The purpose of this study is to investigate a more effective physiotherapy technique for individuals with paralysis and muscle weakness accompanied by contractures. Specifically, the study aims to clarify the effects of hold-relax using NMES on muscle stiffness (MS), ROM, and stretch tolerance (ST).
This study employed a randomized crossover design with fifteen healthy male participants (age 20.4±0.7y.o. , height 170.6±6.0cm, weight 63.0±7.8kg, BMI21.6±2.2kg/m2). Each participant underwent three interventions: rest (control), hold-relax (HR), and hold-relax using NMES (HR-NMES). The HR intervention involved 10 repetitions of 10 seconds of maximal voluntary contraction, each followed by 20 seconds of rest, with the ankle joint positioned in maximum dorsiflexion using the Biodex system. For the HR-NMES intervention, the ankle joint was also positioned in maximum dorsiflexion, and electrical stimulation was applied on tibial nerve at a frequency of 80 Hz (carrier frequency of 2 kHz used by medium-frequency currents, i.e., interference current), with a pulse duration of 300 μs, at the maximum tolerable intensity. The duty cycle consisted of 10 sets of 10 seconds on and 20 seconds off, for a total duration of 300 seconds. HR and HR-NMES were conducted in two sets for each intervention, with intervention 1 and intervention 2 being applied, respectively. The evaluation indices were MS of the medial gastrocnemius (MG), ROM, and ST at maximum ankle dorsiflexion. MS was measured using ultrasonic strain elastography of the MG, while ROM and ST were assessed using a dynamometer (Biodex). Measurements were taken at four time points: before intervention 1 (T1), immediately after a 5-minute intervention 1 (T2), immediately after a 5-minute intervention 2 (T3), and 15 minutes after intervention 2 (T4). Statistical analysis was conducted using two-way repeated measures ANOVA followed by Bonferroni post hoc tests.
A significant interaction was found for MS, ROM, and ST (p 0.05). MS significantly decreased at T2 and T3 compared to T1 in both the HR and HR-NMES (p 0.05). Additionally, ROM and ST significantly increased at T2 and T3 compared to T1 in both conditions (p 0.05). There were no significant differences between the HR and HR-NMES for MS, ROM, or ST.
These findings suggest that hold-relax using NMES is nearly as effective as traditional hold-relax with voluntary contraction in improving MS, ROM, and ST.
Hold-relax with NMES shows promise for clinical application in treating contractures in patients with paralysis or muscle weakness, where voluntary contraction is difficult to achieve.
NMES
Hold-relax NMES
