None listed
Conditions
Interventions
Behavioral, Dietary Supplement : 1) Trial Overview
- Design/Duration: 12-week, randomized, parallel, four-arm RCT.
- Participants: Community-dwelling women =65 y with vitamin D deficiency (25[OH]D <20
VD3)
B) IVD3 – Indoor resistance exercise + VD3
C) VD3 – VD3 only
D) CON – Control (no intervention)
2) Supplement: Common to OVD3/IVD3/VD3
- Compound: Vitamin D3 (cholecalciferol). Form/Route: Oral
in exercise arms, taken immediately post-session.
- Quality/Regulatory: MFDS-registered health functional food
GMP-certified manufacturer (lot/expiry logged).
- Concomitants prohibited: Additional vitamin D products
initiation of EAA/protein supplements or high-dose calcium.
3) Resistance Exercise — Common Protocol (OVD3 & IVD3)
- Mode: Supervised Gymstick/band-based circuit.
- Frequency/Session: 3×/week
60 min (warm-up 5 min ? main 50 min ? cool-down 5 min).
- Main set (full body): 6–8 exercises, 3 sets, 60–90 s rest.
- Examples: Lower—squat, step-up, lunge, hip hinge
Upper—row, chest/overhead - press, band pull-apart
Core/balance—bracing, single-leg stance.
- Intensity/Progression: Target RPE 12–15. Weeks 1–4 familiarization ? Weeks 5–8 progressive overload (? band tension/reps/time-under-tension) ? Weeks 9–12 con
~300–350 kcal/session
loads re-prescribed every 4 weeks.
- Recording: Exercise type, sets, reps, RPE, HR (booklet/app).
- Supervision/Safety: Nationally licensed professionals
immediate stop/ev
Sponsors
Kangwon National University
Eligibility
Sex/Gender
Female
Inclusion criteria
Inclusion criteria: 1. Sex and age: Community-dwelling women aged 65 to 75 years 2. Vitamin D deficiency: Serum 25-hydroxyvitamin D [25(OH)D] concentration < 20 ng/mL 3. Exercise history: No participation in a regular resistance exercise program within the previous 6 months (e.g., no structured strength training performed =3 times/week) 4. Supplement history: No regular intake of vitamin D supplements or other health supplements (e.g., protein or EAA supplements) within the previous 6 months 5. Medical suitability: Judged medically fit to undergo baseline physical fitness testing, blood sampling, and participation in the 12-week study intervention (including exercise intervention, if assigned) 6. Informed consent: Able to understand the study purpose and procedures and willing to provide written informed consent 7. Protocol compliance: Able to comply with the assigned intervention and assessment schedule (pre/post testing, attendance, and supplementation monitoring)
Exclusion criteria
Exclusion criteria: 1. Medical conditions limiting participation: Musculoskeletal disorders, cardiopulmonary disease, uncontrolled metabolic disease (e.g., diabetes), or stage 3 or higher hypertension, or any condition judged to make exercise participation or fitness testing unsafe or infeasible 2. Cognitive/communication limitations: Severe cognitive impairment or inability to understand study procedures, communicate adequately, or follow instructions 3. Medication-related confounding: Current use of medications that may affect vitamin D metabolism, muscle function, or inflammatory responses 4. Risk of contamination: Planned use of additional vitamin D supplements, high-dose calcium products, protein/EAA supplements, or initiation of a new regular exercise program during the study period 5. Safety concerns: Any condition associated with increased risk of pain, dizziness, falls, dehydration, or other adverse events during study participation 6. Poor expected adherence: Inability to comply with the assigned intervention (exercise/supplementation) and assessment schedule throughout the study period 7. Other reasons: Any other reason judged by the principal investigator or study physician to make participation inappropriate
Design outcomes
Primary
| Measure | Time frame |
|---|---|
| Change in serum 25-hydroxyvitamin D [25(OH)D] concentration (ng/mL): Change from baseline to week 12 and between-group comparison | — |
Secondary
| Measure | Time frame |
|---|---|
| Changes in myokines (serum levels): myostatin (ng/mL), follistatin (ng/mL), irisin (ng/mL), and IL-15 (pg/mL), Change from baseline to week 12 and between-group comparison;Changes in muscle growth factors (serum levels): GH (ng/mL), IGF-1 (ng/mL), and IGFBP-3 (ng/mL), Change from baseline to week 12 and between-group comparison;Changes in inflammatory markers (serum levels): TNF-a (pg/mL) and IL-6 (pg/mL), Change from baseline to week 12 and between-group comparison;Changes in body composition: body weight (kg), skeletal muscle mass (kg), fat mass (kg), and body fat percentage (%), Change from baseline to week 12 and between-group comparison;Changes in senior fitness test: upper-body muscle function [relative handgrip strength (%)], lower-body muscle function [30-second chair stand (repetitions)], flexibility [chair sit-and-reach (cm)], cardiorespiratory endurance [2-minute step test (repetitions)], balance [Timed Up and Go, 3 m (seconds)], and coordination [figure-of-8 walk (seconds)], including changes from baseline to Week 12 and between-group comparisons. | — |
Countries
Korea, Republic of
Contacts
Public ContactKang Sunghwun
Kangwon National University
Outcome results
None listed