A brief review on concurrent training: From laboratory to the field

The majority of sports rely on concurrent training (CT; e.g., the simultaneous training of strength and endurance). However, a phenomenon called “Concurrent training effect” (CTE), which is a compromise in adaptation resulting from concurrent training, appears to be mostly affected by the interference of the molecular pathways of the underlying adaptations from each type of training segments. Until now, it seems that the volume, intensity, type, frequency of endurance training, as well as the training history and background strongly affect the CTE. High volume, moderate, continuous and frequent endurance training, are thought to negatively affect the resistance training-induced adaptations, probably by inhibition of the Protein kinase B—mammalian target of rapamycin pathway activation, of the adenosine monophosphate-activated protein kinase (AMPK). In contrast, it seems that short bouts of high-intensity interval training (HIIT) or sprint interval training (SIT) minimize the negative effects of concurrent training. This is particularly the case when HIIT and SIT incorporated in cycling have even lower or even no negative effects, while they provide at least the same metabolic adaptations, probably through the peroxisome proliferator-activated receptor-γ coactivator (PGC-1a) pathway. However, significant questions about the molecular events underlying the CTE remain unanswered. © 2018 by the author. Licensee MDPI, Basel, Switzerland

Reliability of resting intramuscular fiber conduction velocity evaluation

Characterization of the least number of muscle fibers analyzed for a quick and reliable, evaluation of intramuscular fiber conduction velocity (MFCV) is of importance for sport scientists. The aim of this study was to evaluate the reliability of vastus lateralis' intramuscular MFCV measuring either 25 or 50 different muscle fibers per participant, as well as to compare intramuscular MFCV measured in 25 (C25), 50 (C50), or 140 (C140) muscle fibers. Resting vastus lateralis' MFCV was measured in 21 young healthy males (age 22.1±2.4 years) using intramuscular microelectrodes in different days. Test-retest reliability of MFCV's parameters was calculated for C25 and C50, while MFCV was compared among C25, C50, and C140. Significant differences of MFCV parameters were observed between C25 condition and those of C50 and C140. The differences in MFCV values between conditions C50 and C140 were non-significant. A close correlation was found for MFCV between C50 and C140 (r=0.884-0.988, P=.000). All reliability measures of MFCV measured with 50 fibers were high (eg, ICC=0.813-0.980, P=.000), in contrast to C25 (eg, ICC=0.023-0.580 P>.05). In conclusion, an average of 50 different fibers per subject is sufficient to provide a quick and reliable intramuscular evaluation of vastus lateralis MFCV. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Lt

Can exercise-induced muscle damage be a good model for the investigation of the anti-inflammatory properties of diet in humans?

Subclinical, low-grade, inflammation is one of the main pathophysiological mechanisms underlying the majority of chronic and non-communicable diseases. Several methodological approaches have been applied for the assessment of the anti-inflammatory properties of nutrition, however, their impact in human body remains uncertain, because of the fact that the majority of the studies reporting anti-inflammatory effect of dietary patterns, have been performed under laboratory settings and/or in animal models. Thus, the extrapolation of these results to humans is risky. It is therefore obvious that the development of an inflammatory model in humans, by which we could induce inflammatory responses to humans in a regulated, specific, and non-harmful way, could greatly facilitate the estimation of the anti-inflammatory properties of diet in a more physiological way and mechanistically relevant way. We believe that exercise-induced muscle damage (EIMD) could serve as such a model, either in studies investigating the homeostatic responses of individuals under inflammatory stimuli or for the estimation of the anti-inflammatory or pro-inflammatory potential of dietary patterns, foods, supplements, nutrients, or phytochemicals. Thus, in this review we discuss the possibility of exercise-induced muscle damage being an inflammation model suitable for the assessment of the anti-inflammatory properties of diet in humans. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

The emerging role of skeletal muscle as a modulator of lipid profile the role of exercise and nutrition

The present article aims to discuss the hypothesis that skeletal muscle per se but mostly its muscle fiber composition could be significant determinants of lipid metabolism and that certain exercise modalities may improve metabolic dyslipidemia by favorably affecting skeletal muscle mass, fiber composition and functionality. It discusses the mediating role of nutrition, highlights the lack of knowledge on mechanistic aspects of this relationship and proposes possible experimental directions in this field. © 2022, The Author(s)

The Specific Impact of Nutrition and Physical Activity on Adolescents’ Body Composition and Energy Balance

Purpose: The aim of the present study was to identify the contribution of nutrition, physical activity (PA), and total energy intake and expenditure on body weight and composition in adolescents. Methods: Body composition, PA, and dietary intakes from 904 Greek adolescents (446 boys and 458 girls; Age: 14.6 ± 1.5 yrs), were evaluated. All participants were assigned into three groups according to their age-sex adjusted Fat Mass Index: (A) Normal weight (N; N = 503), (B) Overweight (OW; N = 253), and (C) Obese (O; N = 148). Results: Significant differences were found for body weight and composition, basal metabolic rate (BMR) expressed per kg of body mass (normal weight children exhibited the highest values), physical-total energy expenditure, and energy balances between the groups (η2: 0.138 to 0.657; p < .05). In contrast, no differences were found for macronutrients’ and total energy intakes, food consumption and quality (η2: 0.002 to 0.099; p > .05) between the three examined groups. Strong, negative correlations were observed between body weight, body fat percentage, PA, and total energy expenditure (r: −0.311 to −0.810; p < .001). Lower, negative correlations were found between body weight, body fat percentage, and macronutrients’ daily intakes (r:-0.235 to −0.432; p < .05). BMR and total energy expenditure had strong, negative relative strengths for the determination of body weight and fat percentage. Conclusions: In conclusion, it seems that BMR, PA, and total daily energy expenditure expressed per body weight and not the nutritional and total energy intakes, were the primary determinant parameters of body composition and weight in adolescents. © 2020 SHAPE America

Kinetic studies and mechanism of hydrogen peroxide catalytic decomposition by cu(II) Complexes with polyelectrolytes derived from l-alanine and glycylglycine

The catalytic decomposition of hydrogen peroxide by Cu(II) complexes with polymers bearing L-alanine (PAla) and glycylglycine (PGlygly) in their side chain was studied in alkaline aqueous media. The reactions were of pseudo-first order with respect to [ H2 O2 ] and [L-Cu(II)] (L stands for PAla or PGlygly) and the reaction rate was increased with pH increase. The energies of activation for the reactions were determined at pH 8.8, in a temperature range of 293-308K. A suitable mechanism is proposed to account for the kinetic data, which involves the Cu(II)/Cu(I) redox pair, as has been demonstrated by ESR spectroscopy. The trend in catalytic efficiency is in the order PGlygly > PAla, due to differences in modes of complexation and in the conformation of the macromolecular ligands. Copyright © 2010 Spyridon Skounas et al

Orientation finding using a grid based visual compass

In this paper an extension of the model-based visual compass is presented, which can be updated continuously, allowing a robot to orient itself in a changing environment. To build a model, colors in the image are discretized to an automatically generated color profile, and transitions between these classes within vertical lines are used as feature. Experiments show how well a model can be learned at the center of field and how this model can be extended to other location with a randomly walking robot. Finally, the strength of the approach is demonstrated in a dynamic environment, where a good estimate of the orientation is maintained while the surroundings are changed in a controlled way

Intramuscular fiber conduction velocity, isometric force and explosive performance

Conduction of electrical signals along the surface of muscle fibers is acknowledged as an essential neuromuscular component which is linked with muscle force production. However, it remains unclear whether muscle fiber conduction velocity (MFCV) is also linked with explosive performance. The aim of the present study was to investigate the relationship between vastus lateralis MFCV and countermovement jumping performance, the rate of force development and maximum isometric force. Fifteen moderately-trained young females performed countermovement jumps as well as an isometric leg press test in order to determine the rate of force development and maximum isometric force. Vastus lateralis MFCV was measured with intramuscular microelectrodes at rest on a different occasion. Maximum MFCV was significantly correlated with maximum isometric force (r = 0.66, p < 0.01), nevertheless even closer with the leg press rate of force development at 100 ms, 150 ms, 200 ms, and 250 ms (r = 0.85, r = 0.89, r = 0.91, r = 0.92, respectively, p < 0.01). Similarly, mean MFCV and type II MFCV were better correlated with the rate of force development than with maximum isometric leg press force. Lower, but significant correlations were found between mean MFCV and countermovement jump power (r = 0.65, p < 0.01). These data suggest that muscle fiber conduction velocity is better linked with the rate of force development than with isometric force, perhaps because conduction velocity is higher in the larger and fastest muscle fibers which are recognized to contribute to explosive actions. © Editorial Committee of Journal of Human Kinetics 2016

Rate of force development and muscle architecture after fast and slow velocity eccentric training

The aim of the study was to investigate the rate of force development (RFD) and muscle architecture early adaptations in response to training with fast-or slow-velocity eccentric squats. Eighteen young novice participants followed six weeks (two sessions/week) of either fast-velocity (Fast) or slow-velocity (Slow) squat eccentric-only training. Fast eccentric training consisted of nine sets of nine eccentric-only repetitions at 70% of 1-RM with <1 s duration for each repetition. Slow eccentric training consisted of five sets of six eccentric-only repetitions at 90% of 1-RM with ~4 sec duration for each repetition. Before and after training, squat 1-RM, countermovement jump (CMJ), isometric leg press RFD, and vastus lateralis muscle architecture were evaluated. Squat 1-RM increased by 14.5 ± 7.0% (Fast, p < 0.01) and by 5.4 ± 5.1% (Slow, p < 0.05). RFD and fascicle length increased significantly in the Fast group by 10–19% and 10.0 ± 6.2%, p < 0.01, respectively. Muscle thickness increased only in the Slow group (6.0 ± 6.8%, p < 0.05). Significant correlations were found between the training induced changes in fascicle length and RFD. These results suggest that fast eccentric resistance training may be more appropriate for increases in rapid force production compared to slow eccentric resistance training, and this may be partly due to increases in muscle fascicle length induced by fast eccentric training. © 2019 by the authors. Licensee MDPI, Basel, Switzerland