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[Purpose] The purpose of this study was to examine immediate effects of strength training and NJF distal resistance training in wrist joints by using writing time and evaluation of proprioception using the JPE test. [Subjects and Methods] The subjects were 12 young healthy people (24.2 ± 3.1 y, 169.7 ± 6.5 cm, 65.3 ± 12.6 kg). Two isotonic contraction techniques were applied on the wrist joint: wrist joint extension muscle strength training (MST) and the wrist joint extension pattern of NJF. The uppercase English alphabet writing time and joint position errors of the left upper limb were measured before and after one intervention session of MST and NJF. [Results] The decrease in errors in wrist extension angle repetition and the writing time represented the improvement resulting from NJF. [Conclusion] This result suggests that the subdominant hands wrist joint proprioception and writing function can be improved by NJF together with proximal resistance training.
Patients with cervical spinal cord injury or stroke often have impaired proprioception of upper limbs and reduced muscle strength and range of movement (ROM). Proprioception training, muscle strength training (MST), and ROM training are usually implemented in physical therapy programs for patients with cervical spinal cord injury and stroke1). A number of research studies have focused on increasing muscle strength and/or ROM of upper limbs. After stroke, the function of the hemiplegia side is always greatly affected and part or all of the upper limb’s motor function disappears. Therefore, the handedness exchange is very important for patients with hemiplegia to improve activities of daily living. Patients’ subdominant hands proprioception training has been used in clinics for handedness exchange. And after cervical spinal cord injury, patients’ upper limb proprioception is evaluated to know the extent of the disability and its effects on activities of daily living. Besides, it has also been used as a part of treatment for cervical spinal cord injury as well as practical functional treatment in occupational therapy rehabilitation programs.
Along with muscle strength, proprioception sense is also decreased in patients with cervical spinal cord injury or stroke. The joint position error (JPE) test is considered the primary measure of upper limb proprioception and has been widely used as an outcome indicator for patients with cervical spinal cord injury and hemiplegia2). A decrease in JPE indicates the increased ability to reposition joints after active movements. In clinical treatments and researches, resistance to wrist joint flexion is used to enhance the strength of the radialis and ulnar extensor muscle of the wrist, whereas in clinical treatments, isotonic contraction is used. Evaluation of proprioception is not performed to assess or compare other manipulation therapies3).
Neuromuscular joint facilitation (NJF) is a new therapeutic exercise based on kinesiology that integrates the facilitation element of proprioceptive neuromuscular facilitation (PNF) and joint composition movements, aiming to improve movements of the joint through passive, active, and resistance exercises4). NJF is used to increase strength, flexibility and ROM5), and improve wrist joint functions. NJF uses the same motion pattern as PNF, but the location of resistance of NJF is different. The proximal resistance is applied to the scaphoid or triangular bone in wrist patterns.
The purpose of this study was to examine immediate effects of strength training and NJF distal resistance training in wrist joints by using writing time and evaluation of proprioception using the JPE test.
The subjects were 12 young healthy people (8 males and 4 females). The subjects’ characteristics are detailed in Table 1. All of the subjects were right-handed. The purpose and contents of this research were explained to the subjects, and they gave their informed consent to participate in the study. The study was approved by the Research Ethics Committee of China Rehabilitation Research Center (IRB no. 2014-26).
The subjects sat on chairs and placed their left upper limbs on tables in front. The subjects’ shoulder joints were flexed at 45° and their elbow joints were flexed at 45°. Two isotonic contractions were performed on wrist joints extension: the wrist joint extension muscle strength training (MST) and the wrist joint extension pattern of NJF. All interventions were carried out by one physiotherapist. Resistance was applied to the highest level possible that allowed subjects to complete the isotonic exercise.
1. MST group: One hand of the examiner was placed against the dorsal palm. The other hand of the examiner was placed on the distal forearm to fixate the wrist joint. Resistance was applied as the subjects performed wrist joint extension.
2. NJF group: The wrist extension-radial drift (ERD) pattern and wrist extension-ulnar drift (EUD) pattern of NJF were performed. In the ERD pattern, one hand of the examiner was placed against the distal second dorsal metacarpal and traction and resistance were increased. The examiner’s other hand was on the triangular bone, which was moving distally when wrist joints extended. In the EUD pattern, one hand of the examiner was placed against the distal fifth dorsal metacarpal and traction and resistance were increased. The examiner’s other hand was on the scaphoid, which was moving distally when wrist joints extended. When the subjects performed the wrist joint extension pattern, traction and resistance were applied throughout the process by two hands.
In both MST and NJF groups, the interventions were carried out ten times. In the NJF, traction and resistance were applied five times on the scaphoid and five times on the triangular bone6). There was a 1-hour rest period between interventions in the MST and NJF groups, and two interventions and tests were performed within 1 day. All trials were performed at random. Before and after one intervention of MST and NJF, JPE and the writing time were measured.
In the JPE test, the ROM measurement equipment (BioVal 4.51, SyCoMoRe 8.51, RM Ingenierie, France) was used. The fixed and mobile arms were the vertical axis of the radius and fifth metacarpal; the extension angles of wrist joints were recorded by the computer. The subjects were asked to close their eyes, and the examiner extended the subject’s wrist joints at random angles. The subjects’ wrist joints were put back to tables, and they were asked to extend their wrists at approximately the same angles as in the initial extension. Errors in wrist extension angles were recorded. Each measurement was carried out five times, and the average value was used for analysis.
In the writing time evaluation, the subjects were asked to write the uppercase English alphabet by left hand on A4 paper. There were writing grids of which each area was 1 cm2 on A4 paper. The time of writing uppercase English alphabet was measured.
Two-way repeated-measures analysis of variance (ANOVA) was used to test for statistically significant differences, and the factors were intervention and group. If any significant interaction was found, the paired t-test was performed to compare the outcome indicators before and after the intervention. Data were analyzed using SPSS Ver. 17.0 for Windows (SPSS, Chicago, IL, USA). The level of statistical significant was set at 0.05.
Two-way ANOVA revealed significant interactions among the JPEs and the writing time of the two groups, indicating that the changes between the groups were significantly different (Table 2). The errors in wrist extension angle repetition were reduced, and the writing time was increased by NJF intervention.
Compared with that of the MST group, the NJF group’s errors in wrist extension angle repetition were reduced, and the writing time was decreased significantly.
These results can be attributed to the improvement in functions of periarticular muscles of subdominant hands wrist joints due to the application of the proximal resistance. The alignment of the wrist joint capsule, the functions of periarticular muscles of wrist joints, and the wrist position sense were improved; therefore, the JPE and the writing time were decreased in the NJF group. In the NJF resistance exercise, the midcarpal joints were hustled using the proximal resistance on the scaphoid or triangular bone7).
These results suggest that the wrist joint proprioception and functions can be improved by NJF together with proximal resistance training, which can be used as a new form of exercise for improving functions of subdominant hands wrist joints.