Unilateral and Bilateral Resistance Training in Hypertension

Condition(s) studied

Investigational drug(s) / intervention(s)

Unilateral Resistance Training: Participants will complete a supervised unilateral resistance training program twice weekly for 12 weeks. Exercise intensity will be prescribed at 60-70% of one-repetition maximum (1RM). Exercises include leg press, knee extension, leg curl, seated row, and chest press performed separately with the right and left limbs. Each session consists of 2-3 sets of 8-12 repetitions with at least 1 minute of rest between sets. Training loads will be progressively increased based on participants' performance and perceived exertion using the Modified Borg Scale.

Bilateral Resistance Training: Participants will complete a supervised bilateral resistance training program twice weekly for 12 weeks. Exercise intensity will be prescribed at 60-70% of one-repetition maximum (1RM). Exercises include leg press, knee extension, leg curl, seated row, and chest press performed simultaneously with both limbs. Each session consists of 2-3 sets of 8-12 repetitions with at least 1 minute of rest between sets. Training loads will be progressively increased according to participants' performance and perceived exertion using the Modified Borg Scale.

Study summary

Hypertension is associated with autonomic nervous system dysfunction, reduced muscle strength, and impaired functional capacity, all of which contribute to increased cardiovascular risk and decreased quality of life. Resistance training is recommended as a non-pharmacological intervention for hypertension; however, it remains unclear whether unilateral and bilateral resistance training produce different physiological adaptations, particularly regarding cardiac autonomic function.

This randomized controlled trial aims to compare the effects of unilateral and bilateral resistance training on heart rate variability (HRV), muscle strength, and functional capacity in adults with hypertension. Eligible participants aged 40-75 years with a confirmed diagnosis of hypertension will be randomly allocated to one of three groups: a unilateral resistance training group, a bilateral resistance training group, or a control group. Randomization will be performed using a computer-generated block randomization procedure with sex stratification to ensure balanced group allocation.

Participants in the two intervention groups will complete a supervised 12-week resistance training program, performed twice weekly at an intensity of 60-70% of one-repetition maximum (1RM). The unilateral training group will perform exercises using one limb at a time, whereas the bilateral training group will perform the same exercises simultaneously with both limbs. The control group will receive no structured exercise intervention during the study period but will receive general information regarding the benefits of physical activity.

Assessments will be conducted at baseline and after the 12-week intervention. The primary outcome will be heart rate variability measured using a Polar H10 heart rate sensor and Elite HRV software. Secondary outcomes will include peripheral muscle strength assessed by one-repetition maximum testing, functional capacity assessed using the Six-Minute Walk Test and the Glittre Activities of Daily Living Test, and blood pressure measured using a sphygmomanometer.

The findings of this study are expected to provide evidence regarding the optimal resistance training strategy for improving autonomic function and physical performance in individuals with hypertension, thereby supporting the development of safer and more individualized exercise prescriptions.

Eligibility

Primary outcome measure(s)

• Muscle Strength — Baseline and Week 12
  Muscle strength will be assessed using one-repetition maximum (1RM) testing for leg press, knee extension, leg curl, seated row, and chest press exercises.
• Functional Capacity — Baseline and Week 12
  Functional capacity will be evaluated using the Six-Minute Walk Test (6MWT). Walking distance and physiological responses will be recorded before and after the intervention.
• RMSSD — Baseline and Week 12
  Change in the root mean square of successive differences (RMSSD) measured using heart rate variability analysis. RMSSD is reported in milliseconds (ms). Minimum value: 0 ms. There is no fixed maximum value. Higher values indicate greater parasympathetic activity and improved cardiac autonomic function (better outcome).
• SDNN — Baseline and Week 12
  Change in the standard deviation of normal-to-normal intervals (SDNN) measured using heart rate variability analysis. SDNN is reported in milliseconds (ms). Minimum value: 0 ms. There is no fixed maximum value. Higher values indicate greater overall heart rate variability and improved cardiac autonomic function (better outcome).
• pNN50 — Baseline and Week 12
  Change in the percentage of successive normal-to-normal intervals differing by more than 50 ms (pNN50). The outcome is expressed as a percentage (%). Minimum value: 0%. Maximum value: 100%. Higher values indicate greater parasympathetic activity (better outcome).
• Mean RR Interval — Baseline and Week 12
  Change in mean RR interval measured using heart rate variability analysis. The outcome is expressed in milliseconds (ms). Minimum value: 0 ms. There is no fixed maximum value. Higher values generally indicate a lower resting heart rate and improved autonomic regulation (better outcome).
• Total Power — Baseline and Week 12
  Change in total power measured using heart rate variability analysis. The outcome is expressed in milliseconds squared (ms²). Minimum value: 0 ms². There is no fixed maximum value. Higher values indicate greater overall heart rate variability (better outcome).
• LF Power — Baseline and Week 12
  Change in low-frequency (LF) power measured using heart rate variability analysis. The outcome is expressed in milliseconds squared (ms²). Minimum value: 0 ms². There is no fixed maximum value. Higher values generally indicate greater autonomic modulation.
• HF Power — Baseline and Week 12
  Change in high-frequency (HF) power measured using heart rate variability analysis. The outcome is expressed in milliseconds squared (ms²). Minimum value: 0 ms². There is no fixed maximum value. Higher values indicate greater parasympathetic activity (better outcome).
• LF Peak — Baseline and Week 12
  Change in low-frequency peak (LF Peak) measured using heart rate variability analysis. The outcome is expressed in hertz (Hz). Minimum value: 0 Hz. There is no fixed maximum value.
• HF Peak — Baseline and Week 12
  Change in high-frequency peak (HF Peak) measured using heart rate variability analysis. The outcome is expressed in hertz (Hz). Minimum value: 0 Hz. There is no fixed maximum value.

Trial sites (1)

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