The aim of this study was to examine the training effects of an injury prevention programme on neuromuscular control, strength and performance in male amateur football players. Eighty-one players were allocated to the “FIFA 11+” (n = 42) or a control group (CON, n = 39). The “FIFA 11+” group performed the programme 3 times a week for 9 weeks; the control group completed the usual warm-up. Primary outcomes were: time-to-stabilisation test and eccentric/concentric flexors strength. Secondary outcomes were: eccentric/concentric extensors strength, star excursion balance test, core-stability test, vertical jump, sprint, and agility. After controlling for covariates, significant between-group differences after the intervention (in favour of the “FIFA 11+” players) were found for time-to-stabilisation (-2.8%, 90% confidence interval [CI] -4.4 to -1.2%) and core-stability (-8.9%, -14.6 to -3.1%). Differences were also found for eccentric (3.8%, 1.4 to 6.2%) and concentric flexors strength (3.2%, 0.6 to 5.9%) at 60° · s⁻¹ but this difference was only possibly meaningful (62.4%) from a practical point of view. No substantial and/or significant differences were found for the other outcomes. Performing “FIFA 11+” for 9 weeks can improve neuromuscular control. Possible worthwhile differences were found for flexors strength but there were no substantial effects in the other performance measures.

Nordic Walking (NW) owes much of its popularity to the benefits of greater energy expenditure and upper body engagement than found in conventional walking (W). Muscle activation during NW is still understudied, however. The aim of the present study was to assess differences in muscle activation and physiological responses between NW and W in level and uphill walking conditions. Nine expert Nordic Walkers (mean age 36.8±11.9 years; BMI 24.2±1.8 kg/m²) performed 5-minute treadmill trials of W and NW at 4 km/h on inclines of 0% and 15%. The electromyographic activity of seven upper body and five leg muscles and oxygen consumption (VO₂) were recorded and pole force during NW was measured. VO₂ during NW was 22.3% higher at 0% and only 6.9% higher at 15% than during W, while upper body muscle activation was 2- to 15-fold higher under both conditions. Lower body muscle activation was similarly increased during NW and W in the uphill condition, whereas the increase in erector spinae muscle activity was lower during NW than W. The lack of a significant increase in pole force during uphill walking may explain the lower extra energy expenditure of NW, indicating less upper body muscle activation to lift the body against gravity. NW seemed to reduce lower back muscle contraction in the uphill condition, suggesting that walking with poles may reduce effort to control trunk oscillations and could contribute to work production during NW. Although the difference in extra energy expenditure between NW and W was smaller in the uphill walking condition, the increased upper body muscle involvement during exercising with NW may confer additional benefit compared to conventional walking also on uphill terrains. Furthermore, people with low back pain may gain benefit from pole use when walking uphill.

This study aimed to determine whether the fatigue induced by a mountain ultramarathon (MUM) led to changes in energy cost and kinematic during level and graded running. Pre- and post-race, 14 ultratrail runners ran on a level, uphill (5%) and downhill (5%) treadmill at 10 km · h(-1). Kinematic data were acquired using a photocell system. Post-race, the downhill energy cost increased by 13.1% (P < 0.001). No change was noted in level and uphill running. Duty factor and stride frequency were increased, whereas swing time, cycle time and stride length were decreased in all conditions (P < 0.05). Contact time was increased and the rate of force generation was decreased only in the uphill and downhill conditions (P < 0.05). Positive correlations were observed between performance time and the pre- to post-changes in the energy cost of level (r = 0.52, P = 0.04) and uphill running (r = 0.50, P = 0.04). MUM-induced fatigue resulted in physiological and spatiotemporal changes, though the response to fatigue varied considerably between running conditions. These changes resulted in a significant increment only in the downhill energy cost. Incorporating downhill locomotion in the training programmes of ultratrailers may help to improve performance-related physiological and biomechanical parameters.

The interactions between systolic arterial pressure (SAP) and R-R interval (RR) fluctuations after acute myocardial infarction (AMI) were investigated by measures of synchronization separating the feedback from the feedforward control and capturing both linear and nonlinear contributions. The causal synchronization, evaluating the ability of RR to predict SAP (χ_s/t) or vice versa (χ_t/s), and the global synchronization (χ) were estimated at rest and after head-up tilt in 35 post-AMI patients, 20 young and 12 old. Significance and nonlinearity of the coupling were assessed by surrogate data analysis. Tilting increased the number of young subjects in which RR-SAP link was significant (from 17 to 19) and linear (from 11 to 18). In AMI, both significance and linearity of the coupling were low at rest (26 significant and 24 nonlinear) and further reduced after tilt (17 significant and 16 nonlinear). Old subjects showed a partial recovery of linearity after tilt (rest: 1 linear of 7 significant; tilt: 5 linear of 8 significant). In young subjects, the causal synchronization indexes were balanced and increased from rest (χ_t/s= 0.072 ± 0.037 and χ_s/t = 0.054 ± 0.028) to tilt (χ_t/s = 0.125 ± 0.071 and χ_s/t = 0.108 ± 0.053). On the contrary, in old subjects and AMI patients, the feedforward was prevalent to the feedback coupling at rest (old: χ_t/s = 0.041 ± 0.023 and χ_s/t = 0.069 ± 0.042; AMI: χ_t/s = 0.050 ± 0.030 and χ_s/t = 0.089 ± 0.053). Tilting blunted the unbalance in old subjects (χ_t/s = 0.065 ± 0.052 and χ_s/t = 0.069 ± 0.044) but not in AMI patients (χ_t/s = 0.040 ± 0.019 and χ_s/t = 0.060 ± 0.040). Thus, after AMI, nonlinear mechanisms are elicited in RR-SAP interactions. Furthermore, the neural regulation of the cardiovascular system resulted in imbalance as a consequence of impaired feedback and enhanced feedforward control mechanisms.

The aims of the study were to describe the physiological profile of a 65-km (4000-m cumulative elevation gain) running mountain ultra-marathon (MUM) and to identify predictors of MUM performance. Twenty-three amateur trail-runners performed anthropometric evaluations and an uphill graded exercise test (GXT) for VO2max, ventilatory thresholds (VTs), power outputs (PMax, PVTs) and heart rate response (HRmax, HR@VTs). Heart rate (HR) was monitored during the race and intensity was expressed as: Zone I (VT2) for exercise load calculation (training impulse, TRIMP). Mean race intensity was 77.1%±4.4% of HRmax distributed as: 85.7%±19.4% Zone I, 13.9%±18.6% Zone II, 0.4%±0.9% Zone III. Exercise load was 766±110 TRIMP units. Race time (11.8±1.6h) was negatively correlated with VO2max (r = -0.66, P <0.001) and PMax (r = -0.73, P <0.001), resulting these variables determinant in predicting MUM performance, whereas exercise thresholds did not improve performance prediction. Laboratory variables explained only 59% of race time variance, underlining the multi-factorial character of MUM performance. Our results support the idea that VT1 represents a boundary of tolerable intensity in this kind of events, where exercise load is extremely high. This information can be helpful in identifying optimal pacing strategies to complete such extremely demanding MUMs.