Peak week recommendations for bodybuilders: an evidence based approach

Bodybuilding is a competitive endeavor where a combination of muscle size, symmetry, “conditioning” (low body fat levels), and stage presentation are judged. Success in bodybuilding requires that competitors achieve their peak physique during the day of competition. To this end, competitors have been reported to employ various peaking interventions during the final days leading to competition. Commonly reported peaking strategies include altering exercise and nutritional regimens, including manipulation of macronutrient, water, and electrolyte intake, as well as consumption of various dietary supplements. The primary goals for these interventions are to maximize muscle glycogen content, minimize subcutaneous water, and reduce the risk abdominal bloating to bring about a more aesthetically pleasing physique. Unfortunately, there is a dearth of evidence to support the commonly reported practices employed by bodybuilders during peak week. Hence, the purpose of this article is to critically review the current literature as to the scientific support for pre-contest peaking protocols most commonly employed by bodybuilders and provide evidence-based recommendations as safe and effective strategies on the topic.

Skin-interfaced microfluidic system with personalized sweating rate and sweat chloride analytics for sports science applications

Advanced capabilities in noninvasive, in situ monitoring of sweating rate and sweat electrolyte losses could enable real-time personalized fluid-electrolyte intake recommendations. Established sweat analysis techniques using absorbent patches require post-collection harvesting and benchtop analysis of sweat and are thus impractical for ambulatory use. Here, we introduce a skin-interfaced wearable microfluidic device and smartphone image processing platform that enable analysis of regional sweating rate and sweat chloride concentration ([Cl−]). Systematic studies (n = 312 athletes) establish significant correlations for regional sweating rate and sweat [Cl−] in a controlled environment and during competitive sports under varying environmental conditions. The regional sweating rate and sweat [Cl−] results serve as inputs to algorithms implemented on a smartphone software application that predicts whole-body sweating rate and sweat [Cl−]. This low-cost wearable sensing approach could improve the accessibility of physiological insights available to sports scientists, practitioners, and athletes to inform hydration strategies in real-world ambulatory settings.

Housing Sulfur in Polymer Composite Frameworks for Li–S Batteries

Extensive efforts have been devoted to the design of micro-, nano-, and/or molecular structures of sulfur hosts to address the challenges of lithium–sulfur (Li–S) batteries, yet comparatively little research has been carried out on the binders in Li–S batteries. Herein, we systematically review the polymer composite frameworks that confine the sulfur within the sulfur electrode, taking the roles of sulfur hosts and functions of binders into consideration. In particular, we investigate the binding mechanism between the binder and sulfur host (such as mechanical interlocking and interfacial interactions), the chemical interactions between the polymer binder and sulfur (such as covalent bonding, electrostatic bonding, etc.), as well as the beneficial functions that polymer binders can impart on Li–S cathodes, such as conductive binders, electrolyte intake, adhesion strength etc. This work could provide a more comprehensive strategy in designing sulfur electrodes for long-life, large-capacity and high-rate Li–S battery.

Fluid and Electrolyte Intake and Loss in Elite Soccer Players during Training

This study measured fluid balance during a 90-min preseason training session in the first team squad (24 players) of an English Premier League football team. Sweat loss was assessed from changes in body mass after correction for ingested fluids and urine passed. Sweat composition was measured by collection from patches attached to the skin at 4 sites. The weather was warm (24-29 °C), with moderate humidity (46–64%). The mean ± SD body mass loss over the training session was 1.10 ± 0.43 kg, equivalent to a level of dehydration of 1.37 ± 0.54% of the pre-training body mass. Mean fluid intake was 971 ± 303 ml. Estimated total mean sweat loss was 2033 ±413 ml. Mean sweat electrolyte concentrations (mmol/L) were: sodium,49± 12; potassium,6.0± 1.3;chloride, 43 ± 10. Total sweat sodium loss of 99 ± 24 mmol corresponds to a salt (sodium chloride) loss of 5.8 ± 1.4 g. Mean urine osmolality measured on pre-training samples provided by the players was 666 ±311 mosmol/kg (n=21). These data indicate that sweat losses of water and solute in football players in training can be substantial but vary greatly between players even with the same exercise and environmental conditions. Voluntary fluid intake also shows wide inter-individual variability and is generally insufficient to match fluid losses.