This excerpt from Strength Training describes the hormone response to exercise and their functions within the human body.

Considering the great popularity of eccentric-based training, the purpose of this review is to first provide the scientific rationale for its use; second, summarize the eccentric-based training modalities that can be used; and finally, offer practical recommendations on how to implement eccentricbased modalities to enhance sports performance. The molecular and neural mechanisms underlying eccentric actions are partially distinct from those of concentric and isometric actions. During eccentric actions, theories suggest a strain-induced modulation of actin-myosin interactions at the crossbridge level, activation of structural protein titin, and winding of titin on actin. Eccentric acute physiological responses differ from concentric exercise responses, including variations in neuromuscular, metabolic, hormonal, and anabolic signaling. Eccentric training elicits greater improvements in muscle strength, power, and stretch-shortening cycle function compared with concentric-only or traditional resistance training. Therefore, eccentric-based training can lead to unique neuromuscular (e.g., improved coordination of motor units) and morphological (e.g., increased muscle fascicle length and enhanced distal cross-sectional area) adaptations that could play a key role in sport performance. Practitioners may implement eccentric exercises with external loads, fully eccentric-based exercises (e.g., Nordic hamstring curl), accentuated eccentric loading, flywheel resistance exercise, and plyometrics to develop specific physical adaptations in line with their goals. Eccentric work (e.g., for hamstrings) can be obtained during other exercises such as downhill running tasks, decelerations, and sprinting activities. Practitioners need to be aware that no single “silver bullet” training modality exists; consequently, practitioners should use a combination of eccentric-based training approaches with their athletes to obtain the desired adaptations.

If manipulation of the training variables is not tailored correctly to the desired adaptations and specific training goals, an athlete can experience symptoms of nonfunctional overreach. If this process continues, the athlete can develop overtraining syndrome.

The catecholamines—primarily epinephrine, but also norepinephrine and dopamine—are secreted by the adrenal medulla and are important for the acute expression of strength and power because the hormones act as central motor stimulators and peripheral vascular dilators to enhance enzyme systems and calcium release in muscle.

Adequate nutrition generally promotes training adaptations and thus optimal performance. Adolescence is characterized by a pubescence growth spurt, increasing energy and nutrient needs. Most team sports literature focuses on male athletes, with little on adolescent female team sports. Adolescent female athletes are at an increased risk of inadequate energy, and micronutrient intakes because of the pursuit of high fitness levels, and society pressures. This may cause hormonal irregularities, delayed development, poor bone health, and increased risk of injury. This review synthesizes information on the nutritional needs of adolescent female team sport players for performance and health.

This PTQ article discusses current research examining the relationship between training volume and muscle hypertrophy and provides guidelines for optimizing training outcomes. Visit NSCA online to read more on exercise science and sport performance.

This article addresses three main areas of resistance exercise that best prepares tactical personnel for load carriage.

This excerpt from Strength Training, Second Edition briefly details hormones and their role in the human body.

Due to the principle of specificity, training should be tailored to the goal of the lifter in terms of the prioritization of strength, hypertrophy, health, and functional outcomes. If the goal is muscular hypertrophy, it may be beneficial to vary the repetition range, and to utilize a variety of loads and loading strategies in the pursuit of maximizing hypertrophy.

Circuit training is quick and effective way to induce training adaptations that are similar to the demands that tactical officers face in their career. This is a basic layout of a circuit training program that can be implemented to recruits during training to prepare them for the physical demands they will face.