The option that is not a strict safety rule in strength training is 'Do not hold your breath.' While proper breathing is important, the other options provide direct safety practices essential for injury prevention. Therefore, option D is the least related to safety in this context.
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The option that is not a strict safety rule in strength training is "Do not hold your breath." While proper breathing is important, the other options are directly related to safety practices essential during strength training. Thus, option D is less about safety compared to the other statements. ;