The role of lactate in the exercise-induced human growth hormone response: evidence from McArdle disease

• Published in: British journal of sports medicine 2009-07, Vol.43 (7), p.521-525
• Main Authors: Godfrey, R J, Whyte, G P, Buckley, J, Quinlivan, R
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Biopsy; Blood vessels; Exercise; Exercise - physiology; Exercise Test; Female; Glycogen Storage Disease Type V - blood; Growth hormones; Human growth; Human Growth Hormone - metabolism; Humans; Lactic Acid - metabolism; Male; Metabolism; Middle Aged; Musculoskeletal system; Nitric oxide; Physiology; Rodents; Sports medicine; Studies; Walking; Young Adult
• ISSN: 0306-3674; 1473-0480
• DOI: 10.1136/bjsm.2007.041970

Purpose:Increased blood lactate concentration has been suggested as a primary stimulus for the exercise-induced growth hormone response (EIGR). Patients with McArdle disease are unable to produce lactate in response to exercise and thus offer a unique model to assess the role of lactate in the EIGR. Accordingly, McArdle’s patients were exercised to test the hypothesis that lactate is a major stimulus of the EIGR.Methods:11 patients with McArdle disease (3 male, 8 female; age: 35.5 (SD 13.9) years, height: 166 (8) cm, body mass: 75.2 (13.1) kg) were recruited for the study. The patients walked initially at 0.42 m/s, increasing by 0.14 m/s per 3 min stage. Exercise was terminated when participants completed 3 minutes at 1.80 m/s or when a Borg CR10 pain scale rating of “4” was reached. Stages were separated by 60 s for capillary blood sampling for analysis of hGH and blood lactate concentration.Results:McArdle’s patients’ blood lactate levels remained at resting levels (0.3–1.2 mmol/l) as exercise intensity increased. Nine out of 11 participants failed to demonstrate an EIGR obtaining hGH values below the clinical definition of a response (>3 μg/l).Conclusion:The absence of an EIGR in nine out of 11 participants suggests that lactate could play a major role in the EIGR in humans.