(12) TEST-RETEST RELIABILITY OF A NOVEL AND PORTABLE LEG PRESS DYNAMOMETER IN YOUNG AND OLDER ADULTS

Age-related changes in lower body (LB) strength are commonly examined using powered and weight-loaded leg press dynamometers.  However, there is a need for a reliable and portable leg press dynamometer to examine LB strength in field settings. 

Purpose: The purpose of this investigation was to examine test-retest reliability and minimum difference (MD) values of a novel and portable isometric leg press dynamometer in young and older adults. 

Methods: Twenty young adults (9 women; age = 20.8 ± 0.89 years; BMI = 23.9 ± 2.4 kg/m²) and fifteen older adults (9 women; age = 69.3 ± 3.1 years; BMI = 25.6 ± 4.5 kg/m²) visited the laboratory on two occasions (2 – 10 days apart).  Prior to both visits, participants were required to refrain from any vigorous lower body exercise for 48 hours, any form of exercise for 24 hours, alcohol or recreational drug use for 24 hours and caffeine for 12 hours.  Females completed visits during the follicular phase of the menstrual cycle and were required to take a pregnancy test.  Each participant was seated in the custom built and calibrated leg press dynamometer while secured with a seatbelt across their waist.  Participants sat at 60° of knee flexion, 90° of hip flexion, and 0° of dorsiflexion.  Following a brief warm-up, participants performed three maximal voluntary contractions (MVCs) with two minutes of rest between MVCs.  Maximal isometric peak force (PF) was determined from the highest 500 ms epoch across of all MVCs. 

Results: The young adults (1740.7 ± 518.0 N) had greater PF values (P < 0.001) than the older adults (1116.9 ± 369.6 N).  There was no significant systematic error across sessions for the entire sample (Day 1 = 1344.3 ± 511.3 N; Day 2 = 1403.0 ± 541.8 N; P = 0.128) or separately for young (P = 0.507) and older adults (P = 0.101).  Reliability statistics are included in Table 1. 

Conclusions: These data suggest this isometric leg press dynamometer is a reliable, portable, and cost-effective tool that can detect age-related differences in LB strength between young and older adults.  PRACTICAL APPLICATION: The custom-built leg press dynamometer may be an attractive LB assessment for researchers and practitioners who work in various field settings that may not have access to more common laboratory leg press dynamometers.   

Acknowledgements: None