This study aimed to determine mountain ultra-marathon (MUM) performance factors in a large group of endurance mountain runners. Maximal aerobic speed (MAS) was assessed one week prior to the MUM. The level and graded (10%) energy cost of running, stiffness, knee extensors force (KE_f), and jump height on a counter movement jump (CMJ) were measured in 24 male ultra runners before (pre) and immediately after (post) the Interlacs Trail (75 km and 3 930/3 700 m d+/d−). Performance time was correlated with MAS (r=− 0.74, p<0.001), fraction of MAS (F_MAS) sustained (r=− 0.89, p<0.001), KE_f (r=− 0.51, p<0.05), and KE_f loss (r=− 0.51, p<0.05). A multiple regression analysis was performed using performance time in minutes (T) and the calculated individual characteristics, resulting in T=− 11.852×F_MAS−37.195×MAS−0.118×KE_f+2090.581 (R²=0.98, with 95% confidence interval). Contrary to expectations, performance was neither correlated to the level or uphill energy cost of running nor to the changes of these costs post-MUM. To perform in a MUM, training should take into account muscle strength of the KE, MAS and F_MAS.

Background: There is limited knowledge regarding the potential benefits of physical activity in patients with metastatic breast cancer. Objective: The Advanced stage Breast cancer and Lifestyle Exercise (ABLE) Trial aimed to assess the feasibility of a physical activity intervention in women with metastatic breast cancer and to explore the effects of physical activity on functional, psychological, and clinical parameters. Methods: The ABLE Trial was a single-arm, 6-month intervention study with a home-based, unsupervised, and personalized walking program using an activity tracker. At baseline and 6 months, we assessed anthropometrics, functional fitness, physical activity level, sedentary behavior, quality of life, fatigue, and tumor progression. Paired proportions were compared using the McNemar test and changes of parameters during the intervention were analyzed using the Wilcoxon signed-rank test, the Mann-Whitney test, and Spearman rank correlations. Results: Overall, 49 participants (mean age 55 years; recruitment rate 94%) were enrolled and 96% adhered to the exercise prescription (attrition rate 2%). Statistically significant improvements in the 6-minute walking distance test (+7%, P<.001) and isometric quadriceps strength (+22%, P<.001), as well as decreases in body mass index (-2.5%, P=.03) and hip circumference (-4.0%, P<.001) were observed at 6 months. Quality of life remained stable and a nonstatistically significant decrease (-16%, P=.07) in fatigue was observed. Conclusions: The high recruitment and adherence rates suggest the willingness of patients with metastatic breast cancer to participate in a physical activity program. The beneficial outcomes regarding physical fitness and anthropometry of this unsupervised physical activity program may encourage these patients to maintain a physically active lifestyle. Future randomized controlled trials with larger sample sizes are warranted. Trial Registration: ClinicalTrials.gov NCT03148886; https://clinicaltrials.gov/ct2/show/NCT03148886

Rapid force production is critical to improve performance and prevent injuries. However, changes in rate of force/torque development caused by the repetition of maximal contractions have received little attention. The aim of this study was to determine the relative influence of rate of torque development (RTD) and peak torque (T_peak) on the overall performance (i.e. mean torque, T_mean) decrease during repeated maximal contractions and to investigate the contribution of contractile and neural mechanisms to the alteration of the various mechanical variables. Eleven well-trained men performed 20 sets of 6-s isokinetic maximal knee extensions at 240°·s^-1, beginning every 30 seconds. RTD, T_peak and T_mean as well as the Rate of EMG Rise (RER), peak EMG (EMG_peak) and mean EMG (EMG_mean) of the vastus lateralis were monitored for each contraction. A wavelet transform was also performed on raw EMG signal for instant mean frequency (if_mean) calculation. A neuromuscular testing procedure was carried out before and immediately after the fatiguing protocol including evoked RTD (eRTD) and maximal evoked torque (eT_peak) induced by high frequency doublet (100 Hz). T_mean decrease was correlated to RTD and T_peak decrease (R²=0.62; p<0.001; respectively β=0.62 and β=0.19). RER, eRTD and initial if_mean (0-225 ms) decreased after 20 sets (respectively -21.1±14.1, -25±13%, and ~20%). RTD decrease was correlated to RER decrease (R²=0.36; p<0.05). The eT_peak decreased significantly after 20 sets (24±5%; p<0.05) contrary to EMG_peak (-3.2±19.5 %; p=0.71). Our results show that reductions of RTD explained part of the alterations of the overall performance during repeated moderate velocity maximal exercise. The reductions of RTD were associated to an impairment of the ability of the central nervous system to maximally activate the muscle in the first milliseconds of the contraction.