Introduction: Undernutrition during early life causes chronic disease with specific impairments to the heart and skeletal muscle. Purpose: To determine the effects of early-life undernutrition on adult exercise capacity as a result of cardiac and skeletal muscle function. Methods: Pups were undernourished during gestation (GUN) or lactation (PUN) using a cross-fostering nutritive mouse model. At postnatal day 21 (PN21), all mice were weaned and refed a control diet. At PN67, mice performed a maximal treadmill test. Echocardiography and Doppler velocity analysis was performed at PN72, following which skeletal muscle cross-sectional area (CSA) and fiber type were determined. Results: Maximal running capacity was reduced (Diet: P=0.0002) in GUN and PUN mice. Left ventricular mass (Diet: P=0.03) and posterior wall thickness during systole (Diet*Sex: P=0.03) of GUN and PUN mice was reduced, causing PUN mice to have reduced (Diet: P=0.04) stroke volume (SV). Heart Rate (HR) of GUN mice showed a trend (Diet: P=0.07) towards greater resting values than other groups. PUN mice had greater CSA of SOL fibers. PUN had a reduced (Diet: P=0.03) proportion of type-IIX fibers in the EDL and a greater (Diet: P=0.008) percentage of type-IIB fibers in the EDL. Conclusion: Gestational and Postnatal undernourishment impairs exercise capacity.
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