Title

Cardio-metabolic and neuromuscular adaptations following whole-body eccentric resistance training in older adults

Author Identifiers

Wafina Rohadhia

ORCID: 0000-0001-7404-9227

Date of Award

2019

Degree Type

Thesis

Degree Name

Master of Science (Sports Science)

School

School of Medical and Health Sciences

First Advisor

Professor Ken Nosaka

Second Advisor

Dr Favil Singh

Third Advisor

Dr Desmond Menon

Field of Research Code

110602, 110321, 110104

Abstract

Regular exercise is key to minimise the negative effects of aging on health; however, it is reported that 65% of older Australians are categorised as physically inactive. Recent studies reported that eccentric resistance training (ECC-RT) is an effective modality to produce cardio-metabolic and neuromuscular benefits for older adults. The present study tested the hypothesis that ECC-RT of several major muscle groups would produce positive changes in cardio-metabolic and neuromuscular parameters in older adults with metabolic syndrome.

Six men and 11 women aged between 60 and 80 (70.0 ± 5.0) years old with dyslipidaemia and BMI >25 kg/m2 participated in this study. It is important to note that no control group nor control period applied before the participants commenced their training. All participants performed a whole-body ECC-RT program consisting of eight exercises (i.e. chest press, lateral pulldown, leg extension, leg curl, biceps curl, triceps extension, calf raises and abdominal crunch). The training sessions were performed twice a week for 8-weeks (16 sessions in total), with progressively increasing intensity from 10-100% of the individual’s one repetition maximum (1RM) for each exercise. Physical function (400-m walk, 30-s repeated chair rise, timed up-and-go), 1RM strength for all exercises, blood lipid profiles (total cholesterol, LDL, HDL, triglyceride), and glycaemic control parameters (fasting glucose, insulin, fructosamine, HOMA-IR index) were measured at baseline, mid-point (after 8 training sessions), and post-training (1-2 days after the last training session). Sensory organisation (SOT), body composition and isometric (MVIC) and isokinetic concentric (MVCC) maximal voluntary contraction (MVC) strength of the knee and elbow extensors and flexors were measured at baseline and post-training.

1RM strength increased significantly (p<0.05) for all exercises with 34–115% improvements from baseline. Physical function variables such as 400-m walk (12 ± 7%), 30-s repeated chair rise (18 ± 15%), timed up-and-go (13 ± 6%), and sensory organisation test (6 ± 8%) also showed significant improvements from baseline to post-training. However, no significant increases in isometric and isokinetic concentric MVC strength of the knee and elbow extensors and flexors were found. Although some participants showed some changes in body composition variables, no significant changes in percentage of body fat, fat mass and lean body mass were evident as a group. Total cholesterol (TC) (-5 ± 11%) and LDL-cholesterol (-8 ± 13%) decreased significantly after 4-weeks of training, and HDL-cholesterol showed a significant increase after 8-weeks (4 ± 9%), but the magnitude of changes in these variables were not large. Triglyceride (TG), fasting glucose, insulin, HOMA-IR and fructosamine did not show any significant changes over time. These results did not necessarily support the hypothesis, but were in agreement with previous studies that showed improvements in muscle strength and physical functions following ECC-RT. Interestingly, the magnitude of the changes in 1RM strength (leg extension, leg curl, triceps extension, biceps curl) did not necessarily correlate with those of MVIC and MVCC assessed by the isokinetic dynamometer for the same muscle groups (i.e. the increases in 1RM strength were much greater than that of MVIC and MVCC). Although the TC, LDL and HDL-cholesterol showed some improvements, the magnitude of the changes was not large. TG and other glycaemic control parameters did not show significant changes, although previous studies reported greater changes after ECC-RT of the knee extensors or descending stair walking training. It is interesting that the amount of muscles trained in the present study appear to be much greater than that of previous studies, but the training effects found in the present study were less. It may be that 16 sessions of whole-body ECC-RT over 8-weeks were not enough to induce large changes in some of the parameters. Thus, future studies need to examine whether ECC-RT with varying frequency, volume, intensity and duration could produce more positive changes in body composition and blood markers in older adults.

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