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Updated: Sep 7, 2025
Acquisition and Semi-Automated Analysis of Respiratory Muscle Surface Electromyography
Published on: January 24, 2025
Training the equine respiratory muscles: Inspiratory muscle strength
Laura E Fitzharris1, Melanie J Hezzell1, Alison K McConnell2
1Bristol Veterinary School, University of Bristol, Langford, Bristol, UK.
Background:
Little is known about the response of the equine respiratory muscles to training.
Objectives:
To measure an index of inspiratory muscle strength (IMSi) before and after a period of conventional exercise training (phase 1) and inspiratory muscle training (IMT), comparing high-load (treatment) and low-load (control) groups (phase 2).
Study Design:
Prospective randomised controlled trial.
Methods:
Phase 1: Twenty National Hunt Thoroughbred racehorses performed an inspiratory muscle strength test (IMST) twice on two occasions; when unfit at timepoint A (July), and when race fit at timepoint B (October). Phase 2: Thirty-five Thoroughbred racehorses at race fitness were randomly assigned into a high-load (treatment, n = 20) or low-load (control, n = 15) IMT group. The high-load group followed an IMT protocol that gradually increased the inspiratory pressure applied every 4 days. The low-load group underwent sham IMT with a low training load. The IMT was performed 5 days/week for 10 weeks. The IMST was performed twice on two occasions, timepoint B (October) and timepoint C (January). Conventional exercise training and racing continued during the study period. The peak IMSi values obtained from the different groups at timepoints A, B and C were compared using a Wilcoxon Signed Rank Test.
Results:
Phase 1: There was a significant increase in IMSi from timepoint A: 22.5 cmH2 O (21-25) to timepoint B: 26 cmH2 O (24-30) (p = 0.015). Phase 2: From timepoint B to C there was a significant increase in IMSi for the high-load group 34 cmH2 O (28-36) (p = 0.001) but not the low-load group 26 cmH2 O (24-30) (p = 0.929). The peak IMSi at timepoint C was significantly higher for the high-load than low-load group (p = 0.019).
Main Limitations:
Single centre study with only National Hunt horses undergoing race-training included.
Conclusions:
In horses undergoing race training there is a significant increase in IMSi in response to conventional exercise training and high-load IMT.
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