INTRODUCTION
Spinal cord injuries (SCIs) damage the spinal cord, resulting in nervous system dysfunction and loss of motor control [1]. With advances in medical care, the average life expectancy of individuals with SCIs has markedly increased in recent decades [2]. However, this population continues to experience significant health challenges, including profound physical disabilities, secondary musculoskeletal and respiratory complications, and chronic skin conditions [3]. A sedentary lifestyle, common among individuals with SCIs, further elevates the risk of cardiovascular diseases, type 2-diabetes, and obesity, negatively impacting the quality of life [4]. Therefore, optimizing mobility, independence, and overall well-being is essential for improving health-related quality of life (HRQOL).
HRQOL is a multidimensional construct that reflects individuals’ perceptions of their physical, functional, emotional, and social well-being [5,6]. Although muscle paralysis is the most apparent outcome of SCIs, affected individuals often experience a wide range of complications including mobility impairment, pain, sexual dysfunction, and bladder and bowel incontinence, all of which significantly impair HRQOL [7]. Prior research has shown that HRQOL in this population is influenced by a combination of medical, psychological, and social factors rather than by physical conditions alone [8]. Several studies have evaluated the HRQOL after rehabilitation in individuals with SCIs [9,10]. For instance, a cross-sectional study of 165 individuals with SCIs and 5,152 healthy controls demonstrated significantly lower HRQOL scores in the SCIs group, particularly in the subdomains of physical functioning (PF), bodily pain (BP), general health (GH), and vitality (VT) [9]. Similarly, a prospective cohort study involving 153 males with SCIs revealed markedly lower PF and GH scores than the scores in healthy controls [10].
Although previous evidence supports the positive effects of exercise on cardiopulmonary fitness and muscular strength in individuals with SCIs [11,12], fewer studies have explored the direct impact of exercise interventions on HRQOL. Nightingale et al. reported that a six-week moderate-intensity arm crank training program significantly improved HRQOL outcomes and reduced fatigue in patients with SCIs [13]. Moreover, positive associations between physical activity and HRQOL have been observed in populations with other chronic conditions, including multiple sclerosis [14], cancer [15], and coronary artery disease [16]. However, the existing literature on populations with SCIs has largely focused on either aerobic or resistance training alone, with limited integration of these modalities.
This gap is noteworthy given the multidimensional consequences of SCIs and the potential for a combined intervention to address both the physical and psychological domains more comprehensively. Aerobic exercise enhances cardiovascular function, improves blood flow in the paralyzed limbs, and helps regulate autonomic function, which is often impaired in individuals with high-level injuries. Resistance training supports muscular strength, joint stability, and metabolic health in the innervated regions, which can improve mobility, glycemic control, and independence. Furthermore, both exercise modes have been associated with reductions in fatigue, pain, and depressive symptoms, which are factors that significantly affect the HRQOL in this population. A combined approach may offer synergistic benefits by simultaneously addressing multiple physiological and psychosocial domains. Despite this potential, few studies have implemented personalized interventions that integrate both modalities in individuals with SCIs.
This study addresses this gap by implementing a six-week, evidence-based, individualized program combining aerobic and resistance exercises tailored to the specific needs and functional levels of individuals with SCIs. Therefore, this exploratory randomized controlled trial aimed to examine the effects of a personalized six-week exercise program on the HRQOL of individuals with SCIs. We hypothesized that participants receiving the intervention would demonstrate significant improvements in both the physical and mental components of HRQOL compared to controls.
METHODS
Study design and participants
Participants were recruited from three Seoul metropolitan area hospitals between July 2014 and Dec 2014. While patients waited in the waiting room, the research staff explained the purpose of the study to them. Patients who agreed to participate signed an informed consent form and were interviewed individually by well-trained research staff. The eligibility criteria were as follows: (1) SCIs > 6 months, (2) age 18-65 years, and (3) no regular exercise over the past 6 months. The exclusion criteria were as follows: (1) cardiovascular disease; (2) uncontrolled type 2 diabetes; (3) uncontrolled hypertension; (4) pressure ulcers; and (5) orthopedic complications. For this two-arm 6-week pilot randomized controlled trial, eligible patients with SCIs were randomly assigned to an exercise or control group before baseline measurements by their primary physicians in a 1:1 ratio using a computer-generated random number sequence. The allocation sequence was generated by a biostatistician using a randomized research website program. All measurements were performed at baseline and after a 6-week intervention period at Yonsei Severance Hospital by a trained exercise specialist. The trial was registered at cris. nih.go.kr (Clinical Research Information Service number: KCT0008257). The participant characteristics and recruitment procedures are summarized in Table 1 and Figure 1, respectively.
Personalized physical exercise programs
The individualized exercise program implemented in this study was developed using a structured eight-phase process based on scientific evidence and clinical expertise. The initial phase involved a systematic literature review and needs assessment to identify appropriate exercise modalities, intensities, durations, and barriers specific to individuals with SCIs. Building on these findings, a health risk assessment model was formulated using the input from a multidisciplinary expert panel. The exercise protocol was then designed according to the FITT framework, addressing frequency, intensity, time, and type, which is widely endorsed for exercise prescription in populations with chronic conditions, such as SCIs [17]. Subsequently, the draft program was pilot-tested with a small cohort of individuals with SCIs to evaluate its safety, feasibility, and tolerability. Feedback was obtained through structured interviews and focus group discussions involving the participants, caregivers, rehabilitation physicians, and exercise specialists. This feedback provided successive refinements through expert consultations, culminating in the final version of the intervention protocol. The final program was tailored to each participant by accounting for their level of spinal injury, body composition, joint limitations, and presence of comorbid conditions, including cardiovascular disease and type 2-diabetes. These clinical considerations informed the selection and progression of exercises in terms of type, intensity, and duration. The participants engaged in supervised exercise sessions three times per week for six weeks, with each session lasting approximately 60 min, totaling 18 sessions. A typical session included a 25-min warm up phase, consisting of 5 min of joint mobility, 15 min of aerobic training on an arm ergometer, and 5 min of stretching. This was followed by a 30-min main training phase involving resistance, circuit, and aerobic exercises, and concluded with a 5-min cool down. Aerobic training was prescribed at moderate to vigorous intensity using the Borg Rating of Perceived Exertion (RPE) scale, targeting a score between 4 and 8 on a 10-point scale [18]. This RPE range corresponds to a moderate to vigorous effort and has been validated as a reliable intensity guide for individuals with SCIs, particularly during upper-body exercises [19]. Exercise intensity was monitored and adjusted weekly based on the participants’ feedback and prior exertion levels to ensure both safety and progression. Table 2 outlines the standardized structure of the exercise program. However, exercise selection, volume, intensity, and rest intervals were individualized based on each participant’s neurological level, comorbid conditions (e.g., joint-related issues, diabetes, and cardiovascular risk), and weekly performance. The modifications were made in consultation with a clinical exercise specialist to ensure safety and appropriateness. Two representative cases are presented to illustrate the practical application of individualized exercise programming. Participant A, a 45-year-old male with T12 complete SCIs and type-2 diabetes, was prescribed an extended aerobic session (20 min of hand cycling at 60-80 rpm) and core-focused exercises (e.g., seated crunches, side bends) to enhance metabolic control and trunk stability, with weekly progression based on RPE scores and glycemic response. Participant B, a 31-year-old female with C6 incomplete SCIs and rotator cuff dysfunction, followed a modified protocol that excluded triceps-based movements, including low-resistance band rows and isometric neck/shoulder stabilization. Aerobic training was limited to 10-12 min at RPE 4-6 to minimize joint strain. In both cases, weekly adjustments were made in response to functional status and clinical feedback, demonstrating the neurological level, comorbidities, and individual tolerance-informed exercise prescriptions.
Measurements
Anthropometric measurement
All measurements were performed at baseline and after completion of the 6-week exercise program. Body weight was measured to the nearest 0.1 kg on a scale adapted for use with wheelchairs, and height was measured to the nearest millimeter in a supine position with the legs outstretched and feet dorsiflexed. Waist circumference was measured to the nearest millimeter in the supine position using a tape (Gullick II Tape Measure, Gays Mills, WI, USA) at the midpoint between the inferior portion of the lateral rib cage and the iliac crest. Body composition was measured using a bioelectrical impedance analyzer (Inbody S10®, Seoul, South Koreac), which was designed to determine body composition for patients in the supine position. Bioelectrical impedance analysis has been previously validated against dual-energy X-ray absorptiometry, and the two techniques exhibit a correlation coefficient > 0.9 in both able-bodied persons [20,21] and people with SCI [22].
Health-related quality of life
HRQOL for study participants with SCIs was determined using the short-form health survey-36 (SF-36), which was developed for self-administration for respondents aged 14 years and above [23]. In the questionnaire used in this study, the SF-36 walk-wheel (SF-36ww) was modified for people with SCIs using the original questions in the standard SF-3624. This questionnaire includes 36 items that evaluate QOL in eight domains: PF, role-physical (RP), BP, GH, VT, social functioning (SF), role-emotional (RE), and mental health (MH). The SF-36 also provides two different summary measures of HRQOL, the physical component summary (PCS) and the mental component summary (MCS), computed from the respective domain scores. Higher domain and summary scores, ranging from 0 to 100, indicate better perceptions of health status.
Statistical analysis
Statistical analyses were performed using the SPSS software (Windows version 21.0; SPSS Inc., Chicago, IL, USA). The primary analysis, which included all randomized participants, was included in the statistical analysis (intention-to-treat analysis). Data were summarized as means with standard deviations or medians with interquartile ranges for continuous variables and as percentages for categorical variables. Comparisons of variables across groups (exercise vs. control) were performed using the chi-square test for categorical variables and the t-test or Wilcoxon rank-sum test for continuous variables, as appropriate. The significance for the outcomes was set at p value <.05.
RESULTS
Participant characteristics
Descriptive statistics for the demographic and clinical variables are presented in Table 1. Of the 17 patients (male, n = 11; female, n = 6) with SCIs at injury levels between C4 and L1, 12, two participants (one in the exercise group and one in the control group) dropped out for medical reasons. The mean age was 35.1 ± 5.4 years, mean waist circumference was 85.1 ± 11.8 cm, and mean duration of injury was 7.6 ± 4.9 years. The participants in the exercise group successfully completed a 6-week personalized exercise training program in 18 sessions.
Changes in quality-of-life components
The 6-week personalized physical exercise program significantly improved HRQOL in the exercise group, as evidenced by SF-36 an increases in multiple components, including PF, RP, BP, GH, VT, RE, and MH (p < 0.05) (Table 3). Conversely, the control group showed no significant changes in the SF-36 component scores, except for decreased GH (p < 0.05). Additionally, the exercise group demonstrated significant improvements in both PCS and MCS scores compared with the control group (p =0.002 for PCS and p =0.001 for MCS), as depicted in Figures 2A and 2B.
DISCUSSION
This randomized controlled trial evaluated the efficacy of a personalized six-week physical exercise program on HRQOL, as measured using the SF 36, in patients with SCIs. The findings demonstrated statistically significant improvements in seven of the eight HRQOL subdomains, spanning both physical and mental health dimensions. Notable enhancements were observed in PF, RP, BP, GH, VT, RE, and MH, along with significant increases in the PCS and MCS scores.
Improvements in the physical domains are consistent with prior research showing that structured exercise improves musculoskeletal strength, pain regulation, and functional mobility in individuals with SCIs [25-28]. For example, Ditor et al. reported reductions in pain and fatigue after long-term supervised exercise [29], whereas Hicks et al. reported improvements in strength and endurance after combined resistance and aerobic training [30]. These outcomes are likely mediated by the enhanced neuromuscular coordination, improved vascular function, and systemic anti-inflammatory responses induced by regular physical activity.
In addition to physical improvements, our findings revealed clinically meaningful improvements in emotional and psychosocial health, particularly in the RE and MH domains. These results support the evidence that exercise can alleviate the symptoms of depression, anxiety, and social withdrawal prevalent in individuals with SCIs. Prior studies have highlighted the association between physical activity, psychological resilience, and enhanced community participation [31,32]. Mechanistically, these effects may be driven by increased self-efficacy, favorable neurochemical changes, and enhanced opportunities for social engagement [33,34]. Our intervention, which integrated aerobic and resistance exercises, may have had a synergistic effect on the biopsychosocial outcomes. Although many previous interventions have focused on single modalities [35], our combined approach appears to address the multifaceted needs of patients with SCIs more comprehensively. To better understand the practical significance of these findings, it is essential to examine the effect sizes. The exercise group experienced a mean increase in MCS of 10.2 ± 4.4, whereas the control group showed a mean decline of 8.0 ± 7.8. These divergent patterns suggest not only statistical significance but also a meaningful clinical impact.
The observed decline in general and mental health scores among control participants emphasized the progressive nature of secondary complications associated with SCIs. Factors such as chronic musculoskeletal pain, fatigue, autonomic dysfunction, and compounded psychological stress are commonly reported in individuals with SCIs and may be exacerbated by physical inactivity [36,37]. Additionally, psychosocial determinants, including social isolation, reduced access to rehabilitation services, and persistent emotional distress, can further compromise well-being and quality of life [38]. The absence of structured physical activity likely intensifies these issues, reinforcing sedentary behavior, impairing sleep quality, and diminishing opportunities for positive psychological engagement. These findings highlight the importance of maintaining consistent and individualized exercise participation to prevent physical deterioration and mental health decline. Moreover, reliance on self-reported outcome measures, such as the SF-36, although useful for capturing subjective health perceptions, introduces potential sources of bias [39]. Individual responses may be influenced by mood fluctuations, environmental contexts, and expectations. To address these limitations, future research should integrate objective outcome indicators, including inflammatory and metabolic biomarkers, and clinicians should assess the functional capacity and validate neuropsychological tools. This multimodal approach strengthened the validity of our findings and provided a more comprehensive understanding of exercise efficacy in this population. In addition, longitudinal follow-up is essential to assess the sustainability of intervention effects and determine whether short-term gains translate into long-term improvements in HRQOL.
Our study provides valuable insights into the efficacy of personalized exercise programs for enhancing the HRQOL in individuals with varying degrees of SCIs. Nonetheless, the methodological limitations of this study warrant further consideration. Most notably, the modest sample size (N = 17; 11 in the exercise group and six in the control group) imposes constraints on the generalizability of the findings. Recruitment of individuals with SCIs or other physical disabilities presents inherent challenges including limited participant pools, comorbid health conditions, and accessibility barriers [40,41]. Therefore, we adopted an exploratory randomized clinical trial design to evaluate preliminary feasibility and generate foundational data that may guide future large-scale trials. In addition, heterogeneity in injury levels combined with cultural, socioeconomic, and lifestyle variability among participants may have introduced confounding influences that affect the internal validity [42].
Another methodological consideration involves the single- blind design of the trial. Given the nature of the intervention, participant blinding was not feasible, which introduces the possibility of performance or expectancy effects in self-reported outcomes, such as HRQOL. To mitigate this limitation, we employed blinded outcome assessors and adhered to standardized assessment protocols. Furthermore, we utilized the SF-36, a validated and widely recognized instrument, thereby enhancing the reliability of the self-reported data. This approach is consistent with best practices in rehabilitation research, where full blinding is often unattainable; however, methodological rigor can be upheld through assessor blinding and consistent evaluation procedures [43]. Nevertheless, the reliance on self-reported outcome measures remains a limitation. Although SF-36 captures important dimensions of perceived health and functioning, it may be subject to mood-related bias or expectancy effects. Future studies should incorporate complementary objective indicators such as functional mobility tests, inflammatory biomarkers, and physical performance metrics to provide a more comprehensive assessment of intervention outcomes and reduce the potential for measurement bias.
In addition to the measurement limitations, the design of the control condition also warrants consideration. The control group did not receive attention-matched or placebo-based intervention. While this approach enabled a clear comparison between structured exercise and usual care, it limited the ability to distinguish the physiological benefits of exercise from the psychological influences related to social interaction, instructor engagement, and routine participation. These non-specific factors may have contributed to the observed differences between groups. Future studies should consider including active control conditions such as low-intensity stretching, educational sessions, and social activities to better isolate the specific effects of physical exercise on HRQOL outcomes.
Despite these limitations, this study has several strengths. It addresses a significant gap in studies conducted in South Korea, in which randomized controlled trials exploring exercise-based HRQOL interventions among individuals with SCIs remain limited. The implementation of a personalized evidence-based exercise program that integrates both aerobic and resistance components is a robust and multidimensional approach. Our findings offer a valuable framework for future research and underscore the potential of structured exercise interventions to enhance HRQOL in this underserved population. Future studies employing larger sample sizes, longer durations, and longitudinal follow-up are essential to substantiate and expand on these preliminary findings.
In conclusion, this study demonstrated that a six-week personalized exercise program integrating aerobic and resistance training was effective in enhancing HRQOL among individuals with spinal cord injuries. While these findings offer promising evidence for the feasibility and impact of individualized exercise interventions in this population, future studies should incorporate objective outcome measures to validate self-reported improvements and strengthen the evidence base.
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