Ischemic preconditioning (IPC) is a non-invasive protective maneuver that alternates short periods of occlusion and reperfusion of tissue blood flow. Given the heterogeneity in the magnitude and frequency of IPC-induced improvements in physical performance, here we aimed to investigate, in a well-controlled experimental set-up, the local effects of IPC in exposed muscles in terms of tissue oxygenation and muscle fatigue. Nineteen subjects were enrolled in one of the two groups, IPC (3 × 5/5 min right arm ischemia/reperfusion; cuff inflations 250 mmHg) and SHAM (3 × 5/5 min pseudo ischemia/reperfusion; 20 mmHg). The subjects performed a fatiguing contraction protocol before and 30 min after the IPC treatment, consisting of unilateral intermittent isometric elbow flexions (3 s ON/OFF, 80% of maximal voluntary contraction) until exhaustion. While muscle strength did not differ between groups, post- vs. pre-treatment endurance was significantly reduced in the SHAM group (4.1 ± 1.9 vs. 6.4 ± 3.1 repetitions until exhaustion, p < 0.05) but maintained in IPC (7.3 ± 2.0 vs. 7.1 ± 4.3, n.s.). The decrease in tissue oxygenation and the increase in deoxygenated hemoglobin were significantly reduced post- vs. pre-IPC (p < 0.05), but not post- vs. pre-SHAM. The results suggest that IPC delays the onset of fatigue likely through improved metabolic efficiency of muscles.

This study examines the subjective attributes that coaches consider most important for identifying and developing the talent of junior élite football players. It also explores whether players’ physical fitness efficiency moderates these attributes and influences playing time during the regular season. Forty-three junior élite football players and four Italian Serie A club coaches participated in the study, contributing their unique perspectives and experiences. Players’ physical fitness was assessed using the Yo-Yo Intermittent Recovery Level 1 test, while coaches rated players’ abilities through a structured questionnaire. A significant positive relationship was found between ’understanding of the game and position on the field’ and total playing time (t = 3.498, p < 0.01, β = 0.953). Physical efficiency further strengthened this relationship when players’ fitness levels were average (b = 0.624, p < 0.001) and one standard deviation above the mean (b = 0.891, p < 0.001). These findings highlight the importance of tactical awareness in earning playing time and suggest that physical fitness enhances the effect of cognitive abilities on performance. This study provides insights into how coaches assess talent and underscores the value of integrating physical and tactical development in youth football, providing a testament to the power of collaboration in advancing our understanding of talent identification in sports.

Sex differences in response to hypovolemia are still an open issue, which is readdressed here by exploiting the potential of near-infrared spectroscopy (NIRS) to monitor the response of lower body negative pressure (LBNP) in upper and lower limbs. In 28 subjects in a supine position, non-invasive arterial blood pressure was continuously monitored along with NIRS parameters from the forearm and thigh during randomized 90 s exposure to LBNP at −10, −20, −30, and −40 mmHg, followed by one 5 min exposure to −30 mmHg. LBNP did not affect arterial blood pressure, slightly increased the heart rate, and affected blood volume in both limbs (p < 0.005). Slopes of tissue oxygenation and deoxy-hemoglobin revealed pressure (p < 0.001) and sex (p < 0.05) dependences for the vasoconstrictive response to LBNP in both arms and legs, with some evidence of larger vasoconstriction in legs. Most variables reached a stable value within 90 s in the arm, while longer time courses were observed in the leg. NIRS is a valuable methodology to detect early LBNP-induced hemodynamic changes, providing that blood volume and blood flow contribution are discriminated. A comparative analysis of time courses proved useful in revealing stronger vasoconstrictive responses in males than in females and in lower limbs than in upper limbs. The same approach could be applied to other experimental contexts.

Purpose: Ischemic pre-conditioning (IPC) offers protection against future ischemic events and may improve sports performance due to several mechanisms at local and systemic levels. This study investigates the local effects on muscle contractility in electrically induced muscle contractions, thus effectively excluding any uncontrolled change in the motor drive. Methods: Twenty-one subjects were divided into two groups: 12 subjects in the IPC group (3 × 5/5 min right arm ischemia/reperfusion; cuff pressure 250 mmHg) and 9 subjects in the SHAM group (same treatment at 20 mmHg). The adductor pollicis was contracted by supramaximal stimulation of the ulnar nerve with single pulses, trains of stimuli (5, 8, 10 and 12 Hz, 1-s duration) and bursts (4 pulses, 25 Hz), all separated by 5-s intervals. The stimulation sequence was delivered before and 15 and 30 min after IPC/SHAM treatment. The isometric contraction force, the superficial electromyographic signal, and tissue oxygenation were continuously monitored. Results: A significant force decrease in time was observed at 8, 10 (p < 0.01) and 12 Hz (p < 0.05) along with a decrease in half-relaxation time in single twitches and bursts (p = 0.01), regardless of treatment. This general time-related weakening was more marked in IPC than SHAM at 5-Hz stimulation. No effects were observed on the magnitude of the superficial electromyographic signal. Conclusion: Data indicate that IPC does not increase muscle force during electrically stimulated contractions, supporting the idea that IPC’s ergogenic effects are not due to increased muscle contractility.