This study investigated possible differences using the same stretch-shortening exercise (SSE) protocol on generally accepted monitoring markers (dependent variables: changes in creatine kinase, muscle soreness, and voluntary and electrically evoked torque) in males across three lifespan stages (childhood versus adulthood versus old age). The protocol consisted of 100 intermittent (30 s interval between jumps) drop jumps to determine the repeated bout effect (RBE) (first and second bouts performed at a 2-week interval). The results showed that indirect symptoms of exercise-induced muscle damage after SSE were more expressed in adult males than in boys and elderly males, suggesting that the muscles of boys and elderly males are more resistant to exercise-induced damage than those of adult males. RBE was more pronounced in adult males than in boys and elderly males, suggesting that the muscles of boys and elderly males are less adaptive to exercise-induced muscle damage than those of adult males.

Background: The quadriceps tendon (QT) autograft has recently drawn attention for anterior cruciate ligament reconstruction (ACLR). Finding the best autograft option for adolescents after an ACL injury is essential to ensure them a high-quality active lifestyle. There are no studies comparing the all-soft-tissue QT autograft with the hamstring tendon (HT) autograft in such population. Methods: In this study, 68 patients younger than 18 years of age were assigned to the HT (38 patients) or the QT (30 patients) ACLR group. The groups were similar, allowing their comparison. The instrumented knee laxity was evaluated with a Genourob arthrometer. In total, 48 patients (27 HT and 21 QT) were tested 3 months post-op, and 45 patients (26 HT and 19 QT) were tested 6 months post-op. Results: We found that 3 months post-op, the side-to-side anterior tibial translation measurements (GNRB1) were worse in the HT than in the QT group (1.4 (0.2–5.2; 1.715) vs. 0.6 (0.1–2.1; 0.905) mm, p = 0.02). There was no difference in side-to-side anterior tibial translation at 6 months post-op (GNRB2) between the HT and the QT group (1 (0.2–5.3; 1.519) vs. 1.1 (0.3–3.4; 1.279) mm, p = 0.927). At 3 months post-op, the side-to-side anterior tibial translation (GNRB1) was worse in males than in females. irrespective of the graft choice (1.45 (0.1–5.2; 1.696) vs. 0.4 (0.1–3.4; 0.89) mm, p = 0.016). The displacement curve slopes 6 months post-op were better for females (3 (0–13.1; 3.335) vs. 5.3 (0–26.1; 7.848), p = 0.014). At 3 months post-op, the GNRB measurements showed that the side-to-side anterior tibial translation (GNRB1) was better for females when the HT autograft had been used (0.45 (0.2–3.4; 0.942) vs. 2.4 (0.3–5.2; 2.333) mm, p = 0.003). In general, both autografts provided excellent objective outcomes at early follow-up. Conclusions: The all-soft-tissue QT autograft should be considered as a reliable alternative for ACLR in adolescents. This autograft has at least the same properties as the HT autograft in the early stages after ACL reconstruction in adolescent athletes and, in some respects, seems superior to the HT autograft. Research should continue to find the best possible graft choice for the most active and willing-to-return-to-sport population.

Purpose: Evidence on the safety of single-joint isometric exercises of the lower legs remains limited. Thus, the aims of this study were to examine intraocular pressure (IOP) and retinal vessel responses during a 1 min isometric knee extension task and to assess potential sex-related differences. Materials and Methods: This prospective, parallel-group, quasi-experimental exploratory trial enrolled 43 healthy young adults (22 males and 21 females; age range: 19–35 years), who performed a 1 min sustained maximal-effort isometric knee extension task. The cardiovascular response, IOP, and retinal vessel diameters were assessed. Results: The isometric task increased fatigue, heart rate, systolic blood pressure (SBP), and mean arterial pressure in both sexes (p < 0.05), with males exhibiting a significantly greater rise in SBP than females (p < 0.05). A significant reduction in IOP was observed only in males (p < 0.05). Central retinal arteriolar equivalent decreased in both sexes (p < 0.05), whereas central retinal venular equivalent (CRVE) increased exclusively in females (p < 0.05). Despite the difference in the CRVE response, both sexes exhibited a comparably reduced arteriolar-to-venular diameter ratio (p < 0.05). Conclusions: To sum up, the isometric maximal-effort knee extension exercise increased cardiovascular loads in both sexes, with males showing a greater SBP rise and a reduction in IOP. Although retinal microvascular responses were sex specific, both sexes showed a similar reduction in the arteriolar-to-venular diameter ratio, indicating a consistent shift in microvascular regulation.

Background and Objectives: A prominent area of research in adolescent ACL reconstruction (ACLR) involves graft selection, with particular interest in the quadriceps tendon (QT) as an alternative to hamstring tendon (HT) autografts, although comparative studies on muscle strength outcomes and patient satisfaction in adolescents remain limited. This study aims to evaluate the influence of QT and HT autografts on muscle strength and satisfaction outcomes post-ACLR in adolescents. Methods: This prospective study was conducted at the Lithuanian University of Health Sciences, enrolling 68 patients aged 12–17. ACLRs were performed using QT or HT autografts. Muscle strength was assessed using an isokinetic dynamometer (Biodex), while patient satisfaction was evaluated through IKDC, Lysholm, and ACL-RSI surveys preoperatively and 12 months postoperatively. Results: 54 patients (24 QT and 30 HT) completed the study. The data are non-parametric and are presented as median (IQR). Isokinetic measurements indicated that QT harvesting led to significantly lower extension strength compared to HT 6 months (p = 0.019) and 12 months post-op (p < 0.001) but showed better H/Q ratios 6 months (p = 0.019) and 12 months post-op (p < 0.001). There was no significant difference between the QT and HT groups in ACL-RSI and Lysholm scores. IKDC scores were significantly higher in the HT group (p = 0.009). Conclusions: QT autografts provide favorable H/Q ratios, yet they exhibit weaker extension strength and lower satisfaction outcomes compared to HT. These results suggest a need for individualized rehabilitation protocols and further research to optimize ACLR graft selection for adolescents.