MRI Cartilage Assessment of the Subtalar and Midtarsal Joints During a Transcontinental Ultramarathon – New Insights into Human Locomotion

Abstract

MR measurements can be accurately performed during 4486 km of running, opening a window into in vivo assessment of hindfoot articular cartilage under extreme ultra-endurance loading. This observational cross-sectional study included 22 randomized participants of TransEurope FootRace between Italy and the North Cape, which was accompanied by a trailer-mounted 1.5T MRI scanner over 9 weeks. Four follow up MR examinations of subtalar and midtarsal joints were performed. Statistics of cartilage T2* and thickness were obtained. Nearly all observed joints showed an initial significant mean T2* increase of 20.9% and 26.3% for the left and right side, followed by a relative decrease of 28.5% and 16.0% during the second half, respectively. It could be demonstrated that mobile MRI field studies allow in vivo functional tissue observations under extreme loading. Elevated T2* values recovered during the second half of the ultramarathon supported the evidence that this response is a physiological adaptive mechanism of chondrocyte function via upregulation of de novo synthesis of proteoglycans and collagen. These changes occurred in a distinct asymmetric pattern leaving a "biochemical signature" of articular cartilage that allows in vivo insight into joint loading. In conclusion, the normal articular cartilage of the hindfoot is resilient and adaptive, leaving extreme endurance activities up to limitless human ambition.

Femoropatellar Joint Reaction Detected During a 4486 KM Ultramarathon with Mobile MRI

“…Furthermore, the participants represent a highly selective population without any malalignment of the lower extremities and a specific running style optimized over years of endurance training. However, in contrast to the FPJ, the quantitative mobile MRI examinations of the FTJ ("unpublished observations"), ankle and hind foot joints have shown a significant and MSUM-specific T2 * -cartilage reaction (increase) during TFER [74,75]. So, in the case of the MSUM TEFR, there is a relevant adaptation of the articular cartilage in the axially loaded joints of the lower limb, which is confirmed by the results of the chondral biomarker analyzes by Mündermann et al [76] as part of the TEFR project.…”

“…However, this response, which is based on a physiological increase in collagen fiber anisotropy and concomitant pressing out of free water from cartilage [31,33,78], could not be detected by our MSUM study and also not in other marathon studies, in which MRI was performed only after several UM stages in a row or 1-2 days after the marathon race, respectively. The reason is that this short-term T2( * )-effect is masked by the long-term T2( * )-reactions of the cartilage [29,34,74,75].…”

Motivation in ultra-marathon runners

“…Extreme conditions and exhausting efforts allow the human body to attain very high levels of abilities for physical performance and mental toughness. Most recent studies analyzed energetic, dietary and water intake influence on runners,9 heart rate variability, cardiac autonomic modulation and psychological correlates,10 articular cartilage assessment,11 use of non-steroidal anti-inflammatory drugs,12 diarrhea problems,13 injuries and health considerations,14 nausea,15 and gastrointestinal symptoms 16. Relatively well-known already are the somatic characteristics of ultra-marathon participants’17 or the influence of ultra-running on different biomarkers characterizing the decreased body homeostasis,18–20 or even skin manifestation of systemic disease during races 21.…”

T2*-Mapping of Knee Cartilage in Response to Mechanical Loading in Alpine Skiing: A Feasibility Study

“…In all of the segments, the intrachondrial T2* signal increased after overnight recovery in three of the four subjects. Other study results show an increase in the T2/T2* signal after the prolonged exposure to a marathon [ 35 ]. Increasing T2* values reflect free water dissociated from its chemical bonding to PG [ 10 ] and is related to PG content [ 34 ].…”

“…As there are still no limit values defined, which allow for the differentiation of the initial intrachondral T2/T2* signal behavior after loading with respect to physiological and pathological cartilage reaction, and because of the recognition that recurrent cartilage load may also be a chondroprotective and regenerative stimulus for articular cartilage [ 32 , 35 ], direct observation of only the immediate cartilage response to skiing load may well be half the truth in terms of the overall effect. Therefore, such studies should include longer-term observation periods.…”