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Objective: To rate athletes' functional ability and return to sport (RTS) success at the end of their individual, formal, medically prescribed rehabilitation after anterior anterior cruciate ligament (ACL) reconstruction. Methods: In our prospective multicenter cohort study, 88 (42 females) adults aged 18-35 years after acute unilateral ACL rupture and subsequent hamstring grafting were included. All patients were prospectively monitored during their rehabilitation and RTS process until the end of their formal rehabilitation and RTS release. As outcome measures, functional hop and jump tests (front hop, balance hops, and drop jump screening test) and self-report outcomes (Knee Injury and Osteoarthritis Outcome Score, ACL-RTS after injury) were assessed. Literature-based cut-off values were selected to rate each performance as fulfilled or not. Results: At 7.5 months (SD 2.3 months) after surgery, the percentage of participants meeting the functional thresholds ranged from 4% (Knee Injury and Osteoarthritis Outcome Score SPORT) and over 44% (ACL-RTS after injury sum score) to 59% (Knee Injury and Osteoarthritis Outcome Score activities of all daily living) in the self-report and from 29% (Balance side hop) to 69% (normalized knee separation distance) in performance testing. Only 4% fulfilled all the cut-offs, while 45% returned to the same type and level of sport. Participants who successfully returned to their previous sport (type and level) were more likely to be "over-cut-off-performers." Conclusions: The low share of the athletes who fulfilled the functional RTS criteria highlights the importance of continuing the rehabilitation measures after the formal completion to assess the need for and success of, inter alia, secondary-preventive therapies. [ABSTRACT FROM AUTHOR]

Low‐load blood‐flow‐restriction resistance training (LL‐BFR‐RT) is gaining popularity, but its physiological effects remain unclear. This study aimed to compare LL‐BFR‐RT with low‐load resistance exercise (LL‐RT) and high‐load resistance exercise (HL‐RT) on metabolism, electrolytes, and ions in the lower extremities by invasive catheter measurements, which are crucial for risk assessment. Ten healthy men (27.6 ± 6.4 years) completed three trials of knee‐extensor exercises with LL‐RT (30% 1RM), LL‐BFR‐RT (30% 1RM, 50% limb occlusion pressure), and HL‐RT (75% 1RM). The exercise protocol consisted of four sets to voluntary muscle failure with 1 min of rest between sets. Blood gas analysis was collected before, during, and after each trial through intravenous catheters at the exercising leg. LL‐BFR‐RT had lower total workload (1274 ± 237 kg, mean ± SD) compared to LL‐RT (1745 ± 604 kg), and HL‐RT (1847 ± 367 kg, p < 0.01), with no difference between LL‐RT and HL‐RT. Pain perception did not differ significantly. Exercise‐induced drop in oxygen partial pressure, lactate accumulation and electrolyte shifts (with increased [K+]) occurred during under all conditions (p < 0.001). Creatine kinase and lactate dehydrogenase increased significantly 24‐ and 48‐h postexercise under all three conditions (p < 0.001). This study, using invasive catheter measurements, found no significant differences in metabolic, ionic, and electrolyte responses among LL‐BFR‐RT, LL‐RT, and HL‐RT when exercised to voluntary muscular failure. LL‐BFR‐RT reduced time to failure without specific physiological responses. [ABSTRACT FROM AUTHOR]

Introduction: In recent years, elastography has become a widely accepted methodology to assess the longitudinal shear elastic modulus of skeletal muscle. Ultrasound shear wave elastography is the gold standard used for such a purpose. However, its low sample rate (1-2 Hz) and the impossibility of being used in several muscles simultaneously limit potential biomechanical applications. In this work, we overcome such limitations by using a surface wave elastography method (NU-SWE). Methods: The NU-SWE comprises a wearable device suitable for measuring several muscles simultaneously. Elasticity can be measured at high-frequency rates (~15 Hz), by propagating several pulse trains of low-frequency (~100 Hz) superficial waves separated by a short time interval. These pulses propagate along the medium surface and are recorded by a linear array of vibration sensors placed on the skin of each measured muscle. In this context, this work carried out a proof of concept, showing how NU-SWE enables performing experimental protocols previously impracticable with ultrasound elastography. Thus, we measured the longitudinal shear elasticity of the biceps brachii and brachioradialis muscles simultaneously at 15 Hz during isometric elbow flexions exerted at different torque development rates. Furthermore, for comparison, we measured the electromyographic activity of both muscles. Results: Our results show that the maximum elasticity reached by the brachioradialis increases with contraction rate, while the biceps brachii behaves inversely. Discussion: This study provides new insights concerning muscle synergism, evidenced by changes in muscle elasticity during torque production. More generally, it shows that NU-SWE could help widen elastography-driven research in biomechanics. [ABSTRACT FROM AUTHOR]

This scoping review aims to provide a comprehensive overview of biological mechanisms underlying the menstrual cycle's impact on various performance-determining anatomical and physiological parameters. It is intended to identify the various proposed vital concepts and theories that may explain performance changes following hormonal fluctuations. The review was performed following the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews protocol. A framework of six groups was built such as skeletal muscle physiology, muscle damage, tendons and ligaments, neuromuscular control, cardiovascular system, and exercise metabolism to cluster studies thematically and to specify the concept of "performance." Original research studies published between 1970 and 2021 that were conducted with a naturally menstruating population were considered. Changes in performance regarding the menstrual cycle phase were crucial for inclusion. Topic-specific reviews and systematic reviews were included if they addressed the impact of female steroid hormones on any structure or part of the human body. The review indicates that the impact of estrogen and progesterone is primarily responsible for observed changes in athletic performance during the menstrual cycle. Estrogen seems capable of fostering protein synthesis, diminishing collagen metabolism, preventing muscle damage due to its antioxidant effects, and restraining inhibitory, while promoting excitatory, control by interacting with neurotransmitters. Progesterone is assumed to increase thermoregulation and enhance ventilatory drive by interacting with hypothalamic pathways and may further amplify inhibitory control by interacting with neurotransmitters. The female steroid hormones and the endocrinologic system collaborate in complex interrelationships with biological systems to maintain homeostasis. However, proposed mechanisms are often derived from animal studies and studies conducted in vitro and still remain to be proven true in the human regularly menstruating population. In the future, it is crucial to rely on studies that followed the methodology for cycle monitoring recommendations thoroughly. Otherwise, it is not possible to determine whether hormonal fluctuations cause observed changes in performance or not. [ABSTRACT FROM AUTHOR]