A 28-Day Carbohydrate-Restricted Diet Improves Markers of Cardiometabolic Health and Performance in Professional Firefighters. Issue 12 (December 2019)

• Record Type: Journal Article
• Authors: Waldman, Hunter S.; Smith, JohnEric W.; Lamberth, John; Fountain, Brent J.; McAllister, Matthew J.
• Is Part Of: Journal of strength and conditioning research. Volume 33:Issue 12(2019)
• Publication Date: 2019-12
• Subjects: low-carbohydrate diet -- protein -- high-stress occupation -- metabolism -- nutrition -- metabolic flexibility; Physical education and training -- Periodicals; Weight training -- Physiological aspects -- Periodicals; Physical fitness -- Periodicals; 613.7
• DOI: 10.1519/JSC.0000000000003354
• Languages: English
• ISSNs: 1064-8011

Abstract

Abstract : Abstract: Waldman, HS, Smith, JW, Lamberth, J, Fountain, BJ, and McAllister, MJ. A 28-day carbohydrate-restricted diet improves markers of cardiometabolic health and performance in professional firefighters. J Strength Cond Res 33(12): 3284–3294, 2019—We investigated the effects of a 4-week ad-libitum, nonketogenic, carbohydrate-restricted (<25% of calories) diet (CRD) on cardiometabolic and performance markers in firefighters (FF). Subjects ( n = 15) completed 9 sessions (trials 1–3 [familiarization], trials 4–6 [baseline], and trials 7–9 [post-CRD]). Following habitual western diet, anthropometric measures were assessed, glucose tolerance measured, and then completed a graded cycling test, maximal Wingate test, and conducted their FF physical performance assessment (FPPA) to measure performance while metabolic variables and perceptual responses were recorded. Subjects then adhered to a CRD for a 4-week duration and returned for repeat testing. Body fat as measured by BodPod, and 7-site skinfold thickness decreased ( p < 0.01), and a decrease was observed in blood pressure (BP) ( p < 0.01; ∼5 mm Hg) after CRD. There were no differences found for glucose tolerance, but an increase was found for fat oxidation rates ( p < 0.01; ∼0.07 g·min −1 ) and a decrease in carbohydrate oxidation rates across a range of intensities ( p < 0.01; ∼0.24 g·min −1 ). Finally, the 2.41-km run and pull-up performance during the FPPA improved ( p < 0.01; ∼41 second and 3 repetitions, respectively) and with no differences observed between treatments regarding the Wingate test. To date, this is the first CRD implemented with FF and resulted in decreased fat mass (∼2.4 kg), BP, and improvements to performance on the FPPA while preserving high-intensity exercise. These data suggest that a 28-day CRD can benefit markers of health in professional FF without detriments to occupational performance.