Strength Endurance Test: Plank

The plank is a core-strengthening exercise that involves maintaining a position similar to the top of a push-up. Here's how to perform it:

1. Start Position: Begin by getting into a push-up position, with your hands directly under your shoulders and your body forming a straight line from head to heels.

2. Engage Core: Engage your abdominal muscles and glutes to keep your body in a straight line. Ensure your neck is in line with your spine, and your gaze is slightly ahead of you.

3. Hold Position: Maintain this position, avoiding sagging or lifting your hips too high, and aim to hold it for a specific duration (e.g., 20 seconds to a minute or more, depending on your fitness level).

4. Breathing: Breathe steadily and avoid holding your breath. Focus on keeping your core muscles engaged throughout.

5. Release: Gently lower yourself to the ground to finish the plank exercise.

The plank is an effective exercise for building core strength, improving posture, and enhancing overall stability. Variations like side planks or plank with leg lifts can further target different muscle groups and add challenge as you progress.

Normative data for the plank exercise, in terms of how long an individual should be able to hold the position, can vary widely based on factors like age, fitness level, and specific goals.

General guidelines suggest that holding a plank for about 20-60 seconds is a good starting point for beginners, but some individuals can hold it for several minutes. Advanced practitioners or athletes might aim for longer durations, but it's crucial to prioritize proper form over duration to prevent injury.

Specific normative data for the plank exercise might be available in research studies or fitness assessments conducted by fitness organizations. These can vary based on age groups, fitness levels, and other demographic factors. Consulting with fitness professionals or referring to studies on fitness assessments may provide more specific normative data for the plank exercise across different populations.

References: 

• Tong, Tom K., Shing Wu, and Jinlei Nie. "Sport-specific endurance plank test for evaluation of global core muscle function." Physical Therapy in Sport 15.1 (2014): 58-63.
• Strand, Sarah L., et al. "Norms for an isometric muscle endurance test." Journal of human kinetics 40 (2014): 93.
• Imai, Atsushi, and Koji Kaneoka. "The relationship between trunk endurance plank tests and athletic performance tests in adolescent soccer players." International journal of sports physical therapy 11.5 (2016): 718.