# Changes in serum metal concentrations following high-intensity interval training: A 16-week pilot study

## TL;DR

A 16-week high-intensity interval training program reduced both essential and toxic metals in the blood, which may be linked to improved metabolic health and body composition.

## Contribution

This study is the first to show that HIIT can alter serum metal concentrations, linking metal changes to anthropometric improvements.

## Key findings

- HIIT significantly reduced levels of both essential and toxic metals like manganese, mercury, and lead.
- Manganese reduction was negatively correlated with hip circumference, suggesting a link to body composition changes.
- Nickel levels increased with greater hip circumference, indicating a possible metabolic relationship.

## Abstract

•HIIT for 16-weeks reduced both essential and toxic serum metal levels.•High-intensity training altered the body’s metal accumulation profile.•Manganese reduction was linked to lower hip circumference post-HIIT.•Exercise-induced metal shifts may relate to metabolic health outcomes.

HIIT for 16-weeks reduced both essential and toxic serum metal levels.

High-intensity training altered the body’s metal accumulation profile.

Manganese reduction was linked to lower hip circumference post-HIIT.

Exercise-induced metal shifts may relate to metabolic health outcomes.

High-Intensity Interval Training (HIIT), involving brief bouts of intense exercise with rest or low-intensity intervals, benefits cardiovascular, metabolic health, and body composition. However, its impact on serum metal concentrations in adults remains unclear. This study investigated the effects of a 16-week HIIT protocol on serum metal levels.

Adults over 18-years-old with a Body Mass Index (BMI) above 25 kg/m2. Participants trained for 40-minutes three times per week, with two supervised and one unsupervised session. Each session included a 10-minute warm-up at 70 % of maximum Heart Rate (HRmax), followed by four 4-minute intervals at 90 % HRmax, interspersed with three 3-minute active pauses at 70 % HRmax. Before and after the 16-week intervention, anthropometric and biochemical parameters were assessed.

Fifteen participants [mean (SD) age: 42 (6); BMI: 30.6 (2.7)] completed the study. Significant reductions were observed in both toxic (e.g., mercury, lithium, lead, nickel, aluminum) and essential metals (e.g., manganese): mercury (p = 0.025, Cohen’s d = 0.58), lithium (p = 0.009, d = 1.01), aluminum (p = 0.025, d = 0.49), manganese (p = 0.009, d = 0.96), nickel (p = 0.025, d = 0.58), and lead (p = 0.025, d = 0.40). A negative correlation was found between the change in hip circumference and manganese (r = -0.538; p = 0.047), and a positive correlation with nickel (r = 0.600; p = 0.023).

These findings suggest potential associations between changes in metal concentrations and anthropometric outcomes following HIIT.