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

Abstract

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.