Fig. 1: HIIT was superior to LICT for increasing bone mass in mice.

A Graphical overview of the experimental design. Twenty-four male mice 8 weeks old were randomly divided into three groups with eight mice in each group. All mice were acclimatized and fed for one week; the LICT and HIIT groups underwent 1 week of adaptation training, followed by 8 weeks of treadmill exercise at 12 m/min in the LICT group and 10 rounds of treadmill exercise alternating between 80–90% of maximal speed and 40–50% of maximal speed in the HIIT group. This figure was originally created by the authors using Microsoft PowerPoint. B The proximal femur (top) and trabecular bone of the femoral metaphysis (bottom) are shown in representative micro-CT images of the femur of mice. Scale bar: 1 mm (all panels). C Quantitative analysis of trabecular bone parameters by micro-CT in the femurs of female mice. BMD bone mineral density, BV/TV bone volume/tissue volume ratio, Tb.N trabecular number, Tb.Sp trabecular separation, Tb.Th trabecular thickness. n = 6, *p < 0.05, **p < 0.01, ***p < 0.001. D Quantitative analysis of trabecular bone parameters by micro-CT in the femurs of male mice. n = 6, *p < 0.05, **p < 0.01, ***p < 0.001. E Representational figures of HE staining of trabecular bone in the femurs of female and male mice. Scale bars, 200 μm. F Quantification of trabecular bone area in the femurs of female mice. All data are presented as mean ± SD, n = 6, **p < 0.01, ***p < 0.001. G Quantification of trabecular bone area in the femurs of male mice. All data are presented as mean ± SD, n = 6, **p < 0.01, ***p < 0.001. H 3-point bending testing for evaluating femurs whole-bone mechanical properties in female mice. n = 6, *p < 0.05, **p < 0.01. I 3-point bending testing for evaluating femurs whole-bone mechanical properties in male mice. n = 6, **p < 0.01, ***p < 0.001. J Representational micro-CT images showing the cortical bone of the femur in mice. Scale bar: 1 mm. K Quantitative analysis of cortical bone parameters by micro-CT in the femurs of female mice. n = 6, **p < 0.01, ***p < 0.001. L Quantitative analysis of cortical bone parameters by micro-CT in the femurs of male mice. n = 6, **p < 0.01, ***p < 0.001.