Background We previously measured the rate of regaining muscle strength during rehabilitation of lower leg muscles in patients following lower leg casting. Our primary aim in this study was to measure the rate of gain of strength in healthy individuals undergoing a similar training regime. Our secondary aim was to test the ability of MRI to provide a biomarker for muscle function.
Methods Men and women were recruited in three age groups: 20–30, 50–65 and over 70 years. Their response to resistance training of the right lower leg twice a week for 8 weeks was monitored using a dynamometer and MRI of tibialis anterior, soleus and gastrocnemius muscles at 2 weekly intervals to measure muscle size (anatomical cross-sectional area (ACSA)) and quality (T2 relaxation). Forty-four volunteers completed the study.
Results Baseline strength declined with age. Training had no effect in middle-aged females or in elderly men in dorsiflexion. Other groups significantly increased both plantarflexion and dorsiflexion strength at rates up to 5.5 N m week-1 in young females in plantarflexion and 1.25 N m week-1 in young males in dorsiflexion. No changes were observed in ACSA or T2 in any age group in any muscle.
Conclusion Exercise training improves muscle strength in males at all ages except the elderly in dorsiflexion. Responses in females were less clear with variation across age and muscle groups. These results were not reflected in simple MRI measures that do not, therefore, provide a good biomarker for muscle atrophy or the efficacy of rehabilitation.
- strength isometric isokinetic
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Contributors RMA and JRM designed the study. JRM performed the initial analysis. RMA performed additional analysis and prepared the first draft of the paper. FJG was the senior radiologist, TWR was the MR physicist and together they directed the MRI and analysis. AR advised on the exercise training regime and HW on muscle function and physiology. MP and FG recruited the volunteers, put them through the exercise training, assessed their strength and ensured their adherence to the scanning protocols. ZW performed the image analysis to segment the images and make the MR measurements. All authors revised the paper critically for intellectual content and approved the final version. All authors agree to be accountable for the work and to ensure that any questions relating to the accuracy and integrity of the paper are investigated and properly resolved.
Funding This study was supported by an award (Ref: WHMSB_AU118) from the Translational Medicine Research Collaboration—a consortium made up of the Universities of Aberdeen, Dundee, Edinburgh and Glasgow, the four associated NHS Health Boards (Grampian, Tayside, Lothian and Greater Glasgow & Clyde), Scottish Enterprise and Wyeth. The funder played no part in the design, execution, analysis or publication of this study.
Competing interests None declared.
Patient consent All the participants were healthy volunteers. No personal or identifying data on any of the participants are included in this paper.
Ethics approval North of Scotland Research Ethics Committee.
Provenance and peer review Not commissioned; internally peer reviewed.
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