Author(s): LIN, T., CHIEN, K., CHAN, Y., YEH, F., HSIAO, W., CHEN, Y., Institution: NATIONAL TAIWAN SPORT UNIVERSITY, Country: TAIWAN, Abstract-ID: 1649

INTRODUCTION:
Appetite is a key regulator of energy balance, and nutrient intake is critical for exercise performance and post-exercise recovery. However, the effects of real-world outdoor hiking on appetite, nutrient intake, and food preferences remain unclear. This study therefore examined how different relative exercise intensities, based on individuals' habitual hiking speed, influence appetite responses, nutrient intake, and food preferences in middle-aged and older adults.
METHODS:
Thirty-one adults (55.5 ± 10.21 years) participated in this study. Body weight and equipment weight were assessed prior to the hike. After consuming a standardized breakfast, participants completed a two-stage outdoor hike at their habitual pace. Throughout the hike, heart rate and dietary intake were continuously recorded to characterize real-world hiking behavior. Subjective appetite (including hunger and total appetite score [APP]), food preferences, and rating of perceived exertion (RPE) were assessed at multiple time points: post-standardized meal; pre- and post-Stage 1 (Menghuan Lake); pre- and post-Stage 2 (Qingtiangang); and 30 min post-hike. The APP was calculated from desire to eat, hunger, fullness, and satisfaction, following Anderson et al. (2024). Based on heart rate data, participants were categorized into a high-intensity (HI) and a low-intensity (LI) group using a 60% heart rate reserve (HRR) threshold (Garber et al., 2011).
RESULTS:
Mean HRR during the hike was significantly higher in the HI group than in the LI group (HI: 73.8 ± 8.90% vs. LI: 50.6 ± 5.26%, p < 0.001). Immediately after hiking at Qingtiangang, the HI group reported greater hunger (HI: 3.7 ± 2.26 vs. LI: 0.9 ± 1.86, p = 0.001) and higher APP (HI: 2.5 ± 2.11 vs. LI: 0.9 ± 1.49, p = 0.026), yet consumed significantly less carbohydrate (HI: 11.9 ± 17.44 g vs. LI: 28.2 ± 27.90 g, p = 0.029) and protein (HI: 0.2 ± 0.64 g vs. LI: 6.2 ± 7.22 g, p = 0.026) than the LI group. At 30 min post-hike, the HI group continued to show higher hunger (HI: 3.1 ± 1.78 vs. LI: 0.4 ± 2.13, p = 0.001) and APP (HI: 2.0 ± 1.64 vs. LI: 0.4 ± 1.80, p = 0.005), whereas between-group differences in carbohydrate and protein intake were no longer observed. In terms of food preferences, the HI group demonstrated a significantly stronger preference for whole grains than the LI group at 30 min post-hike (HI: 0.4 ± 3.18 vs. LI: -1.0 ± 1.30, p = 0.023).
CONCLUSION:
During real-world hiking, individuals exercising at higher relative intensity consume less carbohydrate and protein, and subsequently exhibit greater subjective appetite both immediately and 30 min post-exercise. Although HI hikers develop a stronger post-exercise preference for whole-grain foods, this heightened appetite and healthier food preference do not translate into a corresponding increase in actual post-exercise carbohydrate and protein intake. Refs: 1. Anderson KC, et al. (2024). J Endocr Soc, 8(11), bvae165. 2. Garber CE, et al. (2011). Med Sci Sports Exerc, 43(7), 1334-1359.