AIM
To examine the importance of peak .VO(2) in determining repeated-sprint ability (RSA), we recruited 20 well-trained females (10 team-sport athletes and 10 endurance-trained runners; mean SD peak .VO(2): 3.3+/-0.2 L x min(-1)) who were homogenous with respect to peak .VO(2) (mean difference = 0.05 L x min(-1)).


METHODS
Tests consisted of a RSA cycle test (5 x 6-s max sprints every 30 s) and a peak .VO(2) test. Venous and capillary blood was sampled immediately before and after the 5 x 6-s cycle test for the determination of hypoxanthine concentration ([Hx]), lactate concentration ([La-]) and pH; blood buffer capacity (beta(blood)) was also estimated.


RESULTS
The team-sport athletes had significantly higher peak power for the 1(st) sprint (P(1); W x kg(-1)), total work for 5 x 6-s sprints (W(tot); J x kg(-1)) and power decrement across the 5 sprints (P(dec)), (p<0.05). There were also significant between-group differences for post-test values of [Hx], [La-] and pH (p<0.05). While there was no significant difference in beta(blood) between the 2 groups (p=0.10), there was a moderate effect (d=0.77).


CONCLUSION
These results suggest that factors in addition to peak .VO(2) are likely to be important for RSA.

Determinants of repeated sprint ability (RSA) in well-trained team-sport athletes and endurance-trained athletes

Review question: Do supplementary oral antioxidants compared with placebo, no treatment/standard treatment or another antioxidant improve fertility outcomes for subfertile women (standard treatment includes folic acid < 1 mg).
Background: many subfertile women undergoing fertility treatment also take dietary supplements in the hope of improving their fertility. This can be a very stressful time for women and their partners. It is important that these couples be given high quality evidence that will allow them to make informed decisions on whether taking a supplemental antioxidant when undergoing fertility treatment will improve their chances or cause any adverse effects; this is especially important as most antioxidant supplements are uncontrolled by regulation. This review aimed to assess whether supplements with oral antioxidants increase a subfertile woman's chances of becoming pregnant and having a baby.
Search date: The evidence is current to April 2013.
Study characteristics: The review included 28 randomised controlled trials that compared antioxidants with placebo or no treatment/standard treatment, or with another antioxidant in a total of 3548 women.
Funding sources: Funding sources were reported by only six of the 28 included trials.
Key results: Antioxidants were not found to be effective for increasing rates of live birth or clinical pregnancy. Based on these results, we would expect that out of 100 subfertile women not taking antioxidants, 23 would become pregnant, compared with between 22 and 36 per 100 who would become pregnant if taking antioxidants to improve their chances of becoming pregnant. Antioxidants did not appear to be associated with the adverse events of miscarriage or multiple or ectopic pregnancy.
Quality of the evidence: The quality of the evidence in this review for live birth, clinical pregnancy and adverse effects was rated 'very low' to 'low'.

Antioxidants for female subfertility

Using a short-duration step protocol and continuous indirect calorimetry, whole-body rates of fat and carbohydrate oxidation can be estimated across a range of exercise workloads, along with the individual maximal rate of fat oxidation (MFO) and the exercise intensity at which MFO occurs (Fatmax). These variables appear to have implications both in sport and health contexts. After discussion of the key determinants of MFO and Fatmax that must be considered during laboratory measurement, the present review sought to synthesize existing data in order to contextualize individually measured fat oxidation values. Data collected in homogenous cohorts on cycle ergometers after an overnight fast was synthesized to produce normative values in given subject populations. These normative values might be used to contextualize individual measurements and define research cohorts according their capacity for fat oxidation during exercise. Pertinent directions for future research were identified.

/pdf/contextualising-maximal-fat-oxidation-during-exercise-4pkay7u5ct.pdf

Contextualising Maximal Fat Oxidation During Exercise: Determinants and Normative Values.

Skeletal muscle is a malleable tissue capable of altering the type and amount of protein in response to disruptions to cellular homeostasis. The process of exercise-induced adaptation in skeletal muscle involves a multitude of signalling mechanisms initiating replication of specific DNA genetic sequences, enabling subsequent translation of the genetic message and ultimately generating a series of amino acids that form new proteins. The functional consequences of these adaptations are determined by training volume, intensity and frequency, and the half-life of the protein. Moreover, many features of the training adaptation are specific to the type of stimulus, such as the mode of exercise. Prolonged endurance training elicits a variety of metabolic and morphological changes, including mitochondrial biogenesis, fast-to-slow fibre-type transformation and substrate metabolism. In contrast, heavy resistance exercise stimulates synthesis of contractile proteins responsible for muscle hypertrophy and increases in maximal contractile force output. Concomitant with the vastly different functional outcomes induced by these diverse exercise modes, the genetic and molecular mechanisms of adaptation are distinct. With recent advances in technology, it is now possible to study the effects of various training interventions on a variety of signalling proteins and early-response genes in skeletal muscle. Although it cannot presently be claimed that such scientific endeavours have influenced the training practices of elite athletes, these new and exciting technologies have provided insight into how current training techniques result in specific muscular adaptations, and may ultimately provide clues for future and novel training methodologies. Greater knowledge of the mechanisms and interaction of exercise-induced adaptive pathways in skeletal muscle is important for our understanding of the aetiology of disease, maintenance of metabolic and functional capacity with aging, and training for athletic performance. This article highlights the effects of exercise on molecular and genetic mechanisms of training adaptation in skeletal muscle.

The molecular bases of training adaptation

Background: High-intensity interval training (HIIT) is as a time-efficient alternative to moderate- or low-intensity continuous exercise for improving variables related to endurance and anaerobic performance in young and adolescent athletes Objectives: To assess original research about enhancement of endurance and anaerobic exercise performance in young and adolescent athletes performing HIIT Method: Relevant articles published in peer-reviewed journals were retrieved from the electronic databases PubMed and SPORTDiscus in December 2017 Inclusion criteria were: (i) controlled trials (HIIT vs alternative training protocol) with pre-post design; (ii) healthy young athletes (≤18 years); (iii) assessing variables related to endurance and exercise performance Hedges' g effect size (ES), and associated 95% confidence intervals were calculated for comparison of any outcome between experimental (HIIT) and alternative training protocol Results: Twenty four studies, involving 577 athletes (mean age: 155 ± 22 years), were included in this review HIIT exerted no or small positive mean ES on peak oxygen uptake (VO2peak), running performance, repeated sprint ability, jumping performance and submaximal heart rate Although the mean ES for changes in VO2peak with HIIT is small (mean g = 010±028), the average increase in VO2peak from pre to post HIIT-interventions were 72 ± 69% vs 43 ± 69% with any other alternative intervention HIIT largely and positively affected running speed and oxygen consumption at various lactate- or ventilatory-based thresholds, as well as for sprint running performance Calculations showed negative mean ES for change-of-direction ability (large), and peak blood lactate concentrations (small) Mean duration per training session for HIIT was shorter than for control interventions (28 ± 15 min vs 38 ± 24 min) Conclusion: The present findings suggest that young athletes performing HIIT may improve certain important variables related to aerobic, as well as anaerobic, performance With HIIT, most variables related to endurance improved to a higher extent, compared to alternative training protocols However, based on ES, HIIT did not show clear superiority to the alternative training protocols Nevertheless, young athletes may benefit from HIIT as it requires less time per training session leaving more time for training sport specific skills

/pdf/high-intensity-interval-training-performed-by-young-athletes-19gnr275lq.pdf

High-Intensity Interval Training Performed by Young Athletes: A Systematic Review and Meta-Analysis

High intensity exercise preconditioning provides differential protection against brain injury following experimental stroke

The purpose of this study was to compare the effects of diet and exercise vs acupuncture, diet and exercise on the body weight and related parameters of adult women. Twenty-seven obese women with a body fat percentage of more than 30% were randomized into three groups. The first experimental group had diet and exercise, whereas the second experimental group had diet, exercise and acupuncture. The control group received no intervention at all. The study period lasted for 8 weeks. Body weight, skin fold thickness, body mass index and fat mass were measured before and after 8 weeks. Body mass index and fat mass, decreased significantly (P<0.05) in both experimental groups when compared with the control group. However, there was no significant difference between the two experimental groups. Changes in lean body mass after 8 weeks were not significantly different from those in the control group. It is concluded that acupuncture combined with diet and exercise does not generate larger reductions in body weight, fat mass or body mass index than diet and exercise alone.

The effects of triple therapy (acupuncture, diet and exercise) on body weight: a randomized, clinical trial

Exercise is recognized as an effective method of weight management and short-term appetite regulation tool. The effect of different exercise intensities on appetite regulation hormones in healthy overweight participants has not been intensively studied. The aim of this study was to examine the influence of exercise at individual anaerobic threshold (IAT) and maximal fat oxidation (Fatmax) intensities on the nesfatin-1 response and metabolic health biomarkers in overweight men. Nine healthy overweight males (age, 23.1 ± 1.1 years) volunteered in this study in a counterbalanced order. Blood samples were obtained before, immediately after, and following the first 45 min of recovery for measuring plasma variables. There was significant decrease in plasma levels of nesfatin-1 and leptin after exercise at the IAT intensity which remained lower than baseline following 45 min of recovery. However, nesfatin-1 and leptin levels did not change significantly in any time courses of Fatmax intensity (P > 0.09). Plasma interleukin-6 (IL-6) concentration increased during exercise in both intensities (P < 0.05), whereas changes in free fatty acids (FFAs) and epinephrine concentrations were significant only at the IAT. In addition, a significant correlation was found among nesfatin-1 levels with insulin (r = 0.39, P < 0.05) and glucose (r = 0.41, P < 0.05) at basal and in response to exercise. These results indicate that IAT has a greater exercise-induced appetite regulation effect compared with Fatmax. Based on these data, the intensity of exercise may have an important role in changes of nesfatin-1, leptin, FFA, and epinephrine concentrations even though this was not the case for IL-6 and insulin resistance.

Effects of exercise at individual anaerobic threshold and maximal fat oxidation intensities on plasma levels of nesfatin-1 and metabolic health biomarkers

Problem statement: Soccer is a team sport with an intermittent nature in which the athletes
need to improve their physical fitness and skill factors in order to engage in high intensity exercises.
The aim of this study was a comparison of small-side game and interval training on some selected
physical fitness in amateur soccer players. Approach: Twenty , soccer players (height 165.34±4.75 cm, weight 58.5±5.22 kg , age 15.7± 0.7 years), were randomly selected and assigned to two groups (intermittent training, specific training in form of Small-Side Game (SSG)) 3 times a week for 6  weeks. The intensity of two training programs was similar according to heart rate (70-95% HR max, progressively and time (4 bouts of 4 min at 70% -95% of maximum heart rate with 3 min active rest periods). For measuring the above variables 12-min running test and RAST test were used, respectively. Data analysis by independent and dependent T test, the level of significance in all statistical analyses was set at p≤0.05. Results: Results showed that the 6-week training of both groups significantly increased in all the variables, (Vo2 max, maximum power, minimum power, average power and RSA variable). Conclusion: according to the results of the study, it is recommended to employ specific training in preparatory programs (especially, of in-season), because such training, in a similar amount of time improve the same physical fitness factors of amateur soccer players and they are applicable in soccer players.

/pdf/a-comparison-of-small-side-games-and-interval-training-on-1q0vpwoxtt.pdf

Maryam Nourshahi

Papers

High intensity exercise preconditioning provides differential protection against brain injury following experimental stroke

The effects of triple therapy (acupuncture, diet and exercise) on body weight: a randomized, clinical trial

Effects of exercise at individual anaerobic threshold and maximal fat oxidation intensities on plasma levels of nesfatin-1 and metabolic health biomarkers

A Comparison of Small-Side Games and Interval Training on Same Selected Physical Fitness Factors in Amateur Soccer Players

The correlation between resting serum leptin and serum angiogenic indices at rest and after submaximal exercise.