A rat model of progressive isometric strength training

This study presents an isometric model of strength resistance training in r ats. Seven rats were trained for five weeks with increasing load, once a da y for six days per week while seven rats served as control group. Mechanica l strength of the hindlimb muscle group was measured on anaesthetised rats with a force transducer linked to the Achilles tendon after electrical stim ulation of the sciatic nerve. Training resulted in a 74 +/- 2% strength gai n in experimental (E) vs control (C) rats and in a reduction of fatigabilit y with no change in gastrocnemius, soleus and extensor digitorum longus wei ghts. The fibres composition of the gastrocnemius showed a 50% increase of IIA fibres and a 17% fall of IIB fibres. Consequently, this new model of is ometric training is suitable for physiological studies.