233 International Journal of Sport Nutrition and Exercise Metabolism, 2011, 21, 233-239 © 2011 Human Kinetics, Inc. Exercise-Induced Trace Mineral Element Concentration in Regional Versus Whole-Body Wash-Down Sweat Lindsay B. Baker, John R. Stofan, Henry C. Lukaski, and Craig A. Horswill Simultaneous whole-body wash-down (WBW) and regional skin surface sweat collections were completed to compare regional patch and WBW sweat calcium (Ca), magnesium (Mg), copper (Cu), manganese (Mn), iron (Fe), and zinc (Zn) concentrations. Athletes (4 men, 4 women) cycled in a plastic open-air chamber for 90 min in the heat. Before exercise, the subjects and cycle ergometer (covered in plastic) were washed with deionized water. After the onset of sweating, sterile patches were attached to the forearm, back, chest, forehead, and thigh and removed on saturation. After exercise, the subjects and cycle ergometer were washed with 5 L of 15-mM ammonium sulfate solution to collect all sweat miner- als and determine the volume of unevaporated sweat. Control trials were performed to measure mineral contamination in regional and WBW methods. Because background contamination in the collection system was high for WBW Mn, Fe, and Zn, method comparisons were not made for these minerals. After correction for minimal background contamination, WBW sweat [Ca], [Mg], and [Cu] were 44.6 ± 20.0, 9.8 ± 4.8, and 0.125 ± 0.069 mg/L, respectively, and 5-site regional (weighted for local sweat rate and body surface area) sweat [Ca], [Mg], and [Cu] were 59.0 ± 15.9, 14.5 ± 4.8, and 0.166 ± 0.031 mg/L, respectively. Five-site regional [Ca], [Mg], and [Cu] overestimated WBW by 32%, 48%, and 33%, respec- tively. No individual regional patch site or 5-site regional was signifcantly correlated with WBW sweat [Ca] (r = –.21, p = .65), [Mg] (r = .49, p = .33), or [Cu] (r = .17, p = .74). In conclusion, regional sweat [Ca], [Mg], and [Cu] are not accurate surrogates for or signifcantly correlated with WBW sweat composition. Keywords: sweat composition, sweat calcium concentration, sweat copper concentration, sweat magnesium concentration Baker, Stofan, and Horswill are with the Gatorade Sports Science Institute, Barrington, IL. Lukaski is with the Grand Forks Human Nutrition Research Center, USDA-Agricultural Research Service, Grand Forks, ND. Mineral elements such as calcium (Ca), magnesium (Mg), copper (Cu), manganese (Mn), iron (Fe), and zinc (Zn) are important in the regulation of many physi- ological processes, including those affecting physical performance. There is evidence that some athletes have inadequate mineral intakes, as well as lower than normal mineral status (Clarkson & Haymes, 1995; Haralambie, 1981; Lukaski, 1995, 2004; Sinclair & Hinton, 2005). Mg defciency has been shown to impair performance, and Mg supplementation may improve muscle strength and power and aerobic performance in Mg-defcient indi- viduals (Brilla & Gunther, 1995; Brilla & Haley, 1992; Institute of Medicine [IOM], 2006). Ca balance plays an important role in determining bone-mineral density, and poor Ca status may be related to increased risk for stress fractures (American Dietetic Association [ADA] et al., 2009; Clarkson & Haymes, 1995). As a functional component of superoxide dismutase, Cu acts to control damage from reactive oxygen species in cells. Mn and Zn are critical in many aspects of energy metabolism, and Fe is essential for oxygen transport to active muscles (Clarkson & Haymes, 1995; Lukaski, 1995). Daily dietary mineral requirements are determined in part by the output of minerals via urinary, fecal, and dermal losses. Because of increased dermal (specifcally, cell-free sweat) mineral losses during exercise and evi- dence that some athletes have lower than normal min- eral status, there has been much interest and discussion regarding the potentially higher mineral requirements for athletes than for nonathletes (ADA et al., 2009; Clarkson & Haymes, 1994; IOM, 2006; Lukaski, 1995). In fact, the IOM (2006) has stressed the need for more research to understand the effects of physical activity on mineral losses and to determine how much of each mineral is required to replenish losses incurred during exercise. The concentrations of Ca, Mg, Cu, Mn, Fe, and Zn in sweat collected from exercising humans vary widely among studies. The reported ranges include 14–74, 1–17, 0.03–2.51, 0.02–0.07, 0.11–0.92, and 0.29–2.19 mg/L for Ca, Mg, Cu, Mn, Fe, and Zn, respectively (Aruoma, Reilly, MacLaren, & Halliwell, 1988; Bullen, O’Toole, & Johnson, 1999; Chinevere, Kenefck, Cheuvront, Lukaski, & Sawka, 2008; Cohn & Emmett, 1978; Costa, Calloway, & Margen, 1969; DeRuisseau, Cheuvront, Haymes, & Sharp, 2002; Kilding et al., 2009; Lamanca, Haymes, Daly, Moffatt, & Waller, 1988; Montain, Cheuvront, & Lukaski, 2007; Paulev, Jordal, & Pedersen, 1983; Shirreffs & Maughan, 1997; Verde, Shephard, Corey, & Moore, 1982; Waller & Haymes, 1996). Although it is likely that physiologic variability (acquired or inher- ent differences at the level of the sweat gland) accounts for some of the intersubject and interstudy variability