Isometric strength and dynamic back extensor endurance are unrelated in children ages 6-10 years: a pilot study

Area of Science:

• Pediatric Exercise Science
• Musculoskeletal Biomechanics
• Childhood Physical Fitness

Background:

• Assessing back extensor muscle function is crucial for understanding pediatric physical health.
• Previous research has explored various methods for evaluating back muscle strength and endurance in children.
• Standardized protocols are needed to accurately measure different components of back muscle fitness.

Purpose of the Study:

• To evaluate the correlation between isometric back extensor force and dynamic endurance in children aged 6-10 years.
• To determine the test-retest reliability of both isometric and dynamic back extension tests.
• To ascertain if these two measures assess distinct aspects of back muscle fitness.

Main Methods:

• Sixty-nine children (6-10 years) participated in the study.
• Isometric back extension force was measured using a calibrated dynamometer.
• Dynamic back extension endurance was assessed by repetitions at a specific frequency (20/min).
• Both tests were repeated after a one-week interval to assess reliability.

Main Results:

• High test-retest reliability was found for both isometric force (r=0.79) and dynamic endurance (r=0.55).
• The correlation between isometric force and dynamic endurance was low (r=0.03), indicating they measure different constructs.
• Both tests demonstrated moderate to high reliability individually.

Conclusions:

• Isometric back extensor force and dynamic endurance tests are reliable but assess different components of back muscle fitness in children.
• These distinct measures should not be used interchangeably for assessing overall back extensor muscle fitness.
• Further research is recommended to explore the impact of varying dynamic test parameters (e.g., frequency, mat height).