Reliability of a Clinical Test for Measuring Eccentric Knee Flexor Strength Using a Handheld Dynamometer.

Area of Science:

• Sports Medicine
• Biomechanics
• Rehabilitation Science

Background:

• Eccentric knee flexor strength is crucial for preventing and rehabilitating hamstring injuries.
• Accurate assessment of this strength is vital for athletes.

Purpose of the Study:

• To evaluate the reliability of a clinical test for eccentric knee flexor strength using a handheld dynamometer during the Nordic hamstring exercise.
• To compare the handheld dynamometer's measurements with a load cell-based device.

Main Methods:

• Reliability study involving 50 male amateur athletes (soccer/rugby players).
• Eccentric knee flexor strength was measured using a handheld dynamometer.
• Test-retest reproducibility was assessed over two sessions one week apart.

Main Results:

• The handheld dynamometer yielded smaller force values compared to a load cell (P < .05, large effect sizes).
• Test-retest reliability showed moderate intraclass correlation (0.60–0.62) and moderate to good correlation (0.67–0.76).
• Typical error ranged from 23–31 N, and coefficient of variation was 9–11%.

Conclusions:

• The handheld dynamometer is an affordable and relatively reliable tool for clinical eccentric knee flexor strength assessment.
• Direct comparison of results with load cell devices is not recommended due to measurement differences.