Adipose tissue browning is a physiological process that increases energy expenditure and may combat against obesity and its related risk factors. Fibroblast growth factor 21 (FGF21) and irisin, hormones affected by exercise that also affect adipose tissue browning, have not been widely studied with regard to exercise type and duration. This study compared the effect of high-intensity interval training (HIIT) and high-intensity resistance training (HIRT) on irisin and FGF21 in men living with overweight and obesity. After completing a training program three times weekly for 8 weeks, participants’ serum levels of irisin and FGF21 were significantly increased in the HIIT and HIRT groups compared with the control group ( p < 0.05). Additionally, body fat percentage and body weight in both training groups were significantly reduced in comparison with the control group ( p < 0.05). Thus, HIIT and HIRT programs may be used as a feasible modality to promote favourable changes in body composition and irisin and FGF21, factors critical for browning white adipose tissue in men living with overweight and obesity.

Chronic methamphetamine use increases apoptosis, leading to heart failure and sudden cardiac death. Previous studies have shown the importance of high-intensity interval training (HIIT) in reducing indices of cardiac tissue apoptosis in different patients, but in the field of sports science, the molecular mechanisms of apoptosis in methamphetamine-dependent rats are still unclear. The present article aimed to investigate the changes in cardiac apoptosis markers in methamphetamine-dependent rats in response to HIIT. Left ventricular tissue was used to evaluate caspase-3, melusin, FAK, and IQGAP1 gene expression. Rats were divided into four groups: sham, methamphetamine (METH), METH-control, and METH-HIIT. METH was injected for 21 days and then the METH-HIIT group performed HIIT for 8 weeks at 5 sessions per week. The METH groups showed increased caspase-3 gene expression and decreased melusin, FAK, and IQGAP1 when compared to the sham group. METH-HIIT showed decreased caspase-3 and increased melusin and FAK gene expression compared with the METH and METH-control groups. The IQGAP1 gene was higher in METH-HIIT when compared with METH, while no difference was observed between METH-HIIT and METH-control. Twenty-one days of METH exposure increased apoptosis markers in rat cardiac tissue; however, HIIT might have a protective effect, as shown by the apoptosis markers.