Date Published: February 3, 2017
Publisher: Public Library of Science
Author(s): Giorgia Antoni, Elisabetta Marini, Nicoletta Curreli, Valerio Tuveri, Ornella Comandini, Stefano Cabras, Silvia Gabba, Clelia Madeddu, Antonio Crisafulli, Andrea C. Rinaldi, Maciej Buchowski.
The aim of this study was to determine the energy expenditure of a group of cavers of both genders and different ages and experience during a 10 hour subterranean exploration, using portable metabolimeters. The impact of caving activity on body composition and hydration were also assessed through bioelectrical impedance, and nutritional habits of cavers surveyed. During cave activity, measured total energy expenditure (TEE) was in the range 225–287 kcal/h for women-men (MET = 4.1), respectively; subjects had an energy intake from food in the range 1000–1200 kcal, thus inadequate to restore lost calories. Bayesian statistical analysis estimated the effect of predictive variables on TEE, revealing that experienced subjects had a 5% lower TEE than the less skilled ones and that women required a comparatively larger energy expenditure than men to perform the same task. BIVA (bioelectrical impedance vector analysis) showed that subjects were within the range of normal hydration before and after cave activity, but bioelectrical changes indicated a reduction of extracellular water in men, which might result in hypo-osmolal dehydration in the case of prolonged underground exercise. All these facts should be considered when planning cave explorations, preparing training programs for subjects practising caving, and optimizing a diet for cavers. Further, information gathered through this study could be of value to reduce accidents in caves related to increase in fatigue.
Caves are an hostile environment for human beings. Total darkness, high air humidity, muddy and slippery conditions, the recurring presence of rivers, waterfalls and/or lakes, characterise the underground world . Temperature is usually constant within a cave, but can vary greatly in absolute terms, as caves are found in a variety of settings, from cold alpine environment to warm tropical rain forests. Notwithstanding these conditions, tens of thousands of cavers worldwide enjoy the exploration of natural cave systems as a recreational outdoor activity, although it certainly cannot be considered a mass sport . Caves are abundant around the world. In Italy alone, some forty thousands caves are known . In Britain, the main caving areas are the Mendip Hills, the Yorkshire Dales, and the Derbyshire Peak District, where limestone formations can be found . The US are home to some of the most extensive cave systems in the word, including Mammoth Cave, with more than 400 miles explored .
Anthropometric parameters of all 40 cavers involved in the study, and data concerning measured energy expenditure of the 36 cavers wearing metabolimeters during underground activity, are shown in Table 1. Results of the IET show that on average AT occurred at 163.9±12.5 w (i.e. about 74.5% of Wmax), while their Wmax was 220.5±16.5 w. VO2max was 2532.7±348.6 ml*min-1 (i.e. 34.6±3.4 ml/kg*min-1). These data indicated that cavers had a level of aerobic fitness higher than that of a sedentary population. Mean BMI was indicative of normal weight in both genders, even if a non-trivial proportion (50%) of men was overweight. However, cavers of both genders in general showed a quite low quantity of relative fat mass with respect to the reference sample of Italo-Spanish young adults, as measured through specific BIVA (Fig 3). Comparison of dietary intake and energy expenditure (TEE) in a normal day versus the full cave day and cave activity per se, offers interesting cues (Table 1). For both men and women, despite the fact that the intake during full cave day was significantly greater than an average normal day, energy expenditure during cave day largely exceeded the energy supplied by diet. Also, cave activity burned more energy than that present in food consumed underground. During full cave day, most of the intake was concentrated in the post-cave meal.
This is the first study to measure energy expenditure during cave exploration. Whether caving should be regarded as a sport or rather a recreational physical activity is a matter of discussion. Historically, caving can be considered a descendant of mountaineering (alpinism) and climbing, and most of the caving techniques and equipment derive directly from those used in those disciplines. Climbing (climbing wall) will be on display as a new sport at the Buenos Aires Youth Olympic Games in 2018, a teaser of what is to come in 2020 at the Olympic Games in Tokyo . On the other hand, what certainly is lacking in caving to be fully defined as a sport is that it does not include any element of competition . We opt for considering caving as a recreational physical activity.
In conclusion, we have provided evidence that, despite inherent logistic difficulties, energy expenditure and modification of physiological parameters and body composition during caving can be measured and interpreted. Also, nutritional habits and hydration of cavers were assessed, revealing interesting details that will be useful in defining an ideal diet for this special type of physical activity that requires a protracted, although moderately intense, exercise under singular environmental conditions. Since the scientific literature on caving is scarce, its distinguishing characteristics call for more research to better determine the physiological basis of this activity in a variety of settings and for multiple purposes. From a methodological point of view, we have shown the usefulness and suitability of bioimpedance vector analysis to evaluate body composition variations in subjects performing physical activity in extreme environments, such as those related to cave exploration.