Combines
矫 ('upright/straight') +
健 ('strong/healthy') for a specific blend: not just strong (
强壮), but strong AND elegant — the bearing of an athlete, gymnast, or someone aging well. Common collocations:
矫健的步伐 ('vigorous strides'),
身手矫健 ('nimble and powerful'),
矫健的身姿 ('graceful, athletic figure').