THE EFFECT ON HYDRATION OF CONSUMING HYPOTONIC, ISOTONIC AND WATER BEVERAGES DURING AN 18- HOLE ROUND OF GOLF

BY LAWRENCE HAYES AND CLARE PHEASEY, DEPARTMENT OF EXERCISE AND SPORT SCIENCE, MANCHESTER METROPOLITAN UNIVERSITY

INTRODUCTION

Rarely has the physiology of golf been examined in depth. Wells and Collier give an overview of energy demands along with nutritional and hydration advice, but no results were presented to support these recommendations (1). In contrast, there is a large body of research into the area of optimal sports drinks (2). Most of these studies have compared sodium (Na+) concentration (3) or carbohydrate content (4). To date, the authors are unaware of any published research in the field of hydration for golf.

PURPOSE

The purpose of this study was to determine the effectiveness of carbohydrate and/or Na+ inclusion in a beverage during an 18-hole round of golf.

Figure 1: Consumption of 100ml water

METHODS Following institutional ethics approval, nine male amateur golfers (mean±standard deviation (SD): age 20.8±1.9 years, stature 180.2±6.7cm, body mass 76.3±11.0kg, handicap

0.0O

-0.2O -0.4O -0.6O -0.8O -0.9O -1.0O

-1.2O -1.4O

Figure 2: Body-weight change after 18 holes for all conditions 20 Beverage hypotonic isotonic water

17.5±6.2 shots) participated in a randomised crossover design in groups of three at least 6 days apart. During each round, participants consumed a different drink: hypotonic (0.5g sodium per litre), isotonic (0.5g sodium and 6.75g carbohydrate per litre) or water. Nude body weight (BW) was measured before commencing the round, after the ninth hole and after the eighteenth hole. Participants consumed 200ml immediately after the initial weighing and then 100ml before each tee shot. Heart rate (HR) was monitored throughout. Change in BW was calculated as follows: pre-round BW – post-round BW + urine output – drink consumed.

STATISTICAL ANALYSIS Repeated measures one-way factorial analysis of variance (ANOVA) with a

Bonferroni correction was conducted on each variable.

KEY FINDINGS

No significant differences (P<0.05) were found between isotonic, hypotonic or water beverages for fluid retention represented by change in BW (Table 1, Figure 2). DISCUSSION

Neither Na+ nor carbohydrate was found to have a significant effect on hydration during an 18-hole round of golf in the British spring. However, it should be noted that even with a prescribed hydration protocol the golfers remained in negative fluid balance. In a hotter or more humid climate, more attention should be paid to the hydration strategies and fluid composition, as the magnitude of fluid losses would be expected to be greater.

References 1. Wells, Collier Golf Nutrition: What to eat before and after you practice and play. 2007 electronic version. 2. Shirreffs SM. The optimal sports drink. Sportmedizin und Sporttraumatologie 2003;51:25–29 3. Twerenbold R, Knechtle B, Kakebeeke TH, Eser P, et al. Effects of different sodium concentrations in replacement fluids during prolonged exercise in women. British Journal of Sports Medicine 2003;37:300–303 4. Kavouras SA, Armstrong LE, Maresh CM, Casa DJ, et al. Rehydration with glycerol: endocrine, cardiovascular, and thermoregulatory responses during exercise in the heat. Journal of Applied Physiology 2006;100:4422–4450

TABLE 1: BODY WEIGHT (BW) CHANGES, MEAN HEART RATE (HR) AND MEAN URINE OUTPUT FOR ALL CONDITIONS. VALUES ARE MEAN±STANDARD DEVIATION (SD)

Hypotonic

Mean HR (beats.min-1)

Mean BW change after 9 holes (kg-1)

Mean BW change after 18 holes (kg-1)

Shots taken 108.6±7.8 -0.32±0.24 Isotonic 105.7±6.2 -0.33±0.31 Water 104.3±7.9 Mean 106.0±7.3 -0.32±0.34 -0.32±0.29

-0.48±0.25 -0.60±0.32 -0.72±0.40 -0.60±0.33 91.4±7.9

89.9±8.6 Mean urine output (l) -1.26±0.57 89.3±6.8 -1.42±0.65 -1.34±0.47 90.6±7.6 -1.33±0.55 sportEX dynamics 2009;21(Jul):18-23

Body weight change (kg)