Italian consensus statement (2020) on return to play after lower limb muscle injury in football (soccer).

Return to play (RTP) decisions in football are currently based on expert opinion. No consensus guideline has been published to demonstrate an evidence-based decision-making process in football (soccer). Our aim was to provide a framework for evidence-based decision-making in RTP following lower limb muscle injuries sustained in football. A 1-day consensus meeting was held in Milan, on 31 August 2018, involving 66 national and international experts from various academic backgrounds. A narrative review of the current evidence for RTP decision-making in football was provided to delegates. Assembled experts came to a consensus on the best practice for managing RTP following lower limb muscle injuries via the Delphi process. Consensus was reached on (1) the definitions of 'return to training' and 'return to play' in football. We agreed on 'return to training' and RTP in football, the appropriate use of clinical and imaging assessments, and laboratory and field tests for return to training following lower limb muscle injury, and identified objective criteria for RTP based on global positioning system technology. Level of evidence IV, grade of recommendation D.

Patients with myogenic temporomandibular disorders have reduced oxygen extraction in the masseter muscle.

OBJECTIVE: The objective of the present study is to investigate if changes in the oxygen saturation of masseter muscle during a chewing task can differentiate patients with myogenic temporomandibular disorders (TMD) from healthy subjects and if these differences are related to the gravity of the disorder and to the orofacial myofunctional status. MATERIALS AND METHODS: Twelve women with moderate TMD (TMD group; 37 ± 16 years) and ten healthy control women (CTRL group 24 ± 5 years) participated. Validated protocols were used to evaluate the severity of TMD and the orofacial myofunctional status. Oxygen saturation in the masseter muscle was measured using near-infrared spectroscopy (NIRS) during unilateral chewing of a silicon device. Data were compared using Student's t test, Mann-Whitney test, and Spearman's rank correlation coefficient. RESULTS: The women of the TMD group showed higher total score of severity of symptoms of TMD, lower total score of the orofacial myofunctional status, and lower oxygen extraction capacity during mastication than healthy control subjects (p < 0.01). Moreover, percentage O2 extraction was significantly related to the severity of signs/symptoms of TMD and of orofacial myofunctional disorders (p < 0.01). CONCLUSION: Women with TMD had a lower muscle oxygen extraction capacity than healthy subjects: the higher the signs and symptoms' severity, the lower the O2 extraction. NIRS proposes as an important instrumental method to assess the metabolic alterations in the muscles of patients with TMD. CLINICAL RELEVANCE: The findings could be useful to complement clinical assessments, favoring the diagnosis and providing extra data for planning the rehabilitation of TMD patients, especially those with associated myofunctional orofacial disorders.

Determinants of the half-turn with the ball in sub-elite youth soccer players.

We explored the biomechanics of the 180° change-of-direction with the ball (half-turn) in soccer. We aimed at identifying movement strategies which enhance the players' half-turning performance, by characterising technique kinematics and understanding the structure of biomechanical and anthropometrics variables. Ten Under-13 sub-elite male players were recorded with an optoelectronic motion analyser while performing a 5-m straight dribbling followed by a half-turn with the sole. Joints kinematics differences between faster and slower trials were found in support-side hip rotation, driving-side hip adduction, trunk flexion and rotation, and arms abduction. To unveil the data-set structure, a principal component (PC) analysis and a stepwise linear discriminant analysis were performed using 30 biomechanical parameters and four anthropometric variables for each trial. Seven retained PCs explained 79% of the overall variability, featuring combinations of original variables that help in understanding the factors facilitating fast half-turns: keeping short steps, minimising lateral and forward body movements, and centre-of-mass lowering, even with ample lower limbs ranges of motion (RoM); abducting the upper limbs while limiting trunk flexion and pelvic inclination RoM. Balance and task-constrained exercises may be proposed to improve this technique. Moreover, a quantitative knowledge of the movement structure could give coaches objective insights to better instruct young players.

Training effects on ROS production determined by electron paramagnetic resonance in master swimmers.

Acute exercise induces an increase in Reactive Oxygen Species (ROS) production dependent on exercise intensity with highest ROS amount generated by strenuous exercise. However, chronic repetition of exercise, that is, exercise training, may reduce exercise-induced oxidative stress. Aim of this study was to evaluate the effects of 6-weeks high-intensity discontinuous training (HIDT), characterized by repeated variations of intensity and changes of redox potential, on ROS production and antioxidant capacity in sixteen master swimmers. Time course changes of ROS generation were assessed by Electron Paramagnetic Resonance in capillary blood by a microinvasive approach. An incremental arm-ergometer exercise (IE) until exhaustion was carried out at both before (PRE) and after (POST) training (Trg) period. A significant (P < 0.01) increase of ROS production from REST to the END of IE in PRE Trg (2.82 ± 0.66 versus 3.28 ± 0.66 µmol·min(-1)) was observed. HIDT increased peak oxygen consumption (36.1 ± 4.3 versus 40.6 ± 5.7 mL·kg(-1)·min(-1) PRE and POST Trg, resp.) and the antioxidant capacity (+13%) while it significantly decreased the ROS production both at REST (-20%) and after IE (-25%). The observed link between ROS production, adaptive antioxidant defense mechanisms, and peak oxygen consumption provides new insight into the correlation between ROS response pathways and muscle metabolic function.

Effects of manipulating volume and intensity training in masters swimmers.

PURPOSE: Recently, some studies have suggested that overall training intensity may be more important than training volume for improving swimming performance. However, those studies focused on very young subjects, and/or the difference between high-volume and high-intensity training was blurred. The aim of this study was to investigate in masters swimmers the effects of manipulation of training volume and intensity on performance and physiological variables. METHODS: A group of 10 male masters swimmers (age 32.3 ± 5.1 y) performed 2 different 6-wk training periods followed by 1 wk of tapering. The first period was characterized by high training volume performed at low intensity (HvLi), whereas the second period was characterized by low training volume performed at high intensity (LvHi). Peak oxygen consumption (VO2peak) during incremental arm exercise, individual anaerobic threshold (IAT), and 100-m, 400-m, and 2000-m-freestyle time were evaluated before and at the end of both training periods. RESULTS: HvLi training significant increased VO2peak (11.9% ± 4.9% [mean change ± 90%CL], P = .002) and performance in the 400-m (-2.8% ± 1.8%, P = .002) and 2000-m (-3.4% ± 2.9%, P = .025), with a likely change in IAT (4.9% ± 4.7%, P > .05). After LvHi training, speed at IAT (12.4% ± 5.3%, P = .004) and 100-m performance (-1.2% ± 0.8%, P = .001) also improved, without any significant changes in VO2peak, 2000-m, and 400-m. CONCLUSIONS: These findings indicate that in masters swimmers an increase of training volume may lead to an improvement of VO2peak and middle- to long-distance performance. However, a subsequent period of LvHi training maintains previous adjustments and positively affects anaerobic threshold and short-distance performance.

Aerobic Fitness Affects the Exercise Performance Responses to Nitrate Supplementation.

PURPOSE: Dietary nitrate supplementation has been shown to reduce O2 cost of submaximal exercise, improve exercise tolerance, and enhance performance in moderately trained individuals. In contrast, data have been provided that elite athletes do not benefit from nitrate supplementation. The aim of this study was to evaluate the effects of short-term nitrate supplementation on endurance performance in subjects with different levels of aerobic fitness. METHODS: Twenty-one subjects (mean age, 22.7 ± 1.8 yr) with different aerobic fitness level (V˙O2peak value ranging from 28.2 to 81.7 mL·kg·min) participated in a crossover double-blind placebo-controlled study. Subjects were tested after 6 d of supplementation with either 0.5 l per day of nitrate (5.5 mmol)-containing water (NITR) or nitrate-free water (PLA). Participants performed an incremental running test until exhaustion and four repetitions of 6-min submaximal (approximately 80% of gas exchange threshold) constant load exercise on a motorized treadmill. Moreover, subjects performed a 3-km running time trial on the field. RESULTS: After NITR, a negative correlation between reduction of O2 cost of submaximal exercise and individual aerobic fitness level was observed (r = 0.80; P < 0.0001). A significant inverse correlation was also found between aerobic fitness level and improvement in performance for 3-km time trial after NITR (r = 0.76; P < 0.0001). Additionally, subjects responded differently to dietary nitrate supplementation according to aerobic fitness level with higher-fit subjects showing a lower increase in plasma [NO3] (r = 0.86; P < 0.0001) and [NO2] (r = 0.75; P < 0.0001). CONCLUSIONS: The results of the present study suggest that the individual aerobic fitness level affects the ergogenic benefits induced by dietary nitrate supplementation. The optimal nitrate loading regimen required to elevate plasma [NO2] and to enhance performance in elite athletes is different from that of low-fit subjects and requires further studies.

The "second wind" in McArdle's disease patients during a second bout of constant work rate submaximal exercise.

Patients with McArdle's disease (McA) typically show the "second-wind" phenomenon, a sudden decrease in heart rate (HR) and an improved exercise tolerance occurring after a few minutes of exercise. In the present study, we investigated whether in McA a first bout of exercise determines a second wind during a second bout, separated by the first by a few minutes of recovery. Eight McA (44 ± 4 yr) and a control group of six mitochondrial myopathy patients (51 ± 6 yr) performed two repetitions (CWR1 and CWR2) of 6-min constant work rate exercise (∼50% of peak work rate) separated by 6-min (SHORT) or 18-min (LONG) recovery. Pulmonary O2 uptake (Vo2), HR, cardiac output, rates of perceived exertion, vastus lateralis oxygenation {changes in deoxygenated Hb and myoglobin Mb concentrations, Δ[deoxy(Hb+Mb)], by near-infrared spectroscopy} were determined. In McA, Vo2 (0.86 ± 0.2 vs. 0.95 ± 0.1 l/min), HR (113 ± 10 vs. 150 ± 13 beats/min), cardiac output (11.6 ± 0.6 vs. 15.0 ± 0.8 l/min), and rates of perceived exertion (11 ± 2 vs. 14 ± 3) were lower, whereas Δ[deoxy(Hb+Mb)] was higher (14.7 ± 2.3 vs. -0.1 ± 4.6%) in CWR2-SHORT vs. CWR1; the "overshoot" of Δ[deoxy(Hb+Mb)] and the "slow component" of Vo2 kinetics disappeared in CWR2-SHORT. No differences (vs. CWR1) were observed in McA during CWR2-LONG, or in mitochondrial myopathy patients during both CWR2-SHORT and -LONG. A second-wind phenomenon was observed in McA during the second of two consecutive 6-min constant-work rate submaximal exercises. The second wind was associated with changes of physiological variables, suggesting an enhanced skeletal muscle oxidative metabolism. The second wind was not described after a longer (18-min) recovery period.

Exercise testing in late-onset glycogen storage disease type II patients undergoing enzyme replacement therapy.

Enzyme replacement therapy (ERT) has recently became available for patients with glycogen storage disease type II. Previous studies have demonstrated clinical efficacy of enzyme replacement therapy, however, data on physiological variables related to exercise tolerance are scarce. Four glycogen storage disease type II late-onset patients (45 ± 6 years) performed an incremental exercise on a cycle ergometer, up to voluntary exhaustion, before (BEFORE) and after 12 months of ERT (AFTER). Peak workload, oxygen uptake, heart rate, cardiac output (by impedance cardiography) and vastus lateralis oxygenation indices (by continuous-wave near-infrared spectroscopy, NIRS) were determined. Peak workload and oxygen uptake values significantly increased during ERT (54 ± 30 vs. 63 ± 31 watt, and 17.2 ± 4.4 vs. 19.7 ± 3.5 ml/kg/min, respectively, in BEFORE vs. AFTER). On the other hand, for both peak cardiac output (12.3 ± 5.3 vs. 14.8 ± 4.5L/min) and the NIRS-determined peak skeletal muscle fractional O(2) extraction, expressed as a percentage of the maximal values during a transient limb ischemia (30 ± 39% vs. 38 ± 28%), the observed increases were not statistically significant. Our findings suggest that in glycogen storage disease type II patients enzyme replacement therapy is associated with a mild improvement of exercise tolerance. The findings need to be validated during a longer follow-up on a larger group of patients.