Neuromuscular adaptations to work-matched maximal eccentric versus concentric training

Sumiaki Maeo, Xiyao Shan, Shun Otsuka, Hiroaki Kanehisa, Yasuo Kawakami

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

It is unclear whether the superiority of eccentric over concentric training on neuromuscular improvements is due to higher torque (mechanical loading) achievable during eccentric contractions or due to resulting greater total work. Purpose This study aimed to examine neuromuscular adaptations after maximal eccentric versus concentric training matched for total work. Methods Twelve males conducted single-joint isokinetic (180°·s-1) maximal eccentric contractions of the knee extensors in one leg (ECC-leg) and concentric in the other (CON-leg), 6 sets per session (3-5 sets in the initial 1-3 sessions), 2 sessions per week for 10 wk. The preceding leg performed 10 repetitions per set. The following leg conducted the equivalent volume of work. In addition to peak torque during training, agonist EMG and MRI-based anatomical cross-sectional area (ACSA) and transverse relaxation time (T2) at midthigh as reflective of neural drive, hypertrophy, and edema, respectively, were assessed weekly throughout the training period and pre- and posttraining. Whole muscle volume was also measured pre- and posttraining. Results Torque and EMG (in trained contraction conditions) significantly increased in both legs after week 1 (W1) and week 4 (W4), respectively, with a greater degree for ECC-leg (torque +76%, EMG +73%: Posttraining) than CON-leg (+28%, +20%). ACSA significantly increased after W4 in ECC-leg only (+4%: Posttraining), without T2 changes throughout. Muscle volume also increased in ECC-leg only (+4%). Multiple regression analysis revealed that changes (%Δ) in EMG solely explained 53%-80% and 30%-56% of the total variance in %Δtorque through training in ECC-leg and CON-leg, respectively, with small contributions (+13%-18%) of %ΔACSA for both legs. Conclusion Eccentric training induces greater neuromuscular changes than concentric training even when matched for total work, whereas most of the strength gains during 10-wk training are attributable to the increased neural drive.

Original languageEnglish
Pages (from-to)1629-1640
Number of pages12
JournalMedicine and Science in Sports and Exercise
Volume50
Issue number8
DOIs
Publication statusPublished - 2018 Aug 1

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Leg
Torque
Muscles
Hypertrophy
Edema
Knee
Joints
Regression Analysis

Keywords

  • EDEMA
  • HYPERTROPHY
  • KNEE EXTENSION TORQUE
  • NEURAL DRIVE
  • WEEKLY ASSESSMENT

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation

Cite this

Neuromuscular adaptations to work-matched maximal eccentric versus concentric training. / Maeo, Sumiaki; Shan, Xiyao; Otsuka, Shun; Kanehisa, Hiroaki; Kawakami, Yasuo.

In: Medicine and Science in Sports and Exercise, Vol. 50, No. 8, 01.08.2018, p. 1629-1640.

Research output: Contribution to journalArticle

Maeo, Sumiaki ; Shan, Xiyao ; Otsuka, Shun ; Kanehisa, Hiroaki ; Kawakami, Yasuo. / Neuromuscular adaptations to work-matched maximal eccentric versus concentric training. In: Medicine and Science in Sports and Exercise. 2018 ; Vol. 50, No. 8. pp. 1629-1640.
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abstract = "It is unclear whether the superiority of eccentric over concentric training on neuromuscular improvements is due to higher torque (mechanical loading) achievable during eccentric contractions or due to resulting greater total work. Purpose This study aimed to examine neuromuscular adaptations after maximal eccentric versus concentric training matched for total work. Methods Twelve males conducted single-joint isokinetic (180°·s-1) maximal eccentric contractions of the knee extensors in one leg (ECC-leg) and concentric in the other (CON-leg), 6 sets per session (3-5 sets in the initial 1-3 sessions), 2 sessions per week for 10 wk. The preceding leg performed 10 repetitions per set. The following leg conducted the equivalent volume of work. In addition to peak torque during training, agonist EMG and MRI-based anatomical cross-sectional area (ACSA) and transverse relaxation time (T2) at midthigh as reflective of neural drive, hypertrophy, and edema, respectively, were assessed weekly throughout the training period and pre- and posttraining. Whole muscle volume was also measured pre- and posttraining. Results Torque and EMG (in trained contraction conditions) significantly increased in both legs after week 1 (W1) and week 4 (W4), respectively, with a greater degree for ECC-leg (torque +76{\%}, EMG +73{\%}: Posttraining) than CON-leg (+28{\%}, +20{\%}). ACSA significantly increased after W4 in ECC-leg only (+4{\%}: Posttraining), without T2 changes throughout. Muscle volume also increased in ECC-leg only (+4{\%}). Multiple regression analysis revealed that changes ({\%}Δ) in EMG solely explained 53{\%}-80{\%} and 30{\%}-56{\%} of the total variance in {\%}Δtorque through training in ECC-leg and CON-leg, respectively, with small contributions (+13{\%}-18{\%}) of {\%}ΔACSA for both legs. Conclusion Eccentric training induces greater neuromuscular changes than concentric training even when matched for total work, whereas most of the strength gains during 10-wk training are attributable to the increased neural drive.",
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N2 - It is unclear whether the superiority of eccentric over concentric training on neuromuscular improvements is due to higher torque (mechanical loading) achievable during eccentric contractions or due to resulting greater total work. Purpose This study aimed to examine neuromuscular adaptations after maximal eccentric versus concentric training matched for total work. Methods Twelve males conducted single-joint isokinetic (180°·s-1) maximal eccentric contractions of the knee extensors in one leg (ECC-leg) and concentric in the other (CON-leg), 6 sets per session (3-5 sets in the initial 1-3 sessions), 2 sessions per week for 10 wk. The preceding leg performed 10 repetitions per set. The following leg conducted the equivalent volume of work. In addition to peak torque during training, agonist EMG and MRI-based anatomical cross-sectional area (ACSA) and transverse relaxation time (T2) at midthigh as reflective of neural drive, hypertrophy, and edema, respectively, were assessed weekly throughout the training period and pre- and posttraining. Whole muscle volume was also measured pre- and posttraining. Results Torque and EMG (in trained contraction conditions) significantly increased in both legs after week 1 (W1) and week 4 (W4), respectively, with a greater degree for ECC-leg (torque +76%, EMG +73%: Posttraining) than CON-leg (+28%, +20%). ACSA significantly increased after W4 in ECC-leg only (+4%: Posttraining), without T2 changes throughout. Muscle volume also increased in ECC-leg only (+4%). Multiple regression analysis revealed that changes (%Δ) in EMG solely explained 53%-80% and 30%-56% of the total variance in %Δtorque through training in ECC-leg and CON-leg, respectively, with small contributions (+13%-18%) of %ΔACSA for both legs. Conclusion Eccentric training induces greater neuromuscular changes than concentric training even when matched for total work, whereas most of the strength gains during 10-wk training are attributable to the increased neural drive.

AB - It is unclear whether the superiority of eccentric over concentric training on neuromuscular improvements is due to higher torque (mechanical loading) achievable during eccentric contractions or due to resulting greater total work. Purpose This study aimed to examine neuromuscular adaptations after maximal eccentric versus concentric training matched for total work. Methods Twelve males conducted single-joint isokinetic (180°·s-1) maximal eccentric contractions of the knee extensors in one leg (ECC-leg) and concentric in the other (CON-leg), 6 sets per session (3-5 sets in the initial 1-3 sessions), 2 sessions per week for 10 wk. The preceding leg performed 10 repetitions per set. The following leg conducted the equivalent volume of work. In addition to peak torque during training, agonist EMG and MRI-based anatomical cross-sectional area (ACSA) and transverse relaxation time (T2) at midthigh as reflective of neural drive, hypertrophy, and edema, respectively, were assessed weekly throughout the training period and pre- and posttraining. Whole muscle volume was also measured pre- and posttraining. Results Torque and EMG (in trained contraction conditions) significantly increased in both legs after week 1 (W1) and week 4 (W4), respectively, with a greater degree for ECC-leg (torque +76%, EMG +73%: Posttraining) than CON-leg (+28%, +20%). ACSA significantly increased after W4 in ECC-leg only (+4%: Posttraining), without T2 changes throughout. Muscle volume also increased in ECC-leg only (+4%). Multiple regression analysis revealed that changes (%Δ) in EMG solely explained 53%-80% and 30%-56% of the total variance in %Δtorque through training in ECC-leg and CON-leg, respectively, with small contributions (+13%-18%) of %ΔACSA for both legs. Conclusion Eccentric training induces greater neuromuscular changes than concentric training even when matched for total work, whereas most of the strength gains during 10-wk training are attributable to the increased neural drive.

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KW - NEURAL DRIVE

KW - WEEKLY ASSESSMENT

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