Dose-response association between different screen time behaviors and cardiorespiratory fitness among elementary and junior high school students: A population-based cross-sectional study in a Japanese city

Q: What are the key findings of this study?

Among elementary school students, gaming for ≥4 hours per day was associated with significantly lower cardiorespiratory fitness compared to no gaming (B = -0.43), with significant inverse dose-response trends observed across both age groups.

Q: What is the clinical evidence from this study?

Study design: Cross-Sectional. Population: Cardiorespiratory fitness (n=1343). Intervention: Recreational screen time (gaming and video/SNS use) vs. No screen time. Primary outcome: Cardiorespiratory fitness assessed by 20-m shuttle run (z-scores) (B = -0.43, 95% CI -0.70, -0.16, p=0.002).

Q: What does this research mean for the field?

Longer recreational screen time, particularly gaming for 4 or more hours per day, is associated with significantly lower cardiorespiratory fitness among elementary school students. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

Takafumi Abe; Jun Kitayuguchi; Masamitsu Kamada; Shinpei Okada; Noritoshi Fukushima; Tetsuhiro Kidokoro; Chiaki Tanaka

doi:10.1016/j.jesf.2026.200510

August 24, 2026Journal of Exercise Science & FitnessOpen Access

Dose-response association between different screen time behaviors and cardiorespiratory fitness among elementary and junior high school students: A population-based cross-sectional study in a Japanese city

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Key result

Gaming ≥4 hours daily linked to significantly lower cardiorespiratory fitness in school-age children.

B = -0.43
95% CI -0.70, -0.16
P=0.002
n=1,343

Figures

Why the study?

Excessive screen time has been linked to lower cardiorespiratory fitness in youth, but evidence regarding the dose-response relationship remains limited.

Does longer recreational screen time reduce cardiorespiratory fitness in elementary and junior high school students?

Key Points

To examine the dose-response associations between specific recreational screen-time behaviors—gaming and video viewing or social networking service use—and cardiorespiratory fitness among elementary and junior high school students.
Analyzed 664 elementary school students (aged 9-12 years; 51.8% boys) and 679 junior high school students (aged 12-15 years; 47.6% boys) recruited in Unnan City, Japan, in 2023.
Assessed cardiorespiratory fitness through the 20-m shuttle run (expressed as z-scores) and screen-based behaviors via self-reported questionnaires.
Conducted multiple linear regression and restricted cubic spline analyses adjusted for sex, grade, breakfast consumption, sleep duration, and sports club participation.
Among elementary school students, gaming for 2-<4 h (B = -0.28, 95% CI: -0.53, -0.04) and ≥4 h (B = -0.43, 95% CI: -0.70, -0.16) was associated with significantly lower cardiorespiratory fitness compared to no gaming (P for trend = 0.001).
Elementary students reporting ≥4 h of video or social networking service use had significantly lower fitness (B = -0.33; P for trend = 0.001), with restricted cubic spline analyses detecting no non-linearity in either behavior.
Among junior high school students, individual duration categories did not differ significantly from the reference group, but significant inverse trends were observed for gaming (P for trend = 0.013) and video/social networking service use (P for trend = 0.014).

Study Design

Type

Cross-Sectional (n=1,343)

Multicenter

Yes

Structured PICO

Does longer recreational screen time reduce cardiorespiratory fitness in elementary and junior high school students?

P

Population

1,343 elementary and junior high school students aged 9 to 15 years in Japan were assessed to evaluate the dose-response association between recreational screen time and cardiorespiratory fitness.

E

Exposure

Different durations of recreational screen time (gaming and video viewing or social networking service [SNS] use), categorized as <2 h, 2 to <4 h, and ≥4 h per weekday.

C

Comparator

No recreational screen time (reference group).

O

Outcome

Cardiorespiratory fitness (CRF) assessed by the 20-m shuttle run test and expressed as z-scores.surrogate

Main Result

Mean Difference: -0.43 (95% CI -0.7–-0.16)

p-value: p=0.002

Longer durations of purpose-specific recreational screen time (gaming and video/SNS use) are associated with lower cardiorespiratory fitness in children and adolescents in a dose-response manner.

Limitations

Cross-sectional design precludes causal inference
Self-reported screen time and covariates are subject to recall and social-desirability bias
Unmeasured confounders including objectively measured physical activity, diet quality, body mass index, biological maturation, and socioeconomic status
Sample from a single rural area of Japan may limit generalizability
Small number of participants in the non-user reference group reduced precision
Screen-time questionnaire has not undergone formal validation
Cross-sectional design precludes causal inference.
Self-reported screen time and covariates are subject to recall and social-desirability bias.
Inability to adjust for unmeasured confounders such as objectively measured physical activity, diet quality, body mass index, biological maturation, and socioeconomic status.
Sample from a single rural area in Japan may limit generalizability.
Small sample size in some screen-time categories (particularly the non-user reference group) reduced precision.
Exclusion of about one-fifth of eligible students, mostly due to record-linkage failure.
Screen-time questionnaire has not undergone formal validation.

Implication

Prolonged gaming may link to lower fitness in children; hypothesis-generating for prospective trials before any practice change.

Abstract

Background/objective: Excessive screen time has been associated with lower cardiorespiratory fitness (CRF) in youth, but evidence on the dose-response association remains limited. This cross-sectional study examined screen time and CRF among elementary school (ES) and junior high school (JHS) students. Methods: Of 870 ES and 876 JHS students recruited in Unnan City, Japan, in 2023, the analytical sample comprised 664 ES students (aged 9-12 years; 51.8% boys) and 679 JHS students (aged 12-15 years; 47.6% boys). CRF was assessed by the 20-m shuttle run and expressed as z-scores. Screen-based behaviors (gaming and video viewing or social networking service [SNS] use) were assessed by questionnaire. Multiple linear regression and restricted cubic spline analyses were adjusted for sex, grade, breakfast consumption, sleep duration, and sports club participation. Results: Among ES students, gaming for 2-<4 h (B = -0.28, 95% CI: -0.53, -0.04) or ≥4 h (B = -0.43, 95% CI: -0.70, -0.16) was associated with lower CRF than no gaming, with an inverse trend (P for trend = 0.001). Similarly, ≥4 h of video/SNS use was associated with lower CRF (B = -0.33; P for trend = 0.001). Among JHS students, no individual category was significant, but both showed inverse trends (P for trend = 0.013 and 0.014, respectively). Restricted cubic splines showed no detectable non-linearity. Conclusion: Longer recreational screen time was associated with lower CRF in both groups-significantly lower in higher categories among ES students and significant inverse trends among JHS students. Longitudinal and experimental studies are needed to establish causality.

Discussion

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Cite This Study

Abe et al. (2026) conducted a cross-sectional in Cardiorespiratory fitness (n=1,343). Recreational screen time (gaming and video/SNS use) vs. No screen time was evaluated on Cardiorespiratory fitness assessed by 20-m shuttle run (z-scores) (B = -0.43, 95% CI -0.70, -0.16, p=0.002). Among elementary school students, gaming for ≥4 hours per day was associated with significantly lower cardiorespiratory fitness compared to no gaming (B = -0.43), with significant inverse dose-response trends observed across both age groups.

synapsesocial.com/papers/6aa34b58229fb590e7c60be8 https://doi.org/10.1016/j.jesf.2026.200510

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Dose-response association between different screen time behaviors and cardiorespiratory fitness among elementary and junior high school students: A population-based cross-sectional study in a Japanese city

Figures

Key Points

Study Design

Structured PICO

Main Result

Limitations

Implication

Abstract

Discussion

Cite This Study

Dose-response association between different screen time behaviors and cardiorespiratory fitness among elementary and junior high school students: A population-based cross-sectional study in a Japanese city

Figures

Key Points

Study Design

Structured PICO

Main Result

Limitations

Implication

Abstract

Discussion

Cite This Study

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