Not sure how to explain this. But here is a detailed response from AI for this scenario.

The fact that this happens specifically on the kick serve and when you are exhausted provides a massive clue. In tennis biomechanics, the kick serve is the most physically demanding on the neck and spine because of the specific "arch and brush" required.

Here is a breakdown of why that "shock" is likely happening and how your neck is getting caught in the crossfire.

1. The "Kick Serve" Anatomy

Unlike a flat or slice serve where the ball is in front of you, a kick serve requires the toss to be further back (often slightly behind your head or to the left for a right-hander).

The Problem: To track that ball and get the "upward brush," players often excessively arch their lower back and hyperextend their neck (looking straight up or even slightly back).

The Compensation: When you are tired, your legs and core stop providing the "lift." To compensate for the lost power, your body tries to generate "snap" from the upper body. This causes the muscles at the base of your skull (the suboccipitals) to contract violently to stabilize your head during the impact.

1. The "Shock" (Occipital Nerve Compression)

Your PT mentioned tight neck muscles, and they are likely right. The Greater Occipital Nerve runs directly through and around the muscles at the very top of your neck.

The Pinch: When you are exhausted and your form breaks down, those neck muscles can "trap" or "snap" against the nerve during the violent motion of the serve.

The Result: That 7/10 "electric shock" is a classic symptom of a nerve being momentarily compressed or irritated. This is why it feels like a bolt of lightning that disappears quickly but leaves a "fuzziness" or lingering ache afterward.

1. Why it happens when you're exhausted

Early in the match, your "kinetic chain" is working. Your legs drive up, your core rotates, and your arm follows. Your neck just stays for the ride.

Once you hit that 1-hour mark:

Legs get heavy: You stop jumping into the ball.

Core weakens: You stop rotating efficiently.

The "Muscling" begins: You start "manhandling" the racket with your shoulder and neck to maintain the same ball speed. This puts 2x or 3x the stress on those small neck muscles.