Measuring the circumference of the upper arm is a common practice for monitoring muscle growth, assessing body composition, or ensuring proper clothing fit. The process requires a soft, flexible tape measure and a consistent approach to yield meaningful data. Both flexed and relaxed measurements are appropriate and provide distinct information about the muscle. Precision in technique is necessary regardless of the chosen state, allowing for accurate tracking of changes over time.
Why Use Both Relaxed and Flexed Measurements
Both relaxed and flexed measurements serve different, yet complementary, purposes when monitoring physical development. The relaxed measurement provides a baseline for the overall girth of the arm, reflecting total arm mass, including muscle, bone, and fat tissue. This measurement is often used when comparing size against population averages.
The flexed measurement captures the muscle’s potential and its peak size under maximal contraction. Flexing the bicep shortens the muscle belly, causing it to bulge outward and resulting in a larger circumference. Tracking the flexed size indicates the muscle’s ability to contract and the development of the “peak.” Using both data points offers a more comprehensive view of arm development.
Step-by-Step for the Relaxed Measurement
To take an accurate relaxed bicep measurement, the subject should stand upright with the arm hanging loosely at the side. The arm must be completely unflexed, with the palm facing inward or in a neutral position, ensuring the muscle is at its resting length.
The measurement should be taken at the midpoint of the upper arm, which is halfway between the tip of the shoulder bone (acromion process) and the tip of the elbow bone (olecranon). The tape measure is wrapped around the arm at that exact spot. The tape must be snug against the skin without compressing the underlying tissue and kept parallel to the floor.
Step-by-Step for the Peak Flexed Measurement
Achieving the peak flexed measurement requires the subject to fully contract the bicep muscle. The most common technique involves bending the arm at the elbow, often to a 90-degree angle, and making a tight fist while actively squeezing the bicep. Some find it easier to take this measurement while seated, resting the elbow on a surface, or standing with the arm raised horizontally.
The measuring tape is placed around the highest point of the muscle belly, which is the point of greatest circumference during the contraction. This location will be higher up the arm than the midpoint used for the relaxed measurement. It is helpful to have a second person perform the measurement to ensure the tape is level and accurately positioned.
Maintaining Consistency for Accurate Tracking
The reliability of tracking progress depends on consistency in the measurement process, regardless of whether a relaxed or flexed state is chosen. It is standard practice to choose one arm, typically the dominant one, and consistently measure that side, or to measure both arms to check for symmetry. The same soft measuring tape should be used for every session to eliminate tool variations.
A significant variable that affects arm size is the timing of the measurement relative to exercise and hydration. Taking a measurement immediately after a workout can temporarily inflate the size due to the “pump” from increased blood flow. Therefore, measurements should be taken at the same time of day, such as first thing in the morning, to ensure the muscle is in a resting state. Recording the results immediately after the measurement is completed helps prevent tracking errors.