How will you explain the sudden boost of energy, increased strength to lift very heavy objects during emergency situations

It is known as adrenaline rush.

Explanation:

Adrenaline rush refers to a sudden emergence of energy resulting due to an enhancement in the hormone and the neurotransmitter epinephrine or adrenaline. It may comprise an upsurge of heart rate, perspiration, blood sugar content, blood pressure, and metabolism.  

Adrenaline is considered as the fight or flight hormone. It is discharged in response to an exciting, stressful, threatening or dangerous circumstance. It helps the body to react more briskly. If the hormone gets discharged quite enough, the body then starts to remember the old connected feelings that can eventually result in a serious addiction.  

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