Context: Although skin-temperature assessment has received much attention in recent years as a possible internal-load measurement, scientific evidence is scarce. Purpose: To analyze baseline skin temperature and its rewarming through means of a cold-stress test before and after performing a marathon and to study the association between skin temperature and internal/external-load measurements. Methods: A total of 16 runners were measured 48 and 24 h before and 24 and 48 h after completing a marathon. The measurements on each day of testing included urine biomarkers of oxidative stress, pain and fatigue perception, skin temperature (at baseline and after a cold-stress test), and jump performance. Results: Reduced jump performance (P < .01 and effect size [ES] = 0.5) and higher fatigue and pain perception were observed 24 h after the marathon (P < .01 and ES > 0.8). Although no differences in baseline skin temperature were observed between the 4 measuring days, posterior legs presented lower constant (P < .01 and ES = 1.4) and higher slope (P = .04 and ES = 1.1) parameters in the algorithmic equations fitted for skin-temperature recovery after the cold-stress test 24 h after the marathon than on the day before the marathon. Regressions showed that skin-temperature parameters could be predicted by the ratio of ortho-tyrosine isomer to phenylalanine (oxidative stress biomarker) and body fat composition, among others. Conclusions: Although baseline skin temperature was not altered 24 or 48 h after a marathon, the application of cold stress after the marathon would appear to be a good method for providing information on vasoconstriction and a runner’s state of stress.

Objective: The objective of this study was to determine the association between skin temperature response and the physiological stress after a half marathon. Approach:Seventeen runners were measured 48 h before, 24 h before, 24 h after and 48 h after completing a half marathon. The measurements on each day of testing included blood markers (creatine kinase [CK] and glutamate oxaloacetate transaminase [GOT]), perception of pain and fatigue (using a visual analogue scale), skin temperature (using infrared thermography), and jump performance (using countermovement jump test).Main results: CK (p<0.001 and ES=2.1), GOT (p=0.04 and ES=1.3), and perception of fatigue and pain (p<0.001 and ES>1.0) increased 24 h after the half marathon, whereas jump performance decreased (p<0.01 and ES=0.4). No increase of skin temperature was observed in the tests after the competition and no regression model was able to predict physiological stress using skin temperature. Only a bivariate correlation was observed between the 24 h variation (pre -24h) of CK and the skin temperature of the posterior upper limb (p=0.04 and r= 0.5), and between the 48 h variation (pre -48h) of pain perceived and the skin temperature of the knee (p<0.01 and r= 0.6). Significance: In conclusion, follow-up on basal skin temperatures does not seem to be an adequate method to detect physiological stress after a half marathon. In line with the observed results, we recommend caution when interpreting peaks in basal skin temperature in field sports assessments.

This study aimed to analyse differences in pacing profiles in four marathon competitions and to explore that pacing per time category. A database of 91,493 runners gathered from 4 different races was analysed (Valencia, Chicago, London and Tokyo Marathon). Participants were categorized in accordance with their completion time. The relative speed of each section for each runner was calculated as a percentage of the average speed for the entire race. In the four marathons studied, the first 5 km differed widely, presenting London the highest relative speeds (5 km: CI95% London vs. Valencia [12.1, 13.6%], p < 0.001 and ES = 2.1; London vs. Chicago [5.5, 7.1%], p < 0.001 and ES = 1.1; London vs. Tokyo [15.2, 16.8%], p < 0.001 and ES = 2.3). Races did not differ at each section for high-performance runners (sub-2:30), but differences between races increased as the time category increases (e.g. 35 km and sub-3:00: CI95% London vs. Tokyo [−3.1, −1.8%], p < 0.001 and ES = 0.7; 35 km and sub-5:00: London vs. Tokyo [−9.8, −9.2%], p < 0.001 and ES = 1.3). The difference in relative speed between the first and second half of the marathon was higher in London than in the other marathons (e.g. CI95% London vs. Valencia [10.3, 10.8%], p < 0.001 and ES = 1.3). In conclusion, although race characteristics affect pacing, this effect was higher as the category time increases. Race pacing characteristics should be taken into consideration for runners and coaches choosing the race and working on pacing strategies, for researches to extrapolate or interpret results, or for race organizations to improve its pacing characteristics.

Introduction Although the use of sports compression socks is becoming more popular, there is still a lack of knowledge regarding the helpfulness of these garments for physical movement or sports use. One of the main effects attributed to the use of compression sock is the facilitation of venous blood flow return which is thought to improve performance and recovery. Methodology In this study, 10 trained runners performed 2 treadmill running tests for 30 min to 75% of their maximum aerobic speed, without sports socks (control) and with different sports compression socks. We measured popliteal vein flow volume before and after each test using magnetic resonance imaging. Results and discussion No differences were observed between the conditions before the test ( p > 0.05), but there were differences between the high compression socks condition and the control after the test ( p < 0.05). Exercise increased the venous flow in both legs in the control ( p < 0.001) as well as in the right leg with the high compression sock type ( p < 0.01) but there were no differences in the behaviour of the different sock compression levels ( p > 0.05). Conclusion The use of sports compression socks with different levels of compression does not increase the volume of venous blood return via the popliteal vein in trained athletes after running for 30 min.

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