Mental Effort During Low Load Resistance Training in Older Adults

Participants in both training groups will perform 8 weeks of low intensity, whole-body resistance training. Participants in the control group will participate in all testing procedures but not perform any training. Participants from all groups will be instructed to otherwise maintain their normal physical activity levels and dietary habits.

All training sessions will be supervised by research personnel at a Kennesaw State University fitness center. Participants will complete 2 training sessions per week for 8 weeks. Each training session will last about 45-60 minutes and consist of 5 exercises, including both multi-joint (leg press, chest press, back row) and single-joint (knee extension, bicep curl) exercises. Participants will perform 2 sets of 15 repetitions for each exercise for the first 2 weeks, then volume will be increased by progressing to 3 sets for the remaining 6 weeks. There will be a 60-second rest interval between sets and a similar tempo will be used between groups.

Both training groups will perform the same training protocol, but participants in the maximal mental effort group will mentally urge their muscles to contract maximally during each repetition. That is, despite using a low intensity, participants will imagine the feeling of maximal muscle contraction of the primary muscles during each repetition.

Several measures of strength, neuromuscular function, physical function, and body composition will be measured before and after the training or control period.

• Change in isokinetic knee extensor muscle activation as measured by electromyography amplitude [Срок оценки: Baseline, Week 8]
• Change in isometric knee extensor strength as measured by newton-meters of torque [Срок оценки: Baseline, Week 8]
• Change in knee extensor muscle activation as measured by electromyography amplitude [Срок оценки: Baseline, Week 8]
• Change in motor unit firing rate as measured relative to the motor unit recruitment threshold [Срок оценки: Baseline, Week 8]
• Change in motor unit action potential size as measured relative to the motor unit recruitment threshold [Срок оценки: Baseline, Week 8]
• Change in handgrip strength as measured in kilograms of force [Срок оценки: Baseline, Week 8]
• Change in walking speed as measured by time taken to walk 4 meters [Срок оценки: Baseline, Week 8]
• Change in chair rise performance as measured by number of chair rises performed in 30 seconds [Срок оценки: Baseline, Week 8]
• Change in bicep curl strength as measured by load lifted in pounds [Срок оценки: Baseline, Week 8]
• Change in dynamic strength of the lower body muscles during the leg press as measured by load lifted in pounds for 5 repetitions [Срок оценки: Baseline, Week 5, Week 8]
• Change in muscle composition as measured by ultrasound-derived grey-scale analysis [Срок оценки: Baseline, Week 8]
• Change in skeletal muscle size as measured by ultrasound-derived cross-sectional area [Срок оценки: Baseline, Week 8]