Extending the Applicability of Iso-inertial Eccentric Training

Abstract

Background: Eccentric (ECC) training has been widely studied because it has the potential to produce high forces, which can enhance gains in strength and muscle hypertrophy. In light of this potential, a disconnect exists between laboratory studies on ECC training and what is commonly performed by exercisers. Purpose: The goal of this thesis was to extend the applicability and accessibility of ECC focused training by furthering the knowledge of ECC training performed with common equipment using practical, easy to perform protocols. Study One: Study one compared supramaximal to submaximal ECC training. Results indicated that when training to volitional fatigue, there was no difference in muscle hypertrophy between submaximal and supramaximal ECC training, and submaximal ECC training sessions were perceived to be easier. These results advance the understanding of high vs. low intensity training for muscle hypertrophy and suggest that submaximal ECC training may be an effective alternative strategy to supramaximal ECC training. Study Two: Study two investigated approaches to manipulate the level of involvement of the ECC phase of contractions in conventional lifts. Findings indicated that when comparing CON only to conventional training, or CON with an emphasized (longer) ECC phase, all increased CON strength compared to control, but only the CON with an emphasized ECC increased muscle hypertrophy compared to control. This study provides evidence that emphasizing the ECC phase of a lift is an effective way to enhance muscle hypertrophy without sacrificing CON strength increases. Study Three: The purpose was to explore the interplay of contraction type and intensity on iso-inertial and isokinetic strength and muscle hypertrophy. The main finding of this study was that across both training contraction types, high intensity training was superior to low intensity for increasing both iso-inertial and isokinetic strength. Additionally, ECC was more effective for muscle hypertrophy than CON, regardless of training intensity. Together, these findings highlight the specific response of training intensity and contraction type and add knowledge regarding the transferability of strength across modalities. Conclusion: The findings of this thesis verify the effectiveness of iso-inertial ECC training, advancing both the theoretical understanding, and the practical implementation of these protocols.