This randomized controlled trial will investigate whether delaying the start of morning training from 7:00 AM to 9:00 AM improves nocturnal sleep and change-of-direction performance in elite badminton athletes. A total of 38 athletes with an established morning-training routine will be randomly assigned in a 1:1 ratio to either a usual morning-training group starting at 7:00 AM or a delayed morning-training group starting at 9:00 AM. Both groups will follow the same training content, duration, intensity, coaching arrangements, and recovery procedures for three weeks.
Nocturnal sleep will be objectively monitored using wrist-worn activity monitors, with total sleep time as the primary outcome. Change-of-direction performance will be assessed using the modified 505 test. Additional outcomes will include sleep opportunity, sleep efficiency, sleep onset latency, nighttime awakenings, bedtime and wake time, nap duration, 24-hour total sleep, training load, and training adherence.
The study aims to determine whether a later morning-training schedule can provide athletes with greater sleep opportunity without compromising training quality or physical performance.
Elite badminton athletes receiving systematic professional badminton training and able to competently perform the modified 505 change-of-direction test.
A stable morning-training schedule during the previous 4 weeks.
Ability to maintain the same training phase, training location, and accommodation conditions throughout the study period.
Ability to complete baseline monitoring, the 3-week intervention, and pre- and post-intervention assessments.
Injury or musculoskeletal condition that prevents safe completion of maximal-effort change-of-direction testing.
Unstable cardiovascular, neurological, or other health conditions.
Deemed unsuitable for maximal-effort training or testing by sports medicine personnel.
Planned participation in a major competition, off-site training camp, or trans-time-zone travel during the study period.
Parallel
Usual Morning Training Schedule
BehavioralParticipants assigned to the usual morning-training group will begin each scheduled morning training session at 7:00 AM. The intervention will last for 3 consecutive weeks, with five morning-training sessions per week and 15 sessions in total. Each session will last approximately 90 minutes and will include standardized warm-up, badminton-specific technical training, footwork and change-of-direction exercises, multi-shuttle or tactical training, and cool-down. Training content, duration, workload, rest intervals, coaching arrangements, venue, diet, and recovery procedures will be matched to those of the delayed morning-training group.
Delayed Morning Training Schedule
BehavioralParticipants assigned to the delayed morning-training group will begin each scheduled morning training session at 9:00 AM, representing a 120-minute delay from the usual 7:00 AM schedule. The intervention will last for 3 consecutive weeks, with five morning-training sessions per week and 15 sessions in total. Each session will last approximately 90 minutes and will follow the same standardized training content and workload as the usual morning-training group. No mandatory roll call, early class, group activity, or other required task will be scheduled before the 9:00 AM training session.
Average Nocturnal Total Sleep Time During the Intervention Period
Nocturnal total sleep time will be objectively measured using a wrist-worn activity monitor. Total sleep time is defined as the total number of minutes classified as sleep within the main nocturnal sleep period, excluding periods classified as wakefulness. The primary outcome will be calculated for each participant as the mean nocturnal total sleep time across valid target nights during the 3-week intervention period. Higher values indicate longer nocturnal sleep duration.
Modified 505 Change-of-Direction Test Completion Time
Change-of-direction performance will be assessed using the modified 505 test under standardized conditions. Each participant will complete three valid trials, and the fastest valid completion time will be used as the outcome value. Completion time will be measured in seconds using electronic timing gates. Lower values indicate better change-of-direction performance.
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