In the first episode Liang Jia He (Chinese: 梁家河篇) of the series Chairman Xi's Beginning (Chinese: 習總書記的初心), Xi said (in Mandarin Chinese)
因爲我那時候，抗 200 斤麥子，十里山路不換肩的
... because I, at that time, carried 200 jin of wheat, and walked 10 li of mountain road without switching shoulders.
The video is on YouTube, uploaded by CCTV's official account. The above claim appears at 1'23".
One Chinese jin is half a kilogram and one Chinese li is half a kilometer, so Xi said he carried 100 kg of wheat and walked 5 km. This seems rather impractical as a man himself rarely weighs 100 kg, and walking 5 km of bumpy mountain road without switching shoulders adds another level of harshness.
Is it true that Xi actually did this?