Does Age Have Different Influence Between Mountain and City Marathons? -An Analysis from Switzerland

) Does Age Have Different Influence Between Mountain and City Marathons? - An Analysis


Introduction
With increasing age, a decrease in endurance capacity results.
[1] This counts for different organ systems such as heart, lung, skeletal muscle or endocrine system on different structural and functional level [1][2][3][4]. Studies tax the decrease of endurance capacity after the 30. Year of life with 15 % per decade [5][6][7][8]. To keep in mind with increasing distance the optimum of maximum distance is based on adaptations while years through training higher [5][6][7][8]. The detected optimal age for middle distances is between 20 and 30 years, for marathon races around 35 years and increases to 40 or more years for ultra-races [8][9][10][11]. Addressing changes in general endurance performance in leisure sports men for marathon running analysis of the big sample of over 900`000 course times revealed that for 20-to 79-year old marathon and halfmarathon runners that interestingly no significant decrease based solely on age could be detected respectively decrease was mainly a result of physical inactivity [1]. Physical activity seems to hinder aging and has protective potentials for many illnesses [11][12][13][14]. Hints exist, that especially endurance sports respectively running has preventive potential due to the fact that this kind of activity was developed by our ancestors in the hunter and gatherer time during the development of Homo yielding to a divergence between chimpanzee and human [11][12][13][14][15][16]. The astonishing evolutionary fact is to mention that hunter and gatherer were running in average 9 to 15 km per day and in contrast to often proclaimed these ancestors lived-when surviving the first years of life-long and healthy lives of 70 and more years [17,18]. Depending on running and gait pattern biological requirements are differing and requirements on cardiopulmonary and musculoskeletal system change, whereby smallest changes such as shoe influences gait pattern and secondary cardiopulmonary system [3,[14][15][16] (Figure 1). Especially uphill running in mountainous terrain compared to other forms (e.g. track and field or street running) is characterized through different biomechanical patterns underlying different age associated changes [19,20]. This yields to the central question of the study whether with increasing age differences in age associated decrease in performance can be detected in mountain versus city marathons. Is the optimal age depending on terrain flat versus mountainous different? As hypothesis with potential possibility of falsification it is postulated, that there is no difference in optimal age between city and Mountain marathon [21].

The race-course description
Starting in Trubschachen (731 Meter above Sea Level) on asphalt streets and then mainly on small trails to Risisegg, Schaffmatt, Altengrat, Chrützboden, Schwesternboden to Napf (1408 Meter above sea level). Descent is on west side to Niederänzi, Höchänzi, Lushütte, Hohmatt, Schynen, Bachschwand back to Trubschachen. Total race is 41.98 km with an ascent and descent of 1270 Meters.

Statistical procedures
For each year 2011-2016 means and standard deviation of course times were calculated. To analyze relationship between course time and age linear regressions were conducted. Furthermore, polynomial interpolation of 2. Degree were calculated, yielding through differentiation to the local minimum [22,[23][24][25][26][27]. To analyze effects of total performance with additional ascent and descent of 1270 meters analyzes were conducted with the concept of performance km [28]. Differences of course times between city marathons and Napfmarathon were analyzed with two-sided paired t-tests. Figure 2 shows all course times of the matched sample for city marathon with an average course time of 3 h 39 ± 41 min and right for Napfmarathon with 4 h 40 ± 43 min. Average age of the matched sample was 49.8 ± 9.1 years representing a typical senior cohort.  (y-axis) and age in years (x-axis) for Napfmarathon (black) and city marathons (grey), given is an OLS-regression as well as R 2 (n = 67).

Figure 4:
Relationship of course times in min. (y-axis) and age in years (x-axis) for Napfmarathon (black) and city marathons (grey), given is a Polynomial interpolation 2. degree as well as R 2 . Course time minimum for Napfmarathon is 34.5 years and city marathons 35.4 Jahre (n = 67).
The analyzed polynomial Interpolation 2. Degree for the matched sample yielding to a u-shaped age course time relationship with optimal age of 34 years in Napfmarathon and 35 years in city marathons (Figure 4), whereby these findings are supported by others [24].  If all course times are taken, local minimum for men is around 34 years nearly equivalent for both competitions forms ( Figure 5). In woman with 28.7 years a lower value results a pattern also found for Jungfraumarathon where reasons were attributed towards differences in lean mass [22][23][24][25][26][27] (Figure 6). Trying to compare results from statistical regressions, with β = 1.7 for Napfmarathon versus β = 2.1 for city marathon a smaller increase in course times results with increasing age (Figure 3) Furthermore, R 2 = 0.15 for Napfmarathon is smaller than R 2 = 0.19 for city marathons (Figure 3). Trying to analyze effect of absolute performance (considering height differences in Napfmarathon) to control, concept of performance km, whereby 100 Meter Ascent and 1km horizontal distance are equivalents [28]. For the matched sample for city marathon an average km of 5 min 14 sec ± 55 sec and for Napfmarathon quantified with performance concept 5 min 1 sec ± 46 sec result. Furthermore, analyses reveal in Figure  6, that Napfmarathon with a regression weight of β = 0.0369 is smaller than in city marathon with β = 0.0487, in line with the before mentioned and implying, that the decrease in physical endurance performance in Napf marathon is smaller compared to city marathons. Besides other reasons the simple fact of the total larger amount of performance is probably one important reason [3,7,8,11,22]. The meter above sea level of the race (700 to 1400 Meter) respectively the effect of a smaller oxygen pressure doesn`t seem to be relevant while analyzing differences (e.g. City marathon in Lucerne took place around 500 meters above sea level) [29]. Figure 6: Relationship of average km conventional and with the concept of performance km for the Napf marathon (y-axis) and the age (x-axis) for Napfmarathon (black) and city marathons (grey)(n = 67).

Discussion
The aim of this study was to compare different effects of age on course times in mountain and city marathons. Recently result lists from marathon races were used as epidemiological data allowing analyzing large samples and age associated alterations of performance [1]. Encompassing analyses of city marathons (e.g cologne Marathon with more than 900`000 course times or Stockholm marathons with more than 300`000 course times can be mentioned [1,26]. For mountain marathons in Switzerland especially the analysis from the Jungfrau Marathon can be mentioned [25]. The advantage of these studies is the large analyzed samples with potential high validity of findings [25]. However, for limitations of possible statistical analyses a matching of course times is not yet possible, making the analyzes despite the small sample interesting. On the search for reasons for differences variance is reduced as a consequence of paired samples however limitations are given based on a small sample size. It must be considered that leisure sportsmen were analyzed having strongly different training habits with comparable performance [3,8]. This thought is supported by an analysis of the Jungfrau Marathon whereby results of best classed runner versus the whole sample where analyzed concerning optimal age [25]. Average course times were with around one hour more clearly higher in Napfmarathon compared to city marathon. This is probably due to the fact, that the absolved height of 1200 Meters. Given the concept of performance km additional 12 performance km had to be absolved yielding to an average performance km of 5 Minutes. This seems to be a little bit low however when comparing with other concepts of distance and height the performance equivalent of 100 Meter ascents seems to be a little bit less than 1 km horizontal distance [30,31]. Analyses reveal that from the age of 35 a decrease in performance capacity results, which is in accordance with a number of other studies [2][3][4][5][6][7]32,33]. Trying to decipher reasons for the age associated decrease in endurance capacity besides the mentioned decrease in cardio-pulmonary system especially collagen tissue -ligaments and tendons -can be mentioned. [34,35]. Furthermore, skeletal muscle is characterized through different contraction forms (arbitrary) concentric versus eccentric and besides other factors in dependence of a course is differently used dependent on topography [3,35,36]. When running downhill eccentric (breaking) muscle work must be conducted, having especially relevance for the second part of the race of Napfmarathon possible to combine with the results [37][38][39]. Furthermore, Analysis reveal a closer relationship between age and course times in city marathons versus Napfmarathon. Coming to reasons the higher total amount of performance in Napfmarathon is to mention, whereby results are in accordance that with increasing age performance for longer distances is better. Furthermore, in contrast to Jungfraumarathon the whole Height has to be made downhill (relevance of eccentric muscle activity) [25]. The analyzed optimal age is for both forms around 35 years and is in accordance with younger studies also detecting a U-shaped relationship (polynomial interpolation of 4. Degree) between age and Marathon time and course time minimum was around 35 years [25].
Trying to decipher the smaller explanation of variance between age and Napfmarathon versus city marathon it seems efficient to come back to the cardio-pulmonary system respectively the decrease in endurance sports of maximal oxygen consumption (VO 2 max), already decreasing after the age of 20 and secondary affecting cardiopulmonary system [2][3][4][5][6]. This explains the increase of course times with increasing age but not the principally closer correlative relationship between age and city marathon versus age and Napfmarathon. This might be a result of the mentioned fact of a higher share of eccentric muscle activity in Napfmarathon while running downhill, where VO 2 max is less relevant [37,38,39]. Eccentric muscle activity has other cardiopulmonary restrictions than concentric, respectively with increasing muscle activity a smaller increase of Oxygen consumption while increasing performance results probably relevant for the smaller association of age and course times in Napfmarathon [40].
Furthermore, associated structures of collagen tissue (tendons and ligaments) are to mention which lose elasticity with increasing age [19,[40][41][42]. For a mountain marathon, the decrease in elasticity could have smaller consequences, due to the fact that in downhill running elasticity of tendons are less important than when running in the flat with the importance of storage of (elastic) energy [40]. The mentioned premise is supported that in collagen tissue alterations of matric proteins and proteoglycans with reduced plasticity and elasticity of ligaments and tendons with increased stiffness result [40][41][42]. Training of these structures could lead to an improvement of age-associated decrease and improve general performance of seniors [36,43,44].