BACKGROUND: Strength training (ST) and/or electrical stimulation (ES) are two methods that have been prescribed for muscles improvement. The purpose of this study was to investigate the effects of six weeks of strength training and combined technique on maximal voluntary isometric contraction (MVIC) in plantar flexor muscles after 4 weeks of detraining. METHODS: Twenty-four healthy and nonathletic female students (age: 20-30 yrs) were randomly assigned to ST, combined training (CT), and control groups. The ST group performed 18 sessions of isometric contraction of plantar flexor muscles in three degrees (15° Dorsiflexion, Neutral, 45° plantarflexion) at 85% of MVIC and the CT group received ES (FES: Phase time of 60 microseconds; stimulation frequency of 40 Hz; duty cycle = 2s on/4s off; isometric contraction; 10 contractions per second at the maximum tolerated intensity without pain) combined with the same protocol as the ST Group. ST and CT subjects were tested before training; after 6 weeks of training; and after 4 weeks of detraining. RESULTS: In comparison with pretest measurers, post-test measures showed that the mean average of plantar flexor strength in the ST group increased from 25.75±7.10 to 45.25±12.66 in neutral position and increased from 32.75±9.66 to 48.00±11.56 in DF position. The mean average of plantar flexor strength in the CT group also increased from 24.52±7.32 to 43.50±10.46 in neutral position and increased from 24.63±11.13 to 34.38±7.76 in DF position. Except for MVC in DF in the CT group, all variables reduced to their original values at the post detraining measures. In comparison with induced adaptations in ST and CT, this finding suggests that after 4 weeks of detraining, these adaptations in CT were maintained more than voluntary isometric training. CONCLUSIONS: It seems that strength changes following CT are longer lasting.
