Joggers running through Wyndham Park were attacked by a man with mental health problems.
Brendan Jablonski of Manthorpe Road, Grantham, admitted common assault following the incident on August 16.
Tracey Ross, prosecuting, said Jablonski grabbed one of the joggers as they passed near the white bridge and forced them into a fence. The second jogger intervened but Jablonski threw a punch, striking him in the chest.
The second jogger then retaliated by punching Jablonski and knocking him to the floor, allowing both joggers to walk away.
In his police interview Jablonski said he had drunk four pints of Stella Artois prior to the incident, even though his medication said he should not drink alcohol.
Rob Arthur, defending, said Jablonski had written a letter to the victims in which he said: “I am very sorry. I never meant for it to happen. I had a lot of problems that week and never meant to take it out on you.”
Mr Arthur told the court Jablonski, 30, has “significant mental health problems” and has been suffering from auditory and visual hallucinations. He informed magistrates that the defendant is due to have a brain scan later this month.
Sentencing was adjourned until September 30 for pre-sentence reports.