Sports training & conditioning

Open water swimming (OWS), either 'wild' such as river swimming or competitive, is a fast growing pastime as well as a part of events such as triathlons. Little evidence is available on which to base high and low water temperature limits. Also, due to factors such as acclimatisation, which disassociates thermal sensation and comfort from thermal state, individuals cannot be left to monitor their own physical condition during swims. Deaths have occurred during OWS; these have been due to not only thermal responses but also cardiac problems...

The ventilatory responses to immersion and changes in temperature are reviewed. A fall in skin temperature elicits a powerful cardiorespiratory response, termed "cold shock," comprising an initial gasp, hypertension, and hyperventilation despite a profound hypocapnia. The physiology and neural pathways of this are examined with data from original studies. The respiratory responses to skin cooling override both conscious and other autonomic respiratory controls and may act as a precursor to drowning. There is emerging evidence that the combination of the reestablishment of respiratory rhythm following apnea, hypoxemia, and coincident sympathetic nervous and cyclic vagal stimulation appears to be an arrhythmogenic trigger...

Cold water submersion can induce a high incidence of cardiac arrhythmias in healthy volunteers. Submersion and the release of breath holding can activate two powerful and antagonistic responses: the 'cold shock response' and the 'diving response'. The former involves the activation of a sympathetically driven tachycardia while the latter promotes a parasympathetically mediated bradycardia. We propose that the strong and simultaneous activation of the two limbs of the autonomic nervous system ('autonomic conflict') may account for these arrhythmias and may, in some vulnerable individuals, be responsible for deaths that have previously wrongly been ascribed to drowning or hypothermia...

This review covers underlying physiological characteristics and training considerations that may affect muscular strength including improving maximal force expression and time-limited force expression. Strength is underpinned by a combination of morphological and neural factors including muscle cross-sectional area and architecture, musculotendinous stiffness, motor unit recruitment, rate coding, motor unit synchronization, and neuromuscular inhibition. Although single- and multi-targeted block periodization models may produce the greatest strength-power benefits, concepts within each model must be considered within the limitations of the sport, athletes, and schedules...

Objectives: Excessive bodybuilding as a pathological syndrome has been classified based on two different theories: bodybuilding as dependency or as muscle dysmorphic disorder (MDD). This study is a first attempt to find psychophysiological data supporting one of these classifications. Methods: Twenty-four participants (bodybuilders vs healthy controls) were presented with pictures of bodies, exercise equipment or general reward stimuli in a control or experimental condition, and were measured with functional near-infrared spectroscopy (fNIRS)...

Long-term exercise is known to have positive effects on the health of adults. Some college "activity" courses are designed to give participants exposure to, and practice with, safe exercise techniques. Whether these 1-semester courses, usually 12-14 weeks, are sufficient to alter physiological characteristics, such as blood pressure or strength, has not been established. Therefore, the purpose of our investigation was to evaluate physiological and performance measures in college students to determine whether changes would result after 14 weeks of a general conditioning activity course...

BACKGROUND: There is a relative paucity of data regarding the effect of anterior cruciate ligament (ACL) reconstruction on the ability of American high school and collegiate football players to return to play at the same level of competition as before their injury or to progress to play at the next level of competition. PURPOSE: (1) To identify the percentage of high school and collegiate American football players who successfully returned to play at their previous level of competition, (2) to investigate self-reported performance for those players able to return to play or reason(s) for not returning to play, and (3) to elucidate risk factors responsible for players not being able to return to play or not returning to the same level of performance...