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  • Author: James Zhang x
  • Sport and Exercise Science/Kinesiology x
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Xuguang Zhang, Niamh O’Kennedy and James P. Morton

The provision of exogenous carbohydrate (CHO) in the form of energy gels is regularly practiced among endurance and team sport athletes. However, in those instances where athletes ingest suboptimal fluid intake, consuming gels during exercise may lead to gastrointestinal (GI) problems when the nutritional composition of the gel is not aligned with promoting gastric emptying. Accordingly, the aim of the current study was to quantify the degree of diversity in nutritional composition of commercially available CHO gels intended for use in the global sports nutrition market. We surveyed 31 product ranges (incorporating 51 flavor variants) from 23 brands (Accelerade, CNP, High5, GU, Hammer, Maxim, Clif, USN, Mule, Multipower, Nectar, Carb-Boom, Power Bar, Lucozade, Shotz, TORQ, Dextro, Kinetica, SiS, Zipvit, Maxifuel, Gatorade and Squeezy). Gels differed markedly in serving size (50 ± 22 g: 29–120), energy density (2.34 ± 0.7 kcal/g: 0.83–3.40), energy content (105 ± 24 kcal: 78–204), CHO content (26 ± 6 g: 18–51) and free sugar content (9.3 ± 7.0 g: 0.6–26.8). Most notably, gels displayed extreme variation in osmolality (4424 ± 2883 mmol/kg: 303–10,135) thereby having obvious implications for both GI discomfort and the total fluid intake likely required to optimize CHO delivery and oxidation. The large diversity of nutritional composition of commercially available CHO gels illustrate that not all gels should be considered the same. Sports nutrition practitioners should therefore consider the aforementioned variables to make better-informed decisions regarding which gel product best suits the athlete’s specific fueling and hydration requirements.

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Hunter J. Bennett, Elizabeth Brock, James T. Brosnan, John C. Sorochan and Songning Zhang

Higher ACL injury rates have been recorded in cleats with higher torsional resistance in American football, which warrants better understanding of shoe/stud-dependent joint kinetics. The purpose of this study was to determine differences in knee and ankle kinetics during single-leg land cuts and 180° cuts on synthetic infilled turf while wearing 3 types of shoes. Fourteen recreational football players performed single-leg land cuts and 180° cuts in nonstudded running shoes (RS) and in football shoes with natural (NTS) and synthetic turf studs (STS). Knee and ankle kinetic variables were analyzed with a 3 × 2 (shoe × movement) repeated-measures ANOVA (P < .05). A significant shoe-by-movement interaction was found in loading response peak knee adduction moments, with NTS producing smaller moments compared with both STS and RS only in 180° cuts. Reduced peak negative plantar flexor powers were also found in NTS compared with STS. The single-leg land cut produced greater loading response and push-off peak knee extensor moments, as well as peak negative and positive extensor and plantar flexor powers, but smaller loading peak knee adduction moments and push-off peak ankle eversion moments than 180° cuts. Overall, the STS and 180° cuts resulted in greater frontal plane knee loading and should be monitored for possible increased ACL injury risks.

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Yong Yang, Sheng Li, Kai Zhang, Xiaoling Xiang, Zhigang Li, SangNam Ahn and James Murphy

Knowledge of how smartphone use in daily life, rather than in the context of intervention, may influence people’s behaviors and health is limited and mixed. The 2017 National Household Travel Survey (NHTS) data were used to examine the associations between daily smartphone use and several outcomes, including engaging in vigorous physical activity, self-perceived being healthy, and the adjusted mean differences for total trips and active travels among older adults (≥65 years) as well as among young and middle-aged groups (18–64 years), respectively. The prevalence of daily smartphone use declined with increasing age. Daily smartphone use was associated with increased total trips and active travel, a higher likelihood of engaging in vigorous physical activity, and in self-perceived being healthy status. The associations were stronger among older adults than young and middle-aged adults. More studies are needed to address the complex pathways among daily smartphone use and other outcomes. Daily smartphone use has the potential to address the unmet daily needs of older adults and bridge health disparities for this disadvantaged group.