Weight training--Physiological aspects.

The purpose of this research was to investigate the effects of eccentric phase
duration on concentric outcomes at 60% and 80% of one-repetition maximum (1RM) in
the squat and bench press. Sixteen resistance-trained males completed four laboratory
visits as follows: Day 1- 1RM testing; Day 2- establishment of normative eccentric
durations; Days 3 and 4- randomized fast (0.75 times) or slow (2 times) eccentric
duration variations, which were controlled by visual and auditory metronomes. Eccentric
duration was significantly and inversely correlated with average concentric velocity
(ACV) at 60% (r = 0.408) and 80% (r = -0.477) of 1RM squat and at 100% of 1RM
bench press. At 60% of 1RM squat, both fast and slow eccentric conditions produced
greater (p<0.001) peak concentric velocity (PCV) than normative duration with fast also
producing greater PCV than slow (p=0.044). Therefore, fast eccentric durations may
benefit concentric velocity.

This research examined the time-course of muscle damage in the squat, bench
press, and deadlift. Ten resistance-trained males performed four sets to failure with 80%
of one-repetition maximum (1RM) for each exercise on three separate weeks. Swelling,
range of motion (ROM), delayed onset muscle soreness (DOMS), lactate dehydrogenase
(LDH), creatine kinase (CK), and average concentric velocity (ACV) were assessed pretraining
and at five timepoints post-training: -0, 24, 48, 72, and 96 hours. Swelling
(p<0.01) increased immediately post-training, and DOMS (p<0.01) increased at 24 hours
post-training in the bench press condition. Additionally, DOMS increased at 48 hours in
both squat and deadlift conditions (p<0.01). Squat and deadlift elevated CK immediately
post-training (p<0.01), but LDH only increased in the squat post-training. Immediately
post in the bench press ACV was decreased (p<0.01) along with in the squat for up to 72
hours (p<0.01), however, ACV did not change following the deadlift (p>0.05).