In high-performance sprint kayak settings, laboratory tests are commonly used to track changes in fitness and performance. 1 Even though commercially available kayak ergometers have been designed to replicate the specific technical demands of kayaking, the metabolic demands of the different
Thiago Oliveira Borges, Nicola Bullock, David Aitken, Gregory R. Cox and Aaron J. Coutts
Thiago Oliveira Borges, Nicola Bullock, David Aitken and Aaron J. Coutts
This study compared 3 commercially available ergometers for within- and between-brands difference to a first-principle calibration rig.
All ergometers underestimated true mean power, with errors of 27.6% ± 3.7%, 4.5% ± 3.5%, and 22.5% ± 1.9% for the KayakPro, WEBA, and Dansprint, respectively. Within-brand ergometer power differences ranged from 17 ± 9 to 22 ± 11 W for the KayakPro, 3 ± 4 to 4 ± 4 W for the WEBA, and 5 ± 3 to 5 ± 4 W for the Dansprint. The linear-regression analysis showed that most kayak ergometers have a stable coefficient of variation (0.9–1.7%) with a moderate effect size.
Taken collectively, these findings show that different ergometers present inconsistent outcomes. Therefore, we suggest that athlete testing be conducted on the same ergometer brand, preferably the same ergometer. Optimally, that ergometer should be calibrated using a first-principle device before any athlete testing block.
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.
Bradley J. Cardinal, Kim A. Rogers, Brian Kuo, Rosalee L. Locklear, Katelyn E. Comfort and Marita K. Cardinal
Guided by critical discourse analysis, commercially available exercise DVDs are described in terms of the instructor and model characteristics, and the motivational content being verbally conveyed by the instructors on the DVDs. Ten commercially available, contemporary, single instructor lead exercise DVDs were obtained from multiple sources. Instructor and model characteristics, emergent relationship patterns, and the motivational content of the primary instructor were analyzed. Most instructors and models were female, Caucasian, slim, and dressed in revealing attire. Motivational statements comprised 26.9% (SD = 11.31) of the transcripts. One in seven motivational statements were negative. With body capital clearly on display and some of the motivational language being suspect in terms of building potential participants’ psychological capital, the value of commercial exercise DVDs is brought into question.
David S. Rowlands, Darrell L. Bonetti and Will G. Hopkins
Isotonic sports drinks are often consumed to offset the effects of dehydration and improve endurance performance, but hypotonic drinks may be more advantageous. The purpose of the study was to compare absorption and effects on performance of a commercially available hypotonic sports drink (Mizone Rapid: 3.9% carbohydrate [CHO], 218 mOsmol/kg) with those of an isotonic drink (PowerAde: 7.6% CHO, 281 mOsmol/kg), a hypertonic drink (Gatorade: 6% CHO, 327 mOsmol/kg), and a noncaloric placebo (8 mOsmol/kg). In a crossover, 11 cyclists consumed each drink on separate days at 250 ml/15 min during a 2-hr preload ride at 55% peak power followed by an incremental test to exhaustion. Small to moderate increases in deuterium oxide enrichment in the preload were observed with Mizone Rapid relative to PowerAde, Gatorade, and placebo (differences of 88, 45, and 42 parts per million, respectively; 90% confidence limits ±28). Serum osmolality was moderately lower with Mizone Rapid than with PowerAde and Gatorade (–1.9, –2.4; mOsmol/L; ±1.2 mOsmol/L) but not clearly different vs. placebo. Plasma volume reduction was small to moderate with Mizone Rapid, PowerAde, and Gatorade relative to placebo (–1.9%, –2.5%, –2.9%; ± 2.5%). Gut comfort was highest with Mizone Rapid but clearly different (8.4% ± 4.8%) only vs PowerAde. Peak power was highest with Mizone Rapid (380 W) vs. placebo and other drinks (1.2–3.0%; 99% confidence limits ±4.7%), but differences were inconclusive with reference to the smallest important effect (~1.2%). The outcomes are consistent with fastest fluid absorption with the hypotonic sports drink. Further research should determine whether the effect has a meaningful impact on performance.
Alejandro Pérez-Castilla, Antonio Piepoli, Gabriel Garrido-Blanca, Gabriel Delgado-García, Carlos Balsalobre-Fernández and Amador García-Ramos
needed for obtaining an accurate prediction of the 1RM. To date, no study has compared the accuracy in the prediction of the 1RM between the multiple-point (more than 2 loads) and 2-point (only 2 loads) methods. The aim of this study was to explore the accuracy of 7 commercially available devices (1
Tom Toolis and Kerry McGawley
, Umeå, Sweden (#2016-506-31M). Using a randomized and counterbalanced crossover design, the athletes completed 2 trials, wearing either commercially available (2XU Pty Ltd, Melbourne, Australia) upper- and lower-body compression garments (COMP) or their standard racing suit (CON). Pressure in all
Zachary C. Pope, Nan Zeng, Xianxiong Li, Wenfeng Liu and Zan Gao
Background: This study examined the accuracy of Microsoft Band (MB), Fitbit Surge HR (FS), TomTom Cardio Watch (TT), and Apple Watch (AW) for energy expenditure (EE) estimation at rest and at different physical activity (PA) intensities. Method: During summer 2016, 25 college students (13 females; M age = 23.52 ± 1.04 years) completed four separate 10-minute exercise sessions: rest (i.e., seated quietly), light PA (LPA; 3.0-mph walking), moderate PA (MPA; 5.0-mph jogging), and vigorous PA (VPA; 7.0-mph running) on a treadmill. Indirect calorimetry served as the criterion EE measure. The AW and TT were placed on the right wrist and the FS and MB on the left—serving as comparison devices. Data were analyzed in late 2017. Results: Pearson correlation coefficients revealed only three significant relationships (r = 0.43–0.57) between smartwatches’ EE estimates and indirect calorimetry: rest-TT; LPA-MB; and MPA-AW. Mean absolute percentage error (MAPE) values indicated the MB (35.4%) and AW (42.3%) possessed the lowest error across all sessions, with MAPE across all smartwatches lowest during the LPA (33.7%) and VPA (24.6%) sessions. During equivalence testing, no smartwatch’s 90% CI fell within the equivalence region designated by indirect calorimetry. However, the greatest overlap between smartwatches’ 90% CIs and indirect calorimetry’s equivalency region was observed during the LPA and VPA sessions. Finally, EE estimate variation attributable to the use of different manufacturer’s devices was greatest at rest (53.7 ± 12.6%), but incrementally decreased as PA intensity increased. Conclusions: MB and AW appear most accurate for EE estimation. However, smartwatch manufacturers may consider concentrating most on improving EE estimate accuracy during MPA.
Kerri L. Vasold, Andrew C. Parks, Deanna M.L. Phelan, Matthew B. Pontifex and James M. Pivarnik
Research comparing portable body composition methods, such as bioelectrical impedance analysis (BIA), to air displacement plethysmography (ADP) is limited. We assessed reliability and validity of predicting fat-free mass (FFM) by the RJL, Omron, and Tanita BIA machines using ADP via BodPod as a criterion. FFM (kg) was assessed twice in college students (N = 77, 31 males and 46 females; age = 19.1 ± 1.2 years) using ADP, RJL, Omron, and Tanita BIAs. Reliability was assessed using analysis of variance to obtain an intraclass correlation statistic (Rxx). Validity was assessed using Pearson correlation (r) coefficient. FFM averaged 75.6 ± 9.4 kg in men and 59.8 ± 7.6 kg in women. Reliability was high in both genders RJL (Rxx = .974–.994), Omron (Rxx = .933–.993), and Tanita (Rxx = .921–.991). Validity within males was also high: RJL (r = .935), Omron (r = .942), and Tanita (r = .934), and only slightly lower in females: RJL (r = .924), Omron (r = .897), and Tanita (r = .898). The RJL, Omron, and Tanita BIA machines appear to be both reliable and valid for predicting FFM of male and female college students. Therefore, any of these three BIA devices is appropriate to use for body composition assessment in a healthy adult population.