Factors Associated with Fatigue in COVID-19 ICU Survivors.

PURPOSE: Approximately 30% of people infected with COVID-19 require hospitalization and 20% of them are admitted to an intensive care unit (ICU). Most of these patients experience symptoms of fatigue weeks post-ICU, so understanding the factors associated with fatigue in this population is crucial. METHODS: Fifty-nine patients [38-78 yr] hospitalized in ICU for COVID-19 infection for 32 [6-80] days including 23 [3-57] days of mechanical ventilation, visited the laboratory on two separate occasions. The first visit occurred 52 ± 15 days after discharge and was dedicated to questionnaires, blood sampling and cardiopulmonary exercise testing, while measurements of the knee extensors neuromuscular function and performance fatigability were performed in the second visit 7 ± 2 days later. RESULTS: Using the FACIT-F questionnaire, 56% of patients were classified as fatigued. Fatigued patients had worse lung function score than non- fatigued (i.e. 2.9 ± 0.8 L vs 3.6 ± 0.8 L; 2.4 ± 0.7 l vs 3.0 ± 0.7 L for forced vital capacity and forced expiratory volume in one second, respectively) and forced vital capacity was identified as a predictor of being fatigued. Maximal voluntary activation was lower in fatigued patients than non-fatigued patients (82 ± 14% vs 91 ± 3%) and was the only neuromuscular variable that discriminated between fatigued and non-fatigued patients. Patient-reported outcomes also showed differences between fatigued and non-fatigued patients for sleep, physical activity, depression and quality of life (p < 0.05). CONCLUSIONS: COVID-19 survivors showed altered respiratory function 4 to 8 weeks after discharge, that was further deteriorated in fatigued patients. Fatigue was also associated with lower voluntary activation and patient-reported impairments (i.e. sleep satisfaction, quality of life or depressive state). The present study reinforces the importance of exercise intervention and rehabilitation to counteract cardiorespiratory and neuromuscular impairments of COVID-19 patients admitted in ICU, especially individuals experiencing fatigue.

Changes in power-force-velocity profile induced by 2 weeks of sprint interval training.

BACKGROUND: This study aimed to determine the effects of a running sprint interval training protocol (R-SIT) on the sprint acceleration mechanical properties and jump performance. Eleven young male basketball players performed 6 R-SIT sessions for 2 weeks. METHODS: Each session consisted of 30-second running bouts repeated 4 to 7 times interspersed by 4 minutes of recovery. Performance was assessed from the individual power-force-velocity profiles (PVFP) over a 20-m sprint and from a countermovement jump at baseline (PRE) and after two weeks of training (POST). RESULTS: Sprint time decreased by 2% over the first 5 and 10 meters (P<0.01) while no significant changes in the time at 20 meters (-0.8%, P=0.09) nor in maximal velocity (-1%, P=0.31) were detected. The average PFVP showed an increase in theoretical maximal force and power output of 5 and 4%, respectively (P<0.05), with no change in theoretical maximal speed (P=0.26). Jump height and power also increased after training (5 and 3% respectively, P<0.01). Players improved their maximal sprint distance covered during the 30-second bouts and became more fatigue-resistant to long sprint events. CONCLUSIONS: Six sessions of R-SIT helped to enhance short sprint times, acceleration and power output.

Location of Hamstring Injuries Based on Magnetic Resonance Imaging: A Systematic Review.

CONTEXT: Hamstring muscle injury location using magnetic resonance imaging (MRI) is not so well described in the literature. OBJECTIVE: To describe the location of hamstring injuries using MRI. DATA SOURCES: PubMed, Web of Science, Scopus, SPORTDiscus, Cochrane Library. STUDY SELECTION: The full text of studies, in English, had to be available. Case reports and reviews were excluded. Included studies must report the location of hamstring injuries using MRI within 8 days of the acute injury. STUDY DESIGN: Systematic review. LEVEL OF EVIDENCE: Level 4. DATA EXTRACTION: A first screening was conducted based on title and abstract of the articles. In the second screening, the full text of the remaining articles was evaluated for the fulfillment of the inclusion criteria. RESULTS: From the 2788 references initially found in 5 databases, we included 34 studies, reporting a total of 2761 acute hamstring injuries. The most frequent muscle head involved was the long head of the biceps femoris (BFLH) (70%), followed by the semitendinosus (ST) (15%), generally associated with BFLH. The most frequent tissue affected was the myotendinous junction (MTJ) accounting for half the cases (52%). Among all lesions, the distribution between proximal, central, and distal lesions looked homogenous, with 34.0%, 33.4% and 32.6%, respectively. The stretching mechanism, while only reported in 2 articles, represented 3% of all reported mechanisms, appears responsible for a specific lesion involving the proximal tendon of the semimembranosus (SM), and leading to a longer time out from sport. CONCLUSION: BFLH was the most often affected hamstring injuries and MTJ was the most affected tissue. In addition, the distal, central, and proximal locations were homogeneously distributed. We also noted that MRI descriptions of hamstring injuries are often poor and did not take full advantage of the MRI strengths. SYSTEMATIC REVIEW REGISTRATION: Before study initiation, the study was registered in the PROSPERO International prospective register of systematic reviews (registration number CRD42018107580).

Cardiorespiratory Fitness and Neuromuscular Function of Mechanically Ventilated ICU COVID-19 Patients.

OBJECTIVES: The aim of the current study was to investigate the level of cardiorespiratory fitness and neuromuscular function of ICU survivors after COVID-19 and to examine whether these outcomes are related to ICU stay/mechanical ventilation duration. DESIGN: Prospective nonrandomized study. SETTING: Patients hospitalized in ICU for COVID-19 infection. PATIENTS: Sixty patients hospitalized in ICU (mean duration: 31.9 ± 18.2 d) were recruited 4-8 weeks post discharge from ICU. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Patients visited the laboratory on two separate occasions. The first visit was dedicated to quality of life questionnaire, cardiopulmonary exercise testing, whereas measurements of the knee extensors neuromuscular function were performed in the second visit. Maximal oxygen uptake (V o2 max) was 18.3 ± 4.5 mL·min -1 ·kg -1 , representing 49% ± 12% of predicted value, and was significantly correlated with ICU stay/mechanical ventilation (MV) duration ( R = -0.337 to -0.446; p < 0.01 to 0.001), as were maximal voluntary contraction and electrically evoked peak twitch. V o2 max (either predicted or in mL· min -1 ·kg -1 ) was also significantly correlated with key indices of pulmonary function such as predicted forced vital capacity or predicted forced expiratory volume in 1 second ( R = 0.430-0.465; p ≤ 0.001) and neuromuscular function. Both cardiorespiratory fitness and neuromuscular function were correlated with self-reported physical functioning and general health status. CONCLUSIONS: V o2 max was on average only slightly above the 18 mL·min -1 ·kg -1 , that is, the cut-off value known to induce difficulty in performing daily tasks. Overall, although low physical capacities at admission in ICU COVID-19 patients cannot be ruled out to explain the association between V o2 max or neuromuscular function and ICU stay/MV duration, altered cardiorespiratory fitness and neuromuscular function observed in the present study may not be specific to COVID-19 disease but seem applicable to all ICU/MV patients of similar duration.

Performance Determinants in Trail-Running Races of Different Distances.

PURPOSE: While the physiological determinants of road running have been widely studied, there is a lack of research in trail-running racing performance. The aim of our study was to determine the physiological predictors of trail-running performance in races of different distances in similar terrain and weather conditions. METHODS: Seventy-five trail runners participating in one of the races of the Ultra-Trail du Mont-Blanc were recruited. Previous to the race, each runner was evaluated with (1) an incremental treadmill test to determine maximal oxygen uptake, ventilatory thresholds, cost of running, and substrate utilization; (2) a power-force-velocity profile on a cycle ergometer; (3) maximal voluntary contractions of the knee extensors and plantar flexors; and (4) anthropometric characteristics. Neuromuscular fatigue was evaluated after the races. Twenty-four runners finished a SHORT (<55 km), 16 finished a MEDIUM (101 km), and 14 finished a LONG (>145 km) race. Correlations and multiple linear regressions were used to find the determinants of performance in each race distance. RESULTS: Performance in SHORT was explained by maximal oxygen uptake and lipid utilization at 10 km/h (r2 = .825, P < .001). Performance in MEDIUM was determined by maximal oxygen uptake, maximal isometric strength, and body fat percentage (r2 = .917, P < .001). A linear model could not be applied in LONG, but performance was correlated to peak velocity during the incremental test. CONCLUSIONS: Performance in trail running is mainly predicted by aerobic capacity, while lipid utilization also influences performance in races <60 km and performance in approximately 100 km is influenced by muscle strength and body composition.

Fatigue Measured in Dynamic Versus Isometric Modes After Trail Running Races of Various Distances.

PURPOSE: Fatigue has previously been investigated in trail running by comparing maximal isometric force before and after the race. Isometric contractions may not entirely reflect fatigue-induced changes, and therefore dynamic evaluation is warranted. The aim of the present study was to compare the magnitude of the decrement of maximal isometric force versus maximal power, force, and velocity after trail running races ranging from 40 to 170 km. METHODS: Nineteen trail runners completed races shorter than 60 km, and 21 runners completed races longer than 100 km. Isometric maximal voluntary contractions (IMVCs) of knee extensors and plantar flexors and maximal 7-second sprints on a cycle ergometer were performed before and after the event. RESULTS: Maximal power output (Pmax; -14% [11%], P < .001), theoretical maximum force (F0; -11% [14%], P < .001), and theoretical maximum velocity (-3% [8%], P = .037) decreased significantly after both races. All dynamic parameters but theoretical maximum velocity decreased more after races longer than 100 km than races shorter than 60 km (P < .05). Although the changes in IMVCs were significantly correlated (P < .05) with the changes in F0 and Pmax, reductions in IMVCs for knee extensors (-29% [16%], P < .001) and plantar flexors (-26% [13%], P < .001) were larger (P < .001) than the reduction in Pmax and F0. CONCLUSIONS: After a trail running race, reductions in isometric versus dynamic forces were correlated, yet they are not interchangeable because the losses in isometric force were 2 to 3 times greater than the reductions in Pmax and F0. This study also shows that the effect of race distance on fatigue measured in isometric mode is true when measured in dynamic mode.

Effects of Three Preseason Training Programs on Speed, Change-of-Direction, and Endurance in Recreationally Trained Soccer Players.

Background: Modern coaches experience a drastic reduction of the available training time with an increasingly large number of competitions during the competitive season. Thus, they must choose wisely the most efficient methods to improve the physical fitness of their players during the preseason. Among all the methods, this study compared the effects of plyometric training (PT), sprint interval training (SIT), and small-sided games (SSGs) on the performance of recreationally trained soccer players. Methods: Seventy-three participants were randomly assigned in one of the three experimental groups (i.e., PT [n = 23], SIT [n = 26] or SSGs [n = 24]) and completed two sessions per week for a total of 3 weeks. Meanwhile, the whole group maintained their habitual soccer-specific training program who do not interfere in the preparation of the season. Repeated sprint ability (RSA), maximal aerobic speed (MAS), and a 30-m sprint were assessed at baseline (PRE) and post-training (POST). Results: Performance in SSGs decreased for the average speed from 0 to 10 m (V 0-10m; -0.84 km h-1, -4 ± 5%, p < 0.001), the maximal distance (D max) covered in the 30-s RSA test (-3.65 m, -3 ± 6%, p < 0.01) and MAS (-0.52 km h-1, -3 ± 6%, p < 0.01). PT increased the mean distance (D mean) covered in the 30-s RSA test (+5.98 m, 5 ± 4%, p < 0.001) and MAS (+0.58 km h-1, 7 ± 5%, p < 0.01) while an improvement of all parameters but the maximal sprint speed reached during the 30-m trip (V max) was found in the SIT group (V 0-10m: +1.462 km h-1, 8 ± 5%, p < 0.001; D max: +7.89 m, 6 ± 5%, p < 0.001; D mean: +8.69 m, 7 ± 5%, p < 0.001 and MAS: +1.74 km h-1, 12 ± 8%, p < 0.001). All SSG POST values were significantly lower than PT and SIT (p < 0.01). D mean and MAS in POST were also significantly higher in SIT than in the PT group (p < 0.001). Conclusion: This study suggests that both PT and SIT could be a better alternative to SSGs to boost performances during preseason. Moreover, SIT seems to produce higher improvements in physical performances than PT.

Differential impacts of trail and ultra-trail running on cytokine profiles: An observational study.

BACKGROUND: Endurance running events are known to cause inflammation and result in increased cytokine production. However, the effects of ultramarathons on cytokine profiles are not well characterized. OBJECTIVE: The aim of this study was to describe and compare the effects of a trail (40 km) race and an ultra-trail (171 km) race on leukocyte concentrations and cytokine profiles. METHODS: The study was conducted during the Ultra-Trail du Mont Blanc® ultra-marathon running event, and included 11 runners who completed the 40 km trail run and 12 runners who completed the 171 km ultra-trail. Blood samples were taken before and after the races. RESULTS: Leukocyte concentrations significantly increased after both races. Circulating levels of IL-6, IL-1ß, MCP-1, and IFN-γ were significantly higher after the longer race compared to the shorter race. Furthermore, while both races resulted in significant increases in IL-6 and IL-8, only the longer race resulted in significant increases in MIP-1ß, IL-7, IL-17a, and IL-4. CONCLUSIONS: These results illustrate that a 171 km ultra-trail race results in greater modulations in cytokine profiles than a traditional trail race.