By The One on One Team
Last Updated: 2/8/2026
Planks: How To Establish a Strong Position and Avoiding Form Leaks
Planks and plank variations are foundational exercises in our programs at One on One. They directly train the core to stabilize and protect the spine while force is transferred through the arms and legs. This essential function allows us to remain strong and safe during training sessions and activities of daily life. While planks are often viewed as a simple core exercise, their effectiveness can diminish significantly when performed incorrectly.
In this Focus Point, we will use our Three Keys for Proper Exercise Form—Setup and Endpoints, Maintain “I,” and Limiting Leaks—to dive into the details of what a well-executed plank looks like and how to avoid common form breakdowns.
Key #1: Setup and Endpoints
A strong plank begins with a proper setup. Proper setup ensures the correct muscles are engaged from the first second and defines the position you must maintain throughout the set.
In a plank, the setup is the endpoint. Your body should form a straight line from heels to ears, with shoulders stacked over elbows or wrists. You should be high on your toes to keep your weight shifted slightly forward into the shoulders.
When you are in a proper position, you should feel:
- Abdominals creating stiffness through the trunk
- Glutes lightly engaged to support a neutral pelvis
- Thighs activated to prevent the knees from bending
- Shoulders packed and supported by the lats
If this position cannot be established at the onset, it will not improve as fatigue sets in. Respecting your endpoint means choosing a plank variation that you can maintain with proper form for the full duration of the set.
Key #2: Maintain “I”
Once the plank begins, the primary objective is maintaining a straight capital “I” throughout the hold.
Your shoulders and hips should remain level, stacked, and connected by a long spine. The abdominals and glutes work together to prevent the hips from dipping or piking, while the upper back and shoulders remain engaged to support the torso.
Maintaining “I” ensures that the plank continues to train spinal stability rather than becoming a passive hold supported by joints instead of muscle.
Key #3: Limiting Leaks
The most obvious form leak in planks occurs when the hips deviate from the capital “I.” They may either sink toward the floor or pike upward to reduce the demand on the core. In addition to this primary leak, there are a couple other subtle breakdowns to be aware of:
- Losing the capital “I” through the upper back and shoulders. Keeping the shoulders packed increases core engagement and stability. As fatigue sets in, the upper back may begin to round or sink, and the shoulders may elevate to offload the core.
- Losing tension in the lower body. Bending the knees allows the hip flexors to play a larger role in stabilizing the pelvis. This can feed compensatory patterns that contribute to poor posture and an increased risk of lower-back discomfort.
Each of these leaks makes the exercise easier on the core muscles, which directly opposes the objective of the plank.
The Bottom Line
For the active aging adult, a strong core is essential. Planks are an effective way to build and maintain that strength, but proper execution is key to realizing their full benefits. The next time you perform a plank, use your checklist—Setup and Endpoints, Maintain “I,” and Limiting Leaks—to ensure you’re getting the most out of the exercise.
