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Multi-joint rate of force development testing protocol affects reliability and the smallest detectible difference
David Drake1,2, Rodney A Kennedy1,3, Eric S Wallace1,3
1a School of Sport , Ulster University , Newtownabbey , N. Ireland.
Journal of Sports Sciences
|February 28, 2019
Summary
The explosive force test protocol is more reliable for assessing rate of force development (RFD) in isometric squats than traditional peak force tests. Researchers should use the explosive protocol for better results.
Area of Science:
- Sports Science
- Biomechanics
- Human Movement
Background:
- Isometric testing is common for assessing rate of force development (RFD).
- Variations in testing methodology can significantly impact performance outcomes.
- Standardizing isometric squat testing protocols is crucial for reliable RFD assessment.
Purpose of the Study:
- To compare the reliability of two isometric squat testing protocols (peak force vs. explosive force).
- To evaluate the influence of two knee flexion angles (100° and 125°) on RFD measures.
- To determine the optimal protocol and joint angle for assessing multi-joint RFD.
Main Methods:
- Eleven strength-trained participants completed test-retest sessions one week apart.
- Two isometric squat protocols (peak force and explosive force) were assessed.
- Tests were conducted at two knee flexion angles (100° and 125°), with force-time data analyzed for RFD.
Main Results:
- Traditional peak force protocols showed unreliable RFD measures at both 100° and 125° knee flexion.
- The explosive force protocol demonstrated reliability at 100° (RFD 0-200ms, 0-250ms) and 125° (RFD 0-150ms, 0-200ms, 0-250ms).
- Force-time characteristics were optimized at the greater knee flexion angle (125°).
Conclusions:
- Average and instantaneous RFD measures from traditional peak force tests lack reliability for multi-joint assessments.
- The explosive RFD test protocol is recommended over the traditional peak force protocol for more reliable multi-joint RFD assessment.
- Higher knee joint angles may optimize force-time characteristics in isometric squats.
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