Effects of 12-Week Home-based Resistance Training on Peripheral Muscle Oxygenation in Children With Congenital Heart...

A hallmark feature of children with congenital heart disease (CHD) is exercise intolerance. Whether a home-based resistance training intervention improves muscle oxygenation (as measured by tissue oxygenation index, TOI) and exercise tolerance ($\dot{\text{V}}$O₂ reserve) during aerobic exercise in children with CHD compared with healthy children is unknown.

We report findings for 10 children with CHD (female/male: 4/6; mean ± standard deviation age: 13 ± 1 years) and 9 healthy controls (female/male: 5/4; age: 12 ± 3 years). Children with CHD completed a 12-week home-based exercise programme in addition to 6 in-person sessions. Exercise tolerance was assessed with a peak exercise test. Vastus lateralis TOI was continuously sampled during the peak $\dot{\text{V}}$O₂ test via near-infrared spectroscopy.

There was a medium effect (Cohen's d = 0.67) of exercise training on lowering TOI at peak exercise (pre: 30 ± 16 %total labile signal vs post: 20 ± 13 % total labile signal; P = 0.099). Exercise training had a small effect (Cohen's d = 0.23) on increasing $\dot{\text{V}}$O₂ reserve by 1.6 mL/kg/min (pre: 27.2 ± 5.7 mL/kg/min vs post: 29.4 ± 8.8 mL/kg/min; P = 0.382). There was also a small effect (Cohen's d = 0.27) of exercise on peak heart rate (pre: 175 ± 23 beats/min vs post: 169 ± 21 beats/min; P = 0.18). TOI, $\dot{\text{V}}$O₂ reserve, and heart rate were generally lower than healthy control participants.

Our findings indicate that home-based resistance training may enhance skeletal muscle oxygen extraction (lower TOI) and subsequently $\dot{\text{V}}$O₂ reserve in children with CHD.