Alvarez C, et al. – The authors tried to find out ‘mediators’ to the effects of 6–weeks of resistance training (RT) or high–intensity interval training (HIT) on glucose control parameters in physically inactive schoolchildren with insulin resistance (IR). Second, they also determined both training–induce changes and the prevalence of responders (R) and non–responders (NR) to decrease the IR level. In context of the findings, the enhancements in the lower body strength and the decreases in waist circumference can explain more the impacts of the improvements in glucose control of IR schoolchildren in R group after 6 weeks of RT or HIT, showing both regimes similar effects on body composition or muscular strength independent of interindividual metabolic response variability.

Methods

• In this study, 56 physically inactive children diagnosed with IR followed a RT or supervised HIT program for 6 weeks.
• They divided participants based on ΔHOMA-IR into glycemic control R (decrease in homeostasis model assessment-IR (HOMA-IR) <3.0 after intervention) and NRs (no changes or values HOMA-IR3.0 after intervention).
• The preliminary endpoint was HOMA-IR associated with their mediators; second, the training-induced changes to glucose control parameters; and third the report of R and NR to improve body composition, cardiovascular, metabolic and performance variables.

Results

• In this mediation analysis, data suggested that improvements (decreases) in abdominal fat by the waist circumference can explain more the effects (decreases) of HOMA-IR in physically inactive schoolchildren under RT or HIT regimes.
• The same analysis displayed that increased one-maximum repetition leg-extension was correlated with the change in HOMA-IR (β=-0.058; P=0.049).
• Moreover, a change in the waist circumference fully mediated the dose-response relationship between changes in the leg-extension strength and HOMA-IR (β=-0.004; P=0.178).
• The evidence showed that RT or HIT were correlated with significant improvements in body composition, muscular strength, blood pressure and cardiometabolic parameters irrespective of improvement in glycemic control response.
• They exhibited evidence that both glucose control RT-R and HIT-R (respectively), had significant improvements in mean HOMA-IR, mean muscular strength leg-extension and mean measures of adiposity.