Context: The combination of extended isometric and eccentric muscle actions (i.e., eccentric quasi-isometric resistance exercise (EQI-RE)) is postulated to have advantages over traditional isotonic resistance exercise (TRD-RE), and researchers and practitioners have suggested potential applications in both training and rehabilitation contexts. Studies investigating EQI-RE have yet to evaluate many purported benefits directly, such as greater time under tension, motor unit recruitment, muscle co-contraction/activation, improvements in strength and hypertrophy, and have not compared sex-differences. As females are generally more resistant to fatigue than males, and exercise volume during EQI-RE will be a function of fatiguability, females may exhibit differing neuromuscular responses to EQI-RE, while accruing more exercise volume, potentially leading to sex-differences in musculotendinous adaptations to EQI-RE. Objective: In trained and untrained males and females, the thesis investigated overall and/or sex-related differences in the acute fatigue response, as well as strength and hypertrophy adaptations to unilateral TRD-RE and EQI-RE of the elbow flexors. Methods: Using isokinetic dynamometry and surface electromyography (sEMG), study one examined sex-differences in the acute kinematic, kinetic, and muscle excitation response during successive unilateral EQI-RE elbow flexion sets. Using a unilateral dumbbell protocol, study two compared acute sex-differences in time under tension, muscle excitation, and co-activation between TRD-RE and EQI-RE. With this protocol, study three used b-mode ultrasonography and estimated 1-repetition maximum testing to evaluate elbow flexor hypertrophy and strength after 8-weeks of TRD-RE or EQI-RE, and between males and females. Results: Females were generally less fatigable than males for both TRD-RE and EQI-RE. Greater and faster muscle excitation was produced by TRD-RE, although there were no appreciable differences in agonist-antagonist co-activation. Females accrued more exercise volume from both TRD-RE and EQI-RE, but there were no sex-differences in muscle hypertrophy and strength. TRD-RE produced significantly greater relative increases in muscle hypertrophy and strength than EQI-RE. Conclusion: The thesis does not equivocally support the proposed benefits of EQI-RE. Females were less fatigable than males during EQI-RE and TRD-RE, but this did not lead to sex-differences in muscle hypertrophy or strength. Overall, TRD-RE was more effective for improving strength and hypertrophy, although EQI-RE still produced significant increases in untrained individuals.