title: Effects of 12-wk eccentric calf muscle training on muscle-tendon glucose uptake and SEMG in patients with chronic Achilles tendon pain.
abstract: High-load eccentric exercises have been a key component in the conservative management of chronic Achilles tendinopathy. This study investigated the effects of a 12-wk progressive, home-based eccentric rehabilitation program on ankle plantar flexors' glucose uptake (GU) and myoelectric activity and Achilles tendon GU. A longitudinal study design with control (n = 10) and patient (n = 10) groups was used. Surface electromyography (SEMG) from four ankle plantar flexors and GU from the same muscles and the Achilles tendon were measured during submaximal intermittent isometric plantar flexion task. The results indicated that the symptomatic leg was weaker (P < 0.05) than the asymptomatic leg at baseline, but improved (P < 0.001) with eccentric rehabilitation. Additionally, the rehabilitation resulted in greater GU in both soleus (P < 0.01) and lateral gastrocnemius (P < 0.001) in the symptomatic leg, while the asymptomatic leg displayed higher uptake for medial gastrocnemius and flexor hallucis longus (P < 0.05). While both patient legs had higher tendon GU than the controls (P < 0.05), there was no rehabilitation effect on the tendon GU. Concerning SEMG, at baseline, soleus showed more relative activity in the symptomatic leg compared with both the asymptomatic and control legs (P < 0.05), probably reflecting an effort to compensate for the decreased force potential. The rehabilitation resulted in greater SEMG activity in the lateral gastrocnemius (P < 0.01) of the symptomatic leg with no other within- or between-group differences. Eccentric rehabilitation was effective in decreasing subjective severity of Achilles tendinopathy. It also resulted in redistribution of relative electrical activity, but not metabolic activity, within the triceps surae muscle.
authors.affiliation: Neuromuscular Research Center, Department of Biology of Physical Activity, University of Jyväskylä, Jyväskylä, Finland; tahir.masood@jyu.fi.
authors.forename: Tahir
authors.initials: T
authors.lastname: Masood
authors.affiliation: Turku PET Centre, University of Turku, Turku, Finland;
authors.forename: Kari
authors.initials: K
authors.lastname: Kalliokoski
authors.affiliation: Institute of Sports Medicine Copenhagen & Musculoskeletal Rehabilitation Research Unit, Bispebjerg Hospital, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: S Peter
authors.initials: SP
authors.lastname: Magnusson
authors.affiliation: Deptartment of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway; and Institute of Sports Medicine Copenhagen & Musculoskeletal Rehabilitation Research Unit, Bispebjerg Hospital, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Jens
authors.initials: J
authors.lastname: Bojsen-Møller
authors.affiliation: Neuromuscular Research Center, Department of Biology of Physical Activity, University of Jyväskylä, Jyväskylä, Finland;
authors.forename: Taija
authors.initials: T
authors.lastname: Finni
mesh_terms: D000125:Achilles Tendon / Q000378:metabolism*; D000328:Adult; D000842:Ankle; D000843:Ankle Joint / Q000378:metabolism; D016022:Case-Control Studies; D004493:Education / Q000379:methods; D004576:Electromyography / Q000379:methods; D015444:Exercise / Q000502:physiology; D005081:Exercise Therapy / Q000379:methods; D005260:Female; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D007866:Leg; D008137:Longitudinal Studies; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism*; D009135:Muscular Diseases / Q000378:metabolism*; D009142:Musculoskeletal Physiological Phenomena; D010146:Pain / Q000378:metabolism*
chemical_list: D005947:Glucose
keywords: Achilles tendon; biomechanics; eccentric exercise; positron emission tomography; tendinopathy