Participant Characteristics
Ten participants, including eight males and two females with SCI, were recruited. The participants were between 27 and 72 years old, averaging 47. 0 (SD=14.84) years old. Demographic characteristics of participants are presented in Table 1.
Muscle strength
Collected data indicated that on the experimental side, the mean difference in forearm muscle strength was significantly higher, with an average increase of 7.5 ± 0.36 kg (mean ± SD) following the 16 exercise sessions. In contrast, the control side displayed a significantly lower increase in muscle strength, with a mean difference of 4.4 ± 0.67 kg. The average muscle strength for each participant in the control and experimental groups before and after the exercise protocol is presented in Figure 2.
Descriptive Statistics
The descriptive statistics of the study variables are reported in Table 2. The average muscle strength after the experiment was 45.15 (12.31), which was greater than before the experiment, 37.64 (11.57). In addition, the average muscle strength in the control group after the intervention was 43.68 (10.89), which was greater than the control group before the intervention, 39.31 (9.60). The absolute z-scores for either skewness or kurtosis are smaller than 1.96, which corresponds with an alpha level of 0.05, indicating that the distribution of the sample in all study variables is normal.
As presented in Figure 3, the average muscle strength after the study increased compared to the average muscle strength before the study in both control (Figure 3a) and experimental (Figure 3b) groups, indicating both traditional and LI-BFR exercise protocols could improve muscle strength. Furthermore, as indicated in Figure 3c, the mean increase of muscle strength in the intervention forearm is higher than the mean increase in the control forearm
Statistical Inferences
Normality Assumption: According to the non-significant results of the Kolmogorov-Smirnov Test (p>0.05), the normality assumption is met, indicating that all the variables are normality distributed.
Paired T-test (Experimental Group): The descriptive results confirmed that the average muscle strength after the intervention (M=45.15, SD=12.31) was higher than before the intervention (M=37.64, SD=11.57). The absolute effect size for the mean differences between the paired samples (before and after the intervention) in the experimental group was d=6.32, indicating a large effect size (≥0.8). Individuals in the experimental group who received the exercise method showed a six-fold increase in muscle strength improvement compared to those who did not receive the exercise method (Cohen's d=-6.32, 95% CI -8.34,-6.68) (Table 3).
Paired T-test (Control Group): The descriptive results indicated that the mean (SD) of muscle strength after the intervention was 43.68 (10.89), which is higher than before the intervention, 39.31 (11.57). The absolute effect size for the mean differences for the paired samples (before and after the intervention) in the control group was d=2.03, indicating a large effect size (≥0.8). That is, in individuals who received the exercise method, in the control group, the muscle strength improvement was twice as high as in individuals who did not receive the exercise method (Cohen`s d=-2.03, 95% CI -5.91,-2.83)(Table 3).
Independent T-test: According to the descriptive results, in the experiment group, the mean (SD) of muscle strength was 7.5 (1.16), which is higher than the control group, 4.4 (2.15). The absolute effect size for the mean differences of the two independent samples (between control & experiment groups) after the intervention was d=1.82, indicating a large effect size (≥0.8). In individuals in the experimental group who received the exercise method, the muscle strength improvement was approximately twice as high as in individuals in the control group who received the exercise method (Cohen`s d=-1.82, 95% CI -4.76, -1.52) (Table 3).
Survey Analysis
The self-assessment data revealed that the PGIC scores were distributed as follows: three participants reported a rating of 1, four participants reported a rating of 2, one participant reported a rating of 3, and two participants reported a rating of 4. The calculated mean for these responses amounted to 2.2. According to the results of the self-assessment questionnaire, the level of satisfaction concerning muscle improvements in the hand/forearm that underwent the LI-BFR exercise method ranged from 7-10. The overall quality of life ratings after receiving the exercise protocol ranged from 2 to 9, with a slight improvement to a great improvement. Participants experienced slightly stronger (n=5, 50%) and significantly stronger (n=4, 40%) strength of the hand/forearm following the LI-BFR exercise protocol. Additionally, about 60% of the participants (n=6) experienced no discomfort or pain, and about 40% (n=4) experienced mild discomfort due to the exercise protocol involving BFR. The participants’ interest in a home-based practice of the LI-BFR to continue this exercise regularly received a rating between 6-10. Most participants (n=6, 60%) would definitely and the rest (n=4, 40%) would likely recommend the LI-BFR exercise to others with a similar condition.
Participants` Feedback
After completing the study, the participants were asked to provide feedback on how the exercise intervention impacted their daily activities. The summary of their comments is presented in Table 4.