Can eccentric exercise of the lower limb be made more efficiently, a pilot study

Abstract 
Background: Eccentric Exercise has been shown to be more effective in building muscle and healing damaged tissue than concentric or isometric exercise. It has also been shown to be effective in increasing motor control. But the duration of therapeutic exercise in physical therapy is limited by insurance to 30-60 minutes a day. 
Objectives: Four standard therapy eccentric exercises of the lower limbs were compared (toe raise, ball exercise, side lying eccentric exercise and incline board exercise) to a trainer called the BTE Eccentron to see if the efficiency of exercise could be increased using one exercise session to meet or beat the four individual exercises. 
Subjects and Methods: The study examined eight randomly selected participants with no known medical conditions (neurological or orthopedic) that would preclude their participation (age=24.1+/-2.1 years height=168.9+/-6.4 cm BMI=23.2+/-3.2). EMG was used to assess muscle recruitment in each exercise. The muscles studies were the gastrocnemius, hamstring, hip adductors, and quadriceps muscles. 
Results: Muscle use on the eccentron was almost double that of the other exercises. Thus, making therapy more efficient. One single exercise bout showed more muscle activation during eccentric exercise than the other four exercises, with an average muscle use almost 4 times higher on the eccentron. 
Conclusion: The Eccentron offers a considerable advantage for clinical treatment making exercise and neuromuscular training more efficient.


Study Rationale and objectives
While there have been numerous review articles on the benefits of eccentric exercise, the problem remains that individual exercises on the lower limb take time to accomplish and with an ever-shrinking insurance environment, the exercises are impractical to accomplish. However, a trainer, the Eccentron, exercises both legs with eccentric exercise at the same time. The purpose of this study was to determine muscle activity during specific lower limb eccentric exercises through the EMG activity and compare it to the eccentron to see if therapy can be shortened and have similar if not better results.

Subjects
The study used eight randomly selected participants with no known medical complications. Participants were between 22 and 27 years old. The age, heights and weights of the group are listed in Table 1.  Exercise four: eccentric loading of the quadriceps muscle group-decline board.
In this exercise the subject was standing on one leg, on a decline board with an angle of 30 degrees. The subject was asked to slowly bend their knee, to the count of 4, until they could no longer see their toes.
They were then instructed to extend their knee. After they performed four repetitions the subject switched legs and performed the same exercise on the opposite side.

EMG
To determine muscle activity, the electromyogram was recorded. EMG was recorded by two electrodes and a reference electrode placed above the active muscle. The relation between tension in muscle and surface EMG amplitude is linear for these four muscles [17,22,

Procedures
All subjects participated in all exercises. The order Volume 1 (1)

Data Analysis
Descriptive data for both the dependent measures and the demographic variables were calculated, and tests of homogeneity of variance and normality were used for the statistical tests assumptions. T-tests and ANOVA were used to compare the study groups' baseline characteristics.

Results
The results of the measurements of muscle activity are shown in Figures 1-4. As shown in Figure 1, the muscle activity in the medial gastrocnemius muscle was significantly higher for the eccentron and the toe raises than the other three exercises (ANOVA p<0.01). There was no significant difference in the EMG activity (muscle activity) for the ball exercise, side lying exercise or the incline board (ANOVA p=.42). The results for the hamstring muscles are shown in Figure 2. As can be seen here, the muscle activity for the hamstring muscles during the eccentron exercise was significantly higher than the other four exercises (ANOVA p<0.01). The average muscle activity was 75% of the maximum strength of these muscles.
However, there were no difference in hamstring muscle activity for the side lying or the incline board exercises (P=0.33) which were different than the ball exercise, the toe raises and eccentron. The hamstring activity during the toe raises was significantly less than the other four exercises (p<0.01 ANOVA).
The results of the muscle activity of the quadriceps group are shown in Figure 3. There was no difference in activity between the eccentron and incline board for this muscle group (p>0.05). But compared to the other three exercises, muscle activity was significantly higher for these two exercises (ANOVA p<0.01). The ball exercise had significantly less activity than the toe raises and the side lying exercise (p<0.05). For the eccentron, muscle activity was over 80% of muscle strength for the quadriceps.  Table 2, the average muscle activity for the four muscles groups is shown for each exercise.

Discussion
The purpose of this study was to evaluate the optimal exercise that could be used for patients undergoing an eccentric exercise program on the lower limbs.