High-Intensity Interval Alternating Concentric-Eccentric Training in Chronic Respiratory Disease

Chronic respiratory diseases, particularly chronic obstructive pulmonary disease (COPD), are commonly associated with exercise intolerance, dyspnea, peripheral muscle dysfunction, and reduced quality of life. Although exercise training is a central component of pulmonary rehabilitation, patients may have difficulty tolerating conventional high-intensity exercise because of ventilatory limitation and leg fatigue.

Eccentric exercise can generate relatively high mechanical workloads with lower oxygen consumption and cardiopulmonary demand than concentric exercise. High-intensity interval training (HIIT), on the other hand, is an effective approach for improving aerobic capacity. This study therefore investigates whether incorporating eccentric cycling into the recovery periods of HIIT can provide additional skeletal muscle stimulation without substantially increasing cardiopulmonary stress.

This is a single-center, prospective, randomized controlled trial conducted at Fu Jen Catholic University Hospital. Forty-five adults with chronic respiratory disease who have participated in pulmonary rehabilitation for more than 3 months will be enrolled and randomly allocated to three groups, with approximately 15 participants in each group: (1) high-intensity interval alternating concentric-eccentric training, (2) high-intensity interval concentric training, or (3) usual care.

Before randomization, participants will undergo graded exercise testing, functional performance assessments, and questionnaires. Participants assigned to the exercise groups will complete supervised training for 12 weeks. The alternating concentric-eccentric group will also undergo an eccentric exercise familiarization period before the formal training program. Participants in the usual-care group will continue routine care with self-regulated exercise intensity for 12 weeks. After the intervention, graded exercise testing, functional assessments, and questionnaires will be repeated.

The study will evaluate changes in functional performance, exercise capacity, muscle function, symptoms, and quality of life to determine whether alternating concentric-eccentric HIIT provides additional benefits compared with conventional concentric HIIT and usual care.

Participants will undergo a 2-week eccentric cycling familiarization period followed by 12 weeks of high-intensity interval training. During the high-intensity intervals, concentric cycling will be performed at 80% of peak work rate, while the recovery intervals will use eccentric cycling at the same external workload.

Behavioral: Alternating Concentric-Eccentric High-Intensity Interval Training

Participants will undergo 12 weeks of high-intensity interval concentric cycling training. High-intensity intervals will be performed at 80% of peak work rate, with recovery intervals performed concentrically at 40% of peak work rate.

Behavioral: Concentric High-Intensity Interval Training

Participants will continue usual care with self-regulated exercise intensity for 12 weeks.

Behavioral: Usual Care

Participants will complete a 2-week eccentric cycling familiarization period followed by 12 weeks of supervised high-intensity interval training, performed twice weekly. Each formal training session lasts approximately 40 minutes and includes a 5-minute warm-up at 30% of peak work rate (Wpeak), 30 minutes of interval training, and a 5-minute cool-down at 30% Wpeak. The interval phase consists of five cycles of 2 minutes of concentric cycling at 80% Wpeak followed by 4 minutes of eccentric cycling performed at the same external workload as the high-intensity concentric interval.

Participants will complete 12 weeks of supervised high-intensity interval concentric cycling training, performed twice weekly. Each session lasts approximately 40 minutes and includes a 5-minute warm-up at 30% of peak work rate (Wpeak), 30 minutes of interval training, and a 5-minute cool-down at 30% Wpeak. The interval phase consists of five cycles of 2 minutes of concentric cycling at 80% Wpeak followed by 4 minutes of concentric cycling at 40% Wpeak.

Participants will continue usual care with self-regulated exercise intensity for 12 weeks. No structured high-intensity interval or eccentric cycling training will be provided as part of the study intervention.

Time frame: Baseline and 12 weeks

The 6-minute walk test will be used to assess functional exercise capacity. The distance walked in 6 minutes on a 30-meter indoor corridor will be recorded in meters. Change from baseline to post-intervention will be compared among the three study groups.

Time frame: Baseline and 12 weeks

The Timed Up and Go test will be used to assess functional mobility, balance, and gait performance. Participants will stand from a chair, walk 3 meters, turn, return to the chair, and sit down. Three trials will be performed, and the fastest completion time in seconds will be used for analysis.

Time frame: Baseline and 12 weeks

Stair climbing performance will be assessed using a fixed number of stairs to evaluate lower-extremity strength, balance, agility, and functional performance. Completion time will be recorded in seconds.

Time frame: Baseline and after 12 weeks of formal training

Health-related quality of life will be assessed using the St. George's Respiratory Questionnaire (SGRQ). Changes in total score from baseline to post-intervention will be evaluated.

Effects of High-Intensity Interval Alternating Concentric-Eccentric Training on Functional Performance in Patients With Chronic Respiratory Disease: A Randomized Controlled Trial