This randomized, single-center, parallel-group superiority trial will evaluate the effect of an 8-week aquatic High-Intensity Interval Training (HIIT) program on balance, physical function, and sarcopenia-related outcomes in individuals with Parkinson's disease (PD). The intervention aims to deliver Tabata-style aquatic HIIT (3 sessions/week) in a therapeutic pool to determine adherence and preliminary efficacy compared with standard care (no structured exercise program).
Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by motor and non-motor symptoms that impair quality of life. Pharmacological treatments alleviate motor symptoms but leave residual motor and non-motor complications and carry long-term adverse effects. Non-pharmacological therapies-particularly exercise-improve motor and non-motor outcomes via mechanisms such as enhanced dopamine release, corticostriatal plasticity, and increased BDNF after vigorous exercise. HIIT (including Tabata protocols) has emerging evidence for benefit in PD but land-based HIIT can be limited by balance deficits and fall risk. Aquatic HIIT may provide a safer environment (buoyancy, reduced joint load, natural resistance) and improve adherence. This single-center trial will recruit 56 participants (aged 55-75) with PD (Hoehn \& Yahr stages 2-3) and balance difficulty to be randomized 1:1 to aquatic HIIT (n=28) or control (standard care; n=28). The intervention comprises 8 weeks of supervised Tabata-format aquatic sessions (20s high intensity/10s rest ×8 cycles per set; warm-up and cool-down included) three times weekly. Primary endpoints include changes in Berg Balance Scale (BBS), Short Physical Performance Battery (SPPB), skeletal muscle mass by BIA, and handgrip strength from baseline to Week 8 (primary endpoint), with safety follow-up to Week 12. Secondary endpoints include PDQ-39, PSQI, adherence, and adverse events monitored with CTCAE criteria.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
SUPPORTIVE_CARE
Masking
NONE
Enrollment
56
The participants in the behavioral component will receive the same supervised aquatic HIIT program described above plus structured behavioral/support measures to maximize adherence and safety. These include: an initial individual education session explaining benefits/risks and protocol; supervised real-time feedback during each session from exercise specialists; flexible scheduling options to accommodate participants; weekly review of attendance and brief motivational follow-up (phone call or in-person) for participants with missed sessions; individualized adjustments to intensity/duration based on participant feedback and safety; and documentation of reasons for non-attendance. All behavioral/support activities are delivered by trained research staff and exercise physiologists and are recorded in session logs. (These measures are drawn from the protocol's adherence and retention strategies.)
Pardis specialized wellness institute
Isfahan, Iran
Rate of changes in Balance Ability
Evaluating the effect of aquatic HIIT on balance using the Berg Balance Scale (BBS), a 14-item performance-based tool assessing static and dynamic balance through functional tasks like sitting to standing, reaching forward, and turning 360 degrees. Items are scored on a 5-point ordinal scale (0-4) based on ability and time to complete, with a total score ranging from 0 (worst) to 56 (best); scores of 0-20 indicate wheelchair-bound, 21-40 indicate walking with assistance, and 41-56 indicate independent. In PD, scores \<45 suggest high fall risk, and the BBS has excellent intra-rater reliability (ICC=0.98), inter-rater reliability (ICC=0.97), and criterion validity, correlating with other PD-specific measures like UPDRS.
Time frame: Pre-intervention and Week 8
Rate of changes in Physical Function
Evaluating the effect of aquatic HIIT on physical function using the Short Physical Performance Battery (SPPB), a composite test including three subcomponents: balance (holding side-by-side, semi-tandem, and tandem stands for up to 10 seconds each, scored 0-4), gait speed (timed 4-meter walk at usual pace, scored 0-4 based on time quartiles), and chair stand (time to complete five rises from a chair without arms, scored 0-4). Total score ranges from 0 (worst) to 12 (best), with scores \<10 indicating high risk for mobility limitations and falls in older adults, including PD patients. The SPPB demonstrates high test-retest reliability (ICC=0.92), intra-rater reliability, and validity in predicting functional decline and executive function associations in PD.
Time frame: Pre-intervention and Week 8
Rate of changes in Muscle Mass (Sarcopenia)
Evaluating the effect of aquatic HIIT on sarcopenia-related muscle mass using Bioelectrical Impedance Analysis (BIA), a non-invasive technique that estimates body composition by measuring resistance and reactance to a low-level electrical current, calculating skeletal muscle mass (ASM) and phase angle (PhA). ASM is indexed to height squared (ASM/height² in kg/m²), with sarcopenia diagnosed per EWGSOP2 criteria (\<7.0 kg/m² for men, \<5.5 kg/m² for women); PhA cut-offs for sarcopenia are ≤4.05° (92.9% sensitivity, 53.8% specificity) for men and ≤3.75° (78.9% sensitivity, 51.1% specificity) for women. In PD, BIA is reliable for detecting sarcopenia (prevalence 40-55%) with high correlation to dual-energy X-ray absorptiometry (DXA) as gold standard (r=0.85-0.90 for ASM), predictive validity (adjOR=0.147 for PhA), and good test-retest reliability (ICC=0.88-0.95), though wide diagnostic variations exist across criteria.
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Time frame: Pre-intervention and Week 8
Rate of changes in Muscle Strength
Evaluating the effect of aquatic HIIT on muscle strength using a Handgrip Dynamometer, a handheld device that quantifies isometric grip force in kilograms or pounds during maximal voluntary contraction (typically 3 trials per hand, with the highest or average value used). Measurements are taken in a standardized seated position with the elbow flexed at 90 degrees; normative values decline with age, and low grip strength (\<27 kg men, \<16 kg women) is a sarcopenia criterion in PD. The dynamometer shows fair to excellent test-retest reliability (ICC=0.95-0.98) and intra-rater reliability in PD, with good validity for overall strength assessment.
Time frame: Pre-intervention and Week 8
Change in Quality of Life
Evaluating improvements in quality of life using the Parkinson's Disease Questionnaire-39 (PDQ-39), a disease-specific 39-item self-report instrument covering eight domains (mobility, activities of daily living, emotional well-being, stigma, social support, cognitions, communication, bodily discomfort). Items are rated on a 5-point Likert scale (0=never to 4=always), with domain scores transformed to 0-100 (higher indicating worse quality of life) and a summary index as the mean. The PDQ-39 has strong convergent validity (correlates with EQ-5D), discriminant validity, internal consistency (Cronbach's alpha=0.51-0.96), and test-retest reliability (0.56-0.90 per domain) in PD.
Time frame: Pre-intervention and Week 8
Change in Sleep Quality
Evaluating changes in sleep quality using the Pittsburgh Sleep Quality Index (PSQI), a 19-item self-report questionnaire (plus 5 roommate-rated items) assessing seven components (subjective quality, latency, duration, efficiency, disturbances, medication use, daytime dysfunction) over the past month. Global score sums to 0-21 (higher=worse sleep), with \>5 indicating poor quality (prevalence \~85% in PD). The PSQI has good internal consistency (Cronbach's alpha=0.83), test-retest reliability (0.85), and validity in PD, correlating with PSG and other scales like PDSS.
Time frame: Pre-intervention and Week 8
Adherence Rate
Determining adherence to the intervention using attendance logs, which record session participation as a percentage (number of attended sessions / total planned sessions; Adherence defined as attending ≥80% of sessions (≤20% missed)."). Logs also note reasons for non-attendance, providing qualitative insights. This method is reliable for monitoring exercise adherence in PD trials, with group rates often \>80% in supervised programs, though individual accuracy requires caution.
Time frame: Week 0 to Week 8 (intervention period)
Adverse Events
Monitoring and reporting adverse events using the Common Terminology Criteria for Adverse Events (CTCAE v5.0 or later), a standardized system categorizing events by organ system and severity grades (1=mild, 2=moderate, 3=severe, 4=life-threatening, 5=death-related). Events are defined as any unfavorable sign, symptom, or disease temporally associated with the intervention; serious events (grades 3-5) prompt reporting to DSMB. CTCAE ensures consistent AE reporting in clinical trials, with updates like v6.0 in 2025.
Time frame: Week 0 to Week 12 (including 4-week follow-up)