Abstract
The popularity of thru-hiking is expanding within the outdoor recreation industry, drawing attention to the physiological demands of prolonged endurance activities in natural environments. This study examined the effects of a long-distance thru-hike on circadian rhythm regulation, body composition, and physical fitness parameters in two adult subjects who undertook the Continental Divide Trail in 2021. Serum cortisol concentrations were measured in the morning and evening at four time points: pre-hike, mid-hike, post-hike, and 16 weeks post-hike. Physical fitness testing included assessments of body composition, maximal oxygen uptake, and muscular endurance were conducted at pre-hike, post-hike, and 16 weeks post-hike. Both subjects demonstrated significant physiological adaptations, including changes in evening serum cortisol concentrations and alterations in adipose tissue and muscle mass. The female subject showed marked improvements in lower body muscular endurance and maximal oxygen uptake, while the male subject experienced reductions in muscle mass and muscular endurance, while maintaining aerobic capacity. These findings suggest that thru-hiking may influence endocrine function and physical fitness dependent on initial fitness status and individual physiological characteristics. This study highlights the need for further research to better characterize the health impacts of thru-hiking.
Keywords
Circadian rhythm, Cortisol, Body composition, Thru-hiking, Cardiovascular endurance,References
- American College of Sports Medicine. (2018). ACSM's guidelines for exercise testing and prescription. Wolters Kluwer.
- Anderson, T., Wideman, L. (2017). Exercise and the Cortisol Awakening Response: A Systematic Review. Sports Medicine - Open, 3.
- Aras, S.G., Runyon, J.R., Kazman, J.B., Thayer, J.F., Sternberg, E.M., Deuster, P.A. (2024). Is Greener Better? Quantifying the Impact of a Nature Walk on Stress Reduction Using HRV and Saliva Cortisol Biomarkers. International Journal of Environmental Research and Public Health, 21(11), 1491.
- Austin, S.B., Rosario, M., McLaughlin, K.A., Roberts, A.L., Gordon, A.R., Sarda, V., Missmer, S., Anatale-Tardiff, L., Scherer, E.A. (2016). Sexual orientation and diurnal cortisol patterns in a cohort of U.S. young adults. Psychoneuroendocrinology, 69, 197–208.
- Batista, J.C., Souza, A.L., Ferreira, H.A., Canova, F., Grassi-Kassisse, D.M. (2015). Acute and Chronic Effects of Tantric Yoga Practice on Distress Index. Journal of Alternative and Complementary Medicine, 21(11), 681–685.
- Bayoumi, M.M.M., Elbasuny, M.M.M., Mofereh, A.M., Assiri, M. ali M., Fesal, A.H.A. (2012). Evaluating Nursing Students’ Anxiety and Depression during Initial Clinical Experience. International Journal of Psychology and Behavioral Sciences, 2(6), 277–281.
- Bushman, B.A. (2018). Developing the P (for Progression) in a FITT-VP Exercise Prescription. ACSM’s Health & Fitness Journal, 22(3), 6.
- Caplin, A., Chen, F.S., Beauchamp, M.R., Puterman, E. (2021). The effects of exercise intensity on the cortisol response to a subsequent acute psychosocial stressor. Psychoneuroendocrinology, 131, 105336.
- Centers for Disease Control and Prevention. (2022).Defining Adult Overweight and Obesity.
- Clow, A., Thorn, L., Evans, P., Hucklebridge, F. (2004). The awakening cortisol response: Methodological issues and significance. Stress, 7(1), 29–37.
- Cole, T.R. (2018). Investigating the Thru-Hiking Experience: A Study on the Pacific Northwest National Scenic Trail.
- Crewther, B., Cronin, J., Keogh, J., Cook, C. (2008). The salivary testosterone and cortisol response to three loading schemes. Journal of Strength and Conditioning Research, 22(1), 250–255.
- Crouse, B.J. (1993). Health Care Needs of Appalachian Trail Hikers. The Journal of Family Practice, 36(5), 521.
- Díaz, M.M., Bocanegra, O.L., Teixeira, R.R., Tavares, M., Soares, S.S., Espindola, F.S. (2013). The Relationship between the Cortisol Awakening Response, Mood States, and Performance. The Journal of Strength & Conditioning Research, 27(5), 1340.
- Drogos, L.L., Wynne-Edwards, K., Zhou, R., Hall, S. E., Tyndall, A.V., Longman, R.S., Eskes, G., Poulin, M. J. (2019). Aerobic exercise increases cortisol awakening response in older adults. Psycho-neuroendocrinology, 103, 241–248.
- Engert, V., Efanov, S.I., Dedovic, K., Dagher, A., Pruessner, J.C. (2011). Increased cortisol awakening response and afternoon/evening cortisol output in healthy young adults with low early life parental care. Psychopharmacology, 214, 261–268.
- García-Sesnich, J.N., Flores, M.G., Ríos, M.H., Aravena, J.G. (2017). Longitudinal and Immediate Effect of Kundalini Yoga on Salivary Levels of Cortisol and Activity of Alpha-Amylase and Its Effect on Perceived Stress. International Journal of Yoga, 10(2), 73.
- Gardner, T.B., Hill, D.R. (2002). Illness and Injury among Long-Distance Hikers on the Long Trail, Vermont. Wilderness & Environmental Medicine, 13(2), 131–134.
- Gatti, R., De Palo, E. (2011). An update: Salivary hormones and physical exercise. Scandinavian Journal of Medicine & Science in Sports, 21(2).
- Giovanelli, L., Aresta, C., Favero, V., Bonomi, M., Cangiano, B., Eller-Vainicher, C., Grassi, G., Morelli, V., Pugliese, F., Falchetti, A., Gennari, L., Scillitani, A., Persani, L., & Chiodini, I. (2021). Hidden hypercortisolism: A too frequently neglected clinical condition. Journal of Endocrinological Investigation, 44(8), 1581–1596.
- Gunnar, M.R., Vazquez, D.M. (2001). Low cortisol and a flattening of expected daytime rhythm: Potential indices of risk in human development. Development and Psychopathology, 13(3).
- Ha, M.S., Baek, Y.H., Kim, J.-W., Kim, D.Y. (2015). Effects of yoga exercise on maximum oxygen uptake, cortisol level, and creatine kinase myocardial bond activity in female patients with skeletal muscle pain syndrome. Journal of Physical Therapy Science, 27(5), 1451–1453.
- Hackney, A.C. (2010). Diurnal hormonal responses in exercise and sports medicine research: Range effect adjustments. Biomedical Human Kinetics, 2(1), 85–88.
- Hadley, M., Levine, J.E. (2006). Endocrinology (6th Edition). Benjamin Cummings.
- Hannibal, K.E., Bishop, M.D. (2014). Chronic stress, cortisol dysfunction, and pain: A psychoneuroendocrine rationale for stress management in pain rehabilitation. Physical Therapy, 94(12), 1816–1825.
- Happ, E., Hofmann, V., Schnitzer, M. (2021). A look at the present and future: The power of emotions in the interplay between motivation, expectation and attitude in long-distance hikers. Journal of Destination Marketing & Management, 19, 100527.
- Heinbockel, T.C., Craighead, D.H. (2021). Case studies in physiology: Impact of a long-distance hike on the Pacific Crest Trail on arterial function and body composition in a highly fit young male. Physiological Reports, 9(5).
- Helgadóttir, B., Hallgren, M., Ekblom, Ö., Forsell, Y. (2016). Training fast or slow? Exercise for depression: A randomized controlled trial. Preventive Medicine, 91, 123–131.
- Hellhammer, D.H., Wüst, S., Kudielka, B.M. (2009). Salivary cortisol as a biomarker in stress research. Psychoneuroendocrinology, 34(2), 163–171.
- Hill, E. E., Zack, E., Battaglini, C., Viru, M., Viru, A., & Hackney, A. C. (2008). Exercise and circulating cortisol levels: The intensity threshold effect. Journal of Endocrinological Investigation, 31(7), 587–591.
- Hill, E., Gómez, E., Goldenberg, M., Freidt, B., Fellows, S., Hill, L. (2014). Appalachian and Pacific Crest Trail Hikers: A Comparison of Benefits and Motivations. Journal of Unconventional Parks, Tourism & Recreation Research, 5(1).
- Holsboer, F. (2001). Stress, hypercortisolism and corticosteroid receptors in depression: Implications for therapy. Journal of Affective Disorders, 62(1–2).
- Knorr, U., Vinberg, M., Kessing, L.V., Wetterslev, J. (2010). Salivary cortisol in depressed patients versus control persons: A systematic review and meta-analysis. Psychoneuroendocrinology, 35(9), 1275–1286.
- Kudielka, K., Hellhammer, Wüst. (2009). Why do we respond so differently? Reviewing determinants of human salivary cortisol responses to challenge. Psychoneuroendocrinology, 34(1).
- Li, A.W., Goldsmith, C.A.W. (2012). The effects of yoga on anxiety and stress. Alternative Medicine Review: A Journal of Clinical Therapeutic, 17(1), 21–35.
- Matousek, R.H., Dobkin, P.L., Pruessner, J. (2010). Cortisol as a marker for improvement in mindfulness-based stress reduction. Complementary Therapies in Clinical Practice, 16(1).
- Mau, M., Aaby, A., Klausen, S. H., & Roessler, K. K. (2021). Are Long-Distance Walks Therapeutic? A Systematic Scoping Review of the Conceptualization of Long-Distance Walking and Its Relation to Mental Health. International Journal of Environmental Research and Public Health, 18(15).
- McArdle, W.D., Katch, F.I., Katch, V.L. (2010). Exercise physiology: nutrition, energy, and human performance. Lippincott Williams & Wilkins.
- McGuigan, M.R., Egan, A.D, Foster, C. (2004). Salivary Cortisol Responses and Perceived Exertion during High Intensity and Low Intensity Bouts of Resistance Exercise. Journal of Sports Science & Medicine, 3(1), 8.
- Mohd Azmi, N.A.S., Juliana, N., Azmani, S., Mohd Effendy, N., Abu, I. F., Mohd Fahmi Teng, N.I., Das, S. (2021). Cortisol on Circadian Rhythm and Its Effect on Cardiovascular System. International Journal of Environmental Research and Public Health, 18(2), 676.
- Ogasawara, Y., Kadooka, S., Tsuchiya, H., Sugo, T. (2022). High cortisol awakening response measured on day following high-intensity exercise. The Journal of Physical Fitness and Sports Medicine, 11(2), 59–66.
- Scerbo, F., Faulkner, G., Taylor, A., Thomas, S. (2010). Effects of exercise on cravings to smoke: The role of exercise intensity and cortisol. Journal of Sports Sciences, 28(1), 11–19.
- Schuring, S.A. (2019). Meandering Motivations: A Look into the Changing Motivations of Appalachian Trail Thru-Hikers [Ohio University].
- Streeter, C.C., Gerbarg, P.L., Saper, R.B., Ciraulo, D.A., Brown, R.P. (2012). Effects of yoga on the autonomic nervous system, gamma-aminobutyric-acid, and allostasis in epilepsy, depression, and post-traumatic stress disorder. Medical Hypotheses, 78(5), 571–579.
- Telles, S., Pathak, S., Kumar, A., Mishra, P., Balkrishna, A. (2015). Influence of Intensity and Duration of Yoga on Anxiety and Depression Scores Associated with Chronic Illness. Annals of Medical and Health Sciences Research, 5(4), 260–265.
- Thirthalli, J., Naveen, G.H., Rao, M.G., Varambally, S., Christopher, R., Gangadhar, B.N. (2013). Cortisol and antidepressant effects of yoga. Indian Journal of Psychiatry, 55(3), S405–S408.
- Vicennati, V., Pasqui, F., Cavazza, C., Pagotto, U., Pasquali, R. (2009). Stress-related development of obesity and cortisol in women. Obesity ,17(9), 1678–1683.
- Wegner, M., Koutsandréou, F., Müller-Alcazar, A., Lautenbach, F., Budde, H. (2019). Effects of Different Types of Exercise Training on the Cortisol Awakening Response in Children. Frontiers in Endocrinology, 10.
- Whitworth, J.A., Williamson, P.M., Mangos, G., Kelly, J.J. (2005). Cardiovascular Consequences of Cortisol Excess. Vascular Health and Risk Management, 1(4), 291.
- Wust, S., Wolf, J., Hellhammer, D.H., Federenko, I., Schommer, N., Kirschbaum, C. (2000). The cortisol awakening response—Normal values and confounds. Noise and Health, 2(7), 79.
- Yoshihara, K., Hiramoto, T., Oka, T., Kubo, C., Sudo, N. (2014). Effect of 12 weeks of yoga training on the somatization, psychological symptoms, and stress-related biomarkers of healthy women. BioPsychoSocial Medicine, 8(1), 1.