Related Experiment Video
Updated: Aug 13, 2026
09:29
Skeletal Muscle Gender Dimorphism from Proteomics
Published on: December 14, 2011
Phase angle identifies a muscle quality phenotype associated with physical performance in U.S. marines
Adam W Potter1, Christy L Christopoulos2, Karl E Friedl1
1U.S. Army Research Institute of Environmental Medicine, Natick, MA, United States.
Frontiers in Physiology
|August 12, 2026
Summary
Phase angle (PhA) offers physiological insights beyond DXA body composition, enhancing physical performance in U.S. Marines. This marker reflects muscle quality-related status, not direct muscle quality.
Area of Science:
- Physiology
- Sports Science
- Body Composition Analysis
Background:
- Dual-energy X-ray absorptiometry (DXA) is a common method for assessing body composition.
- Bioelectrical impedance analysis (BIA) provides an alternative method, yielding phase angle (PhA) as a key metric.
- The physiological significance of PhA beyond DXA-derived measures for physical performance remains an area of investigation.
Purpose of the Study:
- To determine if phase angle (PhA) provides additional physiological information for explaining physical performance in active-duty U.S. Marines, beyond what is explained by DXA-derived body composition.
- To investigate the independent associations of PhA with various physical performance metrics.
- To explore the role of PhA as a marker of muscle quality-related physiological status.
Main Methods:
- Analysis of data from 2,177 active-duty U.S. Marines utilizing BIA, DXA, and physical performance tests.
- Standardization of PhA within sex to create Phase Angle Muscle Quality (PhA-MQ) quartiles.
- Multivariable linear regression models adjusted for DXA metrics (FFMI, %BF), age, and sex to assess independent associations and incremental explanatory value (ΔR², partial R²).
Main Results:
- Physical performance, including the Physical Fitness Test (PFT) and Combat Fitness Test (CFT), increased progressively across PhA-MQ quartiles.
- Phase angle (PhA) remained independently associated with PFT and CFT scores even after adjusting for DXA-derived body composition.
- PhA demonstrated stronger associations with performance efficiency measures (e.g., PFT per kg lean mass) than with estimated VO₂max.
- Continuous spline analyses indicated monotonic relationships between PhA and physical performance.
Conclusions:
- Phase angle (PhA) serves as a physiological marker that is independently associated with enhanced physical performance in U.S. Marines.
- PhA provides physiological information beyond DXA-derived body composition, particularly for performance efficiency.
- These findings suggest PhA reflects a muscle quality-related physiological status rather than being a direct measure of muscle quality itself.
Related Concept Videos
01:15Muscle Contraction
01:27Exercise and Muscle Performance
Exercise induces a range of adaptations in muscle tissue, depending on the type and duration of activity. Such physical training can be broadly categorized into two types: endurance exercises and resistance exercises.
Endurance exercises
Endurance exercises involve running, swimming, or cycling, which require repetitive movements with low force output. When a person engages in endurance exercise, a few noticeable changes occur in their skeletal muscles. For instance, the number of capillaries...
Endurance exercises
Endurance exercises involve running, swimming, or cycling, which require repetitive movements with low force output. When a person engages in endurance exercise, a few noticeable changes occur in their skeletal muscles. For instance, the number of capillaries...
00:55Skeletal Muscle Anatomy
Skeletal muscle is the most abundant type of muscle in the body. Tendons are the connective tissue that attaches skeletal muscle to bones. Skeletal muscles pull on tendons, which in turn pull on bones to carry out voluntary movements.
01:22Muscle Stimulation Frequency
The contraction strength of muscles is regulated by motor neurons, which modulate the frequency of action potentials dispatched to the motor units based on the body's requirements. This process of varying the muscle stimulation frequency allows muscles to contract with a force that is precisely tailored to the needs of the moment, whether lifting a feather or a heavy box.
Wave summation
At low firing rates, motor neurons induce individual twitch contractions in muscle fibers. These twitches...
Wave summation
At low firing rates, motor neurons induce individual twitch contractions in muscle fibers. These twitches...