Does task experience moderate habituation effects in drop jumps? - An intra- and interday reliability and measurement...

Area of Science:

• Biomechanics
• Sports Science
• Human Movement Analysis

Background:

• Drop jumps (DJs) are widely used to assess stretch-shortening cycle efficiency.
• Many studies fail validity guidelines, with ground contact times (GCTs) exceeding 250ms.
• Insufficient test familiarization may explain poor adherence to GCT thresholds in DJs.

Purpose of the Study:

• To investigate the impact of extensive task habituation on test-retest reliability and GCT adherence in drop jumps.
• To compare performance and reliability between experienced and inexperienced participants in drop jump testing.

Main Methods:

• Eighty-nine healthy participants were divided into experienced and inexperienced subgroups.
• Subjects performed 45 drop jumps across five days from three different heights.
• Reliability coefficients and systematic/random errors were quantified between testing days.

Main Results:

• The inexperienced group demonstrated systematic performance improvements, particularly in GCTs (up to d=0.83).
• Mean Absolute Percentage Errors (MAPEs) for reactive strength index (RSI) reached 30% in the inexperienced group.
• The experienced group showed no systematic improvements and smaller random errors (16-17% RSI MAPE).

Conclusions:

• Significant task habituation occurred in the inexperienced subgroup, evidenced by systematic bias.
• The experienced group, already familiar with the protocol, exhibited no test-retest improvements.
• Future DJ research requires explicit reliability reporting and sufficient participant habituation due to differing measurement errors.