Martínez-Navarro, I, Montoya-Vieco, A, Collado, E, Hernando, B, Panizo, N, and Hernando, C. Muscle Cramping in the marathon: Dehydration and electrolyte depletion vs. muscle damage. J Strength Cond Res XX(X): 000–000, 2020—Our aim was to compare dehydration variables, serum electrolytes, and muscle damage serum markers between runners who suffered exercise-associated muscle cramps (EAMC) and runners who did not suffer EAMC in a road marathon. We were also interested in analyzing race pacing and training background. Nighty-eight marathoners took part in the study. Subjects were subjected to a cardiopulmonary exercise test. Before and after the race, blood and urine samples were collected and body mass (BM) was measured. Immediately after the race EAMC were diagnosed. Eighty-eight runners finished the marathon, and 20 of them developed EAMC (24%) during or immediately after the race. Body mass change, post-race urine specific gravity, and serum sodium and potassium concentrations were not different between crampers and noncrampers. Conversely, runners who suffered EAMC exhibited significantly greater post-race creatine kinase (464.17 ± 220.47 vs. 383.04 ± 253.41 UI/L, p = 0.034) and lactate dehydrogenase (LDH) (362.27 ± 72.10 vs. 307.87 ± 52.42 UI/L, p = 0.002). Twenty-four hours post-race also values of both biomarkers were higher among crampers (CK: 2,438.59 ± 2,625.24 vs. 1,166.66 ± 910.71 UI/L, p = 0.014; LDH: 277.05 ± 89.74 vs. 227.07 ± 37.15 UI/L, p = 0.021). The difference in the percentage of runners who included strength conditioning in their race training approached statistical significance (EAMC: 25%, non-EAMC: 47.6%; p = 0.074). Eventually, relative speed between crampers and noncrampers only differed from the 25th km onward (p < 0.05). Therefore, runners who suffered EAMC did not exhibit a greater degree of dehydration and electrolyte depletion after the marathon but displayed significantly higher concentrations of muscle damage biomarkers.

In recent years, increasing numbers of women have participated in extremely long races. In adult males, there is a clear association between physiological levels of endogenous sex hormones and physical performance. However, the influence of plasmatic sex hormones and the effects of different types of hormonal contraception (HC) on the modulation of physical performance in adult females remain to be fully clarified. Eighteen female ultra-endurance athletes were recruited to participate in the study. Different variables were studied, including hematological parameters, body mass index, and body composition. Strength measurements were obtained using the squat-jump and hand-grip test. A repeated-measures analysis demonstrated significant differences in hematological values of CK and LDH pre-race as compared to immediately post-race and after 24/48 h. Furthermore, statistical differences were found in squat-jump and hand-grip test results after the ultramarathon. Testosterone, estradiol, and the testosterone/estrogen ratio were significantly correlated with muscle fatigue and were found to be indirect markers of muscle damage. A multivariate analysis demonstrated the protective role of testosterone against muscle damage and severe fatigue. Fluctuations in endogenous testosterone levels were correlated with greater fatigability and muscle damage after the competition. Adjusting the menstrual cycle with HC would not provide any further benefit to the athlete’s competitive capacity.

Purpose We aimed at exploring whether cardiopulmonary fitness, echocardiographic measures and relative exercise intensity were associated with high-sensitivity cardiac troponin T (hs-TNT) rise and normalization following a marathon. Methods Nighty-eight participants (83 men, 15 women; 38.72 ± 3.63 years) were subjected to echocardiographic assessment and a cardiopulmonary exercise test (CPET) before the race. hs-TNT was measured before, immediately after and at 24, 48, 96, 144 and 192 h post-race. Speed and mean heart rate (HR) during the race were relativized to CPET values: peak speed (%V_VMAX), peak HR (HR_%MAX), speed and HR at the second ventilatory threshold (HR_%VT2 and %V_VT2). Results Hs-TNT increased from pre- to post-race (5.74 ± 5.29 vs. 50.4 ± 57.04 ng/L; p < 0.001), seeing values above the Upper Reference Limit (URL) in 95% of the participants. At 24 h post-race, 39% of the runners still exceeded the URL (High hs-TNT group). hs-TNT rise was correlated with marathon speed %V_VT2 (r = 0.22; p = 0.042), mean HR_%VT2 (r = 0.30; p = 0.007), and mean HR_%MAX (r = 0.32; p = 0.004). Moreover, the High hs-TNT group performed the marathon at a higher Speed %V_VT2 (88.21 ± 6.53 vs. 83.49 ± 6.54%; p = 0.002) and Speed %V_VMAX (72 ± 4.25 vs. 69.40 ± 5.53%; p = 0.009). hs-TNT showed no significant associations with cardiopulmonary fitness and echocardiographic measures, except for a slight correlation with left ventricular end systolic diameter (r = 0.26; p = 0.018). Conclusion Post-race hs-TNT was above the URL in barely all runners. Magnitude of hs-TNT rise was correlated with exercise mean HR; whereas, its normalization kept relationship with marathon relative speed.

The study aimed at assessing the acute physiological effects of running a 65-km vs a 107-km mountain ultramarathon. Nineteen athletes (15 males and 4 females) from the shorter race and forty three athletes (26 males and 17 females) from the longer race were enrolled. Body weight, respiratory and lower limb strength were assessed before and after the race. Blood samples were obtained before, after and 24-h post-race. Body weight loss did not differ between races. A decrease in squat jump height (p<0.01; d = 1.4), forced vital capacity (p<0.01; d = 0.5), forced expiratory volume in 1 s (p<0.01; d = 0.6), peak inspiratory flow (p<0.01; d = 0.6) and maximal inspiratory pressure (p<0.01; d = 0.8) was observed after the longer race; while, after the shorter race only maximal inspiratory pressure declined (p<0.01; d = 0.5). Greater post-race concentrations of creatine kinase (p<0.01; d = 0.9) and C-reactive protein (p<0.01; d = 2.3) were observed following the longer race, while high-sensitivity cardiac troponin was higher after the shorter race (p<0.01; d = 0.3). Sodium decreased post-competition only after the shorter race (p = 0.02; d = 0.6), while creatinine increased only following the longer race (p<0.01; d = 1.5). In both groups, glomerular filtration rate declined at post-race (longer race: p<0.01, d = 2.1; shorter race: p = 0.01, d = 1.4) and returned to baseline values at 24 h post-race. In summary, expiratory and lower-limb fatigue, and muscle damage and inflammatory response were greater following the longer race; while a higher release of cardiac troponins was observed after the shorter race. The alteration and restoration of renal function was similar after either race.

The study aimed to assess the relationship between peak oxygen uptake, ventilatory thresholds and maximal fat oxidation with ultra trail male and female performance. 47 athletes (29 men and 18 women) completed a cardiopulmonary exercise test between 2 to 4 weeks before a 107-km ultra trail. Body composition was also analyzed using a bioelectrical impedance weight scale. Exploratory correlation analyses showed that peak oxygen uptake (men: r=–0.63, p=0.004; women: r=–0.85, p < 0.001), peak speed (men: r=–0.74, p < 0.001; women: r=–0.69, p=0.009), speed at first (men: r=–0.49, p=0.035; women: r=–0.76, p=0.003) and second (men: r=–0.73, p < 0.001; women: r=–0.76, p=0.003) ventilatory threshold, and maximal fat oxidation (men: r=–0.53, p=0.019; women: r=–0.59, p=0.033) were linked to race time in male and female athletes. Percentage of fat mass (men: r=0.58, p=0.010; women: r=0.62, p= 0.024) and lean body mass (men: r=–0.61, p=0.006; women: r=–0.61, p=0.026) were also associated with performance in both sexes. Subsequent multiple regression analyses revealed that peak speed and maximal fat oxidation together were able to predict 66% of male performance; while peak oxygen uptake was the only statistically significant variable explaining 69% of the variation in women’s race time. These results, although exploratory in nature, suggest that ultra trail performance is differently predicted by endurance variables in men and women.