A 3-month school-based exercise and data recording intervention reduces excessive screen time and increases trunk muscle mass in Japanese junior high school students.
A 3-month school-based intervention with biweekly group exercise and daily activity recordings was conducted in 127 Japanese junior high school students. Screen time significantly decreased in students with baseline screen time ≥4 h/day, while it increased in those with <4 h/day. Body mass index and trunk muscle mass increased significantly in both groups, but psychological measures and sleep duration showed no significant changes.
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A 3-month school-based exercise and data recording intervention reduces excessive screen time and increases trunk muscle mass in Japanese junior high school students. The current body of evidence comprises 1 study. EvidenceHub rates the overall confidence at 32/100 (low).
The Claim
A 3-month school-based exercise and data recording intervention reduces excessive screen time and increases trunk muscle mass in Japanese junior high school students.
This conclusion is most relevant to: Japanese junior high school students (initial n=235, final n=127).
What the Research Shows
The conclusion draws on 1 linked study. Highlights from the cited literature:
- ▸Preliminary Impacts of a 3-Month School-Based Exercise and Data Recording Intervention on Lifestyle Habits, Psychological Health, and Physical Health in Japanese Adolescents. (Children (Basel, Switzerland), 2026) — A 3-month school-based intervention with biweekly group exercise and daily activity recordings was conducted in 127 Japanese junior high school students. Screen time significantly decreased in students with baseline screen time ≥4 h/day, while it increased in those with <4 h/day. Body mass index and trunk muscle mass increased significantly in both groups, but psychological measures and sleep duration showed no significant changes.
How It Works
The proposed biological pathway:
- ▸Biweekly group exercise sessions provide structured physical activity
- ▸Daily activity recordings increase self-monitoring and awareness
- ▸Reduced screen time may be due to increased awareness and alternative activities
- ▸Increased trunk muscle mass from exercise sessions
Who Might Benefit
Evidence fit by population:
- ▸Japanese junior high school students (initial n=235, final n=127)
Recommended Dose
N/A
Limitations & Caveats
Important context when interpreting this evidence:
- ▸Single-arm pre-post design without a control group, so changes cannot be definitively attributed to the intervention
- ▸High dropout rate (from 235 to 127 students), potentially introducing selection bias
Frequently Asked Questions
What was the duration of the intervention?▼
The intervention lasted 3 months.
How many students completed the study?▼
127 students completed the program out of 235 initially enrolled.
Did the intervention affect sleep duration?▼
No significant changes in sleep duration were observed.
What was the effect on screen time?▼
Screen time significantly decreased in students with baseline screen time ≥4 h/day, but increased in those with <4 h/day.
References
- 1.Kusumoto Y, Takahashi E, Endo Y, Okazaki K, Asao A, Tanaka Y. “Preliminary Impacts of a 3-Month School-Based Exercise and Data Recording Intervention on Lifestyle Habits, Psychological Health, and Physical Health in Japanese Adolescents..” Children (Basel, Switzerland), 2026. PMID: 42650319 DOI: 10.3390/children13080980