Author(s): HUANG, M.J., CHEN, T.C.2, SINGH, F.1, TAAFFE, D.R.1, NOSAKA, K.1, Institution: EDITH COWAN UNIVERSITY, Country: AUSTRALIA, Abstract-ID: 1641

INTRODUCTION:
Cognitive function of older adults is improved by performing aerobic and/or resistance exercise training [1]. Due to the potentially higher cognitive demand of eccentric exercise [2] and its superior impact on muscle function, physical fitness, insulin sensitivity, and blood lipid profile in comparison to concentric exercise [3], eccentric exercise training may be more effective in improving cognitive function. This study explored whether an 8-week eccentric exercise program would enhance cognitive function more than a stretching exercise program in older adults.
METHODS:
Healthy older women (66-75 y) underwent either home-based eccentric exercise (ECC, n=14) or stretching exercise (STRETCH, n=14) twice weekly for 8 weeks. The ECC group performed 7 eccentric exercises (chair squat, chair recline back, wall kiss, heel drop, elbow extension, glute bridge, lower back) with repetitions increasing from 5 to 40, and the STRETCH group performed 12 stretching exercises (approximately 30 min per session for both groups). Stroop test for color naming (STCN) and conflicting color words, symbol digit modalities test (SDMT), digit span test (DST) and two types of the trail making test (TMT-A, TMT-B), and 6 physical fitness tests were undertaken before and after the training period and 4 weeks after the last training session. Fasting blood samples were taken 3 days before the first training session and 4 days after the last training session, and analysed for insulin sensitivity and lipid profile markers, and brain-derived neurotrophic factor (BDNF). Changes in the variables over time were compared between groups by two-way repeated-measures ANOVA.
RESULTS:
A significant (p<0.05) interaction effect was found for changes in STCN (F=7.34), DST (F=5.13) and TMT-A (F=3.64), with the ECC group showing improvements (P<0.05) in STCN (4.8%), DST (14.7%) and TMT-A (10.2%) from pre- to post-training. However, these changes in cognitive function returned to baseline 4 weeks later. There were no significant changes in other cognitive function tests for either group. Grip strength and 2-min step test showed greater (p<0.05) improvement for the ECC than STRETCH group, and only the ECC group demonstrated improvement in 30-s chair stand, 3-m timed up and go, and 3-m backwards walk tests post-training. There were no significant changes in blood lipid profile and BDNF, but decreases (P<0.05) in serum glucose concentration and whole-blood glycosylated hemoglobin were observed post-training for the ECC group.
CONCLUSION:
These results suggest that the eccentric exercise program was more effective in enhancing some aspects of cognitive and physical function of older adults than stretching exercise; however, the limited training period and exercise frequency may have constrained the magnitude of these effects.
1. Falck et al. Neurobiol Aging, 2019
2. Kan et al. Eur J Apply Physiol, 2019
3. Chen et al. Front Physiol, 2017