Tonight many of us became acquainted with a little known muscle group called the core. Our guide for the night, Mark, had us rolling on the floor like helpless upside-down woodlice as we squeezed and clenched to feel the inner abdominals. Alas, after this had been introduced, we seemed to forget for a while all about this chance encounter as we set off at an easy pace down Cambridge Heath Road, through Broadway Market, down to London Fields and up to Hackney's Rectory Road.

Professor Green, a man of much experience speaks of this 'jungle': "welcome to Hackney, a place where someone's been playing Jumanji." Needless to say the wild streets took us to a proper gangster allotment, run by our gentle host, Pal, at which 20 hardcore volunteers, armed with lethal spades and forks, tore up some invasive dirt to make room for more growing space.

After 30 minutes of resilience and discussion about cheese jokes and how to pick up heavy bags of soil and weeds, our foci were realigned to our cores as the goodgym troupe split into a more relaxed paced and a mental 'caterpillar' paced run back to the hub. The latter group, having rolled an 8 (minute mile), was sucked back into the urban jungle (of Hackney Downs) to sprint repeatedly from the back to the front of a single-file line of runners with perfect posture. This was followed by a decent paced run back to the Arch. One last exercise on our cores, then we gently warmed down and stretched.

Vital stats: Calories burned: around 800 Cores found and exercised: 20 Distance travelled: 7km.

Better than an average gym workout; collaborated with great people; did some good for London.

• Andrew Mort