High-Intensity Interval Resistance Training and Low-to-Moderate-Intensity Resistance Training in Upper Extremity Muscles

Resistance training is widely recognized as an effective intervention for improving muscle strength, functional performance, and overall health. In recent years, high-intensity interval resistance training (HIIRT) has emerged as a time-efficient alternative to conventional resistance training because it combines high-load resistance exercises with brief recovery intervals. Although previous studies have demonstrated the effectiveness of HIIRT for improving muscular performance, evidence regarding upper-extremity-focused HIIRT and its effects on cognitive function, mental health, and health-related quality of life remains limited.

The purpose of this randomized controlled trial is to compare the effects of an 8-week upper-extremity high-intensity interval resistance training (HIIRT) program with those of a conventional low-to-moderate-intensity resistance training (LMRT) program in healthy young adults.

A total of 49 healthy participants aged 18-25 years will be randomly allocated to one of three groups: (1) HIIRT, (2) LMRT, or (3) a control group. Randomization will be performed using age- and sex-stratified block randomization. Participants in both exercise groups will complete supervised training sessions twice weekly for eight consecutive weeks, whereas the control group will receive no structured exercise intervention and will be instructed to maintain their usual lifestyle.

The HIIRT protocol will consist of upper-extremity exercises performed at 80% of one-repetition maximum (1RM) using a cluster-set format with short recovery intervals. The LMRT protocol will include the same exercises performed at 30-70% of 1RM using conventional resistance training principles. Both interventions will include exercises targeting the biceps curl, lat pulldown, pec deck, machine shoulder press, and seated row.

Outcome assessments will be performed before and after the 8-week intervention. Primary outcomes include upper-extremity isotonic muscle strength and functional capacity assessed by the Six-Minute Walk Test. Secondary outcomes include cognitive function assessed by the Montreal Cognitive Assessment, anxiety assessed by the State-Trait Anxiety Inventory and the Generalized Anxiety Disorder-7 questionnaire, flow state assessed by the Dispositional Flow Scale-2, and health-related quality of life assessed by the Short Form-36 Health Survey.

Inclusion criteria

• Healthy young adults aged 18 to 25 years.
• Ability to understand the study procedures and provide written informed consent. Ability to participate safely in an upper-extremity resistance training program. Willingness to attend supervised exercise sessions twice weekly for 8 weeks.
• No participation in another clinical trial during the study period.

Exclusion criteria

• Presence of cardiovascular disease.
• Presence of neurological disease.
• Presence of psychiatric disorder.
• Presence of orthopedic disease or musculoskeletal condition limiting exercise participation.
• Presence of any systemic disease that may interfere with exercise training or study assessments.
• History of surgery affecting participation in the exercise program.
• Cognitive or psychological conditions that could interfere with completion of the assessments.
• Inability or unwillingness to comply with the study protocol.
• Refusal to provide written informed consent.