Muscle pain induced by hypertonic saline in the knee extensors decreases single-limb isometric time to task failure

• Published in: European journal of applied physiology 2020-09, Vol.120 (9), p.2047-2058
• Main Authors: Smith, Samuel A., Micklewright, Dominic, Winter, Samantha L., Mauger, Alexis R.
• Format: Article
• Language: English
• Subjects: Biomedical and Life Sciences; Biomedicine; Fatigue; Human Physiology; Injection; Muscle contraction; Occupational Medicine/Industrial Medicine; Original; Original Article; Osmosis; Pain; Pain perception; Sports Medicine
• ISSN: 1439-6319; 1439-6327
• DOI: 10.1007/s00421-020-04425-2

Purpose Increased nociceptive activity and the experience of exercise-induced pain (EIP) may contribute to fatigue during endurance exercise. To investigate this, a pain model that produces pain similar to EIP and decouples its relationship to exercise intensity is required. This study (1) compared the quality of pain caused by a hypertonic saline injection into the vastus lateralis in resting and exercise conditions, and (2) investigated whether this pain contributes to changes in time to task failure. Methods On separate days, 18 participants completed a time to task failure at 20% maximal voluntary torque (MVT), a resting hypertonic saline intramuscular injection, and in a further three visits a time to task failure at 10% MVT following injection of isotonic saline, hypertonic saline or a control (no injection). Results In a subset of eligible participants ( n  = 12), the hypertonic saline combined with 10% MVT produced a qualitative experience of pain (assessed by the McGill Pain Questionnaire) that felt similar to EIP. 10% MVT with hypertonic saline significantly elevated pain intensity in the first 20% of the time to task failure and caused a significantly ( P