave (Mmax) responses were recorded before and after training in the soleus muscle during maximal isometric ramp contractions. Maximal isometric, concentric, and eccentric muscle strength was measured by use of isokinetic dynamometry. V-wave amplitude increased ∼50% with training ( P < 0.01) from 3.19 ± 0.43 to 4.86 ± 0.43 mV, or from 0.308 ± 0.048 to 0.478 ± 0.034 when expressed relative to Mmax (± SE). H-reflex amplitude increased ∼20% ( P < 0.05) from 5.37 ± 0.41 to 6.24 ± 0.49 mV, or from 0.514 ± 0.032 to 0.609 ± 0.025 when normalized to Mmax. In contrast, resting H-reflex amplitude remained unchanged with training (0.503 ± 0.059 vs. 0.499 ± 0.063). Likewise, no change occurred in Mmax (10.78 ± 0.86 vs. 10.21 ± 0.66 mV). Maximal muscle strength increased 23–30% ( P < 0.05). In conclusion, increases in evoked V-wave and H-reflex responses were observed during maximal muscle contraction after resistance training. Collectively, the present data suggest that the increase in motoneuronal output induced by resistance training may comprise both supraspinal and spinal adaptation mechanisms (i.e., increased central motor drive, elevated motoneuron excitability, reduced presynaptic inhibition).

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Effect of resistance training on muscle strength and rate of force development in healthy older adults: A systematic review and meta-analysis

Experimental Gerontology ◽

10.1016/j.exger.2017.11.020 ◽

2018 ◽

Vol 102 ◽

pp. 51-58 ◽

Cited By ~ 34

Author(s):

Pedrode Camargo Guizelini ◽

Rafael Alves de Aguiar ◽

Benedito Sérgio Denadai ◽

Fabrizio Caputo ◽

Camila Coelho Greco

Keyword(s):

Systematic Review ◽

Older Adults ◽

Resistance Training ◽

Muscle Strength ◽

Meta Analysis ◽

Rate Of Force Development ◽

Healthy Older Adults ◽

Force Development

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Surface electromyographic amplitude does not identify differences in neural drive to synergistic muscles

Journal of Applied Physiology ◽

10.1152/japplphysiol.01115.2017 ◽

2018 ◽

Vol 124 (4) ◽

pp. 1071-1079 ◽

Cited By ~ 44

Author(s):

Eduardo Martinez-Valdes ◽

Francesco Negro ◽

Deborah Falla ◽

Alessandro Marco De Nunzio ◽

Dario Farina

Keyword(s):

Motor Unit ◽

Action Potentials ◽

Discharge Rate ◽

Vastus Lateralis ◽

Signal Amplitude ◽

Surface Emg ◽

Neural Drive ◽

Emg Amplitude ◽

Emg Signal ◽

Synergistic Muscles

Surface electromyographic (EMG) signal amplitude is typically used to compare the neural drive to muscles. We experimentally investigated this association by studying the motor unit (MU) behavior and action potentials in the vastus medialis (VM) and vastus lateralis (VL) muscles. Eighteen participants performed isometric knee extensions at four target torques [10, 30, 50, and 70% of the maximum torque (MVC)] while high-density EMG signals were recorded from the VM and VL. The absolute EMG amplitude was greater for VM than VL ( P < 0.001), whereas the EMG amplitude normalized with respect to MVC was greater for VL than VM ( P < 0.04). Because differences in EMG amplitude can be due to both differences in the neural drive and in the size of the MU action potentials, we indirectly inferred the neural drives received by the two muscles by estimating the synaptic inputs received by the corresponding motor neuron pools. For this purpose, we analyzed the increase in discharge rate from recruitment to target torque for motor units matched by recruitment threshold in the two muscles. This analysis indicated that the two muscles received similar levels of neural drive. Nonetheless, the size of the MU action potentials was greater for VM than VL ( P < 0.001), and this difference explained most of the differences in EMG amplitude between the two muscles (~63% of explained variance). These results indicate that EMG amplitude, even following normalization, does not reflect the neural drive to synergistic muscles. Moreover, absolute EMG amplitude is mainly explained by the size of MU action potentials. NEW & NOTEWORTHY Electromyographic (EMG) amplitude is widely used to compare indirectly the strength of neural drive received by synergistic muscles. However, there are no studies validating this approach with motor unit data. Here, we compared between-muscles differences in surface EMG amplitude and motor unit behavior. The results clarify the limitations of surface EMG to interpret differences in neural drive between muscles.

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Effects of Low Intensity Resistance Training Speed on Body Composition, Muscle Activity and Muscle Strength in Obese Middle-aged Women

Korean Journal of Sport Studies ◽

10.23949/kjpe.2017.07.56.4.39 ◽

2017 ◽

Vol 56 (4) ◽

pp. 575-584 ◽

Cited By ~ 1

Author(s):

Woo-Jung Lee ◽

Sang-Won Seo ◽

Ho-Seong Lee

Keyword(s):

Body Composition ◽

Resistance Training ◽

Muscle Strength ◽

Muscle Activity ◽

Middle Aged ◽

Low Intensity

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The effectiveness of blood-flow restricted resistance training in the musculoskeletal rehabilitation of patients with lower limb disorders: A systematic review and meta-analysis

Clinical Rehabilitation ◽

10.1177/02692155211003480 ◽

2021 ◽

pp. 026921552110034

Author(s):

Nico Nitzsche ◽

Alexander Stäuber ◽

Samuel Tiede ◽

Henry Schulz

Keyword(s):

Blood Flow ◽

Resistance Training ◽

Muscle Strength ◽

Lower Limb ◽

Meta Analysis ◽

Load Resistance ◽

Muscle Volume ◽

Low Load ◽

Study Characteristics ◽

Musculoskeletal Rehabilitation

Objective: This meta-analysis aimed to evaluate the effectiveness of low-load Resistance Training (RT) with or without Blood Flow Restriction (BFR) compared with conventional RT on muscle strength in open and closed kinetic chains, muscle volume and pain in individuals with orthopaedic impairments. Data sources: Searches were conducted in the PubMed, Web of Science, Scopus and Cochrane databases, including the reference lists of randomised controlled trials (RCT’s) up to January 2021. Review method: An independent reviewer extracted study characteristics, orthopaedic indications, exercise data and outcome measures. The primary outcome was muscle strength of the lower limb. Secondary outcomes were muscle volume and pain. Study quality and reporting was assessed using the TESTEX scale. Results: A total of 10 RCTs with 386 subjects (39.2 ± 17.1 years) were included in the analysis to compare low-load RT with BFR and high or low-load RT without BFR. The meta-analysis showed no significant superior effects of low-load resistance training with BFR regarding leg muscle strength in open and closed kinetic chains, muscle volume or pain compared with high or low-load RT without BFR in subjects with lower limb impairments. Conclusion: Low-load RT with BFR leads to changes in muscle strength, muscle volume and pain in musculoskeletal rehabilitation that are comparable to conventional RT. This appears to be independent of strength testing in open or closed kinetic chains.

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Posterior-Chain Resistance Training Compared to General Exercise and Walking Programmes for the Treatment of Chronic Low Back Pain in the General Population: A Systematic Review and Meta-Analysis

Sports Medicine - Open ◽

10.1186/s40798-021-00306-w ◽

2021 ◽

Vol 7 (1) ◽

Author(s):

Nicholas Tataryn ◽

Vini Simas ◽

Tailah Catterall ◽

James Furness ◽

Justin W. L. Keogh

Keyword(s):

Low Back Pain ◽

Back Pain ◽

Resistance Training ◽

Muscle Strength ◽

Adverse Events ◽

Muscular Strength ◽

Meta Analysis ◽

Low Back ◽

Pain Level ◽

General Exercise

Abstract Background While chronic exercise training has been demonstrated to be an effective non-pharmacological treatment for chronic low back pain (CLBP), there has been a relative lack of evidence or clinical guidelines for whether a posterior chain resistance training programme provides any benefits over general exercise (GE). Objectives To determine if chronic posterior chain resistance training (PCRT), defined as exercise programmes of ≥6 weeks duration focused on the thoracic, lumbar and hip extensor musculature, is more effective than GE in improving pain, level of disability, muscular strength and the number of adverse events in recreationally active and sedentary individuals with CLBP. Methods Four electronic databases were systematically searched from 25 September 2019 until 30 August 2020. Using the Joanna Briggs Institute (JBI) Critical Appraisal Tools checklist for randomized controlled trials (RCTs), articles were critically appraised and compared against the inclusion/exclusion criteria. Standardized mean difference (SMD), risk difference (RD) and confidence interval (CI) were calculated using Review Manager 5.3. Results Eight articles were included, with a total of 408 participants (203 PCRT, 205 GE). Both PCRT and GE were effective in improving a number of CLBP-related outcomes, but these effects were often significantly greater in PCRT than GE, especially with greater training durations (i.e. 12–16 weeks compared to 6–8 weeks). Specifically, when compared to GE, PCRT demonstrated a greater reduction in pain (SMD = − 0.61 (95% CI − 1.21 to 0.00), p = 0.05; I2 = 74%) and level of disability (SMD = − 0.53 (95% CI − 0.97 to − 0.09), p = 0.02; I2 = 52%), as well as a greater increase in muscle strength (SMD = 0.67 (95% CI 0.21 to 1.13), p = 0.004; I2 = 0%). No differences in the number of adverse events were reported between PCRT and GE (RD = − 0.02 (95% CI − 0.10 to 0.05), p = 0.57; I2 = 72%). Conclusion Results of the meta-analysis indicated that 12–16 weeks of PCRT had a statistically significantly greater effect than GE on pain, level of disability and muscular strength, with no significant difference in the number of adverse events for recreationally active and sedentary patients with CLBP. Clinicians should strongly consider utilizing PCRT interventions for 12–16 weeks with patients with CLBP to maximize their improvements in pain, disability and muscle strength. Future research should focus on comparing the efficacy and adverse events associated with specific PCRT exercise training and movement patterns (i.e. deadlift, hip lift) in treating this population. Trial registration PROSPERO CRD42020155700.

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