Does strength training influence hamstring muscle-tendon adaptations and changes in running biomechanics?

Healthy, male participants will perform 10 weeks (following randomisation) of either maximal eccentric- or concentric-only knee flexion strength training on an isokinetic dynamometer, consisting of two sessions per week for the duration of the intervention period. This will be conducted at the Movement Analysis Research Laboratory (403.B1.02A) and Exercise Science Research Lab (420.4.12) at Australian Catholic University, Melbourne. Duration of each training session will be approximately 30 mins and all sessions will be completed one-on-one with the investigator. Across the training period, the volume (number) of contractions will be increased as per the progression outlined below: Week 1: Frequency (days per week) = 2 Sets = 3 Repetitions = 6 Total repetitions = 36 Week 2: Frequency (days per week) = 2 Sets = 3 Repetitions = 6 Total repetitions = 36 Week 3: Frequency (days per week) = 2 Sets = 4 Repetitions = 6 Total repetitions = 48 Week 4: Frequency (days per week) = 2 Sets = 4 Repetitions = 6 Total repetitions = 48 Week 5: Frequency (days per week) = 2 Sets = 5 Repetitions = 6 Total repetitions = 60 Week 6: Frequency (days per week) = 2 Sets = 5 Repetitions = 6 Total repetitions = 60 Week 7: Frequency (days per week) = 2 Sets = 6 Repetitions = 6 Total repetitions = 72 Week 8: Frequency (days per week) = 2 Sets = 6 Repetitions = 6 Total repetitions = 72 Week 9: Frequency (days per week) = 2 Sets = 6 Repetitions = 8 Total repetitions = 96 Week 10: Frequency (days per week) = 2 Sets = 6 Repetitions = 8 Total repetitions = 96 All contractions will be completed at 60deg/sec on the isokinetic dynamometer. All participants will perform two sets of three warm-up efforts at 60deg/sec, in the contraction mode used for their training. For all training repetitions, the concentric training participants will be moved to full knee extension (0deg) by the investigator and will be instructed to maximally flex their knee through to 90deg of knee flexion. The lever arm will then be returned to full knee extension, and the subsequent repetition completed. This will be undertaken until all repetitions are completed in their respective set, with a 30 second rest period between sets. The eccentric training participants will begin with their knee at 90deg of flexion. They will then be instructed to maximally flex against the lever arm until full knee extension is reached (0deg). The the lever arm will then be re-positioned to 90deg of knee flexion for the subsequent contraction. This will be undertaken until all repetitions are completed in each set, with a 30 second rest period between sets. Each training session will be separated by at least 48 hours. Participants will also be asked to refrain from additional hamstring strength training during this intervention period. The participants will be paired according to biceps femoris long head aponeurosis width and randomly assigned to (allocation ratio, 1:1) either concentric- or eccentric-only knee flexor strength training group in a randomly selected limb (the contralateral limb served as a within-participant control).