The Central Mechanisms of Resistance Training and Its Effects on Cognitive Function.

Resistance exercise is used extensively in athletic and general populations to induce neuromuscular adaptations to increase muscle size and performance. Exercise parameters such as exercise frequency, intensity, duration and modality are carefully manipulated to induce specific adaptations to the neuromuscular system. While the benefits of resistance exercise on the neuromuscular system are well documented, there is growing evidence to suggest that resistance exercise, even when performed acutely, can lead to neuroplastic changes within the central nervous system (CNS) and improve cognitive functioning. As such, resistance exercise has been proposed as a novel adjuvant rehabilitation strategy in populations that suffer from neurological or neurocognitive impairments (i.e. Parkinson's and Alzheimer's dementia) or even to attenuate age-related declines in cognitive health. In this review, we present evidence for the neuroplastic effects and cognitive benefits of resistance exercise and propose some of the underlying mechanisms that drive neuroplasticity following resistance training. We will further discuss the effects of exercise parameters, in particular exercise frequency, intensity, duration and modality to improve cognitive health. Lastly, we will highlight some of the existing limitations in the literature surrounding the use of resistance exercise to improve cognitive function and propose considerations to improve future studies in this field. In summary, the current evidence supports the role of resistance exercise, as a stand alone or in combination with aerobic exercise, for benefiting cognitive health and that it should be considered as an adjuvant therapy to treat age- or disease-related cognitive declines.

Weight-Cutting Implications for Competition Outcomes in Mixed Martial Arts Cage Fighting.

ABSTRACT: Brechney, GC, Chia, E, and Moreland, AT. Weight-cutting implications for competition outcomes in mixed martial arts cage fighting. J Strength Cond Res 35(12): 3420-3424, 2021-Weight cutting is common among amateur and professional mixed martial arts (MMA) competitors because of the belief that it provides an advantage in combat sports. This study aimed to identify whether fight outcome (win vs. loss vs. type of loss) was influenced by magnitudes of body mass (BM) lost through weight cutting and BM regained before the fight after official weigh-in in amateur and professional MMA athletes with previous weight-cutting experience. Body mass data were collected using self-report from 75 MMA athletes (59 amateur and 16 professional) before commencing weight-cutting practices 7 days before weigh-in, by the regulating body at their official weigh-in 24 hours before the fight and through direct measurement immediately before competition. Data were analyzed according to win; loss by technical knockout or knockout (KO); loss by submission; or loss by the judge's decision. Athletes who lost their fight cut significantly more BM (10.6%) compared with athletes who won (8.6%) (p = 0.04, d = 0.48, 95% confidence interval [CI] = 0.02-0.93), but there were no differences between types of loss. There were no significant differences in recovered BM between athletes who won (6.8%) vs. lost (7.4%), or type of loss. Furthermore, there was a significant relationship between greater magnitudes of BM cut and greater likelihood of losing the fight (B = -0.12, P = 0.048), odd ratio 0.89 (95% CI: 0.79-1.00). This study provides the first line of evidence that excessive weight cutting may be detrimental to fight outcome in MMA.

The effect of active hypohydration on cognitive function: A systematic review and meta-analysis.

Hypohydration is generally considered to have a negative effect on cognitive function, despite several studies reporting comparable findings between hydration states. Recommendations to avoid moderate dehydration (≥ 2% loss in body mass) are commonly made to athletes, on the provision that this deficit may impair optimal cognitive performance. To determine whether cognitive function is impaired by hypohydration, and investigate the existence of the proposed critical water deficit of ≥2% loss in body mass purported to diminish cognitive performance, we conducted a systematic search of the literature and examined appropriate studies by meta-analysis. Overall, cognitive performance was not found to be impaired by hypohydration (g = -0.177; 95% CI = -0.532-0.179; P = .331). Nor were the underlying cognitive domains (complex attention, executive function, learning and memory) impaired (all P > .236), independent of the incurred fluid loss (less than or >2% loss in body mass), although results were not always homogenous (I2 ranging between 0% and 93%). Collectively, these results suggest that hypohydration may not compromise cognitive function, nor any of the investigated subdomains to a greater extent than if euhydration had been maintained. Furthermore, recommendations to avoid moderate hypohydration on the basis of maintaining optimal cognitive function are not substantiated by this meta-analysis.