The expression of heat shock protein in human skeletal muscle: effects of muscle fibre phenotype and training background.

AIM: Exercise-induced adaptations of skeletal muscle are related to training mode and can be muscle fibre type specific. This study aimed to investigate heat shock protein expression in type I and type II muscle fibres in resting skeletal muscle of subjects with different training backgrounds. METHODS: Three groups of subjects were included: healthy active not engaged in any training programme (ACT, n = 12), resistance trained (RES, n = 6) and endurance trained (END, n = 8). Biopsies were obtained from vastus lateralis, and immunohistochemistry was performed using monoclonal antibodies against myosin heavy chain I and IIA, αB-crystallin, HSP27, HSP60 and HSP70. RESULTS: In ACT and RES, but not in END, a fibre type-specific expression with higher staining intensity in type I than type II fibres was seen for αB-crystallin. The opposite (II > I) was found for HSP27 in subjects from ACT (6 of 12 subjects) and RES (3 of 6), whereas all subjects from END displayed uniform staining. HSP60 showed no fibre-specific expression. HSP70 displayed a fibre-specific expression pattern (I > II) in ACT (4 of 12), but not in END or RES. CONCLUSION: This study shows that the level of expression of the different HSPs in human skeletal muscle is influenced by muscle fibre phenotype. The fibre type-specific expression of HSP70 is influenced by resistance and endurance training, whereas those of αB-crystallin and HSP27 is influenced only by endurance training, suggesting the existence of a training-modality-specific action on the adaptive processes including heat shock proteins in human skeletal muscle.

Improved intramuscular blood flow and normalized metabolism in lateral epicondylitis after botulinum toxin treatment.

Lateral epicondylitis is a common cause of elbow pain, and decreased microcirculation in extensor carpi radialis brevis (ECRB) has recently been suggested to contribute to the symptoms. The purpose of this pilot study was to investigate the treatment response after injection of botulinum toxin type A. Ten patients with unilateral epicondylitis and decreased intramuscular blood flow in ECRB participated. Handgrip, 2-pinch grip and muscle strength during radial deviation and dorsal extension of the wrist were recorded. Perceived pain during contraction was evaluated with the Visual Analogue Scale (VAS) and function in daily activities was assessed using the Disability of Arm, Shoulder and Hand instrument (DASH) and the Canadian Occupational Performance Measure instrument (COPM). Intramuscular blood flow was recorded by laser Doppler flowmetry, and microdialysis was used to analyze muscle metabolism. The difference in intramuscular blood flow between the control and the affected side had decreased 3 and 12 months after treatment (P=0.03). Lactate concentration at the 12-month follow-up had decreased (P=0.02); perceived pain was reduced and function in daily activities had improved. Injection of botulinum toxin is an alternative treatment for epicondylitis. Symptom relief may be due to enhanced microcirculation causing an aerobic metabolism.

Decreased intramuscular blood flow in patients with lateral epicondylitis.

The purpose of this pilot study was to investigate intramuscular microcirculation in extensor carpi radialis brevis (ECRB) in patients with lateral epicondylitis. Ten patients with unilateral epicondylitis, mean duration of symptoms of 39 (12-96) months participated. The diagnosis was based on clinical examination and none was under treatment for the last 6 months. Isometric handgrip strength, 2-pinch grip strength and muscle strength during radial deviation and dorsal extension were determined. Functional perceived pain was evaluated by a modified behaviour rating scale and perceived pain during contraction by visual analogue scale. Intramuscular and skin blood flow was recorded by a laser-Doppler flowmetry system technique (LDF) during stable temperature condition. Intramuscular blood flow was significantly lower in the affected side, 22.7+/-9.8 perfusion units (PU), as compared with 35.2+/-11.9 PU in the control side (P=0.01). There was no difference in skin blood flow or temperature between the affected and the control side. A positive correlation was found between the duration of symptoms and the difference in intramuscular blood flow between the affected and the control arm (r=0.65, P=0.06). The present data indicate that decreased microcirculation and anaerobic metabolism in ECRB may contribute to the lateral epicondylitis symptoms.