## 7 Effects of Achilles Tendon Moment Arm Length on Insertional Achilles Tendinopathy  
The Achilles tendon is the largest tendon in the body, and it is very important in the gait cycle because it links the ankle joint to the triceps surae. The insertional Achilles tendinopathy (IAT) is a painful chronic disorder that requires suture bridge surgical therapy. This technique is still under investigation and its level of effectiveness is unclear. [PERSON] et al. [6] performed a retrospective study to analyze the moment arm length in both healthy subjects and in post-operative patients. They observed a significant increase in the force of the IAT group after surgery, suggesting that a long moment arm is one of the causes of IAT and that suture bridge surgery is an effective technique that reduces the Achilles tendon moment arm. Immediate Effects of an Inverted Body Position on Energy Expenditure and Blood Lactate Removal after Intense Running  
Overtraining and overreaching are challenges for all athletes. Thus, physiological and psychological recoveries after training are important for health and optimal performance. [PERSON] and [PERSON] [7] studied the effect of a cool-down strategy with an inverted body position (IBP) on fatigue perception, blood lactate concentration and heart rate in 22 athletes. While the fatigue perception was not significantly modified by this recovery technique, blood lactate level and energy expenditure were significantly lower than in controls, suggesting that this technique could be useful in many disciplines that have short breaks during matches, such as martial arts and wrestling. Ultrasound-Guided Percutaneous Needle Electrolysis and Rehab and Reconditioning Program for Rectus Femoris Muscle Injuries: A Cohort Study with Professional Soccer Players and a 20-Week Follow-Up  
One of the most common sports injuries is rectus femoris muscle strain. Therefore, it is very important to elaborate rehabilitation programs that can induce a fast \"return to play\" in the athletes. [PERSON] et al. [8] studied the effects of a combination of percutaneous needle electrolysis and a specific rehabilitation program in professional soccer players with Rectus femoris muscle strain. The authors demonstrated that the combination of the two techniques permitted a safe \"return to play\", with no re-injuries seen in a long-term check. Effectiveness of Training Prescription Guided by Heart Rate Variability Versus Predefined Training for Physiological and Aerobic Performance Improvements: A Systematic Review and Meta-Analysis  
During physical activity, the balance between the training load and the physiological responses to training, including neuromuscular and cardiovascular activity, is very important. [PERSON] et al. [9] conducted a systematic review comparing the effects of heart-rate variability-guided training versus a predefined training designed to optimize the aerobic performance of athletes. Although they did not find significant differences between the two training methods, this review evidences the potential of the heart-rate variability methodology, suggesting that additional studies are necessary to specify the physiological effects of this method with respect to the generally used strategies. Exercise Training of Secreted Protein Acidic and Rich in Cysteine (Sparc) KO Mice Suggests That Exercise-Induced Muscle Phenotype Changes Are SPARC-Dependent  
The beneficial effects of physical exercise have been well documented, but the molecular basis of these positive outcomes is still unclear. One of the proteins induced by exercise is Secreted Protein Acidic and Rich in Cysteine (SPARC). [PERSON] et al. [10] performed functional studies in _Sparc null_ mice, showing that muscle strength and performance are SPARC-dependent. Future studies on the roles of exercise-related proteins in muscle physiology and diseases will be important to clarify the benefits of physical activity for human health. In fact, all these mediator proteins represent potential molecular targets for pharmacological therapy.