Author(s): HANDFORD, M., MUNDY, P.2, THEIS, N.3, SUCHOMEL, T.4, LAKE, J.5, HUGHES, J.1, Institution: CARDIFF METROPOLITAN UNIVERSITY , Country: UNITED KINGDOM, Abstract-ID: 1379

INTRODUCTION:
Eccentric (ECC) training is gaining recognition in strength and conditioning for improving athletic performance and rehabilitation. Yet, the academic community lacks standard definitions and terminology for eccentric training methods (ETM), complicating the translation of research into practice. Establishing a consensus on ETM principles is essential to guide researchers and practitioners alike.
METHODS:
A two-round Delphi study was undertaking including 12 academics and strength and conditioning coaches with extensive background in ETM. For round one, participants were given statements regarding ETM and asked to agree, disagree or suggest amendments. Based on the feedback, the statements were revised. All 12 participants completed round one and 11 completed round two. The questions addressed were: (Q1) the definition of ECC training; (Q2) the definition and appropriateness of the term ECC overload; (Q3) the necessity for a new construct of ECC muscle action; and (Q4) the importance of creating a measure for time under tension. Consensus was defined as achieving 73% agreement on each question.
RESULTS:
Consensus was achieved for Q1, with 73% participants agreeing on the definition of ECC training. While 64% supported avoiding the term “ECC overload” (Q2), this did not constitute a consensus. For Q3, concerning the creation of a new ECC muscle lengthening construct, 73% of participants concurred, reaching a consensus; however, it was noted that further research is necessary integrating new terminology. 100% agreement was found for adopting the term “time in action”.
CONCLUSION:
ECC training is defines as methods that focus exclusively on the eccentric (ECC) phase or integrate it during multi-phase resistance or plyometric exercises. While a definitive consensus on ECC overload was not reached, it is advised that specific ETM be detailed in lieu of the term; authors opting to use "ECC overload" should provide a precise definition. Regarding muscle lengthening classifications, consensus was achieved for three distinct actions: passive, active, and forced ECC actions. However, further research with a broader participant base is recommended before adopting these terms. Additionally, "time in action" was unanimously approved to describe the overall duration of an exercise, distinguishing it from "time under tension," which refers to the periods a muscle can actively create or decelerate force.