In an observational cohort study on 44 ultramarathon runners over 4,487 km in 64 stages from South Italy to North Cape, Norway (the Trans Europe Foot Race 2009), Schütz et al.  recorded daily sets of data from magnetic resonance imaging (MRI), psychometric, body composition and biological measurements. Beyond the logistical achievement of following the runners and moving a 30-m, 45-tonne 1.5 Tesla whole-body MRI across Europe (!), they succeeded with a high rate of test completion and data collection.
This 'field' experiment is unique since it is impossible to expect subjects pushing to (and sometimes beyond) their limits for 64 days without any day of rest in a laboratory setting. Such commitment can be achieved only in an official competition and is absolutely necessary for exploring the adaptive responses in healthy subjects at the limit of stress.
In our view, in the field of sports medicine, the longitudinal design of this study will allow us to better understand the time course of degeneration/regeneration of some lower leg tissues as knee joint cartilage or ventral tibial periosteum, to describe the adaptive responses (for example, red bone marrow hyperplasia), to differentiate running-induced from age-induced pathologies (for example, retropatelar arthritis), to understand why some painful reactions (for example, 'shin splints') can be 'over-run' whereas others lead to severe injuries (for example, stress fracture) and finally to assess the interindividual susceptibility to injuries.
This study will also bring new information about the complex interplay between cerebral adaptations and hormonal influences resulting from endurance exercise. To date, it is known that moderate exercise is beneficial to brain heath (for example, increased perfusion or increased brain-derived neurotrophic factor (BDNF)) [9, 10]. But the potential deleterious effects (for example, atrophy, ischemia, brain lesions) of extreme loads on brain volume, plasticity and functionality are unknown. In our opinion, these data are paramount for better understanding the dose-response relationship between exercise and brain structure/function. We have shown that central fatigue was a major issue in long-distance running exercise (see, for example, ) yet, to the best of our knowledge, no studies have really assess cerebral alteration related to this type of exercise. This is because the observed decrease in voluntary activation does not mean that cortical alterations really occur, since peripheral changes, that is, the combination of influences including excitatory and inhibitory reflex inputs from muscles, joints, tendons and cutaneous afferents, may inhibit central drive at the spinal and supraspinal levels.
Also of interest is the investigation into pain perception and the possibility to describe interindividual differences in mechanisms of coping. Hormonal mechanisms (for example, cortisol) and neurotransmitters (for example, tryptophan, serotonin) are known to modulate the pain perception . But most previous studies were limited to a single pain stimulus, whereas in the study of Schütz et al.  the stimuli are different among subjects and also fluctuating. The possibility of crossvalidation between the MRI, the psychometric and the biological results is promising for better describing the time course of factors influencing the fluctuation of pain throughout the race.