Differential contributions of ankle plantarflexors during submaximal isometric muscle action: a PET and EMG study.
The objective of this study was to investigate the relative contributions of superficial and deep ankle plantarflexors during repetitive submaximal isometric contractions using surface electromyography (SEMG) and positron emission tomography (PET). Myoelectric signals were obtained from twelve healthy volunteers (27.3±4.2yrs). A tracer ([(18)F]-FDG) was injected during the exercise and PET scanning was done immediately afterwards. The examined muscles included soleus (Sol), medial gastrocnemius (MG), lateral gastrocnemius (LG), and flexor hallucis longus (FHL). It was found that isometric maximal voluntary contraction (MVC) force, muscle glucose uptake (GU) rate, and SEMG of various plantarflexors were comparable bilaterally. In terms of %EMG MVC, FHL and MG displayed the highest activity (∼34%), while LG (∼21%) had the lowest activity. Cumulative SEMG from all parts of the triceps surae (TS) muscle accounted for ∼70% of the combined EMG signal of all four plantarflexors. As for GU, the highest quantity was observed in MG (2.4±0.8μmol*100g(-1)*min(-1)), whereas FHL (1.8±0.6μmol*100g(-1)*min(-1)) had the lowest uptake. Cumulative GU of TS constituted nearly 80% of the combined GU. The findings of this study provide valuable reference for studies where individual muscle contributions are estimated using models and simulations.
Neuromuscular Research Center, Department of Biology of Physical Activity, University of Jyväskylä, Finland. Electronic address: tahir.masood@jyu.fi.
Tahir
T
Masood
Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway; Institute of Sports Medicine Copenhagen & Musculoskeletal Rehabilitation Research Unit, Bispebjerg Hospital, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.
Jens
J
Bojsen-Møller
Turku PET Centre, Turku, Finland.
Kari K
KK
Kalliokoski
Turku PET Centre, Turku, Finland.
Anna
A
Kirjavainen
Department of Orthopaedics and Traumatology, Turku University and University Hospital, Turku, Finland.
Ville
V
Áärimaa
Institute of Sports Medicine Copenhagen & Musculoskeletal Rehabilitation Research Unit, Bispebjerg Hospital, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.
S
S
Peter Magnusson
Neuromuscular Research Center, Department of Biology of Physical Activity, University of Jyväskylä, Finland.
Taija
T
Finni
D000328:Adult; D000842:Ankle / Q000502:physiology*; D053587:Arthrometry, Articular; D004576:Electromyography; D015444:Exercise / Q000502:physiology; D005260:Female; D005947:Glucose / Q000493:pharmacokinetics; D064368:Healthy Volunteers; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D007866:Leg / Q000502:physiology; D008279:Magnetic Resonance Imaging; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D049268:Positron-Emission Tomography; D055815:Young Adult
D005947:Glucose
Biomechanics; Electromyography (EMG); Glucose uptake; Isometric plantarflexion exercise; Positron emission tomography (PET); Triceps surae (TS)