some possible increase in heat exhaustion; kind of like a heat stroke; Unable to get through exercises after receiving the Pfizer Covid Vaccine; This is a spontaneous report from a contactable physician. A 20-years-old male patient received bnt162b2 (PFIZER-BIONTECH COVID-19 mRNA VACCINE, Solution for injection, Batch/Lot number was not reported), dose 2 via an unspecified route of administration, administered in Deltoid Right on 06May2021 06:54 (at 19-years age) as DOSE 2, SINGLE for covid-19 immunisation. The patient medical history and concomitant medications were not reported. patient previously received first dose of bnt162b2 (PFIZER-BIONTECH COVID-19 mRNA VACCINE, Solution for injection) for covid-19 immunisation. The patient experienced some possible increase in heat exhaustion on an unspecified date, unable to get through exercises after receiving the pfizer covid vaccine on 11Jun2021 and, kind of like a heat stroke on an unspecified date. The patient underwent lab tests and procedures which included blood creatine phosphokinase: 476 on 11Jun2021, blood creatinine: 1.7 on 11Jun2021, blood creatinine: 1 on 15Jun2021, blood test: unknown result on 11Jun2021 Mild AKI's and transients. Reporter was a physician and had reported some of his men were actually experiencing some difficulty in carrying out there usual exercises as compared to before. Reporter mentioned some possible increase in heat exhaustion but he is not positive that it is caused by the vaccine. In line with this, he would like to have some information in regards precaution that may be aware of regarding an increase in heat exhaustion after an amount of days after getting the vaccine. Over-all there were 28 people reporting this side effect after getting their second dose on 06Jun2021. There are adverse events that may not have occurred in the clinical trial but may have occurred in the 'real-world' post-authorizaiton setting. Pfizer cannot provide treatment recommendations. However, the CDC has established a project comprised of a team of vaccine safety experts who can be consulted on complex COVID-19 vaccine safety questions. You can also use the search terms, 'CDC' on your search engine to find this website. Be sure to follow the CDC's instructions on making a request (either online or phone) to consult the team. A bunch of other factors probably played a role.  Kind of chasing a wild goose. The caller wants to make sure. The caller reports he was not seen anything else in his research other than a couple reports of pericarditis in young men. The caller wanted to make sure there is no reason to be concerned. The 12 mile mark was only a one time kind of thing. Other physical activity and physical fitness has occurred as usual without any problems. This was a onetime thing just a red herring.  Causality: The caller states the event was probably heat and humidity related issue, peoples conditioning. The caller is assigned to investigate the situation.  The caller wants to make sure he is not missing anything. The caller would like to know any recommendations, the caller states he has not seen taking it easy for longer than a week or two after receiving the Pfizer Covid Vaccine.  Causality: The caller states the event is not a direct correlation, more of an indirect kind of thing that just popped up.  Whether the event is a thing or more of like, a bunch of other reasons the caller can think of that this could happen including heat and humidity. The reporter wanted to make sure as the investigation medical officer the caller is not missing anything and is doing his due diligence.The patient went to the emergency room for further stabilization. The patient was not hospitalized. The patient stayed in the emergency room for 2-3 hours for observation and fluids. The outcome of the events was unknown.  Information on batch/lot number has been requested.; Sender's Comments: Linked Report(s) : US-PFIZER INC-2021757388 Same reporter/ drug/ AE, different patient;US-PFIZER INC-2021757389 Same reporter/ drug/ AE, different patient;US-PFIZER INC-2021757390 Same reporter/ drug/ AE, different patient;US-PFIZER INC-2021757537 Same reporter/ drug/ AE, different patient