PMID- 37637142
OWN - NLM
STAT- PubMed-not-MEDLINE
LR  - 20230829
IS  - 1664-042X (Print)
IS  - 1664-042X (Electronic)
IS  - 1664-042X (Linking)
VI  - 14
DP  - 2023
TI  - Deficits in neuromuscular control of increasing force in patients with chronic 
      lateral epicondylitis.
PG  - 1178557
LID - 10.3389/fphys.2023.1178557 [doi]
LID - 1178557
AB  - Objective: This study investigated the neuromuscular control of increasing and 
      releasing force in patients with chronic lateral epicondylitis (CLE). Methods: 
      Fifteen patients with CLE (10 males, 5 females, 46.5 +/- 6.3 years) and fifteen 
      healthy participants (9 males, 6 females, 45.3 +/- 2.5 years) participated in this 
      study. In addition to power grip and maximal voluntary contraction (MVC) of wrist 
      extension, force fluctuation dynamics and characteristics of inter-spike 
      intervals (ISI) of motor units (MUs) with various recruitment thresholds in the 
      extensor carpi radialis brevis (ECRB) and extensor carpi radialis longus (ECRL) 
      during a designated force-tracking task with a trapezoidal target (0%-75%-0% MVC) 
      were assessed. Results: Besides a smaller MVC of wrist extension, the patients 
      exhibited significantly greater task errors (p = 0.007) and force fluctuations (p 
      = 0.001) during force increment than the healthy counterparts. Nevertheless, no 
      force variables significantly differed between groups during force release (p > 
      0.05). During force increment, the amplitudes of the motor unit action potential 
      of the ECRB and ECRL muscles of the patients were smaller than those of the 
      heathy counterparts (p < 0.001). The patient group also exhibited a higher 
      percentage of motor units (MU) with lower recruitment threshold (<5% MVC) in the 
      ECRL/ECRB muscles and a lower percentage of MU with higher recruitment threshold 
      (>40% MVC) in the ECRB muscle, compared to the healthy group. During force 
      increment, the patient group exhibited a higher rate of decrease in inter-spike 
      intervals (ISIs) of motor units with lower recruitment thresholds (<10% MVC) in 
      the ECRB and ECRL muscles, compared to the control group (p < 0.005). Conclusion: 
      The patients with CLE exhibited more pronounced impairment in increasing force 
      than in releasing force. This impairment in increasing force is attributed to 
      deficits in tendon structure and degenerative changes in the larger motor units 
      of the wrist extensors. To compensate for the neuromuscular deficits, the rate of 
      progressive increase in discharge rate of the remaining smaller motor units (MUs) 
      is enhanced to generate force. Significance: The deficits in neuromuscular 
      control observed in CLE with degenerative changes cannot be fully explained by 
      the experimental pain model, which predicts pain-related inhibition on 
      low-threshold motor units.
CI  - Copyright (c) 2023 Chen, Hu, Hong, Hsu, Kuan, Chen, Su, Chen and Hwang.
FAU - Chen, Yueh
AU  - Chen Y
AD  - Institute of Allied Health Sciences, College of Medicine, National Cheng-Kung 
      University, Tainan, Taiwan.
AD  - Department of Orthopedics, Madou Sin-Lau Hospital, Tainan, Taiwan.
FAU - Hu, Chia-Ling
AU  - Hu CL
AD  - Institute of Allied Health Sciences, College of Medicine, National Cheng-Kung 
      University, Tainan, Taiwan.
FAU - Hong, Chih-Kai
AU  - Hong CK
AD  - Department of Orthopaedic Surgery, National Cheng Kung University Hospital, 
      College of Medicine, National Cheng Kung University, Tainan, Taiwan.
FAU - Hsu, Kai-Lan
AU  - Hsu KL
AD  - Department of Orthopaedic Surgery, National Cheng Kung University Hospital, 
      College of Medicine, National Cheng Kung University, Tainan, Taiwan.
FAU - Kuan, Fa-Chuan
AU  - Kuan FC
AD  - Department of Orthopaedic Surgery, National Cheng Kung University Hospital, 
      College of Medicine, National Cheng Kung University, Tainan, Taiwan.
FAU - Chen, Wei-Li
AU  - Chen WL
AD  - Department of Orthopedics, Madou Sin-Lau Hospital, Tainan, Taiwan.
FAU - Su, Wei-Ren
AU  - Su WR
AD  - Department of Orthopaedic Surgery, National Cheng Kung University Hospital, 
      College of Medicine, National Cheng Kung University, Tainan, Taiwan.
AD  - Musculoskeletal Research Center, Innovation Headquarter, National Cheng Kung 
      University, Tainan, Taiwan.
FAU - Chen, Yi-Ching
AU  - Chen YC
AD  - Department of Physical Therapy, College of Medical Science and Technology, Chung 
      Shan Medical University, Taichung, Taiwan.
FAU - Hwang, Ing-Shiou
AU  - Hwang IS
AD  - Institute of Allied Health Sciences, College of Medicine, National Cheng-Kung 
      University, Tainan, Taiwan.
AD  - Department of Physical Therapy, College of Medicine, National Cheng Kung 
      University, Tainan, Taiwan.
LA  - eng
PT  - Journal Article
DEP - 20230811
PL  - Switzerland
TA  - Front Physiol
JT  - Frontiers in physiology
JID - 101549006
PMC - PMC10450945
OTO - NOTNLM
OT  - EMG
OT  - force variability
OT  - motor unit
OT  - muscle strength
OT  - tennis elbow
COIS- The authors declare that the research was conducted in the absence of any 
      commercial or financial relationships that could be construed as a potential 
      conflict of interest.
EDAT- 2023/08/28 06:42
MHDA- 2023/08/28 06:43
PMCR- 2023/08/11
CRDT- 2023/08/28 04:44
PHST- 2023/03/03 00:00 [received]
PHST- 2023/08/02 00:00 [accepted]
PHST- 2023/08/28 06:43 [medline]
PHST- 2023/08/28 06:42 [pubmed]
PHST- 2023/08/28 04:44 [entrez]
PHST- 2023/08/11 00:00 [pmc-release]
AID - 1178557 [pii]
AID - 10.3389/fphys.2023.1178557 [doi]
PST - epublish
SO  - Front Physiol. 2023 Aug 11;14:1178557. doi: 10.3389/fphys.2023.1178557. 
      eCollection 2023.