The effect of unstable resistance training with blood flow restriction on ankle muscles’ co-contraction of older adults

 older adults show high levels of co-contraction in lower extremities’ muscles due to the deterioration of the neuromuscular and sensory motor systems. Increased co-contraction leads to disruption of daily motor activities, especially movements in which joint stability is critical; therefore, it is important to pay attention to training programs to strengthen muscles and increase intramuscular coordination in older adults. The aim of this study was to investigate the effect of unstable resistance training with and without blood flow restriction on ankle muscles’ co-contraction of older adults.

 27 older adults (62 ± 1.5 years old) were assigned into three groups of unstable resistance training without blood flow restriction, unstable resistance training with blood flow restriction (72± 9 mm Hg) and control. The training program consisted of three to four sets of 15 repetitions of body weight squats for four weeks and three sessions per each week, which were gradually added to the program by 5% of each person's body weight. Pre- and post- intervention, the electromyography signals of Tibialis Anterior and soleus muscles were recorded during walking in order to determine the rates of agonist and antagonist activity and muscles’ co-contraction. For data analysis, repeated measures analysis of variance and analysis of covariance tests with Bonferroni post hoc test were used at 0.05 of level of significance.

 The results showed that in post-test, the activity of the Tibialis Anterior muscle of both training groups was significantly increased compared to pre-test. Also, statistically significant difference was found in co-contraction rates of both groups in post-test. The results of Bonferroni post hoc test showed a statistically significant difference in reduction of co-contraction rates between the resistance training group with blood flow restriction and the control group (P=0.015) and between resistance training group without blood flow restriction with the control group (P=0.005). But no statistically significant difference was found between the two training groups.

 Resistance training on unstable surface with and without blood flow restriction is associated with increased agonist muscle activity, which leads to a decrease in ankle muscles’ co-contraction in older adults.