Acute Effects of Resistance Exercise with Intra-Set Rest in Older Adults

The experimental session will be conducted in an exercise clinic at the University of Sydney Camperdown campus (Susan Wakil Health Building). Specifically, the experimental sessions will involve a 5-minute warm-up followed by 30 minutes spent performing the exercises (inclusive of resistance exercise and recovery times). All sessions will be supervised by an exercise physiologist or exercise scientist with one-on-one supervision provided to participants. There will be 7 days between the two experimental sessions (i.e., wash-out). Familiarisation will be conducted at end of an initial testing visit and will involve performing 2 sets of the chest press and the leg press following the exercise prescription used for the intra-set recovery (ISR) condition (details described below). The ISR condition will involve 4 sets of 2 clusters of 5 repetitions at 70% one-repetition maximum (1RM) with 30 seconds of rest between clusters and 90 seconds of rest between sets. Participants will perform the chest press prior to the leg press (in this order). The warm-up during experimental sessions will involve completing 1 set of 8 repetitions for the exercises performed in the session (i.e., chest press or leg press) with a load equivalent to 40% of 1RM. After 2 minutes of rest following the warm-up, participants will commence the first set of the experimental condition. The Keiser A420 pneumatic (air resistance) equipment (Fresno, CA, USA) will be used for the chest press and leg press. Participants will be instructed to refrain from moderate-vigorous exercise and any activities outside of daily living for the previous 72 hours prior to each session. Participants will also be asked not to start any other new exercise regimen or intentionally change their habitual diet throughout the entire study and assessment.