The Short-Term Effect of Occupational Levels of 50 Hz Electromagnetic Field on Human Heart Rate Variability.

Abstract

Previous studies have indicated that there is no consensus on the effects of extremely low-frequency electromagnetic (ELF-EMF) exposure on the cardiovascular system. This study aimed to explore the short-term effect of ELF-EMF exposure on heart rate (HR) and HR variability (HRV). The sample consisted of 34 healthy males aged 18-27 years. The participants were randomly assigned to the EMF (n = 17) or the Sham group (n = 17). We employed a double-blind repeated-measures design consisting of three 5 min experimental periods. The chest region of each individual in the EMF group was exposed to 50 Hz, 28 μT, linear polarized, continuous EMF during the EMF exposure period. HR and HRV data were recorded continuously by using a photoplethysmography sensor. Within-subject statistical analysis indicated a significant HR deceleration in both the EMF and Sham groups. However, the standard deviation of the NN intervals (SDNN), root mean square of successive differences (RMSSD), low-frequency (LF), and high-frequency (HF) powers increased only in the EMF group and remained stable in the Sham group. We also compared the same HRV indices measured during the EMF and Sham periods between the two experimental groups. The between-subject analysis results demonstrated significantly higher SDNN, RMSSD, LF, and HF values in the EMF group than in the Sham group. The LF/HF ratio did not change significantly within and between groups. On the basis of these results, we concluded that short-term exposure of the chest region to ELF-EMF could potentially enhance parasympathetic predominance during the resting condition. Bioelectromagnetics. 2021;42:60-75. © 2020 Bioelectromagnetics Society.

AI evidence extraction

Main findings

Within-subject analysis showed significant HR deceleration in both EMF and sham groups. HRV indices (SDNN, RMSSD, LF, HF) increased only in the EMF group and remained stable in the sham group; between-group comparisons found higher SDNN, RMSSD, LF, and HF in the EMF group than in the sham group, while LF/HF did not change significantly.

Outcomes measured

• Heart rate (HR)
• Heart rate variability (HRV)
• SDNN
• RMSSD
• Low-frequency (LF) power
• High-frequency (HF) power
• LF/HF ratio

Limitations

• Small sample size (n=34)
• Participants were healthy young males only (18–27 years)
• Short-term exposure only (5 min exposure period)
• Exposure localized to chest region; may not generalize to other exposure scenarios

Suggested hubs

• occupational-exposure (0.9)
  Study describes exposure at occupational levels and uses an experimental design relevant to workplace ELF-EMF.

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    "study_type": "randomized_trial",
    "exposure": {
        "band": "ELF",
        "source": "occupational",
        "frequency_mhz": null,
        "sar_wkg": null,
        "duration": "Three 5 min experimental periods; EMF exposure during one 5 min period"
    },
    "population": "34 healthy males aged 18–27 years",
    "sample_size": 34,
    "outcomes": [
        "Heart rate (HR)",
        "Heart rate variability (HRV)",
        "SDNN",
        "RMSSD",
        "Low-frequency (LF) power",
        "High-frequency (HF) power",
        "LF/HF ratio"
    ],
    "main_findings": "Within-subject analysis showed significant HR deceleration in both EMF and sham groups. HRV indices (SDNN, RMSSD, LF, HF) increased only in the EMF group and remained stable in the sham group; between-group comparisons found higher SDNN, RMSSD, LF, and HF in the EMF group than in the sham group, while LF/HF did not change significantly.",
    "effect_direction": "benefit",
    "limitations": [
        "Small sample size (n=34)",
        "Participants were healthy young males only (18–27 years)",
        "Short-term exposure only (5 min exposure period)",
        "Exposure localized to chest region; may not generalize to other exposure scenarios"
    ],
    "evidence_strength": "moderate",
    "confidence": 0.7800000000000000266453525910037569701671600341796875,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "extremely low-frequency EMF",
        "ELF-EMF",
        "50 Hz",
        "28 μT",
        "occupational exposure",
        "double-blind",
        "sham-controlled",
        "heart rate variability",
        "parasympathetic",
        "SDNN",
        "RMSSD",
        "LF",
        "HF"
    ],
    "suggested_hubs": [
        {
            "slug": "occupational-exposure",
            "weight": 0.90000000000000002220446049250313080847263336181640625,
            "reason": "Study describes exposure at occupational levels and uses an experimental design relevant to workplace ELF-EMF."
        }
    ]
}

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