Considerations for protein intake in managing weight loss in athletes

Abstract

A large body of evidence now shows that higher protein intakes (2–3 times the protein Recommended Dietary Allowance (RDA) of 0.8 g/kg/d) during periods of energy restriction can enhance fat-free mass (FFM) preservation, particularly when combined with exercise. The mechanisms underpinning the FFM-sparing effect of higher protein diets remain to be fully elucidated but may relate to the maintenance of the anabolic sensitivity of skeletal muscle to protein ingestion. From a practical point of view, athletes aiming to reduce fat mass and preserve FFM should be advised to consume protein intakes in the range of ～1.8–2.7 g kg^?1 d^?1 (or ～2.3–3.1 g kg^?1 FFM) in combination with a moderate energy deficit (?500 kcal) and the performance of some form of resistance exercise. The target level of protein intake within this recommended range requires consideration of a number of case-specific factors including the athlete's body composition, habitual protein intake and broader nutrition goals. Athletes should focus on consuming high-quality protein sources, aiming to consume protein feedings evenly spaced throughout the day. Post-exercise consumption of 0.25–0.3 g protein meal^?1 from protein sources with high leucine content and rapid digestion kinetics (i.e. whey protein) is recommended to optimise exercise-induced muscle protein synthesis. When protein is consumed as part of a mixed macronutrient meal and/or before bed slightly higher protein doses may be optimal.     

Augmenting performance feedback does not affect 4 km cycling time-trials in the heat

We compared the effects of (1) accurate and (2) surreptitiously augmented performance feedback on power output and physiological responses to a 4000 m time-trial in the heat. Nine cyclists completed a baseline (BaseL) 4000 m time-trial in ambient temperatures of 30°C, followed by two further 4000 m time-trials at the same temperature, randomly assigning the participants to an accurate (ACC; accurate feedback of baseline) or deceived (DEC; 2% increase above baseline) feedback group. The total power output (PO) and aerobic (P_aer) and anaerobic (P_an) contributions were determined at 0.4 km stages during the time-trials, alongside measurements of rectal (T_rec) and skin (T_skin) temperatures. There were no differences (P > 0.05) in any of the variables between BaseL, ACC and DEC, despite increases (P < 0.05) in T_rec and T_skin. Typical pacing profiles were demonstrated; however, there was no interaction (P > 0.05) between feedback condition and time-trial stage. Providing surreptitiously augmented performance feedback to well-trained cyclists did not alter their performance or physiological responses to a 4000 m time-trial in a hot environment. The assumed influence of augmented performance feedback was nullified in the heat, perhaps reflecting a central down-regulation of exercise intensity in response to an increased body temperature.     

Reliability and validity of a talent identification test battery for seated and standing Paralympic throws

Paralympic throwing events for athletes with physical impairments comprise seated and standing javelin, shot put, discus and seated club throwing. Identification of talented throwers would enable prediction of future success and promote participation; however, a valid and reliable talent identification battery for Paralympic throwing has not been reported. This study evaluates the reliability and validity of a talent identification battery for Paralympic throws. Participants were non-disabled so that impairment would not confound analyses, and results would provide an indication of normative performance. Twenty-eight non-disabled participants (13 M; 15 F) aged 23.6 years (±5.44) performed five kinematically distinct criterion throws (three seated, two standing) and nine talent identification tests (three anthropometric, six motor); 23 were tested a second time to evaluate test–retest reliability. Talent identification test–retest reliability was evaluated using Intra-class Correlation Coefficient (ICC) and Bland–Altman plots (Limits of Agreement). Spearman’s correlation assessed strength of association between criterion throws and talent identification tests. Reliability was generally acceptable (mean ICC = 0.89), but two seated talent identification tests require more extensive familiarisation. Correlation strength (mean r_s = 0.76) indicated that the talent identification tests can be used to validly identify individuals with competitively advantageous attributes for each of the five kinematically distinct throwing activities. Results facilitate further research in this understudied area.     

Cytotoxicity and effect of extraction methods on the chemical composition of essential oils of Moringa oleifera seeds

Renewed interest in natural materials as food flavors and preservatives has led to the search for suitable essential oils. Moringa oleifera seed essential oil was extracted by solvent-free microwave and hydrodistillation. This study assessed its chemical constituents. Cytotoxicity of the oils was investigated using hatchability and lethality tests on brine shrimps. A total of 16 and 26 compounds were isolated from the hydrodistillation extraction (HDE) and solvent-free microwave extraction (SME) oils, respectively, which accounted for 97.515% and 97.816% of total identifiable constituents, respectively. At 24 h when the most eggs had hatched, values of the SME (56.7%) and HDE (60.0%) oils were significantly different (P<0.05) from those of sea water (63.3%) and chloramphenicol (15.0%). Larva lethality was different significantly (P<0.05) between HDE and SME oils at different concentrations and incubation periods. The median lethal concentration (LC₅₀) of the oils was >1000 mg/ml recommended as an index for non-toxicity, which gives the oil advantage over some antioxidant, antimicrobial, therapeutic, and preservative chemicals.     

Thai pre-service science teachers engaging action research during their fifth year internship

As a key element in teacher education programmes, action research is a learning process in which pre-service teachers inquire, reflect on and improve their teaching practices. This qualitative study sought to understand what enhanced or hindered Thai pre-service teachers' action research projects during their student teaching. This study drew upon written reflections, focus-group interviews and observations of seminar sessions. Data analysis was inductive, involving categorical aggregation followed by a search for correspondence and patterns. The results indicated that the pre-service teachers misunderstood action research, and also held a negative attitude toward it, both of which led them to superficial analyses of practice. They struggled with time limitations, data gathering and interpretation strategies. In spite of the struggles they experienced, these pre-service science teachers did learn more about the action research through collaboratively working with cooperating teachers and university supervisors and on-campus seminar discussions held concurrently with the fifth year internship. Recognizing and understanding the reasons and thinking patterns at the root of these teachers' difficulties with learning about action research can form the basis for reflecting on and rethinking the components of science teacher preparation programmes in Thailand.     

Boarding schools: A longitudinal examination of Australian Indigenous and non-Indigenous boarders’ and non-boarders’ wellbeing

Improving educational outcomes for Indigenous Australian students is a key strategy to helping Indigenous people reach their full potential. This has resulted in well-intentioned efforts by Australian educators and governments to ensure Indigenous children have positive school experiences. However, Indigenous students still lag behind their non-Indigenous counterparts in educational outcomes. This is particularly so for Indigenous students living in rural and remote parts of Australia where educational opportunities are limited, especially in high school. One solution to this problem has been to enrol these students in boarding schools in urban and metropolitan centres. While research on the success of boarding schools for Indigenous students is scarce, what little that does exist is not encouraging. The focus of this research was to examine the effects of boarding for Indigenous (n = 11) and non-Indigenous students’ (n = 158) wellbeing (N = 1423) in two large private boys’ schools. Participating students aged 12–18 years old completed a survey measuring wellbeing constructs on two occasions, 12 months apart. Non-Indigenous boys were generally higher in wellbeing compared with Indigenous boys. There was also evidence of improved social wellbeing beyond that of non-Indigenous boarders over time. Overall, while evidence of merit was weak, boarding schools may benefit their Indigenous students’ development in social wellbeing.     

Measurement of three-dimensional hand kinematics during swimming with a motion capture system: a feasibility study

Current trends in swimming biomechanics are focused on accurate measurements. Nowadays, reliable calibration methods have been proposed to reach an accuracy of about 1 mm on rigid structure. But the question remains about the final accuracy for three-dimensional hand kinematics measurement during the underwater phase of front crawl swimming. Furthermore, most research is based on manual tracking with two or more cameras. In this paper we propose a protocol to acquire three-dimensional hand kinematics when swimming in a specific pool with a motion analysis system behind windows. Results highlight the benefits of using such a system in terms of accuracy and feasibility: the time allowed for post-processing is ten times lower and the quantified improved accuracy is better than with manual tracking.